CHAPTER Head and neck: overview and
26
surface anatomy
This chapter contains an overview of the topographical anatomy of the lobes of the cerebral hemispheres and the cerebellum, respectively.
head and neck described in detail in Chapters 27–42, and an account Foramina in the bones of the skull base and facial skeleton transmit
of the clinically relevant surface anatomy. neurovascular bundles that may be compromised at these sites by
pathology or trauma.
The bony orbits contain the eyeballs, oculogyric muscles and lac-
SKIN AND FASCIA
rimal glands with their associated neurovascular supplies (Chs 41 and
42). The temporal bones contain the inner, middle and external ears
FACE AND SCALP (Chs 37 and 38). The maxillae are the largest of the pneumatized bones
of the midface; they contain the maxillary air sinuses and bear the upper
The superficial fascia of the scalp is firm, dense, fibroadipose, and teeth. The mandible bears the lower teeth and articulates with the tem-
closely adherent to the skin and to the underlying muscle, epicranius poral bones at the temporomandibular joints. The skull articulates with
and the epicranial aponeurosis. Posteriorly, the fascia is continuous the first cervical vertebra (atlas); movements of the skull on the cervical
with the superficial fascia of the back of the neck, and laterally it is vertebrae occur at the atlanto-occipital joints.
prolonged into the temporal region, where it is looser in texture. Three The skull provides attachments for many muscles, including all the
fascial layers (a subcutaneous fibroadipose tissue, a superficial musculo- craniofacial muscles, the oculogyric muscles, the muscles that act on
aponeurotic system (SMAS) and the parotid–masseteric fascia) are rec- the temporomandibular joint, the superior constrictor of the pharynx,
ognized on the face superficial to the plane of the facial nerve and its the muscles of the soft palate, all but one of the extrinsic muscles
branches. On the lateral side of the head, above the zygomatic arch, the of the tongue, the muscles of the suboccipital region, and the cranial


temporoparietal fascia lies in the same plane as, but does not blend attachments of trapezius and sternocleidomastoid.
with, the superficial musculo-aponeurotic system. It is superficial to the
temporal fascia and blends superiorly with the epicranial aponeurosis.
CERVICAL VERTEBRAE
The parotid gland is surrounded by a fibrous capsule derived from the
deep cervical fascia.
There are seven cervical vertebrae. They are the smallest of the movable
vertebrae and are characterized by a disproportionately large vertebral
NECK canal. All but the seventh are also characterized by a foramen in each
transverse process, the foramen transversarium (these foramina may be
The superficial cervical fascia is a zone of loose connective tissue absent or sometimes duplicated in the seventh cervical vertebra). The
between dermis and deep fascia, and is joined to both. It contains a first (atlas), second (axis) and seventh (vertebra prominens) cervical
variable amount of adipose tissue and platysma but is hardly dem- vertebrae are atypical.
onstrable as a separate layer. The deep cervical fascia is conventionally
subdivided into three sheets (superficial investing, middle and deep
HYOID BONE AND LARYNGEAL CARTILAGES
layers) that surround the muscles and viscera of the neck to varying
degrees, and the carotid sheath, a condensation of deep fascia around
the common and internal carotid arteries, internal jugular vein, vagus The hyoid bone lies in the midline at the front of the neck at the level
and ansa cervicalis. The fascial layers of the neck define a number of of the third cervical vertebra. It is suspended from the styloid processes
potential tissue ‘spaces’ above and below the hyoid bone (Ch. 31). In by the stylohyoid ligaments and gives attachment to the suprahyoid
health, the tissues within these spaces are either closely applied to each and infrahyoid groups of muscles. The skeletal framework of the larynx
other or are filled with relatively loose connective tissue. However, they is formed by a series of cartilages interconnected by ligaments and
offer potential routes by which unchecked infection may spread within fibrous membranes, and moved by a number of muscles (Ch. 35). The


the head and neck, and between the tissue spaces of the face and the laryngeal cartilages are the single cricoid, thyroid and epiglottic carti-
mediastinum. They also offer convenient planes for dissection during lages, and the paired arytenoid, cuneiform, corniculate and tritiate
surgery. cartilages.
BONES AND JOINTS MUSCLES
SKULL AND MANDIBLE The striated muscles of the head and neck produce the movements
of the facial soft tissues that animate so many aspects of communica-
The skull is composed of 28 separate bones, most of them paired (Ch. tion; the movements at the temporomandibular joint that occur during
27). It can be divided into the cranium, consisting of the calvaria (brain mastication and speech (Ch. 32); the conjugate movements of the
box) and basicranium, which together surround and protect the brain; eyeballs; and the coordinated movements that occur during activities
a delicate facial skeleton composed mainly of thin-walled bones, some such as swallowing, speaking and turning the head in response to
of which contain air-filled cavities that are known collectively as the visual and/or auditory stimuli. The ‘extrinsic’ muscles that run between
paranasal sinuses; and the mandible. The cranial cavity contains the the axial skeleton and upper limb act on the scapula and humerus
brain and the intracranial portions of the cranial nerves; the blood (Ch. 48).
vessels that supply and drain the brain and the haemopoietic marrow The superior tarsal muscle, sphincter and dilator pupillae and the
of the overlying bones; the meninges (dura, arachnoid and pia mater); ciliary muscle are composed of smooth muscle (Chs 41 and 42).
and the cerebrospinal fluid in the subarachnoid space. The cavity is
incompletely divided by dural partitions, notably the falx cerebri, lying
VASCULAR SUPPLY AND LYMPHATIC DRAINAGE
between the cerebral hemispheres, and the tentorium cerebelli, lying
between the cerebellum and occipital lobes. Almost all of the venous
blood from the brain and cranial bones drains via sinuses lying between ARTERIES


the endosteal and meningeal layers of the dura mater into the internal
jugular vein. Internally, the cranial base is divided into anterior, middle The main arterial supply of the head and neck is derived from branches
404 and posterior cranial fossae, which contain the frontal and temporal of the carotid and subclavian arteries (Figs 26.1–26.2). Branches of the


Vascular supply and lymphatic drainage
405
62
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Fig . 26 .1 An overview of the superficial
arteries of the head and neck .
Frontal branch of
superficial temporal artery
Middle branch of
superficial temporal artery
Supratrochlear artery
Supraorbital artery Parietal branch of
superficial temporal artery
Zygomaticotemporal artery
Zygomatico-orbital artery
Zygomaticofacial artery Superficial temporal artery
Transverse facial artery
Angular artery
Posterior auricular artery
Infraorbital artery
Occipital artery
Buccal artery Maxillary artery
Sternocleidomastoid branch of
Superior labial artery occipital artery
Inferior alveolar artery
Inferior labial artery External carotid artery
Vertebral artery
Facial artery
Internal carotid artery
Mental artery
Ascending pharyngeal artery
Lingual artery
Superior thyroid artery
Deep cervical artery
Ascending cervical artery
Common carotid artery Superficial cervical artery
Inferior thyroid artery
Superior intercostal artery
Transverse cervical artery
Thyrocervical trunk Costocervical trunk
Suprascapular artery
Deep branch of
Left subclavian artery transverse cervical artery
Internal thoracic artery (dorsal scapular artery)
Fig . 26 .2 An overview of the deep
Right middle arteries of the head and neck .
meningeal artery
Right middle cerebral artery
Left and right posterior
Left middle cerebral artery
communicating arteries
Anterior communicating artery Middle cranial fossa
Anterior cranial fossa Left posterior cerebral artery
Left and right anterior
Left posterior cerebellar artery
cerebral arteries
Supraorbital artery Basilar artery
Supratrochlear artery Meningeal artery
(from occipital artery)
Ophthalmic artery
Posterior cranial fossa
Infraorbital artery Internal carotid artery
Sphenopalatine artery
Meningeal branch of
Anterior superior alveolar artery vertebral artery
Posterior superior Vertebral artery
alveolar artery Maxillary artery
Buccal artery Occipital artery
External carotid artery
Internal carotid artery
Mental artery
Ascending pharyngeal artery
Inferior alveolar artery
Facial artery
Lingual artery
Superior thyroid artery Deep cervical artery
Common carotid artery


Superior intercostal artery
Vertebral artery Costocervical trunk
Left subclavian artery


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4
NOITCES
internal carotid and vertebral arteries anastomose in the circle of Willis Subclavian artery
within the interpeduncular cistern on the ventral aspect of the brain
(Ch. 19).
The subclavian arteries give off several branches that supply structures
in the head and neck. The vertebral arteries supply the upper spinal
Carotid system
cord, brainstem, cerebellum and occipital lobe of the cerebrum. They
pass through the foramina transversaria of the first six cervical vertebrae,
The cervical portion of the common carotid artery is similar on both enter the cranial cavity through the foramen magnum and unite at the
sides. Each lies within the carotid sheath of deep cervical fascia, together lower border of the pons to form the basilar artery (hence this system
with the internal jugular vein and vagus nerve. In the lower part of the is often called the vertebrobasilar system). Branches from the thyro-
neck, the arteries are separated by a narrow gap that contains the cervical trunk supply the inferior poles of the thyroid gland and the
trachea, and higher up they are separated by the thyroid gland, larynx parathyroid glands, the larynx and the pharynx, and branches from the
and pharynx. At the level of the upper border of the thyroid cartilage costocervical trunks supply deep cervical muscles.
(C4), the common carotid artery bifurcates into external and internal
carotid arteries (see below). The external carotid artery passes upwards
on either side of the neck, inclined at first slightly forwards and then VEINS
backwards and a little laterally. It usually gives off the ascending
pharyngeal, superior thyroid, lingual, facial, occipital and posterior The veins of the neck lie superficial or deep to the deep investing fascia.
auricular arteries, and then enters the parotid salivary gland where it Superficial veins ultimately drain into either the external, anterior or
divides into its terminal branches, the superficial temporal and maxil- posterior external jugular veins; they drain a much smaller volume of


lary arteries. The branches of the external carotid artery supply the face, tissue than the deep veins. Deep veins tend to drain into either the
scalp, tongue, upper and lower teeth and gingivae, palatine tonsil, para- internal jugular vein or the subclavian vein. The internal jugular vein
nasal sinuses and nasopharyngeal tube, external and middle ears, drains blood from the skull, brain, superficial face and much of the
pharynx, larynx and superior pole of the thyroid gland. They also anas- neck. It descends in the neck within the carotid sheath and unites with
tomose with branches of the internal carotid arteries on the scalp, the subclavian vein behind the sternal end of the clavicle to form the
forehead and face, in the orbit, nasopharynx and nasal cavity, and with brachiocephalic vein (Figs 26.3–26.4). At its junction with the internal
branches of the subclavian artery in the pharynx, larynx and thyroid jugular vein, the left subclavian vein usually receives the thoracic duct,
glands. and the right subclavian vein receives the right lymphatic duct.
The internal carotid artery supplies most of the ipsilateral cerebral
hemisphere, eye and accessory organs, the forehead and, in part, the
external nose, nasal cavity and paranasal sinuses. It passes up the neck LYMPHATIC DRAINAGE
anterior to the transverse processes of the upper three cervical vertebrae
and enters the cranial cavity via the carotid canal in the petrous part of Lymph nodes in the head and neck are arranged in two horizontal rings
the temporal bone. The artery has no branches in the neck and so is and two vertical chains on either side of the neck (Fig. 26.5). The outer,
easily distinguishable from the external carotid artery, should the latter superficial, ring consists of the occipital, preauricular (parotid), sub-
require ligation, e.g. to control haemorrhage from a penetrating injury mandibular and submental nodes, and the inner, deep, ring is formed
to the neck. by clumps of mucosa-associated lymphoid tissue (MALT) located
Fig . 26 .3 An overview of the superficial veins
of the head and neck .


Frontal branch of
superficial temporal vein
Supratrochlear vein
Supraorbital vein Parietal branch of
superficial temporal vein
Zygomaticotemporal vein
Transverse facial vein
Superficial temporal vein
Zygomaticofacial vein
Emissary vein in mastoid
Angular vein foramen
Infraorbital vein Pterygoid plexus
Buccal vein Occipital vein
Maxillary vein
Deep facial vein
Posterior auricular vein
Superior labial vein
Facial vein Retromandibular vein
Common facial vein
Lingual vein
Inferior labial vein
Superior thyroid vein
Anterior jugular vein
Middle thyroid vein
Internal jugular vein
External jugular vein
Inferior thyroid vein Superficial cervical vein
Suprascapular vein
Left brachiocephalic vein Subclavian vein


Innervation
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Superior cerebral veins Fig . 26 .4 An overview of the deep veins of the head
and neck .
Superior sagittal sinus
Inferior sagittal sinus
Basilar venous plexus Falx cerebri
Anterior and posterior
intercavernous sinuses Tentorium cerebelli
Great cerebral vein
Superior petrosal sinus
Sphenoparietal sinus
Straight sinus
Superior ophthalmic vein
Cavernous sinus Transverse sinus
Inferior ophthalmic vein Confluence of sinuses
Inferior petrosal sinus
Angular vein Occipital sinus
Maxillary sinus Sigmoid sinus
Pterygoid plexus Left internal jugular vein
Occipital vein
Deep facial vein
Maxillary vein
Vertebral venous plexus
Retromandibular vein
Inferior alveolar vein
Common facial vein
Facial vein
Superior thyroid vein
External palatine vein
Internal jugular vein
Deep cervical vein
Vertebral veins
External jugular vein (cut) Highest intercostal vein
Transverse cervical vein
primarily in the nasopharynx and oropharynx (Waldeyer’s ring). The and thorax, and enters the abdominal cavity by passing through the
vertical chain consists of superior and inferior groups of nodes related diaphragm with the oesophagus.
to the carotid sheath. All lymph vessels of the head and neck drain into
the deep cervical nodes, either directly from the tissues or indirectly via Reflexes
nodes in outlying groups. Lymph is returned to the systemic venous
circulation via either the right lymphatic duct or the thoracic duct.
A number of reflexes involving structures in the head and neck are
mediated by sensory and motor branches of certain of the cranial
nerves, coordinated via appropriate nuclei in the brainstem. They
INNERVATION
include swallowing, gagging, retching and vomiting, sneezing and
coughing; lacrimation; jaw jerk; visual reflexes (pupillary light reflex
CRANIAL NERVES
and accommodation); and the corneal ‘blink’ reflex and the stapedial
reflex. Reflexes that involve energetic exhalation, e.g. sneezing and
There are 12 pairs of cranial nerves. They are individually named and coughing, also involve the recruitment of cervical and thoracic spinal


numbered (using Roman numerals) in a rostrocaudal sequence (see neurones to mediate the coordinated contraction of intercostal and
Table 16.1). Some are functionally mixed, others are either purely abdominal wall muscles that this activity requires.
motor or purely sensory, and some also carry pre- or postganglionic
parasympathetic fibres that are secretomotor to the salivary and lacrimal
glands or motor to the smooth muscle within the eyeball and orbit. SPINAL NERVES
Branches of the oculomotor, trochlear, trigeminal, abducens, facial,
glossopharyngeal, vagus, accessory and hypoglossal nerves supply There are eight pairs of cervical spinal nerves (Fig. 26.6). Cutaneous
muscle groups within the eyeball, face, neck, pharynx, larynx and branches of the dorsal rami of the second, third, fourth and fifth cervical
tongue. Branches of the trigeminal, glossopharyngeal and vagus nerves nerves innervate the scalp and the skin over the back of the neck, and
transmit general sensory information from the skin of the face and part motor branches of all of the cervical dorsal rami supply cervical post-
of the scalp; the epithelium lining the oral and nasal cavities, the para- vertebral muscles. All of the cervical ventral rami supply anterior and
nasal sinuses, middle ear, pharynx and larynx, and the dorsal surface of lateral groups of prevertebral muscles. The upper four cervical ventral
the tongue and the cornea; the intracranial meninges; and the perios- rami form the cervical plexus, whose branches collectively innervate the
teum and bones of the skull. Branches of the trigeminal nerve innervate infrahyoid strap muscles and the diaphragm, and the skin covering the
the temporomandibular joint. The olfactory, optic, trigeminal, facial, lateral and anterior parts of the neck, and the angle of the mandible.
vestibulo cochlear and vagus nerves contain axons that transmit the The lower four cervical ventral rami, together with most of the first
special sensations of olfaction, vision, hearing, balance and taste. The thoracic ventral ramus, form the brachial plexus.


olfactory nerve is the only sensory cranial nerve that projects directly to
the cerebral cortex rather than indirectly via the thalamus (Ch. 25). The
optic nerve terminates in the thalamus (Ch. 23). The other ten pairs of PARASYMPATHETIC NERVES
cranial nerves are attached to the brainstem or, in the case of the acces-
sory nerve, to the upper cervical spinal cord; their component fibres In the head and neck, the parasympathetic system innervates the sal-
arise from or terminate in named cranial nerve nuclei. The cranial ivary and lacrimal glands, the mucous glands of the oral and nasal
nerves pass through named foramina in the skull, often with named cavities and paranasal sinuses, and the sphincter pupillae and ciliary
vessels. muscles in the eyeball. Many thousands of preganglionic parasympa-
With one exception, all of the cranial nerves are confined to the head thetic axons travel in the vagus from cell bodies in the dorsal motor
and neck. The exception is the vagus, which travels through the neck nucleus of the vagus in the medulla. Although they travel through the


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4
NOITCES
Mastoid group
Parotid group
Stylohyoid
Retropharyngeal group
1
Facial group 1
Occipital group
2
1 2
Sternocleidomastoid
Submandibular
3 3
group
4 1 Superior jugular group
Sublingual group
Midjugular group
Submental group 4 2 Splenius capitis
1
Digastric, 1 2 5 2 3 1 Scalenus anterior
anterior belly 3
Scalenus medius
Lateral
Sternohyoid
cervical
Spinal accessory
group
(posterior triangle)
Omohyoid 1
Phrenic nerve group
Thyroid cartilage 2 Scalenus posterior
Inferior jugular group Carotid sinus
Thyroid gland Transverse cervical
(supraclavicular) group
Internal jugular vein
3 Trapezius
Anterior cervical group
Sternocleidomastoid Clavicle
Facial group 1. Malar Submandibular 1. Preglandular Retropharyngeal 1. Lateral
2. Infraorbital group 2. Prevascular group 2. Medial
3. Buccinator 3. Retrovascular
4. Inferior maxillary 4. Retroglandular
5. Intracapsular
Parotid group 1. Subfacial, extraglandular Submental 1. Anterior Anterior 1. Superficial anterior jugular chain
2. Deep intraglandular group 2. Middle cervical group 2. Prelaryngeal
3. Suprafacial 3. Posterior 3. Pretracheal
Fig . 26 .5 An overview of the lymph nodes of the head and neck .
neck in the right and left vagi, they are destined for pulmonary, cardiac, Some preganglionic fibres may synapse around cells in the hilum of
oesophageal, gastric and intestinal targets; they synapse in minute the submandibular gland. Stimulation of the chorda tympani dilates


ganglia in the walls of the viscera and do not innervate structures in the the arterioles in both glands, as well as having a direct secretomotor
head and neck. effect.
There are four pairs of parasympathetic ganglia in the head, named
ciliary, pterygopalatine, otic and submandibular (Fig. 26.7). Pterygopalatine ganglion
Ciliary ganglion
Preganglionic axons travel in the greater petrosal branch of the facial
nerve and the nerve of the pterygoid canal, and relay in the pterygo-
Preganglionic axons originate in the Edinger–Westphal preganglionic palatine ganglion. Postganglionic secretomotor axons innervate secre-
nucleus of the midbrain (Ch. 21). They travel via a branch of the ocu- tory acini and blood vessels in the palatine, pharyngeal and nasal
lomotor nerve (nerve to the inferior oblique) to the ciliary ganglion, mucosa via the palatine and nasal nerves, but whether they also inner-
where they synapse. Postganglionic fibres travel in the short ciliary vate the lacrimal gland via the zygomatic and zygomaticotemporal
nerves, which pierce the scleral coat of the eyeball and run forwards in branches of the maxillary nerve, as was once thought, is less certain. It
the perichoroidal space to enter the ciliary muscle and sphincter pupil- is likely that postganglionic orbital branches, carrying a mixture of
lae. Their activation mediates accommodation of the eye to near objects postganglionic parasympathetic and somatic sensory axons, pass
and pupillary constriction. through the inferior orbital fissure and innervate the lacrimal gland
and ophthalmic artery directly. Some axons pass into the cranial cavity
Submandibular ganglion via the ethmoidal vessels to innervate the choroid; the pterygopalatine
ganglion is believed to be the main source of parasympathetic input to
the choroid.
Preganglionic axons originate in the superior salivatory nucleus. They
emerge from the brainstem in the nervus intermedius and leave the
Otic ganglion


main facial nerve trunk in the middle ear to join the chorda tympani,
which subsequently joins the lingual nerve. In this way, they reach the
submandibular ganglion, where they synapse. Postganglionic fibres Preganglionic axons originate in the inferior salivatory nucleus
innervate the submandibular, sublingual and lingual salivary glands; and travel in the glossopharyngeal nerve and its tympanic branch.
some axons presumably re-enter the lingual nerve to access the lingual They traverse the tympanic plexus and lesser petrosal nerve, and pass
glands, while others pass directly along blood vessels to enter the sub- through the foramen ovale to reach the otic ganglion, where they
mandibular and sublingual glands. synapse. Postganglionic fibres pass by communicating branches to the


Surface anatomy
409
62
RETPaHC
Suture lines can be palpated as irregular ridges. The anterior fontanelle,
at the junction of the coronal and sagittal sutures, may be palpated
C1
Hypoglossal up to 18 months after birth. The mastoid process is palpable medial to
the lobule of the pinna. Deep palpation immediately antero inferior to
C2 the mastoid apex reveals the relatively indistinct resistance offered by
the styloid process and associated soft tissues, and postero inferior pal-
Cervical Lesser occipital pation reveals the firm mass of the transverse process of atlas (C1). The
plexus Hypoglossal external occipital protuberance (inion) is a palpable bony protuberance
C3 located on the posterior midline of the occipital bone. The confluence
Great auricular
of the dural venous sinuses sits mainly to the upper right side of the
inion (Sheng et al 2012). The superior nuchal lines are palpable passing
laterally from the inion. The asterion can be palpated as a slight depres-
C4 sion 1–2 cm behind the pinna at a level approximately at the junction
of the upper third and lower two-thirds of the pinna. It marks the junc-
tion of the occipitomastoid, parietomastoid and occipitoparietal
sutures, and is commonly employed to define the location of transverse–
C5 Dorsal scapular sigmoid sinus junction (Day and Tschabitscher 1998), although it does
not always do so (Sheng et al 2012).
Phrenic
Supraclavicular Mandible
C6 The mental tubercles are palpable on the anterior chin, and the man-
Brachial
plexus dibular body, alveolar processes and teeth are palpable through the
cheek. The lower border of the mandible can be traced to the angle at
C7 Axillary vertebral level C2. The mental foramen, which transmits the mental
nerve and vessels, gradually migrates posteriorly after birth and through
childhood (Balcioglu et al 2011). In adults, it lies an average of 2.5 cm


from the midline face (Udhaya et al 2013), between the root apices of
C8 mandibular teeth 4 and 5 (range: teeth 3–6) (Fishel et al 1976, von Arx
et al 2013, Udhaya et al 2013). Most foramina usually sit either level
Radial with or inferior to the tooth root apex (Fishel et al 1976), and accessory
T1 mental foramina, if present, are mainly situated posterior or inferior to
the main foramen (Katakami et al 2008). The mandibular foramen sits
Median
on the medial surface of the ramus an average of 1.9 cm posterior to
T2 the third molar (Nicholson 1985); a 21 mm needle is therefore suffi-
Ulnar cient to reach the foramen for dental anaesthesia (Menke and Gowgiel
1979). The foramina almost always (Mbajiorgu and Ekanem 2000,
Nicholson 1985) sit level with or below the occlusal plane, the remain-
Fig . 26 .6 An overview of the nerves forming the cervical and brachial der sitting above.
plexuses . (With permission from Waschke J, Paulsen F (eds), Sobotta The mandibular ramus is largely covered by masseter and the parotid
Atlas of Human Anatomy, 15th ed, Elsevier, Urban & Fischer . Copyright gland. Its posterior border is palpable through the parotid up to the
2013 .) neck of the mandibular condylar process, which lies anterior to the
lower tragus/intertragal notch of the pinna. Movement of the condylar
head at the temporomandibular joint is palpable anterior to the tragus
during mouth opening/closing. The coronoid process is palpable an-
auriculotemporal nerve, which conveys them to the parotid gland. terior to the condylar process through the buccal mucosa.
Stimulation of the lesser petrosal nerve produces vasodilator and se-
cretomotor effects. Face
The lateral aspect of the face, from above downwards, consists of the
temporal region, cheek and lower jaw (Ch. 30). The temporal region
SYMPATHETIC NERVES


lies in front of the external ear and above the zygomatic arch. It is
demarcated superiorly and posteriorly by the palpable superior tem-
In the neck, the sympathetic trunk lies behind and medial to the carotid poral line, anteriorly by the frontal process of the zygoma, and inferi-
sheath and anterior to the transverse processes of the cervical vertebrae orly by the zygomatic arch. The palpable zygomatic arch is formed by
and the prevertebral muscles. There are usually three cervical ganglia on the zygomatic process of the temporal bone posteriorly and the tem-
each side – superior, middle and inferior (cervicothoracic); they may poral process of the zygomatic bone anteriorly, both of which articulate
be connected by a solid trunk or by two or three fibrous strands. The via the palpable zygomaticotemporal suture. The variable prominence
ganglia receive preganglionic fibres from neurones whose cell bodies of the ‘cheekbone’ (zygoma) is largely attributable to the shape of the
lie in the intermediolateral column of the upper thoracic spinal cord; body of the underlying zygomatic bone. The sharp posterior margin of
there is no preganglionic output from the cervical spinal cord. Postgan- the frontal process of the zygomatic bone can be palpated superiorly
glionic fibres reach their target tissues in the head and neck via the cervi- to its articulation with the zygomatic process of the frontal bone at the
cal spinal nerves and perivascular nerve plexuses distributed along the palpable zygomaticofrontal suture. From here, the superior temporal
carotid and vertebral arteries (see Fig. 26.7). line can be palpated passing posteriorly in the line of a gentle curve.
The lower temporal line terminates by curving downwards and forwards
to end just above the root of the mastoid process as the supramastoid
SURFACE ANATOMY
crest on the squamous part of the temporal bone. The suprameatal
triangle overlies the lateral wall of the mastoid (tympanic) antrum and
SURFACE ANATOMY OF THE HEAD
is demarcated superiorly by the palpable supramastoid crest (a palpable
ridge of bone posterior to the upper pinna), anteroinferiorly by the


Skeletal landmarks posterosuperior margin of the external acoustic meatus, and posteriorly
by a vertical line through the posterior border of the external acoustic
The palpable bony landmarks of the head can be examined from the meatus. The lateral/Sylvian fissure of the brain aligns with the anterior
back, sides and front (Figs 26.8–26.9). The pericraniocervical line, part of squamosal suture in a zone 2.5–4.0 cm anterior to the external
which demarcates the head from the neck, runs from the midpoint of acoustic meatus (Rahmah et al 2011). The pterion represents the junc-
the chin anteriorly to the external occipital protuberance posteriorly. tion of the frontal, sphenoid, parietal and temporal sutures within the
temporal fossa. It is situated within a 1 cm diameter circle centred
Calvaria
approximately 2.6 cm posterior and 1.3 cm superior to the postero-
Most of the superficial aspect of the calvaria is covered by skin, subcu- lateral margin of the zygomaticofrontal suture (Ma et al 2012). Alter-
taneous tissue and thin muscles; many bony prominences and surfaces natively, the pterion is located approximately 4 cm above the midpoint
are therefore palpable through the hair and are visible in bald people. of the zygomatic arch (Ukoha et al 2013). It usually marks the position


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4
NOITCES
Fig . 26 .7 An overview of the
Supraorbital nerve visceral efferent pathways in the
Short ciliary nerves
head . (Adapted from Drake RL,
Long ciliary nerves
Vogl AW, Mitchell A (eds), Gray’s
Ciliary ganglion
Oculomotor nerve Anatomy for Students, 2nd ed,
Lacrimal Lacrimal nerve Ophthalmic nerve Elsevier, Churchill Livingstone .
gland Communicating branch Maxillary nerve Copyright 2010 .)
Trigeminal nerve
Zygomaticotemporal
nerve Mandibular nerve
Greater petrosal nerve
Facial nerve
Lesser petrosal nerve
Nasociliary nerve Tympanic plexus
Zygomatic nerve Glossopharyngeal
Infraorbital nerve
nerve
Greater petrosal nerve
Pterygopalatine Nerve of
ganglion pterygoid canal
Tympanic
Glands in nasal cavities, Deep petrosal nerve nerve
palate and paranasal sinuses Palatine nerve Inferior
ganglion
Otic ganglion Auriculo-
temporal
nerve
Internal
Lingual nerve Chorda carotid
tympani
Internal plexus
carotid
artery Parotid gland
Submandibular ganglion Internal
carotid
External carotid artery
Sublingual gland nerve
Submandibular
gland Facial artery Superior cervical
ganglion
Preganglionic parasympathetic
Postganglionic parasympathetic Sympathetic trunk
Preganglionic sympathetic
Postganglionic sympathetic
of the anterior (frontal) branch of the middle meningeal artery, with frontozygomatic suture between them may be palpated as a depression.
the remainder of arteries sitting immediately posterior (Ma et al 2012) Approximately 1 cm below this suture, a tubercle (Whitnall’s) may be
(Ch. 28). Knowledge of middle meningeal artery surface anatomy is palpated within the orbital opening; it gives attachment to the lateral
important for accurate positioning of burr-holes to evacuate extradural palpebral and check ligaments. The inferior border of the orbit is


haematomas. The posterior (parietal) arterial branch runs backwards formed by the zygomatic bone laterally and the maxilla medially. It
and parallel with the upper border of the zygomatic arch and is usually blends into the medial margin, which is less obvious, and is formed
exposed vertically above the mastoid process on a level horizontal with above by the frontal bone and below by the lacrimal crest of the frontal
the upper margin of the orbit. The asterion is a craniometric point at process of the maxilla. A shallow fossa behind the lower part of the
the site of the posterolateral, or mastoid, fontanelle. It is found at the medial wall houses the lacrimal sac. The anterior lacrimal crest is a
junction of the lambdoid, occipitomastoid and parietomastoid sutures. guide to the location of the anterior ethmoidal artery, which may occa-
It has been used as a landmark in lateral approaches to the posterior sionally require ligation to control severe epistaxis, and which lies
fossa as it defines the superior limit of bone removal for the craniec- approximately 2.4 cm posterior to the crest. The optic canal lies approx-
tomy. However, the asterion almost always sits over the junction imately 4.5 cm posterior to the infraorbital margin (approximately
between the transverse and sigmoid sinuses, or sometimes inferior to 4.2 cm from the anterior lacrimal crest); these distances are important
the sinus junction (Sheng et al 2012). in orbital floor exploration in order to avoid optic nerve injury. The
The forehead extends from the hair margin of the scalp to the eye- inferior orbital fissure lies approximately 2 cm posterolateral to the
brows. The rounded frontal tuberosity may be felt approximately 3 cm infraorbital margin; it does not contain any important structures and
above the midpoint of each supraorbital margin. The superciliary arch therefore surgery can be performed safely in this region. The infraorbital
is usually palpable above the orbit and is better marked in the male foramen, which transmits the infraorbital nerve and vessels, lies below
than the female. The glabella, a small horizontal ridge, is easily palpable the middle of the infraorbital margin. It commonly aligns with a verti-


between the superciliary arches. Below the glabella, the nasal bones cal axis passing through maxillary tooth 5 (Raschke et al 2013) and sits
meet the frontal bone in a small depression, the nasion, at the root of an average of 2.5 cm (range 1.8–3.3 cm) from the midline face and
the nose. With a little finger inserted into the nostril, the bony margins 6.4 mm (range 3.2–12.1 mm) below the inferior orbital margin, with
of the anterior nasal aperture can be felt; they are formed by the inferior differences noted between genders and side (Chrcanovic et al 2011,
border of the nasal bone, the sharp margins of the nasal notch, and the Raschke et al 2013). In neonates, the infraorbital nerve is located
coapted nasal spines of the maxillae (Ch. 33). approximately half-way along a line drawn from the angle of the mouth
The orbital opening is relatively quadrangular and its margins pal- to the midpoint of the palpebral fissure (Bosenberg and Kimble 1995).
pable (Ch. 41). The supraorbital margin is formed entirely by the The anterior surface of the maxilla is extensive and may be palpated
frontal bone. The supraorbital foramen/notch can be palpated along between the infraorbital margin and the alveolar processes that bear the
the superomedial orbital margin and sits an average of 2.7 cm (range upper teeth. The canine eminence overlies the roots of the canine tooth
1.8–4.3 cm) from the midline face (Chrcanovic et al 2011). Foramen and separates the incisive fossa anteriorly from the deeper canine fossa
position can vary with gender, race, side and climatic origin (Chrcanovic posteriorly. The bone of the canine fossa is thin and may be removed
et al 2011, Tomaszewska et al 2012). This notch/foramen transmits the easily to access the maxillary sinus via an intraoral approach as part
supraorbital nerve and vessels, and pressure exerted here with the fin- of a Caldwell–Luc procedure. The palatine process of the maxilla


gernail can be painful. An additional notch may be found more towards and palatine bone form the palpable roof of the mouth. The incisive/
the bridge of the nose; it transmits the supratrochlear neurovascular nasopalatine foramen sits in the midline palate, immediately posterior
bundle. to the incisive papilla approximately 7.4 mm from the labial surface of
The lateral margin of the orbit consists of the frontal process of the the alveolar ridge (Mraiwa et al 2004) and transmits the sphenopalatine
zygomatic bone and the zygomatic process of the frontal bone. The artery and nasopalatine nerve. The greater palatine foramen, which


Surface anatomy
411
62
RETPaHC
1
4
2
1 3
5 3
2
X
6
5
7
4
X 6
X
8 X 8 7
9 X
9 10
11
X
12
10 11
13
A
14
B
Fig . 26 .8 The lateral aspect of the head and neck . A, Pterion, meningeal arteries, carotid bifurcation, mental and mandibular foramen . Key: 1, anterior
branch of the middle meningeal artery: sits deep to the pterion in over half of subjects; 2, zone of location of the pterion: in a 1 cm diameter circle
centred 2 .5 cm posterior and 1 .5 cm superior (black arrows) to the frontozygomatic suture; 3, lateral (Sylvian) fissure: aligns anteriorly with the anterior
part of the squamosal suture in a zone approximately 3 cm anterior to the external acoustic meatus; 4, mastoid line; 5, posterior branch of the middle
meningeal artery: runs parallel to the zygomatic arch and sits level with the supraorbital margin on the mastoid line; 6, asterion: sits almost always over
or sometimes just below (black arrow) the transverse–sigmoid sinus junction; 7, suprameatal triangle; 8, occlusal plane; 9, zone of location (white) of the
mandibular foramen: in the majority of cases, the foramen sits level with or below the occlusal plane (8), an average of 2 cm posterior to tooth 8; 10,
zone of location (white) of the mental foramen: the foramen commonly sits between the roots of teeth 4 and 5 (range 3–6), usually level with or inferior to
the tooth root apex; X (green), transverse process of C1 (atlas); X (blue), transverse process of C2 (axis); 11, zone of location (white) of the bifurcation of
the common carotid artery: usually above the level of the thyroid lamina; X (red), most common level of common carotid bifurcation (C3) . B, Parotid


gland and duct, CN VII & XI, cutaneous branches of cervical plexus and internal jugular vein . Key: 1, porion line; 2, zygomatic sutural line; 3, zone of
location of the (fronto)temporal nerve; 4, parotid gland; 5, zone of location (white) of the parotid duct (green line): sits within 1 .5 cm of the middle half of
a line passing from the lower tragus to the chelion; 6, lower tragus–chelion line; 7, marginal mandibular nerve; 8, zone of emergence of the cutaneous
branches of the cervical plexus (white), posterior to the middle third of sternocleidomastoid; 9, zone of location of the accessory nerve, from 3–10 cm
below the tip of the mastoid process to 1–10 cm above the insertion of trapezius into the clavicle; 10, hyoid bone; 11, thyroid cartilage (laryngeal
prominence); 12, cricothyroid ligament/membrane; 13, cricoid cartilage; 14, external jugular vein; X (blue), angle of the mandible; X (red), facial artery and
anterior border of masseter crossing the lower border of the mandible; X (orange), superficial temporal artery . (Adapted from Drake RL, Vogl AW, Mitchell
A, et al (eds), Gray’s Atlas of Anatomy, Elsevier, Churchill Livingstone . Copyright 2008 .)
transmits the greater palatine artery and nerve, is commonly located in frenulum at its point of intersection with the sublingual mucosal folds.
the region medial to maxillary tooth 8 (range: from level with tooth 7 The lingual nerve often passes close to the lingual side of the root of
to distal to tooth 8 (Sujatha et al 2005, Jaffar and Hamadah 2003) mandibular tooth 8 (Behnia et al 2000), and can sit posteriorly on the
approximately 16 mm from the midline (Wang et al 1988). retromolar ridge (Pogrel and Goldman 2004).
Soft tissues and viscera Parotid gland
The parotid gland is soft and indistinct to palpation. The sup erior


The muscular, fatty and cutaneous features that so clearly differentiate border sits inferior to the zygomatic arch and passes from the mandibu-
individuals are readily apparent on inspection. The external features of lar condyle towards masseter. The anterior border passes inf eriorly
the eyelids and eyebrows are described on page 680 and page 475, along the posterior border of masseter, often overlying its lateral surface,
respectively. The tympanic membrane may be examined under direct then over the mandibular angle to meet the anterior border of sterno-
vision using an auroscope and is described on page 633. The retinal cleidomastoid, approximately 2 cm posteroinferior to the angle. The
vascular supply may be examined directly by ophthalmoscopy. posterior border corresponds to a curve traced from the mandibular
Temporalis is palpable if the flat of the hand is placed over the tem- condyle to the mastoid process. The deep part of the gland lies within
poral region and the jaw is clenched and relaxed. The anterior border the prestyloid part of the parapharyngeal space. Tumours arising in this
of masseter is palpable and prominent when the jaw is clenched. The region present with medial displacement of the soft palate and tonsil.
masseter is thicker in boys than in girls in both the relaxed and con- The parotid duct arises from the anterior margin of the gland and can
tracted state (Charalampidou et al 2008). With the mouth open, it is be palpated on the anterior border of a clenched masseter. It passes
possible to examine the teeth, gingiva, tongue and the palatine tonsils along, or within 1.5 cm of, the middle half of a line drawn from the
lying between the faucial (palatine) arches formed by palatoglossus lower border of the tragus to the chelion (a bilateral landmark located
(anterolaterally) and palatopharyngeus (posteromedially). Peritonsillar at the outermost corner of the mouth where the upper and lower lips
abscess (quinsy) can cause ipsilateral tonsillar enlargement with con- meet) (Stringer et al 2012) (see Fig 26.8B). The duct runs over masseter


tralateral displacement of the uvula, and parapharyngeal tumours also to its anterior border, and then bends sharply and pierces the underly-
displace the ipsilateral tonsil and palate medially. The openings of the ing buccinator and buccal mucosa opposite maxillary tooth 7, where
submandibular gland ducts can be seen on either side of the lingual the duct orifice is visible and palpable. Duct cannulation is required for


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4
NOITCES
sialography, ductal dilation and basket retrieval of ductal stones
(sialoliths).
Pulses
The facial artery can be palpated as it crosses the lower mandibular
border immediately anterior to masseter and on the face approximately
1 cm lateral to the angle of the mouth. The superficial temporal artery
is palpable immediately anterior to the tragus of the pinna. The artery
divides into frontal and parietal branches approximately 2.5 cm above
1 the zygomatic arch.
Facial nerve
The facial nerve may be injured in its extratemporal course as a result
of facial trauma and laceration, or iatrogenically during surgery involv-
2 ing the parotid or submandibular glands or the temporomandibular
joint, or during facelift procedures. Knowledge of the topographical and
surgical landmarks is therefore essential if the nerve is to be preserved
3 during surgery.
The nerve exits the skull at the stylomastoid foramen and so is ini-
tially deep to the posterior margin of the external acoustic meatus; the
nerve trunk lies approximately 1 cm inferomedial to the tip of the tragal
pointer, and runs anterior to the mastoid apex and C1 transverse
process, within 9 mm and 14 mm, respectively (Greyling et al 2007).
It usually divides within the parotid gland into five main branches that
4
radiate across the face (Fig. 26.10; see Fig. 30.24). Cadaveric and intra-
operative microdissection studies have revealed that the course of its
branches is highly variable and therefore surface coordinates only
approximate their trajectory. The temporal/frontotemporal branches
emerge from the superior surface of the parotid, cross the zygomatic
arch and travel towards the pterion and the superolateral brow. The
Fig . 26 .9 The anterior aspect of the face . Key: 1, zone of supraorbital majority pass in the zone between two lines: line 1 (porion line) joins
foramen and neurovascular bundle (white) approximately 3 cm from the two points each situated 12 mm from the porion on both the supra-


midline of the face; 2, zone of location of the infraorbital foramen and orbitomeatal line and the infraorbitomeatal line; and line 2 (zygomatic
neurovascular bundle (white), approximately 2 .5 cm from the midline of sutural line) is a line joining the zygomaticotemporal and frontozygo-
the face: aligns with a vertical axis passing through maxillary tooth 5; 3, matic sutures (Davies et al 2012). These branches may be injured in
vertical axis through maxillary tooth 5; 4, zone of location of the mental facial rhytidectomy, coronal or endoscopic brow lifting, and temporal
foramen and neurovascular bundle (white), approximately 2 .5 cm (range, craniotomy. The buccal branches run both above and below the parotid
apices of teeth 3–6) from the midline of the face . (Adapted from Drake duct. The marginal mandibular nerve emerges from the anteroinferior
RL, Vogl AW, Mitchell A, et al (eds), Gray’s Atlas of Anatomy, Elsevier, parotid and passes anteriorly. When posterior to the facial artery, the
Churchill Livingstone . Copyright 2008 .)
nerve almost always lies inferior to the lower border of the mandible
by an average of 1.2 cm (range 0.9–1.75 cm) (Batra et al 2010). The
branches that enter the neck re-enter the face by crossing the lower
Zygomaticotemporal nerve Auriculotemporal nerve
Supraorbital Lateral ramus
nerve Medial ramus Temporal branch of
facial nerve
Supratrochlear nerve
Infratrochlear nerve
Zygomatic branch of
facial nerve
Zygomaticofacial nerve
Greater occipital nerve
External nasal nerve
Posterior auricular nerve
Infratorbital nerve
Facial nerve
Upper buccal branch of
facial nerve Lesser occipital nerve
Great auricular nerve
Buccal nerve
Accessory nerve
Mental nerve
Transverse cutaneous
Lower buccal branch of nerve of neck
facial nerve
Supraclavicular nerves
Marginal mandibular branch of
facial nerve
Loop of communication
between cervical branch of


facial nerve and transverse
cutaneous nerve of neck
Fig . 26 .10 The distribution of the cutaneous branches of the trigeminal nerve and of the cervical plexus, and the motor branches of the facial nerve in
the face and neck .


Surface anatomy
413
62
RETPaHC
border of the mandible at the anterior border of masseter and pass
superficial to the facial artery and vein. Regional incisions are therefore
made at least 1.5 cm below the lower mandibular border to avoid nerve
injury, which results in an upturned ipsilateral mouth via paralysis of
depressor anguli oris and depressor labii inferioris (Chowdhry et al
2010).
1
Dermatomes
Our knowledge of individual dermatome position is based on clinical
evidence. The dermatomes of the face arise mainly from cutaneous
branches of the three major divisions of the trigeminal nerve (see Fig. 2
26.10). The skin covering the front and sides of the neck, and over the
angle of the mandible, and over the lateral scalp and posterior aspect 3
of the pinna is supplied by branches of the cervical plexus (C2–C4), 13 4
and the skin over the back of the head is supplied by the greater occipi-
tal nerve (C2, posterior primary ramus) (see Figs 26.10, 30.22, 43.3 and 10 9 5
43.76). 11 7 6
SURFACE ANATOMY OF THE NECK
12 8
Skeletal and cartilaginous landmarks
Fig . 26 .11 The anterior and posterior triangles of the neck . Key:
1, thyroid notch with thyrohyoid ligament (indented region) above;
The neck extends from the pericraniocervical line superiorly to the level 2, laryngeal prominence; 3, median cricothyroid ligament; 4, cricoid
of the clavicle, scapula and thoracic inlet (first rib and superior manu- cartilage; 5, isthmus of thyroid gland; 6, greater supraclavicular fossa (of
brium) inferiorly, where it is continuous with the thoracic cavity and posterior triangle); 7, sternal head of sternocleidomastoid; 8, common
upper limb. The spines of the second and seventh cervical vertebrae are carotid artery; 9, lesser supraclavicular fossa overlying the internal jugular


the most prominent and may be palpated in the midline of the pos- vein; 10, clavicular head of sternocleidomastoid; 11, course of brachial
terior neck (the former via deep palpation). The remaining cervical plexus (upper trunk); 12, subclavian artery; 13, trapezius . (Adapted from
spines are indistinct because they are covered by the ligamentum Drake RL, Vogl AW, Mitchell A, et al (eds), Gray’s Atlas of Anatomy,
nuchae, on either side of which lie the masses of the postvertebral Elsevier, Churchill Livingstone . Copyright 2008 .)
musculature. The transverse process of the first cervical vertebra is pal-
pable in the hollow region posteroinferior to the mastoid apex, and
deep palpation inferior to this reveals the transverse process of the
second cervical vertebra. be further subdivided into submental, muscular, carotid and digastric
The hyoid bone body can be felt in the midline neck a few centi- triangles, and the posterior triangle may be divided into occipital and
metres below and behind the chin, at the junction of the skin of the supraclavicular triangles. Above the hyoid bone, the musculature runs
anterior neck and the floor of the mouth. The greater horns may be in a predominantly horizontal or oblique direction, and below the
palpated between a finger and thumb, and moved from side to side. In hyoid it runs in a vertical direction. The muscles forming the boundaries
the adult, the body of the hyoid bone sits level with the fourth cervical of the subtriangles of the neck are not readily palpable or visible,
vertebra (range C3–C5/6) (Mirjalili et al 2012b); it is higher in children. although they may be landmarked according to their attachment points,
The laryngeal prominence (Adam’s apple) of the thyroid cartilage is e.g. the two bellies of digastric lie along a line from the anterior midline
palpable in the midline neck, and the thyroid laminae can be felt chin to the lateral aspect of the hyoid body and then towards the medial
passing posterolaterally. In the male, the prominence is usually visible, part of the mastoid process.


whereas in the female it is not usually apparent. The curved upper The root of the neck is the transitional zone between the neck,
border of the thyroid cartilage, the midline thyroid notch and the su- thorax and both upper limbs. Communication with the thorax via the
periorly located depression of the thyrohyoid membrane/ligament are thoracic inlet is marked anteriorly by the superior manubrium. The
easily palpable. The upper border of the thyroid cartilage usually lies trachea is palpable in the midline superior to the sternal notch, a
between the fourth and fifth cervical vertebrae (Mirjalili et al 2012b). region that may also contain the left brachiocephalic vein. The apices
The firm, smooth anterior arch of the cricoid cartilage is palpable below of the lungs lie posterior to the medial third of the clavicle (Mirjalili
the inferior border of the thyroid cartilage. The inferior border of the et al 2012a).
cricoid commonly sits at the level of the seventh cervical vertebra (range
anterior triangle
C5–T1); the posterior cricoid overlaps the sixth cervical vertebra (Mir-
jalili et al 2012b). The indentation between the thyroid and cricoid The base of the anterior triangle is formed by the inferior border of the
cartilages is covered by the anterior/median cricothyroid ligament, a mandible and a line from its angle to the mastoid process. The sides
useful site for emergency access to the airway in cases of obstruction at are formed by the midline anteriorly and by the anterior border of
or above the vocal cords (cricothyroid puncture or cricothyroidotomy). sternocleidomastoid laterally. The triangle is best palpated bimanually
In the neonate, the dimensions of the cricothyroid membrane are too with the examiner standing behind the subject and using both hands
small to allow safe passage of an airway (Navsa et al 2005). Confirm- to examine the structures within. Inspection reveals the rounded tendin-
ation of the surface anatomy of the hyoid bone, thyroid and cricoid ous sternal head of sternocleidomastoid, which arises from the supero-


cartilages, and suprasternal notch is essential prior to performing a lateral angle of the manubrium, and the broader, more vertical clavicular
tracheostomy (Ellis et al 2004). head, which arises from the upper surface of the medial third of the
The clavicle is a sigmoid-shaped bone that is easily visible in thin clavicle. The indentation of the lesser supraclavicular fossa sits between
people and is palpable in all except the morbidly obese. Its medial the two heads, anterior to the internal jugular vein before it joins the
two-thirds are rounded and convex anteriorly and the lateral third is subclavian vein posterior to the sternoclavicular joint; the fossa there-
flat and concave anteriorly. The suprasternal (jugular) notch lies between fore represents an access point for central venous cannulation.
the expanded medial ends of the clavicles; the superior edge of the The trachea and its cartilaginous ‘rings’ may be palpated in the
sternal manubrium forms its inferior border. For much of its length, midline inferior to the cricoid cartilage and above the sternal notch. It
the clavicle may be almost encircled by two fingers, but medially its may be deviated laterally by thyroid masses/growth, atelectasis or
ligamentous attachments make definition more difficult. The posterior tension pneumothorax. The thyroid gland consists of two soft, palpa-
end of the first rib may be felt indistinctly within the floor of the pos- ble lobes lying on either side of the lower half of the laminae of the
terior triangle of the neck. thyroid cartilage and upper part of the trachea, their lower borders
extending towards the sternal end of the clavicle on each side. Swal-
lowing may assist palpation of the gland. The lobes are joined by the
Soft tissues and viscera
isthmus (approximately 2 cm wide), which sits anterior to the second
and third tracheal cartilages; these cartilages may therefore be
Triangles and root of the neck impalpable.
The neck is divided into anterior and posterior triangles by sternocleido- Apart from a few retrovisceral nodes and some nodes deep to sterno-


mastoid (Fig. 26.11). In cadaveric specimens, the anterior triangle may cleidomastoid, all head and neck lymph nodes groups are clinically


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4
NOITCES
palpable when enlarged. Lymph nodes above the hyoid bone tend to Subclavian vein
be disposed in a horizontal plane either on or below the pericranio-
The subclavian vein sits anterior to the subclavian artery and follows a
cervical line, and in front of and behind the pinna, whereas the deep
similar course by passing over the first rib into the root of the neck. It
cervical nodes run vertically and are related to the internal jugular vein.
joins the internal jugular vein to form the brachiocephalic vein pos-
The jugulodigastric node group are palpable in the indented region
terior to the sternoclavicular joint (Mirjalili et al 2012a) and lies closest
posterior to the mandibular angle and anterior to sternocleidomastoid.
to the clavicle at the junction of its middle and medial thirds, approxi-
Palpation medial and deep to the inferior border of the mandible can
mately 7 cm from the midline (Hale et al 2010). Subclavian vein can-
reveal nodes within the submental and submandibular triangles. Super-
nulation is described in Chapter 29.
ficial cervical nodes lie adjacent to the external and anterior jugular
veins and are landmarked with them. Anterior jugular vein
The submandibular gland is palpable within the submandibular
The anterior jugular vein runs downwards from beneath the chin,
triangle. It extends approximately 2 cm beneath the lower border of the
approximately a finger’s breadth from the midline. It turns laterally,
posterior part of the body of the mandible and may reach the greater
approximately 2.5 cm from the sternal end of the clavicle, and passes
horn of the hyoid bone. Its posterior border is level with the angle of
beneath sternocleidomastoid to drain into the external jugular vein. The
the mandible and its anterior border extends approximately 4 cm
veins of each side join to form a jugular arch just above the manubrium
anteriorly.
sterni. The anterior jugular vein may be encountered if the operator


drifts laterally while creating a surgical airway.
Posterior triangle
The posterior triangle is bounded by the posterior border of sterno- External jugular vein
cleidomastoid, the middle third of the superior surface of the clavicle
The external jugular vein lies superficial to sternocleidomastoid and
(the base), and the anterior margin of trapezius. Its apex is the point
may be represented by a line that starts just below and behind the angle
where sternocleidomastoid and trapezius approximate at the superior
of the mandible and runs to a point close to the lateral extent of the
nuchal line. The lower portion of the posterior triangle forms the greater
junction of sternocleidomastoid with the clavicle. It drains into the
supraclavicular fossa, an important clinical area that lies just above and
subclavian vein after penetrating the investing layer of deep cervical behind the clavicle at the confluence of the thoracic inlet and the aditus
fascia and may be kinked at this point. If the proximal part of the vein
to the axilla and arm. It is best inspected from in front but palpated
is damaged, it may be held open by the surrounding fascia; air may
from behind. Scalenus anterior and medius are palpable as firm masses
then be sucked in, resulting in an air embolus. The external jugular vein
in the floor of the triangle, posterior to the lower part of sternocleido-
can be distended if venous pressure is raised, e.g. by performing a Val-
mastoid. The near-vertical interscalene groove is palpable between
salva manœuvre (forced expiration against a closed glottis and mouth,
them; at or near the level of the sixth cervical vertebra, it serves as a
and blocked nostrils), by supraclavicular digital pressure or if the vessel
landmark for the upper trunk of the brachial plexus.
is kinked.
When the greater supraclavicular fossa is inspected, the pulsation of
the great veins may be seen if the central venous pressure is raised. The
Internal jugular vein
fossa is also a common site in which to feel pathologically enlarged
supraclavicular lymph nodes. In particular, cancers of the lung can The internal jugular vein runs in the carotid sheath, lying just lateral or


spread to left- and right-sided nodes, and cancers of the upper gastro- anterolateral to the pulsating carotid arteries. It therefore has similar
intestinal tract can spread to left-sided nodes. The subclavian artery may surface markings to those described for the common and internal
be felt pulsating as it crosses the first rib, posterior to the medial end carotid arteries, and is represented by a broad band from the lobule of
of the clavicle, and the upper and middle trunks of the brachial plexus the ear to the sternoclavicular joint, where it joins the subclavian vein
may be felt above and behind it. The posterior end of the first rib may (Mirjalili et al 2012a). The inferior bulb of the internal jugular vein lies
be felt as a fullness in the posterior aspect of the fossa. A point approxi- in the lesser supraclavicular fossa (the depression between the sternal
mately 2.5 cm above the middle of the medial third of the clavicle and clavicular heads of sternocleidomastoid), where it may be accessed
marks the level of the neck of the first rib and is thus the surface marking for central vein cannulation. In children under the age of 5 years, the
for the apex of the dome of the cervical pleura and lung covered by the vein is less than 1 cm deep to skin (Roth et al 2008). The jugular venous
suprapleural membrane (Sibson’s fascia). Any penetrating injury (iatro- pulse reflects the jugular venous pressure (central venous pressure) and
genic or otherwise) in this region will run the risk of creating a is a measure of cardiac function. Pulsation of the great veins may be
pneumothorax. seen in this region if the central venous pressure is raised (e.g. right-
sided heart failure). Internal jugular vein cannulation is described in
Chapter 29.
Course of vessels
Course of nerves
Carotid arteries
In the neck, the common carotid artery and its continuation, the intern-
Accessory nerve
al carotid artery, may be represented by a more or less straight line
passing from the sternoclavicular joint to a point just behind the man- The accessory nerve may follow a straight or tortuous course; descrip-


dibular condyle. The level at which the common carotid artery bifur- tions vary (Symes and Ellis 2005, Mirjalili et al 2012c). Its course has
cates into internal and external carotid arteries is variable (Lo et al traditionally been approximated by a line passing across the floor of
2006). It ranges from the first to the fifth cervical vertebra (Furukawa the posterior triangle, from the junction of the upper and middle thirds
et al 2012), and is found most commonly at the level of the third cervi- of the posterior border of sternocleidomastoid (Erb’s point; see Fig.
cal vertebra (Furukawa et al 2012, Mirjalili et al 2012b). Bifurcations 26.11) to the junction of the lower and middle thirds of the anterior
almost always sit above the upper border of the thyroid cartilage lamina border of trapezius. However, morphometric studies have demonstrated
by an average of 1.6 cm (Mirjalili et al 2012b). Almost half occur at the considerable positional variability. The nerve emerges from the poste-
superior border of the thyroid cartilage, and less frequently opposite rior border of sternocleidomastoid approximately 6.5 cm below the tip
the hyoid bone or between the thyroid cartilage and hyoid bone of the mastoid process, and penetrates the anterior border of trapezius
(Al-Rafiah et al 2011). The common carotid artery may be compressed approximately 4.5 cm above the clavicular insertion of trapezius (Symes
against the prominent transverse process of the sixth cervical vertebra and Ellis 2005; Mirjalili et al 2012c) (Figs 26.8B, 26.10). Accessory
(Chassaignac’s or carotid tubercle), which sits lateral to the cricoid nerves usually divide into 2–4 branches prior to trapezius (Mirjalili et al
cartilage. Above this level, the artery is superficial and its pulsation may 2012c).
be readily felt beneath the anterior border of sternocleidomastoid.
Cervical plexus
Subclavian artery
The cutaneous branches of the cervical plexus emerge from behind the


The subclavian artery enters the root of the neck behind the sterno- posterior border of the middle third of sternocleidomastoid, usually
clavicular joint. It passes through the inferior part of the palpable below the accessory nerve (see Figs 26.8B, 26.10). The great auricular
interscalene groove and arches upwards to reach a point approximately nerve can be damaged during rhytidectomy. It passes superiorly over
2 cm above the clavicle deep to the posterior border of sternocleido- sternocleidomastoid towards the lobule and angle of the mandible; it
mastoid, before passing across the upper surface of the first rib behind can sit over the mid-belly of sternocleidomastoid, approximately 6.5 cm
the middle of the clavicle. The subclavian pulse may be detected behind below the lower border of the external acoustic meatus, with the exter-
the clavicle at the lateral border of sternocleidomastoid or where it nal jugular vein sitting 0.5 cm anteriorly at this position (McKinney and
crosses the first rib. Katrana 1980).


415
62
RETPaHC
key references
Brachial plexus Cervical sympathetic ganglia
The roots and trunks of the brachial plexus can be represented by a line The superior cervical ganglion lies slightly anterior to the (palpable)
passing between the middle of the posterior border of sternocleidomas- transverse process of the second cervical vertebra, while the middle
toid and the middle of the clavicle. In thin individuals, the scalene cervical ganglion, when present, lies just in front of the transverse
muscles are visible when the head is laterally flexed to the contralateral process of the sixth cervical vertebra, the tubercle of which is palpable
side; the roots/upper trunk are palpable in the almost vertical inter- via the anterior neck, lateral to the cricoid cartilage. The inferior cervical
scalene groove, which is located posterior to scalenus anterior. The ganglion may be fused with the first thoracic cervical ganglion, forming
trunks lie in the posterior triangle of the neck, and the divisions lie the stellate or cervicothoracic ganglion. Stellate ganglion block is often
behind the clavicle near the lateral border of the first rib. The cords enter employed to perform a sympathetic nerve block to the head and neck,
the axilla above the first part of the subclavian artery, embrace its second or to the arm (Ellis et al 2004).
part and give off branches around the third part.
KEY REFERENCES
Behnia H, Kheradvar A, Shahrokhi M 2000 An anatomic study of the lingual The asterion has been used as a landmark in lateral approaches to the
nerve in the third molar region. J Oral Maxillofac Surg 58:649–51. posterior fossa. It is not strictly reliable in terms of locating the underlying
The intimate relationship of the lingual nerve to the lower third molar posterior fossa dura but it does lie directly over the transverse–sigmoid sinus
region is a significant factor in the morbidity associated with third molar complex. Caution must therefore be taken when placing burr-holes to avoid
extractions. This extensive cadaver study reported that in 14% of patients damage to the venous sinuses with potentially very serious consequences.
the lingual nerve was located above the lingual crest and that in 22% the


Hale SJ, Mirjalili SA, Stringer MD 2010 Inconsistencies in surface anatomy:
nerve was in direct contact with the lingual plate of the alveolar process.
the need for an evidence-based reappraisal. Clin Anat 23:922–30.
Day JD, Tschabitscher M 1998 Anatomic position of the asterion. Neuro- An argument that an evidence-based framework is essential if surface
surgery 42:198–9. anatomy is to be accurate and clinically relevant.


Head and neck: overview and surface anatomy
415.e1
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Balcioglu HA, Kilic C, Akyol M et al 2011 Horizontal migration of pre- and McKinney P, Katrana DJ 1980 Prevention of injury to the great auricular
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nerve in the third molar region. J Oral Maxillofac Surg 58:649–51. Mirjalili SA, McFadden SL, Buckenham T et al 2012b Vertebral levels of key
The intimate relationship of the lingual nerve to the lower third molar landmarks in the neck. Clin Anat 25:851–7.
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Mirjalili SA, Muirhead JC, Stringer MD 2012c Ultrasound visualization of
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Rahmah NN, Murata T, Yako T et al 2011 Correlation between squamous
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Davies JC, Fattah A, Ravichandiran M et al 2012 Clinically relevant land-
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25:330–9.


SUBSECTION: Head and neck
CHAPTER
27
External skull
The skull is the bony skeleton of the head. It houses the brain, the during the early growth phase of the skull will result in various
organs of special sense, and the upper parts of the respiratory and diges- abnormalities.
tive systems, and provides attachments for many of the muscles of the The bones forming the base of the skull develop mainly via endo-
head and neck. Movement is restricted and is found only in relation to chondral ossification, and also play an important part in the overall
the mandible at the temporomandibular joint and at the atlanto- growth of the face and the neurocranium. The joints between bones in
occipital joint for movement of the head in relation to the neck. the skull base are primary cartilaginous joints. One of the most impor-
The skull consists of the cranium, facial skeleton and mandible. The tant is the spheno-occipital synchondrosis, between the body of the
cranium may be subdivided into the calvaria (sometimes called the sphenoid anteriorly and the basilar part of the occipital bone posteri-
cranial vault) and the basicranium (cranial base). It encloses the brain, orly; fusion between them is generally completed between 13 and 18
cranial nerves, meninges, blood vessels and cerebrospinal fluid within years of age.
the cranial cavity. Internally, the cranial base can be divided into three There are only two sites of synovial articulation associated with the
regions corresponding to the floor of the anterior, middle and posterior exterior of the skull, namely: the temporomandibular joint and the
cranial fossae. An alternative subdivision of the skull distinguishes atlanto-occipital joint (between the condyles of the occipital bone and
between the neurocranium (calvaria and basicranium) and the viscero- the superior articular facets of the atlas). Movement at these joints does
cranium (facial skeleton), which hangs down from the front of the not facilitate rotation but participates in flexion and extension in the
neurocranium and houses the organs of sight, smell and taste, as well anteroposterior plane and bilateral flexion in the transverse plane.


as the openings to the respiratory and digestive systems via the nose Many important neurological and vascular structures enter and exit
and mouth, respectively. In clinical parlance, the terms skull base and the skull via foramina (openings). The skull is a prime site for fractures
cranial base are frequently used as though they are synonymous. Indeed, resulting from trauma, which means that these structures are at risk of
inspection of the inferior surface of a skull confirms that the middle damage following head injury. In addition to the main foramina, irregu-
and posterior cranial bases are the same as the middle and posterior lar emissary foramina allow veins situated externally on the face and
skull bases. However, the anterior cranial base and the anterior skull scalp to communicate with those lying intracranially; spread of infec-
base should not be used interchangeably because the anterior skull base tion along these routes may have serious clinical consequences.
includes the inferior surface of the facial skeleton, whereas the internal In the account of the skull that follows, only generalized standard
surface of the anterior cranial base is the floor of the anterior cranial views will be considered. A more detailed account of each individual
fossa and may be further subdivided into a midline (central) and bone will be found associated with the relevant regional text (Berkovitz
two lateral parts. Developmentally, the parts of the skull where the and Moxham 1994).
bones are derived by endochondral ossification constitute the chon-
drocranium; the remaining bones are derived by intramembranous
FRONTAL (ANTERIOR) VIEW
ossification.
The skull is the most complex bony structure in the body: the young
adult skull is composed of an average of 28 separate bones, many of Viewed from the front, the skull is generally ovoid in shape and is wider
which are paired; some in the median plane are single, though sym- above than below (Fig. 27.1). The upper part is formed by the frontal
metrical. Most of the vault bones are flat, and consist of two tables or bone, which underlies the forehead region above the orbits. Supero-
plates of compact bone enclosing a narrow layer of relatively dense medial to each orbit is a rounded superciliary arch (more pronounced


cancellous marrow (diploic bone). The marrow within the skull bones in males), between which there may be a median elevation, the glabella.
is a site of haemopoiesis, at least in the young individual. These bones The glabella may show the remains of the interfrontal (metopic) suture,
form by intramembranous ossification of a highly vascular connective which usually closes in the first postnatal year (Weinzweig et al 2003),
tissue membrane and have often been referred to as ‘dermal’ in defer- but persists in a small percentage of adult skulls in various ethnic
ence to their alleged ancient phylogenetic origin. The inner table is groups. The frontal bone articulates with the two nasal bones at the
thinner and more brittle while the outer tends to be thicker and more frontonasal sutures, marked by a depression at the root of the nose;
resilient; this is important to remember when examining fractures to the point at which the frontonasal and internasal sutures meet is the
the skull caused by either blunt or sharp trauma. This bone type is also anthropometric landmark known as the nasion.
of considerable value in cranial bone grafting in the young, where the The upper part of the face is occupied by the orbits and the bridge
two tables can be split to produce an autograft. The skull bones vary in of the nose. Each orbital opening is roughly quadrangular in shape (Ch.
thickness in different regions, with the bones of the viscerocranium 41). The upper, supraorbital, margin is formed entirely by the frontal
being rather delicate and therefore particularly susceptible to fracture. bone, interrupted at the junction of its sharp lateral two-thirds and
The majority of bones in the skull articulate via fibrous joints termed rounded medial third by the supraorbital notch or foramen, which
sutures, which facilitate growth rather than movement in the develop- transmits the supraorbital vessels and nerve. The lateral margin of the
ing skull. The three main sutural morphologies reflect the magnitude orbit is formed largely by the frontal process of the zygomatic bone and
of strain placed on them. Thus the margins of adjacent bones of a suture is completed above by the zygomatic process of the frontal bone; the


may be smooth and meet end to end, giving a simple (butt-end) suture suture between them (frontozygomatic) lies in a palpable depression.
(e.g. median palatine suture); may be bevelled, so that the border of The infraorbital margin is formed by the zygomatic bone laterally and
one bone overlaps the other (e.g. parietotemporal suture); or may the maxilla medially. Both lateral and infraorbital margins are sharp
present numerous projections that interlock, giving a serrated jigsaw and palpable. The medial margin of the orbit is formed above by the
appearance (e.g. lambdoid suture). The complexity of serrated sutures frontal bone and below by the lacrimal crest of the frontal process of
increases from the inner to the outer surface. Fusion across sutures the maxilla.
(synostosis) can start early in the third decade, although its variability The central part of the face is occupied mainly by the paired maxillae,
precludes using this information to assess age with any degree of accu- separated by the anterior nasal aperture. Each maxilla contributes to
racy. The process of fusion starts on the internal surface of the cranium the upper jaw, the floor and medial wall of the orbital cavity, the
first and proceeds externally; the coronal and sagittal sutures are often lateral wall of the nose, the floor of the nasal aperture and the bone
the first to display synostosis. By middle age, many of the larger sutures of the cheek. The anterior nasal spine marks the upper limit of the
will show evidence of synostosis, although there are some that rarely intermaxillary suture at the lower margin of the anterior nasal aperture
416 show fusion, e.g. the zygomaticofacial. Premature fusion of sutures and is palpable in the nasal septum. The infraorbital foramen transmits


417
72
RETPAHC
Frontal (anterior) view
A
Internasal suture Frontal bone, squamous part
Frontonasal suture
Frontolacrimal suture
Frontomaxillary suture
Maxilla, frontal process
Sphenofrontal suture Supraorbital foramen
Parietal bone, sphenoidal angle
Coronal suture
Sphenoparietal suture
Supraorbital margin
Frontozygomatic suture
Frontal bone, zygomatic process
Superior orbital fissure Temporal bone
Sphenoid, lesser wing
Sphenoid, greater wing
Sphenozygomatic suture
Zygomatic bone
Inferior orbital fissure Lacrimal bone
Infraorbital margin Nasomaxillary suture
Zygomaticomaxillary suture
Infraorbital foramen
Ethmoid
Bony nasal septum
Vomer
Middle nasal concha
Maxilla, alveolar process
Anterior nasal spine Inferior nasal concha
Mental foramen
Mandible, ramus
Mandible, body
Intermaxillary suture
Maxilla Mandible Nasal bone Vomer Parietal bone Zygomatic bone
Frontal bone Ethmoid Sphenoid Lacrimal bone Temporal bone Inferior nasal concha
1
Coronal
suture
Superior
orbital fissure
Zygomatico-
2 frontal suture
3 Infraorbital
foramen
4
5
6
C
7
Fig. 27.1 A, The bones of the adult skull, frontal aspect. B, An
anteroposterior view of the skull and upper cervical spine, young adult.
Key: 1, sagittal suture; 2, frontal sinus; 3, crista galli; 4, mastoid air cells;
5, nasal septum; 6, inferior concha; 7, dens of axis. C, Reformatted
volume rendered CT scan of anteroposterior view of the skull. (A, With
B permission from Waschke J, Paulsen F (eds), Sobotta Atlas of Human
Anatomy, 15th ed, Elsevier, Urban & Fischer. Copyright 2013.)


ExTERnAl skull
418
4
nOITCEs
the infraorbital vessels and nerve, and lies about 1 cm below the middle The external occipital protuberance is a midline elevation on the
of the infraorbital margin. The maxillary alveolar process bears the occipital bone that can become particularly well developed and palpa-
upper teeth. The short, thick zygomatic process of the maxilla has an ble in males. The location of the protuberance coincides with the
oblique upper surface that articulates with the zygomatic bone at the anthropometric inion. Superior nuchal lines extend laterally from
zygomaticomaxillary suture. The frontal process of the maxilla ascends the protuberance and represent the boundary between the scalp and
posterolateral to the nasal bone to articulate with it medially, the frontal the neck. Inferior nuchal lines run parallel to, and below, the superior
bone superiorly and the lacrimal bone laterally. nuchal lines; a set of highest nuchal lines may sometimes occur above
The anterior nasal aperture is piriform in shape, wider below than the superior lines. The external occipital protuberance, nuchal lines and
above and bounded by the paired nasal bones and maxillae. The upper roughened external surface of the occipital bone between the nuchal
boundary of the aperture is formed by the nasal bones while the lines all afford attachment to muscles of the neck.
remainder is formed by the maxillae. In life, several cartilages (septal,
lateral nasal, major and minor alar) help to delineate two nasal cavities.
SUPERIOR VIEW
The shape of these bones can be used quite successfully to predict the
shape of the cartilaginous nose in forensic facial reconstructions
(Wilkinson and Rynn 2012). Seen from above, the contour of the calvaria varies greatly but is usually
The lower part of the face, below the nose, is formed from the alveo- ellipsoid, or more strictly, a modified ovoid with its greatest width lying
lar arch of the maxillae and the upper dentition, the body of the man- nearer to the occipital pole (Fig. 27.3). Four bones constitute this view


dible, the alveolar process of the mandible and the lower dentition. In and articulate via three well-defined sutures. The squamous part of the
the midline, the mental protuberance produces the characteristic prom- frontal bone is anterior, the squamous part of the occipital bone is
inence of the chin. The mental foramen, which transmits the mental posterior and the two parietal bones meet in the midline and separate
nerve and accompanying vessels, lies in the same vertical plane as the the frontal from the occipital bone. The maximal parietal convexity on
supraorbital and infraorbital foramina. each site is palpable at the parietal tuber or eminence; it is most con-
Anteroposterior radiographs of the skull clearly show the central spicuous in the female (retention of a paedomorphic appearance). The
location of the paranasal air sinuses in the frontal bone, maxilla and superior and inferior temporal lines run close to the parietal eminence
ethmoid. These can be particularly useful indicators of identity when but are best seen in a lateral view.
postmortem images are compared with antemortem clinical films. The coronal suture marks the articulation between the posterior
margin of the frontal bone and the anterior margins of the two pari-
etal bones. It descends across the calvaria and projects inferiorly until
POSTERIOR VIEW
it meets the junction between the greater wing of the sphenoid and
the squamous temporal bone at the pterion. The sagittal suture runs
The parietal, temporal and occipital bones form the entirety of the in the midline between the two parietal bones and extends from the
posterior view (Fig. 27.2). The superolateral region is occupied by the bregma anteriorly to the lambda posteriorly. The lambdoid suture
parietal bones, the mastoid region of the temporal bones makes up delineates the articulation between the posterior borders of the
the inferolateral regions, and the central portion is occupied by the right and left parietal bones and the superior border of the occipital
occipital bone, which is the reason why this aspect is also referred to as bone.


the occipital view. The parietal bones articulate with the occipital bone The bregma represents the position of the anterior fontanelle in the
at the lambdoid suture, which extends inferiorly into the occipitomas- young child. This diamond-shaped, membrane-filled space located
toid and the parietomastoid sutures behind and above the mastoid between the two frontal and two parietal bones of the developing fetal
processes, respectively. The lambda is the anthropometric point where skull persists until approximately 18 months after birth. The lambda,
the occipital bone meets the two parietal bones. Accessory sutural bones at the junction of the sagittal and lambdoid sutures, represents the site
are islands of bone that may be found within a suture. They may arise of the posterior fontanelle, which persists for the first 2–3 months after
from separate centres of ossification and they appear to have no clinical birth.
significance, being of genetic rather than pathological aetiology; their A parietal foramen may pierce either or both parietal bones near the
initial formation is thought to be caused by a degree of dural strain and sagittal suture about 3.5 cm anterior to the lambda. It transmits a small
increased sutural width (Bellary et al 2013). A large, central interparietal emissary vein from the superior sagittal sinus. The vertex is the highest
bone is not uncommon and is sometimes referred to as an Inca bone point on the skull and it usually occupies a position in the middle third
(see Fig. 27.2). of the sagittal suture.
Fig. 27.2 The bones of the adult skull,
posterior aspect. (With permission from
Waschke J, Paulsen F (eds), Sobotta Atlas of
Sagittal suture Human Anatomy, 15th ed, Elsevier, Urban &
Fischer. Copyright 2013.)
Parietal foramen
Parietal foramen
Lambda
Parietal bone
Lambdoid suture
Interparietal bone
Sutural bones
Squamous suture
(Transverse
occipital
Parietomastoid
suture, var.)
suture
Occipitomastoid Temporal bone
suture
Occipital bone
Mastoid foramen


Mastoid notch Mastoid process
Styloid process Superior nuchal line
Interior nuchal line
External occipital crest
External occipital
Inion protuberance


lateral view
419
72
RETPAHC
Nasal bones Fig. 27.3 The bones of the adult skull, superior aspect.
(With permission from Waschke J, Paulsen F (eds),
Sobotta Atlas of Human Anatomy, 15th ed, Elsevier, Urban
& Fischer. Copyright 2013.)
Frontal eminence
Coronal suture
Superior
temporal line
Bregma
Parietal bone
Inferior
temporal line
Parietal
eminence
Sagittal suture
Parietal foramina
Squamous part Lambdoid suture
of occipital bone
Occiput
The zygomatic arch stands proud of the rest of the skull, and the
LATERAL VIEW
temporal and infratemporal fossae communicate via the gap thus
created. In life, this space is largely filled by temporalis. The zygomatic
The skull, viewed from the side, can be subdivided into three zones: bone is the principal bone of the cheek together with the zygomatic
face (anterior), temporal region (middle) and occipital region (poste- processes of the maxilla and temporal bones. The term ‘zygomatic arch’
rior) (Fig. 27.4). The face has been considered in the section on the is generally restricted to the temporal process of the zygomatic bone
anterior view of the skull. and the zygomatic process of the temporal bone, which articulate at the
The temporal region can be divided into an upper temporal fossa zygomaticotemporal suture. The suture between the zygomatic process
and a lower infratemporal fossa, separated by the position of the zygo- of the frontal bone and the frontal process of the zygomatic bone is the
matic arch. The upper temporal fossa is bounded inferiorly by the frontozygomatic suture; the suture between the maxillary margin of the
zygomatic arch, superiorly and posteriorly by the temporal lines, and zygomatic bone and the zygomatic process of the maxilla is the zygo-
anteriorly by the frontal process of the zygomatic bone, and is continu- maticomaxillary suture; and the suture between the sphenoid and zygo-


ous inferiorly with the infratemporal fossa deep to the zygomatic arch. matic bones is the sphenozygomatic suture. As the zygomatic process
The temporal lines often present anteriorly as distinct ridges but become of the temporal bone passes posteriorly, it widens to form the articular
much less prominent as they arch posteriorly across the parietal bone. tubercle of the mandibular fossa anteriorly.
The inferior temporal line becomes more prominent as it curves down The temporal bone is a prominent structure on the lateral aspect of
the posterior part of the squamous temporal bone, forming a supra- the skull. Its squamous part lies in the floor of the upper temporal
mastoid crest at the base of the mastoid process. The superior temporal fossa and its zygomatic process contributes to the structure of the
line gives attachment to the temporal fascia while the inferior temporal cheek. Additional components visible in the lateral view of the skull
line provides attachment for temporalis. are the mandibular (glenoid) fossa and its articular eminence (tuber-
The floor of the temporal fossa is formed by the frontal and parietal cle), the tympanic plate, the external acoustic meatus (external audi-
bones superiorly and the greater wing of the sphenoid and squamous tory meatus), and the mastoid and styloid processes. The mandibular
part of the temporal bone inferiorly. All four bones of one side meet at fossa is bounded in front by the articular eminence and behind by the
a roughly H-shaped sutural junction termed the pterion. This is an tympanic plate. The articular eminence provides a surface over which
important anthropometric landmark because it commonly overlies the mandibular condyle glides during mandibular movements. The
both the anterior branch of the middle meningeal artery and the lateral tympanic plate of the temporal bone contributes most of the margin
fissure of the cerebral hemisphere (Ma et al 2012). The pterion corre- of the external acoustic meatus; the squamous part forms the postero-
sponds to the site of the anterolateral (sphenoidal) fontanelle of the superior region. The external margin is roughened to provide an attach-


neonatal skull, which closes in the third month after birth. ment for the cartilaginous part of the meatus. A small depression, the
The vertical suture between the sphenoid and temporal bones, the suprameatal triangle, lies above and behind the meatus and is related
sphenosquamosal suture, is formed by articulation between the pos- to the lateral wall of the mastoid antrum. The mastoid process is an
terior border of the greater wing of the sphenoid and the anterior border inferior projection of the temporal bone. It lies posteroinferior to the
of the squamous part of the temporal bone. external acoustic meatus and is the site of attachment of sternocleido-
The lateral surface of the ramus of the mandible will be described mastoid. It is in contact behind with the posteroinferior angle of the
briefly here because it lies within the middle region of this view of the parietal bone at the parietomastoid suture and with the squamous part
skull. The ramus is a plate of bone projecting upwards from the body of the occipital bone at the occipitomastoid suture. These two sutures
of the mandible; its lateral surface gives attachment to masseter. The meet the lateral end of the lambdoid suture at the asterion. This coin-
ramus bears two prominent processes superiorly, the coronoid process cides with the site of the posterolateral fontanelle in the neonatal skull,
anteriorly and the condylar process posteriorly, separated by the man- which closes during the second year. A mastoid foramen may be found
dibular notch. The coronoid process is the site of insertion of tempo- near, or in, the occipitomastoid suture; it transmits an emissary vein
ralis; the condylar process articulates with the mandibular fossa of the from the sigmoid sinus. Sutural bones may appear in the parietomas-
temporal bone at the temporomandibular joint. The inferior and pos- toid suture.
terior borders of the mandible meet at the angle; it is more commonly The styloid process lies anterior and medial to the mastoid process
splayed in the male, reflecting the larger site of attachment for medial and gives attachment to several muscles and ligaments. Its base is partly


pterygoid on the internal surface. ensheathed by the tympanic plate and it descends anteromedially, its


ExTERnAl skull
420
4
nOITCEs
A
Squamous suture
Coronal suture
Sphenofrontal suture Superior temporal line
Sphenosquamous suture
Inferior temporal line
Frontal bone, squamous part
Temporal line
Sphenozygomatic suture
Frontozygomatic suture
Ethmoid, orbital plate
Squamous
suture
Frontolacrimal suture
Lambdoid
suture
Lacrimomaxillary suture
Nasal bone
Parietomastoid
suture
Nasomaxillary suture
Temporozygomatic
suture
Occipitomastoid
suture
Anterior
nasal spine
Zygomatico-
maxillary suture
External acoustic meatus
Mandible, condylar process
Occipital condyle
Mandible, body Styloid process
Mental foramen
Mandible, coronoid process
Mental protuberance
Mandible, angle
Frontal bone Lacrimal bone Temporal bone
Parietal bone Zygomatic bone Maxilla
Occipital bone Sphenoid Mandible
Nasal bone Ethmoid
1 5
2 6
7
8
3
9
10
11
4
B C
Fig. 27.4 A, The bones of the adult skull, lateral aspect. B, A true cephalometric lateral skull and cervical spine, young adult. Key: 1, frontal sinus;
2, nasal bone; 3, hard palate; 4, hyoid bone; 5, anterior clinoid process; 6, posterior clinoid process; 7, lambdoid suture; 8, sphenoidal sinus; 9, mastoid
air cells; 10, posterior tubercle of atlas; 11, spinous process of axis. C, Reformatted volume rendered CT scan of lateral view of the skull. (A, with
permission from Waschke J, Paulsen F (eds), Sobotta Atlas of Human Anatomy, 15th ed, Elsevier, Urban & Fischer. Copyright 2013.)