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A CERVICAL VENTRAL RAMI
Right internal jugular vein Left internal jugular vein
Cervical ventral rami, except the first, appear between the anterior and
Jugular trunk Jugular trunk posterior intertransverse muscles. The upper four form the cervical
plexus, and the lower four, together with most of the first thoracic
ventral ramus, form the brachial plexus. Each receives at least one grey
Subclavian trunk ramus communicans, the upper four from the superior cervical sympa
thetic ganglion, the fifth and sixth from the middle ganglion, and the
Subclavian trunk seventh and eighth from the cervicothoracic ganglion.
The first cervical ventral ramus, the suboccipital nerve, emerges
above the posterior arch of the atlas, and passes forwards lateral to its
lateral mass and medial to the vertebral artery. It supplies rectus capitis
Right subclavian vein Left subclavian vein lateralis, emerges medial to it, descends anterior to the transverse
process of the atlas and posterior to the internal jugular vein, and joins
Right lymphatic duct Bronchomediastinal trunk the ascending branch of the second cervical ventral ramus.
The second cervical ventral ramus issues between the vertebral arches
Right brachiocephalic vein
of the atlas and axis. It ascends between their transverse processes,
Left brachiocephalic vein
Bronchomediastinal trunk passes anterior to the first posterior intertransverse muscle and emerges
lateral to the vertebral artery, generally between longus capitis and
Superior vena cava Thoracic duct levator scapulae. The ramus divides into an ascending branch, which
joins the first cervical nerve, and a descending branch, which joins the
ascending branch of the third cervical ventral ramus.
The third cervical ventral ramus appears between longus capitis and
scalenus medius. The remaining ventral rami emerge between scalenus
anterior and the scalenus medius.
B Lymph node of deep
cervical chain Cervical plexus
Internal jugular vein
The cervical plexus is formed by the ventral rami of the upper four cervi
Jugular trunk cal nerves, and supplies some neck muscles and the diaphragm, and


areas of skin on the head, neck and chest (see Figs 26.6, 29.1). It is situ
Subclavian trunk
ated in the neck opposite a line drawn down the side of the neck from
Bronchomediastinal trunk the root of the auricle to the level of the upper border of the thyroid
cartilage. It lies deep to the internal jugular vein, the deep fascia and
Subclavian vein
sternocleidomastoid, and anterior to scalenus medius and levator scap
Lymph node of parasternal ulae. Each ramus, except the first, divides into ascending and descend
chain ing parts, which unite in communicating loops. From the first loop (C2
and 3), superficial branches supply the head and neck; cutaneous nerves
of the shoulder and chest arise from the second loop (C3 and 4). Mus
cular and communicating branches arise from the same nerves. The
branches are superficial or deep. The superficial branches perforate the
cervical fascia to supply the skin, while the deep branches in general
Right lymphatic duct
supply muscles. The superficial branches either ascend (the lesser occip
Subclavian trunk ital, great auricular and the transverse cutaneous nerves) or descend
(supraclavicular nerves). These nerves are described in detail in this
Bronchomediastinal trunk
chapter on page 442. The deep branches form medial and lateral series.
Deep branches – medial series
Communicating branches Communicating branches pass from
the loop between the first and second cervical rami to the vagus and
hypoglossal nerves and to the sympathetic trunk. The hypoglossal
Jugular trunk branch later leaves the hypoglossal nerve as a series of branches, namely:
the meningeal, superior root of ansa cervicalis, nerves to thyrohyoid
and to geniohyoid. A branch also connects the fourth and fifth cervical
Right lymphatic duct rami. The first four cervical ventral rami each receive a grey ramus com
municans from the superior cervical sympathetic ganglion.
The superior root of the ansa cervicalis (descendens hypoglossi) (see
Bronchomediastinal trunk
Figs 29.7A, 29.8) leaves the hypoglossal nerve where it curves round the


occipital artery and then descends anterior to or in the carotid sheath.
It contains only fibres from the first cervical spinal nerve. After giving a
Lymph node of parasternal chain
branch to the superior belly of omohyoid, it is joined by the inferior
root of the ansa from the second and third cervical spinal nerves. The
two roots form the ansa cervicalis (ansa hypoglossi), from which
Fig. 29.16 A, The termination of the right lymphatic trunk and the thoracic
branches supply sternohyoid, sternothyroid and the inferior belly of
duct. B, Variations in the terminal lymphatic trunk nodes of the right side.
(A, From Drake RL, Vogl AW, Mitchell A (eds), Gray’s Anatomy for omohyoid. Another branch is said to descend anterior to the vessels
Students, 2nd ed, Elsevier, Churchill Livingstone. Copyright 2010.) into the thorax to join the cardiac and phrenic nerves.
Muscular branches Muscular branches supply rectus capitis latera
lis (C1), rectus capitis anterior (C1, 2), longus capitis (C1–3) and
longus colli (C2–4). The inferior root of the ansa cervicalis and the
smaller than the ventral; occasionally, it is absent. The first and second phrenic nerve are additional muscular branches.
cervical roots are short, and run almost horizontally to their exit from The inferior root of the ansa cervicalis (nervus descendens cervicalis)
the vertebral canal. From the third to the eighth cervical, they slope (see Figs 29.7A, 29.8) is formed by the union of a branch from the
obliquely down. Obliquity and length increase successively; however, second with another from the third cervical ramus. It descends on
the distance between spinal attachment and vertebral exit never exceeds the lateral side of the internal jugular vein, crosses it a little below the
the height of one vertebra. For details of the neural anastomoses middle of the neck, and continues forwards to join the superior root
between the upper cervical nerves and branches of the facial, vagus, anterior to the common carotid artery, forming the ansa cervicalis (ansa


hypoglossal and accessory nerves, see Shoja et al (2014). hypoglossi), from which all infrahyoid muscles except thyrohyoid are


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4
NOITCES
Facial artery Fig. 29.17 Vessels and nerves of the
neck, left lateral view. The left
Vagus nerve Lesser occipital sternocleidomastoid, the greater part
nerve of the infrahyoid group of muscles
Hypoglossal nerve Greater occipital and numerous vessels have been
nerve removed in order to expose deeper
Superior cervical ganglion structures. Compare with Figure
Accessory nerve
29.7A, which shows a more
superficial level of dissection. The
Ascending cervical
letters V, VI, VII, VIII refer to the
artery
anterior primary rami of C5, C6, C7
Superior thyroid artery (cut)
Phrenic nerve and C8, respectively. (With
permission from Waschke J, Paulsen
Superior root, ansa cervicalis F (eds), Sobotta Atlas of Human
Anatomy, 15th ed, Elsevier, Urban &
Fischer. Copyright 2013.)
Superior thyroid vein Scalenus anterior
V
Inferior thyroid artery
VI Suprascapular nerve
Inferior cervical ganglion VII
Thyrocervical trunk VIII Suprascapular artery
Subclavian artery
Recurrent laryngeal nerve
Inferior thyroid vein
Vertebral vein
Common carotid artery
Axillary artery
Internal jugular vein Thoraco-acromial
artery
Left brachiocephalic vein
Cephalic vein
External jugular vein
First rib
supplied. The inferior root almost always comes from the second and Muscular branches Muscular branches are distributed to sterno
third cervical ventral rami, but sometimes from the second to fourth, cleidomastoid (C2, 3, 4), trapezius (C2 and possibly C3), levator scapu
and occasionally from the third alone. Occasionally, too, it may be lae (C3, 4) and scalenus medius (C3, 4). Branches to trapezius cross
derived either from the second alone or from the first to third. the posterior triangle obliquely below the accessory nerve.
Phrenic nerve The phrenic nerve arises chiefly from the fourth cervi
Brachial plexus


cal ventral ramus but also has contributions from the third and fifth. It
is formed at the upper part of the lateral border of scalenus anterior
and descends almost vertically across its anterior surface behind the The brachial plexus is formed by the union of the ventral rami of the
prevertebral fascia (see Fig. 29.7A; Figs 29.17–29.18). It descends pos lower four cervical nerves and the greater part of the ventral ramus of
terior to sternocleidomastoid, the inferior belly of omohyoid (near its the first thoracic spinal nerve. It may also receive contributions from
intermediate tendon), the internal jugular vein, transverse cervical and the fourth cervical and second thoracic spinal nerves. As its name sug
suprascapular arteries and, on the left, the thoracic duct. At the root of gests, its branches supply the muscles, joints and skin of the upper limb.
the neck, it runs anterior to the second part of the subclavian artery, The relations and distribution of the nerves derived from the brachial
from which it is separated by scalenus anterior (some accounts state plexus are described in detail in the appropriate chapters in Section 6.
that on the left side the nerve passes anterior to the first part of the However, it is also mentioned here because, at its origin, the brachial
subclavian artery), and posterior to the subclavian vein. The phrenic plexus lies in the posterior triangle of the neck, in the angle between
nerve enters the thorax by crossing medially in front of the internal the clavicle and the lower posterior border of sternoc leidomastoid. It
thoracic artery. emerges between the scaleni anterior and medius, superior to the third
In the neck, each nerve receives variable filaments from the cervical part of the subclavian artery, and is covered by platysma, deep fascia
sympathetic ganglia or their branches and may also connect with and skin, through which it is palpable (see Fig. 29.17). It is crossed by
internal thoracic sympathetic plexuses. the supraclavicular nerves, the nerve to subclavius, the inferior belly of
omohyoid, the external jugular vein and the superficial ramus of the


Accessory phrenic nerve The accessory phrenic nerve is com transverse cervical artery. The plexus passes posterior to the medial two
posed of fibres from the fifth cervical ventral ramus that run in a branch thirds of the clavicle, subclavius and the suprascapular vessels, and lies
of the nerve to subclavius. This lies lateral to the phrenic nerve and on the first digitation of serratus anterior and on subscapularis.
descends posterior (occasionally anterior) to the subclavian vein. The
accessory phrenic nerve usually joins the phrenic nerve near the first
rib, but may not do so until near the pulmonary hilum or beyond. The CERVICAL DORSAL RAMI
accessory phrenic nerve may be derived from the fourth or sixth cervical
ventral rami or from the ansa cervicalis. Each cervical spinal dorsal ramus except the first divides into medial
and lateral branches, and all innervate muscles. In general, only medial
Deep branches – lateral series
branches of the second to fourth, and usually the fifth, supply skin.
Communicating branches Lateral deep branches of the cervical Except for the first (sometimes called the suboccipital nerve) and
plexus (C2, 3, 4) may connect with the accessory nerve within sterno second, each dorsal ramus passes back medial to a posterior intertrans
cleidomastoid, the posterior triangle or beneath trapezius. verse muscle, curving round the articular process into the interval


Innervation
465
92
RETPAHC
Anterior longitudinal ligament Third cervical vertebra Fig. 29.18 The root of the
Longus capitis neck. Note the sympathetic
chain, the middle and inferior
Scalenus medius
Vertebral artery cervical sympathetic ganglia,
Middle cervical ganglion the trunks of the brachial
Phrenic nerve plexus, the phrenic nerve and
IV the vertebral artery. (With
Scalenus anterior
permission from Waschke J,
Scalenus posterior Paulsen F (eds), Sobotta Atlas
of Human Anatomy, 15th ed,
Superior trunk Elsevier, Urban & Fischer.
Vertebral artery V Middle trunk Brachial plexus Copyright 2013.)
Thyrocervical trunk VI Inferior trunk
VII
Deep cervical
VIII
artery
Accessory
phrenic artery and vein
Subclavian artery
Inferior cervical
ganglion First rib
Ansa subclavia Phrenic nerve
Common
carotid artery
Longus colli
Arch of aorta
Parietal pleura
Brachiocephalic trunk
Superior vena cava
Right and left brachiocephalic veins
between semispinalis capitis and semispinalis cervicis. The cervical
dorsal rami are described in detail on page 768.
CRANIAL NERVES
Internal jugular vein
Glossopharyngeal nerve
Glossopharyngeal nerve
The glossopharyngeal nerve (see Figs 29.8, 29.11, Fig. 29.19) supplies
motor fibres to stylopharyngeus, parasympathetic secretomotor fibres Stylopharyngeus
to the parotid gland (derived from the inferior salivatory nucleus),
sensory fibres to the tympanic cavity, pharyngotympanic tube, fauces,
tonsils, nasopharynx, uvula and posterior (postsulcal) third of the Pharyngeal branch
tongue, and gustatory fibres for the postsulcal part of the tongue.
The nerve leaves the skull through the anteromedial part of the Hyoglossus
jugular foramen, anterior to the vagus and accessory nerves, and in a
separate dural sheath. In the foramen, it is lodged in a deep groove


leading from the cochlear aqueductal depression, and is separated by Carotid sinus branch
the inferior petrosal sinus from the vagus and accessory nerves. The
groove is bridged by fibrous tissue, which is sometimes calcified. After
External carotid artery
leaving the foramen, the nerve passes forwards between the internal
jugular vein and internal carotid artery, and then descends anterior to
the latter, deep to the styloid process and its attached muscles, to reach
the posterior border of stylopharyngeus. It curves forwards on stylopha
ryngeus and either pierces the lower fibres of the superior pharyngeal
constrictor or passes between it and the middle constrictor to be distrib
Fig. 29.19 The glossopharyngeal nerve in the anterior triangle of the
uted to the tonsil, the mucosae of the pharynx and postsulcal part of neck. (From Drake RL, Vogl AW, Mitchell A (eds), Gray’s Anatomy for
the tongue, the vallate papillae, and oral mucous glands (see Fig. 34.6). Students, 2nd ed, Elsevier, Churchill Livingstone. Copyright 2010.)
Two ganglia, superior and inferior, are situated on the glossopharyn
geal nerve as it traverses the jugular foramen. The superior ganglion is
in the upper part of the groove occupied by the nerve in the jugular superior cervical sympathetic ganglion. Two filaments from the inferior
foramen. It is small, has no branches and is usually regarded as a ganglion pass to the vagus, one to its auricular branch and the other to
detached part of the inferior ganglion. The inferior ganglion is larger its superior ganglion. A branch to the facial nerve arises from the glos
and lies in a notch in the lower border of the petrous part of the tem sopharyngeal nerve below the inferior ganglion, and perforates the
poral bone. Its cells are typical unipolar neurones, whose peripheral posterior belly of digastric to join the facial nerve near the stylomastoid
branches convey gustatory and tactile signals from the mucosa of the foramen.
tongue (posterior third, including the sulcus terminalis and vallate
Branches of distribution


papillae) and general sensation from the oropharynx, where it is
responsible for initiating the gag reflex. The glossopharyngeal nerve has tympanic, carotid, pharyngeal, muscu
lar, tonsillar and lingual branches.
Communicating branches
The glossopharyngeal nerve communicates with the sympathetic trunk Tympanic nerve The tympanic nerve leaves the inferior ganglion,
and vagus and facial nerves. Its inferior ganglion is connected with the ascends to the tympanic cavity through the inferior tympanic


NECk
466
4
NOITCES
A B C D
XII X IX XII X IX XII X IX XII X IX
SCSG SCSG SCSG SCSG
1
5 1 1 5
1
2 8 8 8
2 2
3 4 3
4 12 12
3 9 9
6 7 10 13 11 6 7 10 11
13
Fig. 29.20 The intercarotid plexus and its main trunks. A, Formation of the superficial trunk. B, Formation of the intermediate trunk. C, Formation of the
deep trunk. D, Superimposition of A, B and C. Key: 1, carotid sinus nerve; 2, superficial branch of the carotid sinus nerve; 3, deep branch of the carotid
sinus nerve; 4, carotid branch of the vagus nerve; 5, pharyngeal branch of the vagus nerve with its carotid branch; 6, carotid branch of the hypoglossal
nerve; 7, superficial trunk of the intercarotid plexus; 8, inferior branch of the superior cervical sympathetic ganglion (SCSG); 9, communicating
sympathetic branch to the deep branch of the carotid sinus nerve; 10, intermediate trunk of the intercarotid plexus; 11, superior laryngeal nerve; 12,
communicating branch of the superior laryngeal nerve to the sympathetic; 13, deep trunk of the intercarotid plexus. (Redrawn with permission from Shoja
M, Oyesiku NM, Shokouhi G, et al 2014 Anastomoses between lower cranial and upper cervical nerves: a comprehensive review with potential
significance during skull base and neck operations, part II: glossopharyngeal, vagus, accessory, and hypoglossal nerves and cervical spinal nerves 1–4.
Clin Anat. 2014;27(1):118–30.)
canaliculus and divides into branches that contribute to the tympanic The vagus exits the skull through the jugular foramen, accompanied


plexus. The lesser petrosal nerve is derived from the tympanic plexus. by the accessory nerve, with which it shares an arachnoid and a dural
sheath. Both nerves lie anterior to a fibrous septum that separates them
Carotid branch The carotid branch is often double. It arises just from the glossopharyngeal nerve. The vagus descends vertically in the
below the jugular foramen and descends on the internal carotid artery neck in the carotid sheath, between the internal jugular vein and the
to the wall of the carotid sinus and to the carotid body. The nerve con internal carotid artery, to the upper border of the thyroid cartilage, and
tains primary afferent fibres from chemoreceptors in the carotid body then passes between the vein and the common carotid artery to the root
and from the baroreceptors lying in the carotid sinus wall. It may com of the neck. Its relationships in this part of its course are therefore
municate with the inferior ganglion of the vagus, or with one of its similar to those described for these structures (see Figs 29.7A, 29.8,
branches, and with a sympathetic branch from the superior cervical 29.17). Its further course differs on the two sides. The right vagus
ganglion (Fig. 29.20). descends posterior to the internal jugular vein to cross the first part of
the subclavian artery and enter the thorax. The left vagus enters the
Pharyngeal branches The pharyngeal branches are three or four thorax between the left common carotid and subclavian arteries, and
filaments that unite with the pharyngeal branch of the vagus and the behind the left brachiocephalic vein.
laryngopharyngeal branches of the sympathetic trunk to form the pha After emerging from the jugular foramen, the vagus bears two
ryngeal plexus near the middle pharyngeal constrictor. They constitute marked enlargements: a small, round, superior ganglion and a larger
the route by which the glossopharyngeal nerve supplies sensory fibres inferior ganglion.
to the mucosa of the pharynx.
Superior (jugular) ganglion


Muscular branch The muscular branch supplies stylopharyngeus. The superior ganglion is greyish, spherical and approximately 4 mm in
diameter. It is connected to the inferior glossopharyngeal ganglion and
Tonsillar, lingual and lesser petrosal branches The tonsillar, the sympathetic trunk, the latter by a filament from the superior cervical
lingual and lesser petrosal branches are described on pages 577, 514 ganglion.
and 562, respectively.
Inferior (nodose) ganglion
Lesions of the glossopharyngeal nerve
The inferior or nodose ganglion is larger than the superior ganglion,
Damage to the glossopharyngeal nerve is rarely seen without associated
and is elongated and cylindrical in shape with a length of 25 mm and
involvement of other lower cranial nerves. Transient or sustained hyper
a maximum breadth of 5 mm. It is connected with the hypoglossal
tension may follow surgical section of the nerve and indicates involve
nerve, the loop between the first and second cervical spinal nerves, and
ment of the carotid branch. Isolated lesions of the glossopharyngeal
with the superior cervical sympathetic ganglion. Most visceral afferent
nerve lead to loss of sensation over the ipsilateral soft palate, fauces,
fibres have their cell bodies in the nodose ganglion.
pharynx and posterior third of the tongue, although this is difficult to
Both vagal ganglia are exclusively sensory and contain somatic,
assess clinically and confirmation requires galvanic stimulation. The
special visceral and general visceral afferent neurones. The superior
palatal and pharyngeal (gag) reflexes are reduced or absent and salivary
ganglion is chiefly somatic and most of its neurones enter the auricular
secretion from the parotid gland may also be reduced. Weakness of
nerve, whilst neurones in the inferior ganglion are concerned with
stylopharyngeus cannot be tested individually. Glossopharyngeal neur
visceral sensation from the heart, larynx, lungs and the alimentary tract
algia consists of episodic brief but severe pain, often precipitated by
from the pharynx to the transverse colon. Some fibres transmit
swallowing and experienced in the throat, behind the angle of the jaw


impulses from taste endings in the vallecula and epiglottis. Large affer
and within the ear. Superior jugular bulb thromboses (e.g. in otitis
ent fibres are derived from muscle spindles in the laryngeal muscles.
media) and jugular foramen syndrome (associated with nasopharyn
Vagal sensory neurones in the nodose ganglion may show some soma
geal carcinoma or a jugular paraganglioma) may cause lesions of the
totopic organ ization. Both ganglia are traversed by parasympathetic,
adjacent glossopharyngeal, vagus and accessory nerves, with associated
and perhaps some sympathetic, fibres but there is no evidence that
weakness in the muscles supplied in the pharynx and larynx.
vagal parasympathetic components relay in the inferior ganglion. Pre
ganglionic motor fibres from the dorsal vagal nucleus and the special
Vagus nerve
visceral efferents from the nucleus ambiguus, which descend to the
inferior vagal ganglion, commonly form a visible band, skirting the
The vagus is a large mixed nerve. It has a more extensive course ganglion in some mammals. These larger fibres probably provide
and distribution than any other cranial nerve and runs through the motor innervation to the larynx in the recurrent laryngeal nerve,
neck, thorax and abdomen. Its central connections are described in together with some contribution to the superior laryngeal nerve sup
Chapter 21. plying cricothyroid.


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RETPAHC
Branches in the neck aortic arch, curves below it immediately behind the attachment of the
ligamentum arteriosum to the concavity of the aortic arch, and ascends
The branches of the vagus in the neck are the meningeal, auricular,
to the side of the trachea (see Figs 57.3, 57.61). As the recurrent laryn
pharyngeal, carotid body, superior and recurrent laryngeal nerves and
geal nerve curves round the subclavian artery, or the aortic arch, it gives
cardiac branches.
cardiac filaments to the deep cardiac plexus. On both sides, the recur
rent laryngeal nerve ascends in or near a groove between the trachea
Meningeal branches Meningeal branches appear to start from
and oesophagus. It is closely related to the medial surface of the thyroid
the superior vagal ganglion and pass through the jugular foramen to
gland before it passes under the lower border of the inferior constrictor,
be distributed to the dura mater in the posterior cranial fossa (see
and it enters the larynx behind the articulation of the inferior thyroid
Fig. 28.4B).
cornu with the cricoid cartilage. The recurrent laryngeal nerve supplies
all laryngeal muscles, except the cricothyroid, and it communicates with
Auricular branch The auricular branch (Arnold’s nerve) arises from
the internal laryngeal nerve, supplying sensory filaments to the laryn
the superior vagal ganglion and is joined by a branch from the inferior
geal mucosa below the vocal folds. It also carries afferent fibres from
ganglion of the glossopharyngeal nerve. It passes behind the internal
laryngeal stretch receptors. The recurrent laryngeal nerve is described
jugular vein and enters the mastoid canaliculus on the lateral wall of
further with the larynx.
the jugular fossa. Traversing the temporal bone, it crosses the facial
canal approximately 4 mm above the stylomastoid foramen and here
supplies an ascending branch to the facial nerve. Fibres of the nervus Accessory nerve
intermedius may pass to the auricular branch at this point, which may


explain the cutaneous vesiculation in the auricle that sometimes accom
The accessory nerve (see Figs 29.7A, 29.11, 29.17) arises from an elon
panies geniculate herpes. The auricular branch then traverses the tym
gated nucleus of motor neurones in the lateral aspect of the ventral
panomastoid fissure and divides into two rami. One ramus joins the
horn. Some rootlets emerge directly, while others turn cranially before
posterior auricular nerve and the other is distributed to the skin of part
exiting; their line of exit is irregular rather than linear. They join to form
of the ear and to the external acoustic meatus.
a trunk, the accessory nerve, which ascends intradurally within the
vertebral canal between the ligamentum denticulatum and the dorsal
Pharyngeal branch The pharyngeal branch of the vagus is the main
roots of the spinal nerves. The nerve enters the skull via the foramen
motor nerve of the pharynx (p. 582). It emerges from the upper part of
magnum, behind the vertebral artery. It then turns upwards and passes
the inferior vagal ganglion, passes between the external and internal
laterally to reach the jugular foramen, which it traverses in a common
carotid arteries to the upper border of the middle pharyngeal constric
dural sheath with the vagus, but separated from that nerve by a fold of
tor, and divides into numerous filaments that join rami of the sympa
arachnoid mater.
thetic trunk and glossopharyngeal nerve to form a pharyngeal plexus.
As the accessory nerve exits the jugular foramen, it runs posterolat
A minute filament, the ramus lingualis vagi, joins the hypoglossal nerve
erally and passes either medial or lateral to the internal jugular vein;
as it curves round the occipital artery.
occasionally, it may pass through the vein. The extradural part of the
nerve then crosses the transverse process of the atlas, and is crossed by
Branches to the carotid body Branches to the carotid body are the occipital artery before descending obliquely, medial to the styloid


variable in number. They may arise from the inferior ganglion or travel process, stylohyoid and the posterior belly of digastric. Running with
in the pharyngeal branch, and sometimes in the superior laryngeal the superior sternocleidomastoid branch of the occipital artery, it
nerve. They form a plexus with the glossopharyngeal rami and branches reaches the upper part of sternocleidomastoid and enters its deep
of the cervical sympathetic trunk. surface, to form an anastomosis with fibres from C2 alone, C3 alone,
or C2 and C3 (the ansa of Maubrac). It may also communicate with
Superior laryngeal nerve The superior laryngeal nerve is larger the anterior root of the first cervical nerve (McKenzie branch).
than the pharyngeal branch and issues from the middle of the inferior The accessory nerve occasionally terminates in sternocleidomastoid.
vagal ganglion. It receives a branch from the superior cervical sympa More commonly, it emerges a little above the midpoint of the posterior
thetic ganglion and descends alongside the pharynx, at first posterior, border of sternocleidomastoid, generally above the emergence of the
then medial, to the internal carotid artery, and divides into the internal great auricular nerve (usually within 2 cm of it) and between 4 and
and external laryngeal nerves (see Figs 29.8, 35.12). 6 cm from the tip of the mastoid process. However, the point of emer
The internal laryngeal nerve is sensory to the laryngeal mucosa down gence is very variable. The nerve then crosses the posterior triangle on
to the level of the vocal folds. It also carries afferent fibres from the levator scapulae (see Fig. 29.7A), separated from it by the prevertebral
laryngeal neuromuscular spindles and other stretch receptors. It layer of deep cervical fascia and adipose tissue. Here the nerve is rela
descends to the thyrohyoid membrane, pierces it above the superior tively superficial and related to the superficial cervical lymph nodes.
laryngeal artery and divides into an upper and lower branch. The upper Some 3–5 cm above the clavicle, it passes behind the anterior border


branch is horizontal and supplies the mucosa of the pharynx, the epi of trapezius, often dividing to form a plexus on its deep surface, which
glottis, vallecula and laryngeal vestibule. The lower branch descends in receives contributions from C2–4 (see below), and then enters the deep
the medial wall of the piriform recess, supplies the aryepiglottic fold, surface of the muscle.
the mucosa on the back of the arytenoid cartilage and one or two The cervical course of the accessory nerve follows a line from the
branches to transverse arytenoid (the latter unite with twigs from the lower anterior part of the tragus to the tip of the transverse process of
recurrent laryngeal to supply the same muscle). The internal laryngeal the atlas, and then across the sternocleidomastoid and the posterior
nerve ends by piercing the inferior pharyngeal constrictor to unite with triangle to a point on the anterior border of the trapezius 3–5 cm above
an ascending branch from the recurrent laryngeal nerve. As it ascends the clavicle.
in the neck, it supplies branches, more numerous on the left, to the The accessory nerve is thought to provide the sole motor supply to
mucosa and tunica muscularis of the oesophagus and trachea, and to sternocleidomastoid; the second and third cervical nerves are believed
the inferior constrictor. to carry proprioceptive fibres from it. The supranuclear pathway of
The external laryngeal nerve, smaller than the internal, descends fibres destined for sternocleidomastoid is not simple; current evidence
behind sternohyoid with the superior thyroid artery, but on a deeper favours bilateral hemispheric innervation, although opinion varies as
plane. It lies first on the inferior pharyngeal constrictor, and then pierces to the extent of the ipsilateral input. The motor supply to the descend
it to curve round the inferior thyroid tubercle and reach cricothyroid, ing (upper) and transverse (middle) portions of trapezius is primarily
which it supplies. The nerve also gives branches to the pharyngeal from the accessory nerve under predominantly contralateral supra


plexus and the inferior constrictor. Behind the common carotid artery, nuclear control. Usually, trapezius receives an innervation from the
the external laryngeal nerve communicates with the superior cardiac cervical plexus, in most cases from C3 and C4 (Tubbs et al 2011). A
nerve and superior cervical sympathetic ganglion. study using intraoperative electroneurography and histochemical analy
ses found that, when present, the cervical fibres did not consistently
Recurrent laryngeal nerve The recurrent laryngeal nerve differs, innervate all three parts of the muscle (descending, transverse and
in origin and course, on the two sides. On the right, it arises from the ascending), and that fibres from C2 usually travelled via the accessory
vagus anterior to the first part of the subclavian artery, and curves back nerve, while fibres from C3 and C4 innervated trapezius independently
wards below and then behind it to ascend obliquely to the side of the (Pu et al 2008). In addition to their motor contribution, C3 and C4
trachea behind the common carotid artery. Near the lower pole of the also carry proprioceptive fibres from trapezius.
lateral lobe of the thyroid gland, it is closely related to the inferior On the basis of the incomplete denervation of the muscle that some
thyroid artery and crosses either in front of, behind or between its times happens following sacrifice of both the accessory nerve and the
branches. On the left, the nerve arises from the vagus on the left of the cervical plexus, it has been suggested that trapezius receives a partial


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motor supply from other sources, possibly via thoracic roots. (For a Nerves to thyrohyoid and geniohyoid The nerves to thyrohyoid
detailed review of the applied surgical anatomy of the accessory nerve and geniohyoid arise near the posterior border of hyoglossus. They
plexus, see Brown (2002).) represent the remaining fibres from the first cervical spinal nerves.
Sensory ganglia have been described along the course of the intra
Lesions of the hypoglossal nerve
dural portion of the nerve.
The hypoglossal nerve may be damaged during neck dissection. Com
Lesions affecting the accessory nerve
plete hypoglossal division causes unilateral lingual paralysis and event
Lesions of the accessory nerve may be sustained centrally, at its exit from ual hemiatrophy; the protruded tongue deviates to the paralysed side,
the skull or in the neck. The supranuclear fibres that influence motor and, on retraction, the wasted and paralysed side rises higher than the
neurones innervating sternocleidomastoid decussate twice; a lesion of unaffected side. The larynx may deviate towards the active side in swal
the pyramidal system above the pons therefore produces weakness of lowing, due to unilateral paralysis of the hyoid depressors associated
the ipsilateral sternocleidomastoid and contralateral trapezius. Episodic with loss of the first cervical spinal nerve, which runs with the hypoglos
contraction of sternocleidomastoid and trapezius, often accompanied sal nerve. If paralysis is bilateral, the tongue is motionless. Taste and
by contraction of other muscle groups, e.g. splenius capitis, occurs in tactile sensibility are unaffected but articulation is slow and swallowing
spasmodic torticollis, a focal dystonia. In jugular foramen syndrome, very difficult.
caused by pathologies including nasopharyngeal carcinoma or a jugular The hypoglossal nerve is often used to reanimate the face in patients,
paraganglioma, lesions of the glossopharyngeal, vagus and accessory particularly the elderly, whose facial nerves have been transected. Direct


nerves coexist. The accessory nerve can be injured more distally in the endtoend, endtoside or splitnerve grafts are reliable and offer a
neck by trauma or by surgical exploration in the posterior triangle. If robust, effective and quick alternative to more complex reanimation
the accessory nerve is sacrificed as part of a radical neck dissection and procedures.
the innervation of trapezius is lost, the patient develops intractable
neuralgia due to traction on the brachial plexus caused by the unsup
ported weight of the shoulder and arm. CERVICAL SYMPATHETIC TRUNK
Hypoglossal nerve The cervical sympathetic trunk lies on the prevertebral fascia behind the
carotid sheath and contains three interconnected ganglia: the superior,
The hypoglossal nerve is motor to all the muscles of the tongue, except middle and inferior (stellate or cervicothoracic) (see Figs 29.17–29.18).
palatoglossus. The hypoglossal rootlets run laterally behind the verte There may occasionally, however, be two or four ganglia. The cervical
bral artery, collected into two bundles that perforate the dura mater sympathetic ganglia send grey rami communicantes to all the cervical
separately opposite the hypoglossal canal in the occipital bone, and spinal nerves but receive no white rami communicantes from them.
unite after traversing it. The canal is sometimes divided by a spicule of Their spinal preganglionic fibres emerge in the white rami communi
bone. The nerve emerges from the canal in a plane medial to the intern cantes of the upper five thoracic spinal nerves (mainly the upper three),
al jugular vein, internal carotid artery and ninth, tenth and eleventh and ascend in the sympathetic trunk to synapse in the cervical ganglia.
cranial nerves, and passes inferolaterally behind the internal carotid In their course, the grey rami communicantes may pierce longus capitis
artery and glossopharyngeal and vagus nerves to the interval between or scalenus anterior.
the artery and the internal jugular vein (see Fig. 29.8). Here, it makes
Superior cervical ganglion
a halfspiral turn round the inferior vagal ganglion and is united with


it by connective tissue. It then descends almost vertically between the
vessels and anterior to the vagus to a point level with the angle of the The superior cervical ganglion is the largest of the three ganglia (see Fig.
mandible, becoming superficial below the posterior belly of digastric 29.17). It lies on the transverse processes of the second and third cervi
and emerging between the internal jugular vein and internal carotid cal vertebrae and is probably formed from four fused ganglia, judging
artery. It loops round the inferior sternocleidomastoid branch of the by its grey rami to C1–4. The internal carotid artery within the carotid
occipital artery, crosses lateral to both internal and external carotid sheath is anterior, and longus capitis is posterior. The lower end of the
arteries and the loop of the lingual artery a little above the tip of the ganglion is united by a connecting trunk to the middle cervical gan
greater cornu of the hyoid, and is itself crossed by the facial vein (see glion. Postganglionic branches are distributed in the internal carotid
Figs 29.7A, 29.8, 29.17). Its course is described further on page 514. nerve, which ascends with the internal carotid artery into the carotid
canal to enter the cranial cavity, and in lateral, medial and anterior
Communicating branches
branches. They supply vasoconstrictor and sudomotor nerves to the face
The hypoglossal nerve communicates with the sympathetic trunk, the and neck, dilator pupillae and smooth muscle in the eyelids and
lingual, glossopharyngeal and vagus nerves and the pharyngeal plexus. orbitalis.
Near the atlas, it is joined by branches from the superior cervical sym
pathetic ganglion and by a filament from the loop between the first Lateral branches The lateral branches are grey rami communicantes
cervical ventral ramus and the ascending branch of the second cervical to the upper four cervical spinal nerves and to some of the cranial
ventral ramus that leaves the hypoglossal as the upper root of the ansa nerves. Branches pass to the inferior vagal ganglion, the hypoglossal


cervicalis. The vagal connections are close to the skull, and numerous nerve, the superior jugular bulb and associated jugular glomus or
filaments pass between the hypoglossal nerve and the inferior vagal glomera, and to the meninges in the posterior cranial fossa. Another
ganglion in the connective tissue uniting them. As the hypoglossal nerve branch, the jugular nerve, ascends to the cranial base and divides into
curves round the occipital artery, it receives the ramus lingualis vagi two; one part joins the inferior glossopharyngeal ganglion and the other
from the pharyngeal plexus. Near the anterior border of hyoglossus, it joins the superior vagal ganglion.
is connected with the lingual nerve by many filaments that ascend on
the muscle. Medial branches The medial branches of the superior cervical gan
glion are the laryngopharyngeal and cardiac. The laryngopharyngeal
Branches of distribution branches supply the carotid body and pass to the side of the pharynx,
The branches of distribution of the hypoglossal nerve are meningeal, joining glossopharyngeal and vagal rami to form the pharyngeal plexus.
descending, thyrohyoid and muscular nerves. A cardiac branch arises by two or more filaments from the lower part
of the superior cervical ganglion and occasionally receives a twig from
Meningeal branches Meningeal branches leave the nerve in the the trunk between the superior and middle cervical ganglia. It is thought
hypoglossal canal and return through it to supply the diploë of the to contain only efferent fibres, the preganglionic outflow being from
occipital bone, the dural walls of the occipital and inferior petrosal the upper thoracic segments of the spinal cord, and to be devoid of
sinuses, and much of the floor of the anterior wall of the posterior pain fibres from the heart. It descends behind the common carotid
cranial fossa, probably through pathways other than that of the artery, in front of longus colli, and crosses anterior to the inferior
hypoglossal nerve, e.g. upper cervical spinal nerves (see Fig. 28.4B). thyroid artery and recurrent laryngeal nerve. The courses on the two


sides then differ. The right cardiac branch usually passes behind, but
Descending branch The descending branch (descendens hypo sometimes in front of, the subclavian artery and runs posterolateral to
glossi) contains fibres from the first cervical spinal nerve. It leaves the the brachiocephalic trunk to join the deep (dorsal) part of the cardiac
hypoglossal nerve when it curves around the occipital artery, and runs plexus behind the aortic arch. It has other sympathetic connections.
down on the carotid sheath. It provides a branch to the superior belly About midneck, it receives filaments from the external laryngeal nerve.
of omohyoid before joining with the descendens cervicalis to form the Inferiorly, one or two vagal cardiac branches join it. As it enters the
ansa cervicalis (see Figs 29.7A, 29.8). thorax, it is joined by a filament from the recurrent laryngeal nerve.


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Filaments from the nerve also communicate with the thyroid branches enclosing the vertebral artery. It is usually regarded as a detached part
of the middle cervical ganglion. The left cardiac branch, in the thorax, of the middle cervical or inferior cervical ganglion. Like the middle
is anterior to the left common carotid artery and crosses in front of the cervical ganglion, it may supply grey rami communicantes to the fourth
left side of the aortic arch to reach the superficial (ventral) part of the and fifth cervical spinal nerves. The inferior cervical ganglion sends grey
cardiac plexus. Sometimes, it descends on the right of the aorta to end rami communicantes to the seventh and eighth cervical and first thor
in the deep (dorsal) part of the cardiac plexus. It communicates with acic spinal nerves, and gives off a cardiac branch, branches to nearby
the cardiac branches of the middle and inferior cervical sympathetic vessels and sometimes a branch to the vagus nerve.
ganglia and sometimes with the inferior cervical cardiac branches of the The grey rami communicantes to the seventh cervical spinal nerve
left vagus, and branches from these mixed nerves form a plexus on the vary from one to five (two being the usual number). A third often
ascending aorta. ascends medial to the vertebral artery in front of the seventh cervical
transverse process. It connects with the seventh cervical nerve, and sends
Anterior branches The anterior branches of the superior cervical a filament upwards through the sixth cervical transverse foramen in
ganglion ramify on the common and external carotid arteries and the company with the vertebral vessels to join the sixth cervical spinal nerve
branches of the external carotid, and form a delicate plexus around as it emerges from the intervertebral foramen. An inconstant ramus may
each, in which small ganglia are occasionally found. The plexus around traverse the seventh cervical transverse foramen. Grey rami to the eighth
the facial artery supplies a filament to the submandibular ganglion; the cervical spinal nerve vary from three to six in number.
plexus on the middle meningeal artery sends one ramus to the otic The cardiac branch descends behind the subclavian artery and along


ganglion and another, the external petrosal nerve, to the facial ganglion. the front of the trachea to the deep cardiac plexus. Behind the artery, it
Many of the fibres coursing along the external carotid and its branches connects with the recurrent laryngeal nerve and the cardiac branch of
ultimately leave them to travel to facial sweat glands via branches of the middle cervical ganglion (the latter is often replaced by fine branches
the trigeminal nerve. of the inferior cervical ganglion and ansa subclavia).
The branches to blood vessels form plexuses on the subclavian artery
Middle cervical ganglion and its branches. The subclavian supply is derived from the inferior
cervical ganglion and ansa subclavia, and typically extends to the first
The middle cervical ganglion is the smallest of the three and is occasion part of the axillary artery, although a few fibres may extend further. An
ally absent, in which case it may be replaced by minute ganglia in the extension of the subclavian plexus to the internal thoracic artery may
sympathetic trunk or may be fused with the superior ganglion. It is be joined by a branch of the phrenic nerve.
usually found at the level of the sixth cervical vertebra, anterior or just Within the foramina transversaria and intertransverse spaces, the
superior to the inferior thyroid artery, or it may adjoin the inferior cervi cervical grey rami communicantes form intersegmental arcades as they
cal ganglion. It probably represents a coalescence of the ganglia of the communicate with one another and the ventral rami of the upper five
fifth and sixth cervical segments, judging by its postganglionic rami, or six cervical spinal nerves. These arcades accompany the second part
which join the fifth and sixth cervical spinal nerves (but sometimes also of the vertebral artery and create the appearance of a long nerve known
the fourth and seventh). It is connected to the inferior cervical ganglion as the vertebral nerve. Fine filaments from this nerve and the grey rami
by two or more very variable cords. The posterior cord usually splits to communicantes form the vertebral plexus on the surface of the vertebral
enclose the vertebral artery, while the anterior cord loops down anterior artery. This plexus contains not only sympathetic efferent fibres but also


to, and then below, the first part of the subclavian artery, medial to the somatic sensory fibres from the adventitia of the artery, whose cell
origin of its internal thoracic branch, and supplies rami to it. This loop bodies are located in the cervical dorsal root ganglia. The vertebral nerve
is the ansa subclavia and is frequently multiple, lies closely in contact sends filaments to the posterolateral corners of the cervical interverte
with the cervical pleura, and typically connects with the phrenic nerve, bral discs (Bogduk et al 1988), and gives rise to the meningeal branches
and sometimes with the vagus (see Fig. 29.18). (sinuvertebral nerves) at each cervical segment. The vertebral plexus,
The middle cervical ganglion gives off thyroid and cardiac branches. which contains some neuronal cell bodies, continues into the skull
The thyroid branches accompany the inferior thyroid artery to the along the vertebral and basilar arteries and their branches as far as the
thyroid gland. They communicate with the superior cardiac, external posterior cerebral artery, where it meets a plexus from the internal
laryngeal and recurrent laryngeal nerves, and send branches to the carotid artery. The plexus on the inferior thyroid artery reaches the
parathyroid glands. Fibres to both glands are largely vasomotor but thyroid gland and connects with the recurrent and external laryngeal
some reach the secretory cells. The cardiac branch, the largest sympa nerves, the cardiac branch of the superior cervical ganglion, and the
thetic cardiac nerve, arises either from the ganglion itself or more often common carotid plexus.
from the sympathetic trunk cranial or caudal to it. On the right side, it
Horner’s syndrome
descends behind the common carotid artery, in front of or behind the
Any condition or injury that destroys the sympathetic trunk ascending
subclavian artery, to the trachea, where it receives a few filaments from
from the thorax through the neck into the face results in Horner’s syn
the recurrent laryngeal nerve before joining the right half of the deep
drome, characterized by a drooping eyelid (ptosis), sunken globe
(dorsal) part of the cardiac plexus. In the neck, it connects with the


(enophthalmos), narrow palpebral fissure, contracted pupil (meiosis),
superior cardiac and recurrent laryngeal nerves. On the left side, the
vasodilation and lack of thermal sweating (anhydrosis) on the affected
cardiac nerve enters the thorax between the left common carotid and
side. Classically, this is seen in patients with bronchial carcinomas that
subclavian arteries to join the left half of the deep (dorsal) part of the
have invaded the sympathetic trunk and is also a recognized complic
cardiac plexus. Fine branches from the middle cervical ganglion also
ation of cervical sympathectomy or a radical neck dissection. Avulsion
pass to the trachea and oesophagus.
of the first thoracic nerve from the spinal cord may be diagnosed by
Inferior (or cervicothoracic/stellate) ganglion development of the syndrome after closed traction lesion of the supra
The inferior cervical ganglion (cervicothoracic/stellate) is irregular in clavicular brachial plexus. Congenital Horner’s syndrome has been
shape and much larger than the middle cervical ganglion (see Fig. reported in association with ipsilateral internal carotid artery agenesis
29.18). It is probably formed by a fusion of the lower two cervical and (Fons et al 2009). Special features of congenital Horner’s syndrome are
first thoracic segmental ganglia, sometimes including the second and iris heterochromia, a difference in colour between the two eyes that
even third and fourth thoracic ganglia. The first thoracic ganglion may results from interference with melanocyte pigmentation of the iris by a
be separate, leaving an inferior cervical ganglion above it. The sympa lack of sympathetic stimulation during development, and unilateral
thetic trunk turns backwards at the junction of the neck and thorax, and straight hair.
so the long axis of the cervicothoracic ganglion becomes almost antero
posterior. The ganglion lies on or just lateral to the lateral border of
VISCERA
longus colli between the base of the seventh cervical transverse process
and the neck of the first rib (which are both posterior to it). The verte
bral vessels are anterior, and the ganglion is separated from the pos The main cervical viscera are the submandibular salivary glands, the


terior aspect of the cervical pleura inferiorly by the suprapleural thyroid and parathyroid glands, and the cervical portions of the trachea
membrane. The costocervical trunk of the subclavian artery branches and oesophagus.
near the lower pole of the ganglion, and the superior intercostal artery
is lateral.
A small vertebral ganglion may be present on the sympathetic trunk SUBMANDIBULAR SALIVARY GLAND
anterior or anteromedial to the origin of the vertebral artery and directly
above the subclavian artery. When present, it may provide the ansa Each submandibular salivary gland is situated behind and below the
subclavia and is also joined to the inferior cervical ganglion by fibres ramus of the mandible, in the region of the submandibular triangle,


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between the anterior and posterior bellies of digastric (see Fig. 29.7A). Vascular supply and lymphatic drainage
The gland is described in detail on page 528.
Arteries
THYROID GLAND The thyroid gland is supplied by the superior and inferior thyroid arter
ies and sometimes by an arteria thyroidea ima from the brachiocephalic
trunk or aortic arch (see Figs 29.14, 29.17). The arteries are large and
The thyroid gland, brownishred and highly vascular, is placed
their branches anastomose frequently both on and in the gland, ipsi
anteriorly in the lower neck, level with the fifth cervical to the first
laterally and contralaterally. The superior thyroid artery, which is closely
thoracic vertebrae (see Fig. 29.17). It is ensheathed by the pretracheal
related to the external branch of the superior laryngeal nerve, pierces
layer of deep cervical fascia and consists of right and left lobes con
the thyroid fascia and then divides into anterior and posterior branches.
nected by a narrow, median isthmus. It usually weighs 25 g but this
The anterior branch supplies the anterior surface of the gland, and the
varies. The gland is slightly heavier in females and enlarges during
posterior branch supplies the lateral and medial surfaces. The inferior
menstruation and pregnancy. Estimation of the size of the thyroid
thyroid artery approaches the base of the thyroid gland and divides into
gland is clinically important in the evaluation and management of
superior (ascending) and inferior thyroid branches to supply the infe
thyroid disorders and can be achieved noninvasively by means of
rior and posterior surfaces of the gland. The superior branch also sup
diagnostic ultrasound. Mean thyroid volume increases with age (Cha
plies the parathyroid glands. The relationship between the inferior
noine et al 1991). No significant difference in thyroid gland volume
thyroid artery and the recurrent laryngeal nerve is highly variable and
has been observed between males and females from 8 months to
of considerable clinical importance; iatrogenic injury to the nerves that
15 years.
supply the larynx represents a major complication of thyroid surgery


The lobes of the thyroid gland are approximately conical. Their
(Yalcxin 2006). The recurrent laryngeal nerve is usually related to the
ascending apices diverge laterally to the level of the oblique lines on
posterior branch of the inferior thyroid artery, which may be replaced
the laminae of the thyroid cartilage, and their bases are level with the
by a vascular network (Moreau et al 1998).
fourth or fifth tracheal cartilages. Each lobe is usually 5 cm long, its
greatest transverse and anteroposterior extents being 3 cm and 2 cm,
Veins respectively. The posteromedial aspects of the lobes are attached to the
side of the cricoid cartilage by a lateral thyroid ligament (Berry’s liga The venous drainage of the thyroid gland is usually via superior, middle
ment). The isthmus connects the lower parts of the two lobes, although and inferior thyroid veins (see Figs 29.13, 29.14, 29.17). The superior
occasionally it may be absent. It measures 1.25 cm transversely and thyroid vein emerges from the upper part of the gland and runs with
vertically, and is usually anterior to the second and third tracheal carti the superior thyroid artery towards the carotid sheath; it drains into the
lages, although it can be higher or even sometimes lower because its internal jugular vein. The middle thyroid vein collects blood from the
site and size vary greatly. A conical pyramidal lobe often ascends lower part of the gland; it emerges from the lateral surface of the gland
towards the hyoid bone from the isthmus or the adjacent part of either and drains into the internal jugular vein. The inferior thyroid veins arise
lobe (more often the left). It is occasionally detached or in two or more in a glandular venous plexus, which also connects with the middle and
parts. A fibrous or fibromuscular band, the levator of the thyroid gland, superior thyroid veins. These veins form a pretracheal plexus, from
musculus levator glandulae thyroideae, sometimes descends from the which the left inferior vein descends to join the left brachiocephalic


body of the hyoid to the isthmus or pyramidal lobe. For further reading, vein, and the right descends obliquely across the brachiocephalic artery
see Mohebati and Shaha (2012). to join the right brachiocephalic vein at its junction with the superior
Ectopic thyroid tissue is rare but may be found around the course vena cava. The inferior thyroid veins often open via a common trunk
of the thyroglossal duct or laterally in the neck, as well as in distant into the superior vena cava or left brachiocephalic vein. They drain the
places such as the tongue (lingual thyroid), mediastinum and the sub oesophageal, tracheal and inferior laryngeal veins and have valves at
diaphragmatic organs (Noussios et al 2011). The most frequent location their terminations.
of ectopic thyroid tissue is at the base of the tongue, in particular at the
region of the foramen caecum; often it is the only thyroid tissue present. Lymphatics
Small, detached masses of thyroid tissue may occur above the lobes or Thyroid lymphatic vessels communicate with the tracheal plexus, and
isthmus as accessory thyroid glands. Vestiges of the thyroglossal duct pass to the prelaryngeal nodes just above the thyroid isthmus and to
may persist between the isthmus and the foramen caecum of the tongue, the pretracheal and paratracheal nodes; some may also drain into the
sometimes as accessory nodules or cysts of thyroid tissue near the brachiocephalic nodes related to the thymus in the superior mediasti
midline or even in the tongue, where they are called thyroglossal duct num. Laterally, the gland is drained by vessels lying along the superior
cysts. thyroid veins to the deep cervical nodes. Thyroid lymphatics may drain
directly, with no intervening node, to the thoracic duct.
Surfaces and relations
Innervation
The convex lateral (superficial) surface is covered by sternothyroid,
whose attachment to the oblique thyroid line prevents the upper pole The thyroid gland receives its innervation from the superior, middle and
of the gland from extending on to thyrohyoid. More anteriorly lie ster inferior cervical sympathetic ganglia. Postganglionic fibres from the


nohyoid and the superior belly of omohyoid, overlapped inferiorly by inferior cervical ganglion form a plexus on the inferior thyroid artery,
the anterior border of sternocleidomastoid. The medial surface of the which accompanies the artery to the thyroid gland, and communicates
gland is adapted to the larynx and trachea; its superior pole contacts with the recurrent laryngeal and external branch of the superior laryn
the inferior pharyngeal constrictor and the posterior part of crico geal nerves, with the superior cardiac nerve, and with the plexus on the
thyroid, which separate it from the posterior part of the thyroid lamina common carotid artery.
and the side of the cricoid cartilage. The external branch of the superior
laryngeal nerve is medial to this part of the gland as it passes to supply
Imaging
cricothyroid. Inferiorly, the trachea and, more posteriorly, the recurrent
laryngeal nerve and oesophagus (which is closer on the left) are medial
relations. The posterolateral surface of the thyroid gland is close to the The follicular nature of the thyroid gland is not resolved by current
carotid sheath and overlaps the common carotid artery. imaging techniques and thus presents a homogeneous texture on cross
The anterior border of the gland is thin, and near the anterior branch sectional imaging (ultrasound, computed tomography, magnetic reso
of the superior thyroid artery it slants down medially. The posterior nance imaging (MRI)). Its superficial location makes the thyroid an
border is rounded and related inferiorly to the inferior thyroid artery ideal organ for sonographic examination (Fig. 29.21). The thyroid
and its anastomosis with the posterior branch of the superior thyroid gland is highly vascular and demonstrates intense contrast enhance
artery. On the left side, the lower end of the posterior border lies near ment and increased signal on Tweighted MRI (Fig. 29.22). Radionu
2
the thoracic duct. The parathyroid glands are usually related to the clide imaging of the thyroid may be performed with technetium (99mTc)
posterior border. pertechnetate. This readily available radionuclide is trapped by the


The isthmus is covered by sternothyroid, from which it is separated thyroid in the same way as iodine but is not organified. It yields mor
by pretracheal fascia. More superficially it is covered by sternohyoid, the phological information and will reveal the presence of ectopic thyroid
anterior jugular veins, fascia and skin. The superior thyroid arteries tissue. Functional data can be obtained with the use of 123iodine or
anastomose along its upper border and the inferior thyroid veins leave 131iodine, which is trapped and organified. For further reading, see
the gland at its lower border. Intenzo et al (2012).


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Right common Isthmus of Trachea Left lobe of
carotid artery thyroid thyroid
*
F
CT
BV
Fig. 29.23 A section through parts of several human thyroid follicles, one
Right lobe of thyroid Left common carotid artery of which is labelled (F), showing the follicular epithelium (arrows)
enclosing a lumen filled with colloidal thyroglobulin (CT). Calcitonin-
Fig. 29.21 A thyroid sonogram.
secreting C cells are not readily identifiable in routine preparations of
human tissue, where they appear as poorly staining (clear) cells within
follicles; an example is indicated by the asterisk. A network of blood
Right internal Thyroid isthmus Left lobe of
jugular vein thyroid vessels (BV) within connective tissue septa surrounds the follicles.
(Courtesy of Mr Peter Helliwell and the late Dr Joseph Mathew,
Department of Histopathology, Royal Cornwall Hospitals Trust, UK.)
are short in resting cells, but elongate and often branch on stimulation
by TSH. Follicles showing differing levels of activity may coexist.
Active follicular cells are highly polarized functionally. The secretion
of TSH leads to endocytosis of colloidal droplets at the luminal epithe
lium (see Fig. 29.23). The hormone provokes the cells to extend cyto
plasmic processes into the luminal colloid and sequester droplets of
colloid. The iodinated thyroglobulin in the intracellular colloid drop
lets is then degraded by follicular cell lysosomes, liberating T and T,
3 4
which pass to the base of the cell, where they are released. They are
exported from the thyroid mainly via the blood capillaries and lym
phatics. Prolonged high levels of circulating TSH induce follicular cell
hypertrophy, progressive resorption of colloid and increased stromal
vascularity, and this can result in thyroid enlargement.
C cells Thyroid parenchyma also contains C (clear) cells, so called
because they have palestaining cytoplasm, which is more pronounced
in some species than in the human thyroid. C cells are members of the
amine precursor uptake and decarboxylation (APUD) system of dis


Right lobe Trachea Left common carotid persed neuroendocrine cells. They produce the peptide hormone calci
of thyroid artery tonin (thyrocalcitonin), which lowers blood calcium by inhibiting bone
resorption and calcium recovery from renal tubule ultrafiltrate. C cells
Fig. 29.22 A T-weighted magnetic resonance image at the level of the
2 populate the middle third of each lateral lobe of the thyroid and are
thyroid isthmus. Vessels show flow void; compare with Figure 29.21.
typically found scattered within thyroid follicles, lying inside the basal
lamina but not reaching the follicle lumen. Occasionally, they occur in
Microstructure clusters in the interfollicular stroma, which is why they are also called
parafollicular cells.
The thyroid gland has a thin capsule of connective tissue, which extends
Thyroidectomy
into the glandular parenchyma and divides each lobe into irregularly
shaped and sized lobules. The functional units of the thyroid are fol
licles, which are spherical and cystlike, between 0.02 and 0.9 mm Apart from variable enlargement during menstruation and pregnancy,
in diameter. Follicles consist of a central colloid core surrounded by any thyroid swelling is a goitre, which may press on related structures.
a singlelayered epithelium resting on a basal lamina (Fig. 29.23). Symptoms most commonly are the consequence of pressure on the
Colloid consists almost entirely of an iodinated glycoprotein, iodothy trachea or on the recurrent laryngeal nerves, and there may also be
roglobulin, which is the inactive, stored form of the active thyroid venous engorgement. During thyroidectomy, care must be taken when
hormones, triiodothyronine (T) and tetraiodothyronine or thyroxine tying off the superior and inferior thyroid arteries to avoid damage to
3
(T), and is produced by the follicular epithelial cells. Sufficient iodothy adjacent nerves. The external laryngeal nerve runs close to the superior
4
roglobulin is stored extracellularly within follicles to regulate the meta thyroid artery, and the recurrent laryngeal nerve runs close to the infer


bolic activity of the body for up to 3 months. Follicles are surrounded ior thyroid artery. Total thyroidectomy may be necessary in the treat
by a delicate connective tissue stroma, containing dense plexuses of ment of hyperthyroidism (overactive thyroid), as well as for thyroid
fenestrated capillaries, extensive lymphatic networks and sympathetic enlargement in the euthyroid state. The parathyroid glands and the
nerve fibres that supply the arterioles and capillaries. Some nerve fibres recurrent laryngeal nerves are preserved.
end close to the follicular epithelial cells.
Follicular cells Follicular cells vary from squamous or low cuboidal PARATHYROID GLANDS
to columnar, depending on their level of activity, which is controlled
mainly by circulating hypophysial thyroidstimulating hormone (TSH, The parathyroid glands are small, yellowishbrown, ovoid or lentiform
thyrotropin). Resting follicles are large and lined by squamous or low structures, usually lying between the posterior lobar borders of the
cuboidal epithelium with abundant luminal colloid. Apical microvilli thyroid gland and its capsule. They are commonly 6 mm long, 3–4 mm


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4
NOITCES
across and 1–2 mm from back to front, each weighing about 50 mg. lobar aspects. Parathyroid activity is controlled by variations in blood
Typically, there are two on each side, superior and inferior, but there calcium level; it is inhibited by a rise and stimulated by a fall. The nerves
may be more or there may be only three or many minute parathyroid are believed to be vasomotor but not secretomotor.
islands scattered in connective tissue near the usual sites. Very occasion
ally, an occult gland may follow a blood vessel into a groove on the Microstructure
surface of the thyroid. Normally, the inferior parathyroids migrate only
to the inferior thyroid poles, but they may descend with the thymus
Each parathyroid gland has a thin connective tissue capsule with intra
into the thorax or they may be sessile and remain above their normal
glandular septa but lacks distinct lobules. The parathyroids synthesize
level near the carotid bifurcation. The anastomotic connection between
and secrete parathyroid hormone (PTH, parathormone), a singlechain
the superior and inferior thyroid arteries that occurs along the posterior
polypeptide of 84 aminoacid residues concerned with the control of
border of the thyroid gland usually passes very close to the parathyroids,
the level and distribution of calcium and phosphorus. In childhood,
and is a useful aid to their identification.
the gland consists of wide, irregular, interconnecting columns of chief
The superior parathyroid glands are more constant in location than
or principal cells separated by a dense plexus of fenestrated sinusoidal
the inferior and are usually to be found midway along the posterior
capillaries. After puberty, adipose tissue accumulates in the stroma and
borders of the thyroid gland, although they may be higher. The inferior
typically accounts for about onethird of the adult tissue mass, increas
pair are more variably situated (related to their embryological develop
ing further with age.
ment) and may be either within the fascial thyroid sheath, below the
Chief cells differ ultrastructurally according to their level of activity;
inferior thyroid arteries and near the inferior lobar poles; or outside the
active chief cells have large Golgi complexes with numerous vesicles


sheath, immediately above an inferior thyroid artery; or in the thyroid
and small membranebound granules. Glycogen granules are most
gland near its inferior pole. These variations are surgically important
abundant in inactive cells, which have few of the cytoplasmic features
(Fig. 29.24). A tumour of the inferior parathyroid situated within the
of synthetic or secretory activity, and appear histologically as ‘clear’ cells.
fascial thyroid sheath may descend along the inferior thyroid veins
In normal human parathyroid glands, inactive chief cells outnumber
anterior to the trachea into the superior mediastinum, whereas if it is
active cells in a ratio of 3–5 : 1 (Fig. 29.25). In contrast to the thyroid,
outside the sheath, it may extend posteroinferiorly behind the oesopha
where the activities of adjacent follicular cells are coordinated, indi
gus into the posterior mediastinum. The superior parathyroids are
vidual chief cells of the parathyroid glands go through cycles of secre
usually dorsal, and the inferior parathyroids ventral, to the recurrent tory activity and rest independently, according to serum calcium levels.
laryngeal nerves.
A second cell type, the oxyphil (eosinophil) cell, appears just before
The parathyroid glands are very flattened in crosssection and are not
puberty and increases in number with age. Oxyphil cells are larger than
normally visible by current imaging methods, including scintigraphy,
chief cells and contain more cytoplasm, which stains deeply with eosin.
unless they are enlarged.
Their nuclei are smaller and more darkly staining than those of chief
cells, and their cytoplasm is unusually rich in mitochondria. The func
Vascular supply and lymphatic drainage
tional significance of oxyphil cells and their relationship to chief cells
are uncertain.
Both superior and inferior parathyroid glands are usually supplied by
the inferior thyroid arteries; the superior thyroid may be supplied by
the superior thyroid artery or from anastomoses between the superior ROOT OF THE NECK
and inferior thyroid arteries sometimes. The glands drain into the
plexus of veins on the anterior surface of the thyroid. Lymph vessels are The root of the neck is a zone of transition between four discrete ana


numerous and associated with those of the thyroid and thymus glands. tomical spaces: the neck, the thorax and both upper limbs (see Fig.
29.18). It contains the subclavian vessels; common carotid artery;
Innervation
trunks of the brachial plexus; sympathetic trunk; phrenic, vagus and
recurrent laryngeal nerves (all bilaterally); the terminal portion of the
The nerve supply is sympathetic, either direct from the superior or thoracic duct (on the left side only); the terminal portion of the right
middle cervical ganglia, or via a plexus in the fascia on the posterior lymphatic duct (on the right side only); and the oesophagus and trachea
A B C
Cricothyroidal and juxtacricoidal 77% Behind upper pole of thyroid 22% Retropharyngeal and retro-oesophageal 1%
D E F G
Thymic
tongue 39%
Mediastinal 2%
Lower thyroid 42% Intrathymic Juxtathyroidal 15% Ectopic 2%
Fig. 29.24 The distribution of superior (A–C) and inferior (D–G) parathyroid glands. A, Cricothyroidal and juxtathyroidal. B, Behind the upper pole of the
thyroid. C, Retropharyngeal and retro-oesophageal. D, Lower thyroid. E, Intrathymic. F, Juxtathyroidal. G, Ectopic.


Root of the neck
473
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Cervical rib
A small additional rib (cervical rib) may develop in the root of the neck
in association with the seventh cervical vertebra. It is often fibrous in
nature, although in some cases it may have undergone ossification. A
cervical rib may cause compression of the subclavian artery and the
lower roots of the brachial plexus, in which case affected individuals
will complain of pain, paraesthesia and even pallor of the affected upper
limb, a condition known as thoracic outlet syndrome. The occasional
cooccurrence of rudimentary or absent twelfth ribs with cervical ribs
indicates that a homeotic shift had occurred over a larger part of the
vertebral column in affected fetuses (Bots et al 2011). For further reading
on homeotic transformations of vertebrae, see Ten Broek et al (2012).
OESOPHAGUS – CERVICAL PORTION
The oesophagus is a muscular tube approximately 25 cm long, connect
ing the pharynx to the stomach. It begins in the neck, level with the
lower border of the cricoid cartilage and the sixth cervical vertebra. It
descends, largely anterior to the vertebral column, into the superior
mediastinum. Generally vertical and median, it inclines to the left as
Fig. 29.25 A section of the parathyroid gland, showing clusters and cords
far as the root of the neck, and also bends in an anteroposterior plane
of small, tightly packed chief cells surrounded by vascular sinusoids.
to follow the cervical curvature of the vertebral column.
Scattered oxyphil cells (arrows) are generally larger and more eosinophilic.
(Courtesy of Mr Peter Helliwell and the late Dr Joseph Mathew,
Relations The trachea lies anterior to the oesophagus, attached to it
Department of Histopathology, Royal Cornwall Hospitals Trust, UK.)
by loose connective tissue. The vertebral column, longus colli and pre
vertebral layer of deep cervical fascia are posterior, and the common
carotid artery and posterior part of the thyroid gland are lateral on each
(in the midline). The brachiocephalic veins are formed by the union of side. In the lower neck, where the oesophagus deviates to the left, it


the internal jugular and subclavian veins at the junction of the neck becomes closer to the left carotid sheath and thyroid gland than it is
and thorax, behind the head of the clavicle. on the right. The thoracic duct ascends for a short distance along its left
The essential anatomical landmark in orientating and understanding side. The recurrent laryngeal nerves ascend on each side in or near the
the root of the neck is scalenus anterior, covered by the prevertebral groove between the trachea and the oesophagus.
layer of deep cervical fascia. Anteriorly lie sternocleidomastoid and
subclavius, the intermediate tendon of omohyoid, the subclavian vein, Vascular supply and lymphatic drainage The cervical part of
branches from the thyrocervical trunk of the first part of the subclavian the oesophagus is mainly supplied by branches from the inferior
artery (transverse cervical, suprascapular and ascending cervical arter thyroid arteries. The oesophageal veins drain into the brachiocephalic
ies), and the phrenic nerve. The nerve lies on the surface of scalenus veins, and lymphatic vessels pass to retropharyngeal, paratracheal or
anterior in the root of the neck, before passing between it and the deep cervical lymph nodes.
subclavian vein to enter the superior mediastinum, and is the anatomi
cal key to identifying the muscle intraoperatively. Posteriorly, the roots Innervation The cervical part of the oesophagus is innervated by the
of the brachial plexus and the second part of the subclavian artery sepa recurrent laryngeal nerves and by the sympathetic plexus around the
rate scalenus anterior from scalenus medius. Pathologies that cause inferior thyroid artery.
impingement on either brachial plexus or subclavian artery may present
clinically as an upper limb compression syndrome. The suprapleural
membrane and pleura are intimate posterior relations of scalenus an TRACHEA – CERVICAL PORTION
terior. On each side, the apical (cervical) pleura and the apex of the
lung bulge up into the root of the neck. The height to which the apical The trachea is a tube 10–11 cm long, formed of cartilage and fibromus


pleura rises – with reference to the first pair of ribs and costal cartilages cular membrane. It descends from the larynx, and extends from the level
– varies in different individuals according to the obliquity of the thor of the sixth cervical vertebra to the upper border of the fifth thoracic
acic inlet. Posteriorly, the apical pleura typically reaches the level of the vertebra (see Figs 29.14, 29.22). It lies approximately in the sagittal
neck of the first rib; it forms a domed roof over each side of the thoracic plane but its point of bifurcation is usually a little to the right. The
cavity that is strengthened by the suprapleural membrane. Scalenus trachea is flexible and can rapidly alter in length. It is flattened pos
anterior covers the anterolateral part of the dome of the pleura and teriorly so that in transverse section it is shaped, with some individual
separates it from the subclavian vein. The subclavian artery crosses the variation, like a letter D. Its external transverse diameter is 2 cm in adult
dome below its summit, immediately above the vein. The costocervical males, and 1.5 cm in adult females. The lumen in live adults is 1.2 cm
trunk arches backwards from the subclavian artery and crosses the in transverse diameter. In children, the trachea is smaller, more deeply
summit of the dome; its superior intercostal branch descends behind placed and more mobile. Tracheal diameter does not exceed 3 mm in
the dome, between the first intercostal nerve laterally and the first thor the first postnatal year; during later childhood its diameter in milli
acic sympathetic ganglion medially. metres is about equal to age in years.
Medial relations of scalenus anterior are longus colli and the inferior
thyroid artery. The two muscles are separated by an angular interval Relations The relationships of the trachea to other cervical structures
through which the vertebral artery and vein pass to gain access to the is of clinical significance: tracheostomy is not an uncommon clinical
foramen transversarium of the sixth cervical vertebra, and more anteri procedure (see below). Anteriorly, the cervical part of the trachea is


orly the inferior thyroid artery arches from lateral to medial on its way crossed by skin and by the superficial and deep fasciae. It is also crossed
to the thyroid gland. The cervical sympathetic chain and the inferior by the jugular arch and overlapped by sternohyoid and sternothyroid.
cervical ganglion lie close to the posteromedial aspect of the vertebral The second to fourth tracheal cartilages are crossed by the isthmus of
artery here. The internal thoracic artery descends from the first part of the thyroid gland, above which an anastomotic artery connects the
the subclavian artery; it passes behind the brachiocephalic vein and, on bilateral superior thyroid arteries. Below and in front are the pretracheal
the right side, is crossed by the phrenic nerve. The vagus descends anter fascia, inferior thyroid veins, thymic remnants and the arteria thyroidea
ior to the first part of the subclavian artery; on the right side only, its ima (when it exists). In children, the brachiocephalic artery crosses
recurrent laryngeal branch usually turns around the lower border of the obliquely in front of the trachea at or a little above the upper border
artery. The terminal portions of the thoracic duct and the right lym of the manubrium. The left brachiocephalic vein may also rise a little
phatic duct, on the left and right sides, respectively, cross the triangular above this level. The oesophagus lies pos terior to the trachea and sepa
interval at the level of the seventh cervical vertebra, coming into contact rates it from the vertebral column. The paired lobes of the thyroid
with the medial edge of scalenus anterior. gland, which descend to the fifth or sixth tracheal cartilage, and the
The axillary sheath, an extension of the prevertebral fascia that common carotid and inferior thyroid arteries all lie lateral to the
accompanies the axillary artery and trunks of the brachial plexus, lies trachea. The recurrent laryngeal nerves ascend on each side, in or near
lateral to scalenus anterior. the grooves between the sides of the trachea and oesophagus.


NECk
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NOITCES
Vascular supply and lymphatic drainage The cervical part of For detailed descriptions of the operative procedures, appropriate
the trachea is mainly supplied by branches from the inferior thyroid surgical texts should be consulted. It is worth emphasizing here,
arteries. The tracheal veins drain into the brachiocephalic veins via the however, the importance of understanding the relevant regional
inferior thyroid plexus, and lymphatic vessels drain into the pretracheal anatomy. In creating a surgical airway, potential hazards can be avoided
and paratracheal nodes. by dissecting in the midline. In the midline, the isthmus of the thyroid
gland, which normally overlies the second and third tracheal rings,
should be divided. Careful haemostasis minimizes the risk of cata
Innervation The trachea is innervated by branches from the vagi,
strophic postoperative bleeding. A high bifurcation of the brachio
recurrent laryngeal nerves and sympathetic trunks.
cephalic trunk, or aberrant anterior jugular veins (which usually lie
between the midline and anterior border of sternocleidomastoid) are
Surgical airway The trachea may be accessed directly in the neck via additional anatomical complications (Ger and Evans 1993, Jarvis 1966,
cricothyroidotomy or tracheostomy. There are numerous indications for Racic et al 2005).
performing an elective tracheostomy. They include the need to provide Cricothyroidotomy endangers the cricothyroid artery (a branch of
prolonged intubation and pulmonary toilet, and to manage acute the superior thyroid artery), which is usually found close to the midline,
airway obstruction from supraglottic or glottic pathology or trauma and which reaches the median cricothyroid ligament close to the
(e.g. midface, mandibular or laryngeal fractures). thyroid cartilage.
KEY REFERENCES
Bogduk N, Windsor M, Inglis A 1988 The innervation of the cervical Mohebati A, Shaha AR 2012 Anatomy of thyroid and parathyroid glands
intervertebral discs. Spine 13:2–8. and neurovascular relations. Clin Anat 25:19–31.


A description of the cervical sinuvertebral nerves, which have an upward A review of the pertinent anatomy and embryology of the thyroid and
course in the vertebral canal, supplying the lateral aspects of the disc at parathyroid glands and the critical structures that lie in their proximity.
their level of entry and the disc above.
Moreau S, de Rugy MG, Babin E et al 1998 The recurrent laryngeal nerve:
Brown H 2002 Anatomy of the spinal accessory nerve plexus: relevance to related vascular anatomy. Laryngoscope 108:1351–5.
head and neck cancer and atherosclerosis. Exp Biol Med 227:570–8. An exploration of the considerable variability in the perineural vasculature
Data that explain why some patients acquire a severe functional impairment of the recurrent laryngeal nerve, which lies in close proximity to and is
after surgery despite preservation of the accessory nerve. This provides the usually supplied by the posterior branch of the inferior thyroid artery.
rationale for conservative neck dissection.
Smoker WRK, Harnsberger HR 1991 Differential diagnosis of head and neck
Crile G 1906 Excision of cancer of the head and neck with special reference lesions based on their space of origin. 2. The infrahyoid portion of the
to the plan of dissection based on one hundred and thirty two oper neck. Am J Roentgenol 157:155–9.
ations. J Am Med Assoc 47:1780–6. A pictorial essay that describes the fascia and fascial spaces of the infrahyoid
A seminal paper that considers the surgical anatomy of radical neck portion of the neck. The contents of each space, the common abnormalities
dissection. affecting the space, and the characteristic displacements produced by disease
in each space are reviewed.
Guidera, AK, Dawes PJD, Stringer MD 2012 Cervical fascia: a terminological
pain in the neck. ANZ Surg 82:786–91.
A review that provides a critical appraisal of the terms used to describe the
cervical fascia in order to achieve consensus and uniformity.


Neck
474.e1
92
RETPAHC
REFERENCES
Bogduk N, Windsor M, Inglis A 1988 The innervation of the cervical Maroldi R, Farina D, Ravanelli M et al 2012 Emergency imaging assessment
intervertebral discs. Spine 13:2–8. of deep neck space infections. Semin Ultrasound CT MR 33:432–42.
A description of the cervical sinuvertebral nerves, which have an upward Matthers LH Jr, Smith DW, Frankel L 1992 Anatomical considerations in
course in the vertebral canal, supplying the lateral aspects of the disc at placement of central venous catheters. Clin Anat 5:89–106.
their level of entry and the disc above.
Mohebati A, Shaha AR 2012 Anatomy of thyroid and parathyroid glands
Bots J, Wijnaendts LC, Delen S et al 2011 Analysis of cervical ribs in a series and neurovascular relations. Clin Anat 25:19–31.
of human fetuses. J Anat 219:403–9. A review of the pertinent anatomy and embryology of the thyroid and
Brown H 2002 Anatomy of the spinal accessory nerve plexus: relevance to parathyroid glands and the critical structures that lie in their proximity.
head and neck cancer and atherosclerosis. Exp Biol Med 227:570–8. Moreau S, de Rugy MG, Babin E et al 1998 The recurrent laryngeal nerve:
Data that explain why some patients acquire a severe functional impairment related vascular anatomy. Laryngoscope 108:1351–5.
after surgery despite preservation of the accessory nerve. This provides the An exploration of the considerable variability in the perineural vasculature
rationale for conservative neck dissection. of the recurrent laryngeal nerve, which lies in close proximity to and is
Byon HJ, Lee GW, Lee JH et al 2013 Comparison between ultrasoundguided usually supplied by the posterior branch of the inferior thyroid artery.
supraclavicular and infraclavicular approaches for subclavian venous Nash L, Nicholson HD, Zhang M 2005 Does the investing layer of the deep
catheterization in children–a randomized trial. Br J Anaesth 111: cervical fascia exist? Anesthesiology 103:962–8.
788–92.


Noussios G, Anagnostis P, Goulis DG et al 2011 Ectopic thyroid tissue:
Chanoine JP, Toppet V, Lagasse R et al 1991 Determination of thyroid anatomical, clinical, and surgical implications of a rare entity. Eur J
volume by ultrasound from the neonatal period to late adolescence. Eur Endocrinol 165:375–82.
J Pediatr 150:395–9.
Oliver E, Gillespie M 2010 Deep space neck infections. In: Flint PE (ed.).
Crile G 1906 Excision of cancer of the head and neck with special reference Cummings Otolaryngology Head and Neck Surgery, 5th ed. Ch. 14.
to the plan of dissection based on one hundred and thirty two opera 201–8. Philadelphia: Mosby Elsevier.
tions. J Am Med Assoc 47:1780–6.
Pandit JJ, Bree S, Dillon P et al 2000 A comparison of superficial versus
A seminal paper that considers the surgical anatomy of radical neck
combined (superficial and deep) cervical plexus block for carotid endar
dissection.
terectomy: a prospective, randomized study. Anesth Analg 91:781–6.
Deutsch MD, Kriss VM, Willging JP 1995 Distance between the tonsillar Porzionato A, Macchi V, Stecco C et al 2013 The carotid body in sudden
fossa and internal carotid artery in children. Arch Otolaryngol Head infant death syndrome. Respir Physiol Neurobiol 185:194–201.
Neck Surg 121:1410–2.
Pu YM, Tang EY, Yang XD 2008 Trapezius muscle innervation from the
Fons C, Vasconcelos M, Vidal M 2009 Agenesis of internal carotid artery in spinal accessory nerve and branches of the cervical plexus. Int J Oral
a child with ipsilateral Horner’s syndrome. J Child Neurol 24:101–4. Maxillofac Surg 37:567–72.
Friedmann DR, Eubig J, McGill M et al 2011 Development of the jugular Racic G, Matulic J, Roje Z et al 2005 Abnormally high bifurcation of the


bulb: a radiologic study. Otol Neurotol 32:1389–95. brachiocephalic trunk as a potential operative hazard: case report.
Froes LB, De Tolosa EMC, Camargo RDC et al 1999 Blood supply to the Otolaryngol Head Neck Surg 133:811–13.
human sternocleidomastoid muscle by the sternocleidomastoid branch Seong J, Lieber BB, Wakhloo AK 2005 Morphological agedependent devel
of the occipital artery. Clin Anat 12:412–16. opment of the human carotid bifurcation. J Biomech 38:453–65.
Ger R, Evans JT 1993 Tracheostomy: an anatomicoclinical review. Clin Anat Shah JP, Patel SJ 2012 Cervical lymph nodes. In: Head and Neck Surgery
6:337–41. and Oncology, 4th ed. Edinburgh: Elsevier, Mosby; pp. 353–94.
Grodinsky M, Holyoke EA 1938 The fasciae and fascial spaces of the head, Shoja M, Oyesiku NM, Shokouhi G et al 2014 A comprehensive review with
neck and adjacent regions. Am J Anat 63:367–408. potential significance during skull base and neck operations. Part II:
Guidera, AK, Dawes PJD, Stringer MD 2012 Cervical fascia: a terminological glossopharyngeal, vagus, accessory, and hypoglossal nerves and cervical
pain in the neck. ANZ Surg 82:786–91. spinal nerves 1–4. Clin Anat 27:131–44.
A review that provides a critical appraisal of the terms used to describe the Smoker WRK, Harnsberger HR 1991 Differential diagnosis of head and neck
cervical fascia in order to achieve consensus and uniformity. lesions based on their space of origin. 2. The infrahyoid portion of the
Hedge A, Mohan S, Lim WE 2012 Infections of the deep neck spaces. Sin neck. Am J Roentgenol 157:155–9.
gapore Med J 53:305–11. A pictorial essay that describes the fascia and fascial spaces of the infrahyoid


portion of the neck. The contents of each space, the common abnormalities
Hong JY, Koo BN, Kim WO et al 2010 Effect of head rotation on overlap and
affecting the space, and the characteristic displacements produced by disease
relative position of internal jugular vein to carotid artery in infants and
in each space are reviewed.
children: a study of the anatomy using ultrasonography. J Crit Care 25:
360.e9–360.e13. Som PM, Curtin HD 2011 Head and Neck Imaging, 5th ed. Elsevier.
Intenzo CM, Dam HQ, Manzone TA et al 2012 Imaging of the thyroid in Ten Broek CM, Bakker AJ, VarelaLasheras I 2012 Evodevo of the human
benign and malignant disease. Semin Nucl Med 42:49–61. vertebral column: on homeotic transformations, pathologies and pre
Jarvis JF 1966 Displaced brachiocephalic artery: a potential hazard in tra natal selection. Evol Biol 39:456–71.
cheostomy. S Afr Med J 40:396–7. Tubbs RS, Shoja MM, Loukas M et al 2011 Study of the cervical plexus
Lucas GDA, Laudanna A, Chopard RP et al 1994 Anatomy of the lesser innervation of the trapezius muscle. J Neurosurg Spine 14:626–9.
occipital nerve in relation to cervicogenic headache. Clin Anat 7: Yalcxin B 2006 Anatomic configurations of the recurrent laryngeal nerve and
90–6. inferior thyroid artery. Surgery 139:181–7.
Malgaigne JF 1838 Traité d’Anatomie Chirurgicale et de Chirurgie Expéri
mentale. J.B. Baillière, Paris.
RECOMMENDED READING
Berkovitz BKB, Kirsch C, Moxham BJ et al 2002 Interactive Head and Neck. Robbins KT 1998 Neck dissection. In: Cummings CW et al (eds) Otolaryn
London: Primal Pictures. gology, Head and Neck Surgery, vol. 2, 3rd ed. St Louis: Elsevier, Mosby;


Cady B, Rossi RL (eds) 1991 Surgery of the Thyroid and Parathyroid Glands. pp. 1787–819.
Philadelphia: Elsevier, Saunders. WilsonPauwels L, Akesson EJ, Stewart PA 1998 Cranial Nerves: Anatomy
Kapandji IA 1975 The Physiology of Joints. Edinburgh: Elsevier, Churchill and Clinical Comments. Toronto: Decker.
Livingstone.
Lingeman RE 1998 Surgical anatomy. In: Cummings CW et al (eds)
Otolaryngology, Head and Neck Surgery, vol. 2, 3rd ed. St Louis:
Elsevier, Mosby; pp. 1673–85.


CHAPTER
30
Face and scalp
small buccal mucous (salivary) glands. The buccal fat pad can be used
SKIN
to reconstruct small intraoral defects of the palate and buccal and retro
molar regions following surgery.
The scalp and buccolabial tissues are described here. The structure of
the eyelids is discussed on page 680. Lips
The lips are two fleshy folds surrounding the oral orifice. The centre of
SCALP
each lip contains a thick fibrous strand, consisting of parallel bundles
of skeletal muscle fibres (orbicularis oris, together with incisivus su
The scalp extends from the top of the forehead in front to the sup erior
perior and inferior, and the direct labial tractors), and their attachments
nuchal line behind. Laterally, it projects down to the zygomatic arch
to skin, mucosa or other muscle fibres. The free external surface of each
and external acoustic meatus. It consists of five layers: skin, subcutane
lip is covered by a thin keratinized epidermis, and is continuous with
ous tissue, occipitofrontalis (epicranius) and its aponeurosis, subap
the mucosa at the vermilion (red) zone of the lip. The dermis is well
oneurotic loose areolar tissue and periosteum of the skull (pericranium).
vascularized and contains numerous hair follicles (many of them large
The skin of the scalp is hairy and rich in sebaceous glands; it is the
in the male), sebaceous glands (Fordyce spots) and sweat glands. Sub
most common site for sebaceous cysts. The dense subcutaneous con
cutaneous adipose tissue is scanty. The internal mucous surfaces are
nective tissue has the richest cutaneous blood supply in the body. The
lined with a thick, nonkeratinizing, stratified squamous epithelium.
anterior and posterior muscular bellies of occipitofrontalis are con
The submucosa is well vascularized and contains numerous minor sal
nected by a tough, fibrous, epicranial aponeurosis, and this layer is
ivary glands, which may be harvested for histological confirmation of


therefore often called the aponeurotic layer (galea aponeurotica). These
Sjögren’s connective tissue disease.
three upper layers of the scalp can easily slide on the underlying layer
Between the skin and mucosa, the vermilion zone is covered with a
of loose connective tissue. A scalp flap can be raised within the plane
specialized keratinized stratified squamous epithelium, which is thin
between the galea and the pericranium without compromising either
near the skin, increases in thickness slightly as the mucosa is approached,
the blood or the nerve supply of the scalp because all of these structures
and then thickens abruptly when true mucosa is reached. The epithe
lie in the subcutaneous layer (superficial fascia). Anteriorly based sub
lium is covered with transparent, dead squames and its deep surface is
galeal scalp flaps (bicoronal) provide excellent access to the craniofacial
highly convoluted, interdigitating with abundant long dermal papillae.
skeleton for the correction of congenital deformity such as craniosyn
The latter carry a rich capillary plexus that imparts a dusky red colour.
ostoses; treatment of craniofacial fractures involving the frontal bone,
These surfaces are hairless, their dermis lacks sebaceous, sweat or
nasoethmoidal complex, orbit or zygomatic arch; skullbase surgery; or
mucous glands, and they are moistened with saliva by the tip of the
craniotomies. Pericranial flaps can be used to separate the frontal sinus
tongue. The dense innervation of the lips is reflected in their acute
floor from the nasal cavity in the management of fractures of the pos
sensitivity to light touch sensation, attributable mainly to the increased
terior wall of the frontal sinus (frontal sinus cranialization). Traumatic
density of Meissner’s corpuscles (see Fig 3.27) in the dermal papillae.
scalp avulsion may occur if hair becomes trapped in moving machinery
The size and curvature of the exposed redlip surfaces is subject to
or a shearing force is applied in the subgaleal plane during a road traffic
considerable individual, gender and ethnic variation. The attainment of
accident or fall injury.


adult dimensions is faster in the upper than in the lower lip; the cutane
The arterial blood supply to the scalp is particularly rich, and there
ous upper lip height normally reaches its adult size at the age of 3 years
are free anastomoses between branches of the occipital and superficial
in females and 6 years in males (Farkas et al 1992). In children, all lip
temporal vessels. Scalp lacerations continue to bleed profusely because
dimensions (distances, areas, volumes) are larger in boys than in girls
the elastic fibres of the underlying galea aponeurotica prevent initial
(Ferrario et al 2000). Upper lip length is significantly shorter in females
vessel retraction. Their repair requires a twolayer closure technique to
than in males and follows the growth pattern of the upper airway.
approximate the galea aponeurotica and skin layers. The pericranial
Growth plateaus between the ages of 6 and 9 years, increases again from
layer, if involved, cannot usually be closed because it retracts.
9 to 16 years, and plateaus between 16 and 18 years (Gonçalves
et al 2011).
The line of contact between the lips, the oral fissure, lies just above
EYEBROWS
the incisal edges of the anterior maxillary teeth. On each side, a labial
commissure forms the angle (corner) of the mouth, usually near the
The eyebrows are two arched eminences of skin that surmount the
first premolar tooth. The labial epithelia and internal tissues radiate
orbits. Numerous short, thick hairs are set obliquely in them. Fibres of
over the boundaries of the commissure to become continuous with
orbicularis oculi, corrugator and the frontal part of occipitofrontalis are
those of the cheek. With age, buccolabial (labiomarginal) grooves
inserted into the dermis of the eyebrows.
appear at the corners of the mouth. On each side, the upper lip is sepa
rated from the cheek laterally by the nasolabial groove and is continu
ous above the nasal ala with the circumalar groove (sulcus). The lower
BUCCOLABIAL TISSUE


lip is separated from the chin by the mentolabial groove (sulcus).
Externally, the central region of the upper lip presents a shallow
Cheeks
vertical groove, the philtrum, which is limited above by its attachment
to the columella of the nose, and ends below in a slight tubercle limited
The cheeks are continuous in front with the lips. The external junction by lateral ridges. The lower lip shows a small depression in the midline
is indicated by the nasolabial groove (sulcus) and further laterally by that corresponds to the tubercle. The junction between the external,
the nasolabial fold, which descends from the side of the nose to the hairbearing skin and the red, hairless surface of the upper lip almost
angle of the mouth. The cheek is covered on the outer surface by skin invariably takes the form of a doublecurved Cupid’s bow. From the
and on the inner surface by mucosa. Each cheek contains the buccinator centre, it rises rapidly on each side to an apex that corresponds to the
muscle, and a variable, but usually considerable, amount of adipose lower end of each ridge of the philtrum, and then slopes gently down
tissue, which is often encapsulated to form a biconcave mass, the buccal wards towards the angle of the mouth. The line of contact between the
fat pad (of Bichat), particularly evident in infants. The walls of the cheek redlip surfaces is typically almost horizontal. The Cupid’s bow is inter
also contain fibrous connective tissue, vessels, nerves and numerous rupted in cleft lip anomalies. 475