branches of the upper cervical nerves, which enter through the anterior 28.5–28.6). They lie between the endosteal and meningeal layers of
part of the foramen magnum (second and third cervical nerves) and dura mater, are lined by endothelium and have no valves; their walls
through the hypoglossal canal and jugular foramen (first and second are devoid of muscular tissue (Kılıç and Akakın 2008). They develop
cervical nerves). initially as venous plexuses; most adult sinuses preserve a plexiform
Meningeal branches from the vagus apparently start from the supe- arrangement (to a variable degree), rather than being simple vessels
rior vagal ganglion and are distributed to the dura mater in the posterior with a single lumen. Plexiform arrays of small veins adjoin the superior
cranial fossa. Those from the hypoglossal leave the nerve in its canal and inferior sagittal and straight sinuses, and, less frequently, the trans-
and supply the diploë of the occipital bone, the dural walls of the verse sinuses; ridges of ‘spongy’ venous tissue, known as venous lacunae,
occipital and inferior petrosal sinuses, and much of the floor and an- often project into the lumina of the superior sagittal and transverse
terior wall of the posterior cranial fossa. These meningeal rami may sinuses (Browder and Kaplan 1976, Kaplan and Browder 1976).
not contain vagal or hypoglossal fibres but ascending, mixed sensory The structure of cranial venous sinuses, their plexiform nature and
and sympathetic fibres from the upper cervical nerves and superior their wide connections with cerebral and cerebellar veins vary consider-
cervical sympathetic ganglion. All meningeal nerves contain a postgan- ably, particularly in earlier years, e.g. in infancy the falx cerebelli may
glionic sympathetic component, either from the superior cervical sym- contain large plexiform channels and venous lacunae that augment the
pathetic ganglion or by communication with its perivascular intracranial occipital sinus. These variations must be established for the individual
extensions. The role of the autonomic nerve supply of the cranial dura by catheter-based angiography, magnetic resonance (MR) venography


mater is uncertain. or computed tomographic (CT) venography, when clinical necessity
Sensory nerve endings are restricted to the dura mater and cerebral arises. The existence of arteriovenous shunts has been inferred from the
blood vessels, and are not found in either the brain itself, or in the demonstration of a connection between the middle meningeal arteries
arachnoid or pia mater. Stimulation of these nerve endings causes pain, and the superior sagittal sinus (Browder and Kaplan 1976). Dural ar-
as evidenced during awake craniotomy procedures, and is the basis of teriovenous fistulae are thought to be acquired lesions that form in an
certain forms of headache. The density of dural innervation, particularly area of thrombosis within a sinus. If the sinus remains completely
around the dural venous sinuses, increases during the later part of ges- thrombosed, venous drainage from these lesions takes place through


Meninges
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A Fig. 28.5 The major venous sinuses at the base of the
skull. A, The sinuses coloured dark blue have been
opened up.
Internal carotid arteries
Superior ophthalmic vein
Sphenoparietal sinus
Cavernous sinus
Anterior temporal diploic vein
Middle meningeal vein
Intercavernous sinus
Basilar plexus
Inferior petrosal sinus
Superior petrosal sinus
Sigmoid sinus
Vertebral artery
Occipital sinus
Transverse sinus
A B
Meningeal veins
Superior sagittal sinus
Venous lacunae
Cortical bridging veins
Arachnoid granulation
Venous lacuna
Fig. 28.6 The superior sagittal sinus and venous lacunae. A, An anatomical dissection of a silicon-injected specimen. B, The superior sagittal sinus
opened up after removal of the cranial vault. Note the fibrous bands that cross the sinus from two of the venous lacunae. (A, From the Rhoton
Collection.)
Superior sagittal sinus
cortical veins, or, if the sinus is partially open, venous drainage is
usually into the involved sinus. When the sinus remains closed, the The superior sagittal sinus runs in the attached convex margin of the
elevated pressure within the cortical veins receiving the arterial flow falx cerebri. It grooves the internal surface of the frontal bone, the
carries the risk of haemorrhage. adjacent margins of the two parietal bones and the squamous part of
The named sinuses are the superior and inferior sagittal, straight, the occipital bone (see Figs 28.3, 28.6, 19.11). It begins near the crista
transverse, sigmoid, occipital, cavernous, intercavernous, superior and galli, a few millimetres posterior to the foramen caecum, and receives
inferior petrosal, sphenoparietal, basilar and marginal. primary tributaries from cortical veins of the superior part of the frontal,


Intracranial region
435.e1
82
retPaHc
B
Fig. 28.5 B–C, Digitally subtracted venograms, venous phase. B, Sagittal C
view. C, Posterior view; note the asymmetry of the transverse sinuses.


IntracranIal regIon
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noItceS
Fig. 28.7 A coronal section through the vertex of
Superior the skull to show the relationships between the
sagittal sinus superior sagittal sinus, meninges and arachnoid
granulations. (Adapted from Drake RL, Vogl AW,
Emissary vein Mitchell A (eds), Gray’s Anatomy for Students,
2nd ed, Elsevier, Churchill Livingstone. Copyright
Arachnoid Diploic vein 2010.)
granulation Skull
Venous lacuna Dura mater
Subarachnoid space
Cerebral vein
Pia mater
Arachnoid mater
Falx cerebri
Cerebral cortex
parietal and occipital lobes, and from the anterior part of the orbital Nasion Lateral cerebral sulcus Central sulcus Lambda
surface of the frontal lobe. The sinus is triangular in cross-section, with
the apex directed downwards and continuous with the falx cerebri. Its
lumen is invaded in its intermediate third by projections from its dural
walls, which may divide its lumen into superior and inferior channels.
It is narrow anteriorly, and widens gradually to approximately 1 cm in
diameter as it runs backwards. At its posterior end, the sinus enters the
confluence of the sinuses (also known as the torcular herophili or the
torcula, although the term actually describes the bony gutter in which
the confluence lies), which is situated to one side (usually the right)
of the internal occipital protuberance (see Fig. 28.3). At the confluence
of the sinuses, the superior sagittal sinus usually deviates to become
continuous with the right transverse sinus, but it also usually connects
with the occipital and contralateral transverse sinuses. The size and
degree of communication of the channels meeting at the confluence are
highly variable; any sinus involved may be duplicated, narrowed or
widened near the confluence.
There are usually two or three lateral venous lacunae on each side
of the midline, named frontal (small), parietal (large) and occipital
(intermediate) lacunae; they tend to become confluent in the elderly,
producing a single elongated lacuna on each side. Fine fibrous bands


cross the lacunae, and numerous arachnoid granulations project into
them (see Fig. 28.6; Fig. 28.7). The lacunae mainly drain diploic and
meningeal veins. The cortical veins typically pass beneath the lacunae Sigmoid sinus Inion
on their way to the sinus. The largest cortical vein that connects the
superficial Sylvian (middle cerebral) vein and the superior sagittal sinus Frankfurt plane Middle meningeal artery Suprameatal triangle
is the superior anastomotic vein (vein of Trolard); it often runs in the Fig. 28.8 The relations of the brain, the middle meningeal artery and the
precentral, central or postcentral sulci. Near its posterior end, the supe- transverse and sigmoid sinuses to the surface of the skull. The area
rior sagittal sinus receives veins from the pericranium that pass through enclosed in the yellow circle (including the pterion) is used when
parietal foramina. Acute and complete thrombosis of the superior sagit- performing a pterional craniotomy over the frontal branch of the middle
tal sinus is an extremely severe condition causing acute elevation of the meningeal artery and lateral Sylvian fissure; the area enclosed in the
intracranial pressure and herniation. Slow and progressive occlusion green circle is used when performing a retrosigmoid craniotomy extending
of the sinus, as is typical for sagittal meningiomas, may be compen- to the confluence of the transverse and sigmoid sinuses.
sated by the development of collateral venous drainage with no clinical
the right, is directly continuous with the superior sagittal sinus, and the
consequences.
other with the straight sinus. The right transverse sinus is thus typically
Inferior sagittal sinus larger and drains blood from the superficial parts of the brain, while
The inferior sagittal sinus is located in the posterior half or two-thirds the left transverse sinus mainly drains blood from the deep parts of the
of the free margin of the falx cerebri (see Fig. 28.3). It increases in size brain. On either side, the sinuses run in the attached margin of the


posteriorly, ends in the straight sinus, and receives veins from the falx tentorium cerebelli, first on the squama of the occipital bone, then on
and sometimes from the medial surfaces of the cerebral hemispheres the mastoid angle of the parietal bone. Each follows a gentle antero-
(anterior pericallosal veins). lateral curve, increasing in size as it does so, to the posterolateral part
of the petrous temporal bone. Here it turns down as a sigmoid sinus,
Straight sinus
which ultimately becomes continuous with the internal jugular vein.
The straight sinus lies in the junction of the falx cerebri with the ten- The transverse sinuses receive tributaries from the lateral temporal
torium cerebelli (see Figs 28.3, 19.11). It runs posteroinferiorly as a surface and basal surface of the temporal and occipital lobes. The in-
continuation of the inferior sagittal sinus and drains into the transverse ferior anastomotic vein (vein of Labbé) is the largest vein connecting
sinus, most commonly into the left one. It is not (or is only tenuously) the veins of the Sylvian fissure with the transverse sinus. All tributaries
continuous with the superior sagittal sinus. Its tributaries include the of each transverse sinus may drain first into a lateral tentorial sinus. The
great cerebral vein (vein of Galen), which is formed by the convergence superior petrosal sinuses drain into the transition between the trans-
of the internal cerebral and basal veins, and some superior cerebellar verse and sigmoid sinuses on either side (see Figs 28.3, 28.5).
veins. The latter may drain first into a short sinus within the tentorium,
Sigmoid sinus
known as the medial tentorial sinus.
The sigmoid sinuses are continuations of the transverse sinuses, begin-
Transverse sinus
ning where these leave the tentorium cerebelli (see Fig. 28.5; Fig. 28.8).
The transverse sinuses begin at the confluence of sinuses and attach to Each sigmoid sinus curves inferomedially in a groove on the mastoid
the internal occipital protuberance (see Figs 28.3, 28.5). One, usually process of the temporal bone, crosses the jugular process of the occipital


Meninges
437
82
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Superior intercavernous sinus
Cavernous sinus
Planum sphenoidale Lesser sphenoidal wing
Limbus of the sphenoid
Falciform ligament Optic nerve
Anterior clinoid process
Prechiasmatic sulcus Maxillary nerve (V2)
Internal carotid artery (supraclinoidal)
Diaphragma sellae
Anterior petroclinoidal ligament
Posterior clinoid process
Oculomotor nerve
Mandibular nerve (V3)
Oculomotor triangle
Posterior petroclinoidal ligament
Meckel’s cave
Dorsum sellae Petrous apex
Trigeminal nerve
Clivus
Superior petrosal sinus
Fig. 28.9 The sellar region and adjacent middle and anterior cranial fossae, viewed from above, in a silicon-injected anatomical specimen. The dura has
been removed on the right half of the specimen to show the roof of the cavernous sinus (oculomotor triangle), and the maxillary and mandibular nerves
running on the floor of the middle fossa.
bone and turns forwards to the superior jugular bulb, lying posterior (or sellar) wall of the cavernous sinus. The posterior dural wall is
in the jugular foramen. Anteriorly, a thin plate of bone separates its located behind the dorsum sellae and upper clivus, and is shared with
upper part from the mastoid antrum and air cells. It connects with the basilar plexus. The lateral wall extends from the superior orbital
pericranial veins via mastoid and condylar emissary veins. Neurosurgi- fissure to the petrous apex, and separates the cavernous sinus from
cal approaches to the lateral aspect of the posterior fossa (cerebellopon- Meckel’s cave, which is located inferior and posterior to the sinus. The
tine angle) are classified as retrosigmoid, when the craniectomy is roof of the cavernous sinus is formed by the dura lining the lower
located just behind the sigmoid sinus, and presigmoid, when the margin of the anterior clinoid process anteriorly (clinoidal triangle),
mastoid bone in front of the sinus is drilled away to provide a more and the patch of dura between the anterior and posterior clinoids and


anterior corridor into the posterior fossa. the petrous apex, the oculomotor triangle (see Figs 28.9–28.10).
Each sinus contains the cavernous segment of the internal carotid
Superior petrosal sinus
artery, associated with a perivascular sympathetic plexus. The cavernous
These small, narrow sinuses drain the cavernous sinus into the trans- carotid artery has several portions, from proximal to distal: short
verse sinus on either side (see Figs 28.3, 28.5; Figs 28.9–28.10). Each ascending, posterior genu, horizontal, anterior genu. The anterior genu
leaves the posterosuperior part of the cavernous sinus and runs postero- of the cavernous carotid artery continues as the paraclinoidal segment
laterally in the attached margin of the tentorium cerebelli, crosses above of the carotid artery, which typically protrudes into the sphenoidal
the trigeminal nerve to lie in a groove on the superior border of the sinus cavity. The cavernous carotid gives off two major arterial branches:
petrous part of the temporal bone and ends by joining the transverse the meningohypophysial and inferolateral trunks (see Fig. 28.10). The
sinus at the point where this curves down to become the sigmoid sinus. meningohypophysial trunk arises typically from the posterior genu and
The superior petrosal sinuses may receive cerebellar and brainstem gives off the inferior hypophysial, tentorial and dorsal meningeal arter-
veins, such as the superior petrosal vein, and rarely the inferior cerebral ies. The inferolateral trunk arises a few millimetres distal to the menin-
and tympanic veins; they connect with the inferior petrosal sinuses and gohypophysial and distributes around the nerves on the lateral wall of
the basilar plexus. the sinus. (For more detailed descriptions of these branches, including
their main variations, see Krisht et al (1994), Reisch et al (1996),
Inferior petrosal sinus
Tekdemir et al (1998b).)
The inferior petrosal sinuses drain the cavernous sinus into the internal Several cranial nerves run forwards through the cavernous sinus to


jugular veins (see Figs 28.5, 19.11). They begin at the posteroinferior enter the orbit via the superior orbital fissure (see Fig. 28.10). The oculo-
aspect of the cavernous sinus and run back in the petroclival fissure, a motor and trochlear nerves and the ophthalmic division of the trigemi-
groove between the petrous temporal and basilar occipital bones. On nal nerve all lie in the lateral wall of the sinus. The abducens nerve
each side, the inferior petrosal sinus next passes through the antero- enters the cavernous sinus by passing below the petrosphenoidal liga-
medial part of the jugular foramen, accompanied by a meningeal ment within a dural tunnel (Dorello’s canal) just behind the short
branch of the ascending pharyngeal artery, and descends obliquely ascending portion of the cavernous carotid artery, and then runs on the
backwards to drain into the superior jugular bulb. It sometimes drains inferolateral side of the horizontal portion of the cavernous carotid, just
via a vein in the hypoglossal canal to the suboccipital vertebral plexus. medial to the ophthalmic nerve. The space between the trochlear and
The inferior petrosal sinuses are often plexiform. Each receives laby- ophthalmic nerves at the lateral wall of the sinus, known as the infra-
rinthine veins via the cochlear canaliculus and the vestibular aqueduct, trochlear or Parkinson’s triangle, gives access to the horizontal cavern-
and tributaries from the medulla oblongata, pons and inferior cerebel- ous carotid and posterior genu, meningohypophysial trunk and
lar surface. The venous spaces in the sphenopetroclival area, which are abducens nerve. Unlike the ophthalmic division of the trigeminal nerve,
filled anteriorly by blood from the cavernous sinus, medially by blood the maxillary division of the trigeminal nerve does not run through the
from the basilar plexus, and laterally by blood from the superior pet- cavernous sinus or its lateral wall, but courses beneath the dura of the
rosal sinus, typically drain into the inferior petrosal sinuses (Iaconetta middle cranial fossa below the level of the cavernous sinus (see


et al 2003). Fig. 28.10).
Several major venous spaces can been identified within the sinus in
Cavernous sinus
relation to the cavernous carotid artery: superior, posterior, inferior
The cavernous sinuses are two large venous plexuses that lie on either and lateral (modified from Harris and Rhoton 1976). The superior
side of the body of the sphenoid bone, extending from the superior and inferior ophthalmic veins drain into the inferior space; the basilar
orbital fissure to the apex of the petrous temporal bone, with an average plexus and inferior petrosal sinus drain into the posterior space; the
length of 2 cm and width of 1 cm (see Fig. 28.5). The cavity of the superior petrosal sinus opens into the superior space; and the super-
cavernous sinus is formed when the two layers of dura that cover ficial middle cerebral vein, inferior cerebral veins and sphenoparietal
the anterior aspect of the pituitary gland separate from each other at sinus may drain into the lateral compartment. Veins traversing the
the lateral margin of the sella; the outer (endosteal) layer continues emissary sphenoidal foramen, foramen ovale and foramen lacerum
laterally to form the anterior (or sphenoidal) wall of the cavernous may also drain into the cavernous sinus. Less frequently, the central
sinus, while the inner (meningeal) layer remains attached to the pitui- retinal vein and frontal tributary of the middle meningeal vein also
tary gland and runs back towards the dorsum sellae to form the medial drain into it.


IntracranIal regIon
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A
Pituitary stalk
Internal carotid artery (supraclinoidal)
Posterior clinoid process
Optic nerve
Oculomotor nerve
Anterior clinoid process
Cavernous sinus (supratrochlear triangle)
Trochlear nerve Internal carotid artery (cavernous segment)
Cavernous sinus (infratrochlear triangle)
Trigeminal ganglion Ophthalmic nerve (V1)
Superior petrosal sinus
Anteromedial triangle of the middle fossa
Posteromedial triangle of the middle fossa Maxillary nerve (V2)
Anterolateral triangle of the middle fossa
Greater petrosal nerve
Posterolateral triangle of the middle fossa Mandibular nerve (V3)
Middle meningeal artery at
foramen spinosum
B
Meningohypophysial trunk
Internal carotid artery
(cavernous segment)
Dorello’s canal
Inferolateral arterial trunk
Abducens nerve Ophthalmic nerve (V1) (displaced)
Fig. 28.10 A, A lateral view of the right middle cranial fossa and lateral wall of the cavernous sinus in a silicon-injected anatomical specimen. B, The
ophthalmic nerve has been retracted inferiorly to show the inside of the cavernous sinus (abducens nerve, internal carotid artery and its branches)
through the infratrochlear triangle.
Tumours can arise within the cavernous sinus (meningiomas, haem- complex into the sinus via either ophthalmic veins or emissary veins
angiomas, schwannomas) or extend into the cavernous sinus from that enter the cranial cavity through the foramen ovale. This is a critical
adjacent regions (typically, pituitary adenomas that invade the medial medical emergency with a high risk of disseminated cerebritis and
wall of the sinus). Transcranial microsurgical approaches enter the cav- cerebral venous thrombosis.
ernous sinus through the lateral wall (infratrochlear triangle) or roof
Intercavernous sinuses
(oculomotor triangle) of the sinus. Recently introduced endoscopic
endonasal approaches facilitate access to the cavernous sinus from its The two cavernous sinuses are connected by superior, inferior and pos-


anterior (sphenoidal) and medial (sellar) walls. (For more detailed terior intercavernous sinuses, and the basilar plexus (see Figs 28.5,
descriptions of the microsurgical anatomy of the cavernous sinus, see 28.9). The superior and posterior intercavernous sinuses lie in the
Dolenc (1987), Umansky et al (1994), Seoane et al (1998), Yasuda et al anterior and posterior attached borders of the diaphragma sellae and
(2004), Dolenc and Rogers (2009).) they thus form a complete circular venous sinus. The inferior intercav-
ernous sinuses are irregular and plexiform in nature, and commonly
caroticocavernous sinus fistula and cavernous encountered in a surgical transnasal approach to the pituitary gland.
Obliteration of any intercavernous sinus has no clinical consequences
sinus thrombosis
because all connections are valveless and the direction of flow in them
Direct communication between the intracavernous portion of the in-
is reversible.
ternal carotid artery and the cavernous sinus, creating a caroticocavern-
ous sinus fistula (CCF), may occur as a result of either severe head Basilar venous plexus
trauma or aneurysmal vessel disease. The classic signs are ptosis, prop- The basilar sinus and plexus consist of interconnecting channels
tosis (which may be pulsatile), chemosis, periorbital oedema, and ex- between the two layers of dura mater on the clivus (see Figs 28.5, 28.9).
traocular dysmotility causing diplopia secondary to a combination of The basilar venous plexus interconnects the cavernous sinuses and in-
third, fourth and sixth cranial nerve palsies. Hypo- or hyperaesthesia of ferior and superior petrosal sinuses, and joins the internal vertebral
the ophthalmic divisions of the fifth cranial nerve and a decreased venous plexus.
corneal reflex may also be detected. There may be evidence of dilated,
Sphenoparietal sinus
tortuous retinal veins and papilloedema. These changes can cause per-


manent blindness. CCFs are most commonly treated by passing a cath- The sphenoparietal sinuses are inconstant dural venous channels lying
eter up the carotid into the fistula, and then occluding it with dilatable under the lesser wings of the sphenoid bone, near their posterior edge
balloons or flexible metal coils. Any spreading infection involving the (see Fig. 28.5). Each sinus curves medially to open into the anterior
upper nasal cavities, paranasal sinuses, cheek (especially near the part of the cavernous sinus, and receives small veins from the adjacent
medial canthus), upper lip, anterior nares, or even an upper incisor or dura mater and sometimes the frontal ramus of the middle meningeal
canine tooth, may very rarely lead to septic thrombosis of the cavernous vein. Each may also receive connecting rami, in its middle course,
sinuses; infected thrombi pass from the facial vein or pterygoid venous from the superficial middle cerebral vein, temporal lobe veins and the


Meninges
439
82
retPaHc
anterior temporal diploic vein. When these connections are well devel- ascending pharyngeal artery (entering via the foramen lacerum),
oped, the sphenoparietal sinus is a large channel. It has been suggested branches of the internal carotid and a recurrent branch of the lacrimal
that the term sphenoparietal sinus should be abandoned on the basis artery. In the posterior fossa, the dura is supplied by the meningeal
that it is not an anatomical entity, but an artificial combination of two branches of the occipital artery (one enters the skull by the jugular
independent meningeal vessels, namely: the parietal portion of the foramen and another by the mastoid foramen), the posterior meningeal
anterior branch of the middle meningeal veins and the sinus of the branches of the vertebral artery, occasional small branches of the
lesser wing of the sphenoid (Ruíz et al 2004). ascending pharyngeal artery, which enter by the jugular foramen and
hypoglossal canal, and the dorsal meningeal and tentorial arteries
Occipital sinus
arising from the meningohypophysial trunk. The anatomy of the
The occipital sinus is the smallest of the sinuses and it is typically larger meningeal arteries explains the vascular supply for tumours arising
in children. It lies in the attached margin of the falx cerebelli (see Fig. from the meninges (meningiomas) and the architecture of dural ar-
28.5) and is occasionally paired. It commences near the foramen teriovenous fistulae and malformations. (For detailed information on
magnum in several small channels, one joining the end of the sigmoid the surgical anatomy of the meningeal arteries, see Lasjaunias et al
sinus, and connects with the internal vertebral plexuses. It ends in the (2001), Martins et al (2005).)
confluence of the sinuses (torcula).
Middle meningeal artery
Marginal sinus
The middle meningeal artery is the largest of the meningeal arteries. It
The marginal sinus encircles the foramen magnum. It communicates
arises from the first part of the maxillary artery in the infratemporal


anteriorly with the basilar plexus and with the occipital sinus posteri-
fossa and passes between the roots of the auriculotemporal nerve. It lies
orly. It typically drains to the sigmoid sinus or jugular bulb by small
lateral to tensor veli palatini, then enters the cranial cavity through the
sinuses and may connect extracranially to the internal vertebral venous
foramen spinosum and runs in an anterolateral groove on the squa-
plexus or the paravertebral or deep cervical veins in the suboccipital
mous part of the temporal bone, dividing into frontal and parietal
region.
branches (see Figs 28.10–28.11). The larger frontal (anterior) branch
Emissary veins crosses the greater wing of the sphenoid and enters a groove or canal
in the sphenoidal angle of the parietal bone (the sphenoparietal canal).
Emissary veins traverse cranial apertures and make connections between
It divides into branches between the dura mater and cranium; some
intracranial venous sinuses and extracranial veins. Some are relatively
branches ascend to the vertex. The parietal (posterior) branch curves
constant, while others may be absent. These connections are of clinical
back on the squamous temporal bone, reaches the lower border of the
significance in determining the spread of infection from extracranial
parietal bone anterior to its mastoid angle and divides to supply the
foci to venous sinuses, e.g. the spread of infection from the mastoid to
posterior parts of the dura mater and cranium. These frontal and pari-
the venous sinuses or from the paranasal sinuses to the cavernous sinus.
etal branches anastomose with their fellows and with the anterior and
They are also important because they may provide alternative drainage
posterior meningeal arteries.
pathways in cases of venous sinus thrombosis.
Ganglionic branches supply the trigeminal ganglion and associated
The following emissary veins have been recognized. A mastoid emis-
roots. The petrosal branch enters the hiatus for the greater petrosal
sary vein in the mastoid foramen connects the sigmoid sinus with the
nerve, supplies the facial nerve, geniculate ganglion and tympanic


posterior auricular or occipital veins. A parietal emissary vein in the
cavity, and anastomoses with the stylomastoid artery (El Khouly et al
parietal foramen connects the superior sagittal sinus with the veins of
2008). The superior tympanic artery runs in the canal for tensor tympani
the scalp. The venous plexus of the hypoglossal canal, which is occa-
and supplies the muscle and the mucosa that lines the canal. Temporal
sionally a single vein, connects the sigmoid sinus and the internal
branches traverse minute foramina in the greater wing of the sphenoid
jugular vein. A supracondylar emissary vein connects the sigmoid sinus
and anastomose with deep temporal arteries that supply temporalis. An
and veins in the suboccipital triangle via the posterior condylar canal.
anastomotic branch enters the orbit laterally in the superior orbital
A plexus of emissary veins (venous plexus of foramen ovale) connects
fissure, and anastomoses with a recurrent branch of the lacrimal artery;
the cavernous sinus to the pterygoid plexus via the foramen ovale. Two
enlargement of this anastomosis is believed to account for the occa-
or three small veins traverse the foramen lacerum and connect the
sional origin of the lacrimal artery from the middle meningeal artery.
cavernous sinus and the pharyngeal veins and pterygoid plexus. A vein
in the emissary sphenoidal foramen (of Vesalius) connects the cavern- Accessory meningeal artery
ous sinus with the pharyngeal veins and pterygoid plexus. The internal
The accessory meningeal artery may arise from the maxillary or the
carotid venous plexus, which passes through the carotid canal, connects
middle meningeal artery. It enters the cranial cavity through the foramen
the cavernous sinus and the internal jugular vein. The petrosquamous
ovale, and supplies the trigeminal ganglion, dura mater and bone. Its
sinus is an emissary vein that courses over the lateral superior surface
main distribution is extracranial, principally to medial pterygoid, lateral


of the petrous part of the temporal bone. It arises from the dorsolateral
pterygoid (upper head), tensor veli palatini, the greater wing and ptery-
portion of the transverse sinus, before its confluence with the superior
goid processes of the sphenoid bone, the mandibular nerve and otic
petrosal sinus, and drains anteroinferiorly into the retromandibular
ganglion. It is sometimes replaced by separate small arteries.
vein and anteromedially into the pterygoid venous plexus. It usually
disappears during the development of adult venous patterns in the last Meningeal veins
3 months of prenatal life. A vein may traverse the foramen caecum and
Meningeal veins begin from plexiform vessels in the dura mater and
connect nasal veins with the superior sagittal sinus. An occipital emis-
drain into efferent vessels in the outer dural layer that connect with
sary vein usually connects the confluence of sinuses with the occipital
lacunae associated with some of the cranial sinuses. They include the
vein through the occipital protuberance, and also receives the occipital
middle meningeal and the diploic veins. Intracranial veins also com-
diploic vein. The occipital sinus connects with variably developed veins
municate with extracranial vessels via emissary veins.
around the foramen magnum (so-called marginal sinuses) and thus
with the vertebral venous plexuses; this pathway provides an alternative
Middle meningeal vein (sinus)
venous drainage when the jugular vein is blocked or tied. The ophthal-
The frontal (anterior) branch of the middle meningeal vein crosses the
mic veins are potentially emissary because they connect intracranial to
floor of the middle cranial fossa, from either foramen ovale or foramen
extracranial veins.
spinosum, to the pterion, usually in the form of two parallel channels
that accompany the middle meningeal artery. The vein subsequently
Meningeal arteries and veins
passes cranially along the anterior margin of the parietal squama to
and diploic veins
empty into the venous lakes of the superior sagittal sinus. As they course


under the most lateral aspect of the lesser sphenoidal wing, the anterior
Despite their names, the cranial meningeal arteries are predominantly branches of the middle meningeal vessels are contained for a short
periosteal (Fig. 28.11A). Their main targets are bone and haemopoietic distance within a bony canal, the sphenoparietal canal (of Trolard),
marrow, and only some arterial branches are distributed to the cranial which they leave to enter a groove on the internal surface of the parietal
dura mater per se. squama. The veins lie closer to the bone than the artery, and sometimes
The branches of the meningeal vessels lie mainly in the endosteal occupy separate grooves; they are particularly liable to tear in cranial
layer of dura. In the anterior cranial fossa, the dura is supplied by the fractures. Before entering the sphenoparietal canal, the anterior branch
anterior meningeal branches of the anterior and posterior ethmoidal of the middle meningeal vein usually connects with the sinus of the
and internal carotid arteries and a branch of the middle meningeal lesser sphenoidal wing. The latter is connected medially with the anter-
artery. In the middle cranial fossa, it is supplied by the middle and ac- ior and superior aspect of the cavernous sinus by a channel that crosses
cessory meningeal branches of the maxillary artery, a branch of the over the superior ophthalmic vein to reach the cavernous sinus.


Intracranial region
439.e1
82
retPaHc
B
A
D
C
Fig. 28.12 A, A head CT scan showing a right-sided extradural (epidural)
haematoma. The blood clot is biconvex. B, A bone flap from the same
patient. Note the ramifying grooves in the inner table of the squamous
parts of the temporal and parietal bones. A fracture line crossing these
grooves has torn branches of the middle meningeal artery. C, An acute
subdural haematoma. The crescent-shaped blood clot is causing a severe
midline shift and brain herniation. D, A bilateral subacute subdural E
haematoma. E, A right-sided chronic subdural haematoma.


IntracranIal regIon
440
4
noItceS
A
Middle meningeal artery
Meningeal artery
(from occipital artery)
Anterior meningeal arteries
Posterior (from ethmoidal arteries)
meningeal artery
(from ascending
pharyngeal artery)
Middle meningeal artery
Meningeal branch, Maxillary artery
ascending pharyngeal
artery
B
(cid:54)(cid:68)(cid:74)(cid:76)(cid:87)(cid:87)(cid:68)(cid:79)(cid:3)(cid:86)(cid:88)(cid:87)(cid:88)(cid:85)(cid:72)
(cid:38)(cid:82)(cid:85)(cid:82)(cid:81)(cid:68)(cid:79)(cid:3)(cid:86)(cid:88)(cid:87)(cid:88)(cid:85)(cid:72)
(cid:41)(cid:85)(cid:82)(cid:81)(cid:87)(cid:68)(cid:79)(cid:3)(cid:71)(cid:76)(cid:83)(cid:79)(cid:82)(cid:76)(cid:70)(cid:3)(cid:89)(cid:72)(cid:76)(cid:81)(cid:86)
(cid:50)(cid:70)(cid:70)(cid:76)(cid:83)(cid:76)(cid:87)(cid:68)(cid:79)(cid:3)(cid:89)(cid:72)(cid:76)(cid:81)(cid:86)
(cid:36)(cid:81)(cid:87)(cid:72)(cid:85)(cid:76)(cid:82)(cid:85)(cid:3)(cid:87)(cid:72)(cid:80)(cid:83)(cid:82)(cid:85)(cid:68)(cid:79)(cid:3)(cid:71)(cid:76)(cid:83)(cid:79)(cid:82)(cid:76)(cid:70)(cid:3)(cid:89)(cid:72)(cid:76)(cid:81)(cid:86)


(cid:51)(cid:82)(cid:86)(cid:87)(cid:72)(cid:85)(cid:76)(cid:82)(cid:85)(cid:3)(cid:87)(cid:72)(cid:80)(cid:83)(cid:82)(cid:85)(cid:68)(cid:79)(cid:3)(cid:71)(cid:76)(cid:83)(cid:79)(cid:82)(cid:76)(cid:70)(cid:3)(cid:89)(cid:72)(cid:76)(cid:81)(cid:86)
Fig. 28.11 A, The meningeal arteries. B, The diploic canals and veins after removal of the external table of the calvaria. (A, Adapted from Drake RL, Vogl
AW, Mitchell A (eds), Gray’s Anatomy for Students, 2nd ed, Elsevier, Churchill Livingstone. Copyright 2010. B, With permission from Waschke J, Paulsen
F (eds), Sobotta Atlas of Human Anatomy, 15th ed, Elsevier, Urban & Fischer, 2013.)
The parietal (posterior) trunk of the middle meningeal vein mastoid angle of the parietal bone or through the mastoid foramen;
may traverse the foramen spinosum to end in the pterygoid venous and the occipital, the largest of the four, is confined to the occipital
plexus. The frontal trunk may also reach this plexus via the foramen bone, and may open externally into the occipital vein, or internally into
ovale, or it may end in the sphenoparietal or cavernous sinus (see either the transverse sinus or the confluence of the sinuses.
Fig. 28.5). The middle meningeal vein receives meningeal tributaries
and small inferior cerebral veins, and connects with the diploic and Sinus pericranii
superficial middle cerebral veins. It frequently bears arachnoid Sinus pericranii is a rare condition involving congenital or acquired
granulations. anomalous connections between an extracranial blood-filled nodule
and an intracranial dural venous sinus via dilated diploic and/or emis-
Diploic veins sary veins of the skull (Sheu et al 2002).


The diploic veins are large, thin-walled vessels that occupy channels in
the diploë of the cranial bones (see Fig. 28.11B). Four main trunks are
usually described; these are the frontal, anterior and posterior temporal, ARACHNOID AND PIA MATER
and occipital diploic veins. The frontal opens into the supraorbital vein
and the superior sagittal sinus; the anterior temporal is mainly confined The arachnoid mater and the pia mater together are sometimes referred
to the frontal bone, and opens into the sphenoparietal sinus, and one to as the leptomeninges. They are separated by the subarachnoid space
of the deep temporal veins through an aperture in the great wing of the and joined by trabeculae. They are composed of cells that share a
sphenoid; the posterior temporal is situated in the parietal bone, and common embryological origin from the mesenchyme that surrounds
empties into the transverse sinus either through an opening at the the developing nervous system. The outer layer of the arachnoid, the


441
82
retPaHc
Key references
dura–arachnoid interface, is formed from five or six layers of cells joined a chronic basis with mild or no symptoms, and can be surgically
by numerous desmosomes and tight junctions. This layer forms a drained through small openings in the skull (burr-holes). In many
barrier that normally prevents permeation of CSF through the arach- cases, there is some predisposing factor, such as cerebral atrophy or
noid into the subdural space. The central portion of the arachnoid is increased size of the underlying subarachnoid space. In cases of acute
closely apposed to the outer layer, and is formed from tightly packed subdural haematoma, there is rapid accumulation of blood in the sub-
polygonal cells joined by desmosomes and gap junctions. The cells are dural space, typically after severe head trauma, which requires emer-
more loosely packed in the inner layer of the arachnoid, where they gency neurosurgical drainage through a large craniotomy or craniectomy.
intermingle with bundles of collagen continuous with the trabeculae The distinction between subdural and extradural haematoma on a CT
that cross the subarachnoid space. The leptomeningeal cells are not scan relies on the anatomical features of the clot. Extradural collections
surrounded by basement membrane, except where they are in contact tend to be lentiform in shape, reflecting the pressure required to sepa-
with collagen in the inner layers of the arachnoid and on the deep rate the dura and periosteum. They will not pass deep to any major
aspects of the pia mater. dural sinus and cannot extend along the falx cerebri or tentorium
The anatomical relationships of the arachnoid and pia differ to some cerebelli. In contrast, acute subdural haematomas tend to be biconcave
extent in the cerebral and spinal regions. The cerebral part of the arach- in shape and often follow the line of the dura along the falx or tento-
noid mater invests the brain loosely. It does not enter the sulci or fis- rium (Fig. 28.12).
sures, other than the interhemispheric and Sylvian fissures, and it coats


the superior surface of the pituitary fossa. The arachnoid is easily sepa-
rated from the dura over the surface of the brain, but it is adherent to
the adventitia of the internal carotid and the vertebral arteries where Bonus e-book images and videos
they enter the subarachnoid space. The arachnoid is reflected on to the
surface of blood vessels and cranial nerves in the subarachnoid space,
and this is the basis for microsurgical subarachnoid dissection to expose
Fig. 28.5 B–C, Digitally subtracted venograms, venous phase.
brain vessels and cranial nerves. The subarachnoid cisterns are cavities
formed by the wide separation of the pia and arachnoid, and this is Fig. 28.12 A, A head CT scan showing a right-sided extradural
particularly common on the basal aspect of the brain, where the basal
(epidural) haematoma. B, A bone flap from the same patient.
cisterns are located. Knowledge of the neural and vascular contents of C, An acute subdural haematoma. D, A bilateral subacute
each of the basal cisterns is of particular value to the neurosurgeon in subdural haematoma. E, A right-sided chronic subdural
the planning and execution of intracranial procedures. This is, however, haematoma.
beyond the scope of this chapter and the interested reader is directed
in the first instance to Yasargil (1984). Video 28.1 3D surface rotation of the sella turcica in the horizontal
plane.
Subdural haematoma
Separation of the arachnoid and dura mater requires little physical Video 28.2 3D surface rotation of the sella turcica in the multiaxial
force, which means that damage to small bridging veins in the space plane.
can result in subdural haematoma after even relatively mild head
trauma. In cases of chronic or subacute subdural haematomas, the Video 28.3 3D surface rotation of the sella turcica in the vertical
accumulation is of relatively low pressure and seldom presents as a plane.
medical emergency; even sizeable accumulations may be tolerated on
KEY REFERENCES


Browder J, Kaplan HA 1976 Cerebral Dural Sinuses and their Tributaries. Lasjaunias P, Berenstein A, ter Brugge KG 2001 Surgical Neuroangiography.
Springfield, IL: Thomas. Berlin: Springer.
A description of variations in the form of the superior sagittal and other A comprehensive angiographic study describing the anatomical variations of
venous sinuses. the meningeal arteries.
Dolenc VV 1987 The Cavernous Sinus. Vienna: Springer. Martins C, Yasuda A, Campero A et al 2005 Microsurgical anatomy of the
Professor Dolenc’s description of his pioneering studies on the surgical dural arteries. Neurosurgery 56:211–51.
anatomy of the cavernous sinus, which enabled the development of surgical A detailed anatomical study of the variations of the meningeal arteries and
approaches to this region. their surgical implications.
Fernandez-Miranda JC, Tormenti M, Latorre F et al 2012 Endoscopic endo- Rhoton AL 2007 Cranial Anatomy and Surgical Approaches. Baltimore:
nasal middle clinoidectomy: anatomical, radiological, and technical Lippincott Williams & Wilkins.
note. Neurosurgery 71:ONS233–9; discussion ONS239. An essential masterpiece in microsurgical neuroanatomy and surgical
A brief anatomical note that illustrates the surgical anatomy and variations approaches developed by Professor Rhoton after 40 years devoted to the field.
of the middle clinoid.
Yasargil MG 1984 Microneurosurgery, vol 1. New York: Thieme.
Iaconetta G, Fusco M, Samii M 2003 The sphenopetroclival venous gulf: a A monumental work in which Professor Yasargil describes the basal cisterns
microanatomical study. J Neurosurg 99:366–75. and their implications for microneurosurgery.
A detailed anatomical study of the abducens nerve, Dorello’s canal and the
so-called sphenopetroclival venous gulf.


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Ambekar S, Sonig A, Nanda A 2012 Dorello’s canal and Gruber’s ligament: Krmpotić-Nemanić J, Vinter I, Kelovizć Z et al 2005 Postnatal changes of
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Barges-Coll J, Fernandez-Miranda JC, Prevedello DM et al 2010 Avoiding Lasjaunias P, Berenstein A, ter Brugge KG 2001 Surgical Neuroangiography.
injury to the abducens nerve during expanded endonasal endoscopic Berlin: Springer.
surgery: anatomic and clinical case studies. Neurosurgery 67:144–54. A comprehensive angiographic study describing the anatomical variations of
Bauer DF, Youkilis A, Schenck C et al 2005 The falcine trigeminocardiac the meningeal arteries.
reflex: case report and review of the literature. Surg Neurol 63:143–8. Martins C, Yasuda A, Campero A et al 2005 Microsurgical anatomy of the
Browder J, Kaplan HA 1976 Cerebral Dural Sinuses and their Tributaries. dural arteries. Neurosurgery 56:211–51.
Springfield, IL: Thomas. A detailed anatomical study of the variations of the meningeal arteries and
A description of variations in the form of the superior sagittal and other their surgical implications.
venous sinuses.
Morera VA, Fernandez-Miranda JC, Prevedello DM et al 2010 ‘Far-medial’
Davidson JR, Mack J, Gutnikova A et al 2012 Developmental changes in expanded endonasal approach to the inferior third of the clivus: the
human dural innervation. Childs Nerv Syst 28:665–71. transcondylar and transjugular tubercle approaches. Neurosurgery 66:
Dolenc VV 1987 The Cavernous Sinus. Vienna: Springer. 211–19.
Professor Dolenc’s description of his pioneering studies on the surgical Ozveren MF, Uchida K, Aiso S et al 2002 Meningovenous structures of the


anatomy of the cavernous sinus, which enabled the development of surgical petroclival region: clinical importance for surgery and intravascular
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El Khouly H, Fernandez-Miranda JC, Rhoton AL Jr 2008 Blood supply of Reisch R, Vutskits L, Patonay L et al 1996 The meningohypophyseal trunk
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Fernandez-Miranda JC, Gardner PA, Snyderman C et al 2014 Clival chord- Rhoton AL 2007 Cranial Anatomy and Surgical Approaches. Baltimore:
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Fernandez-Miranda JC, Tormenti M, Latorre F et al 2012 Endoscopic
endonasal middle clinoidectomy: anatomical, radiological, and techni- Ruíz DSM, Fasel JHD, Rüfenacht DA et al 2004 The sphenoparietal sinus
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A brief anatomical note that illustrates the surgical anatomy and variations 112–20.
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study. J Neurosurg 45:169–80. Seoane E, Rhoton AL Jr, de Oliveira E 1998 Microsurgical anatomy of the
Iaconetta G, Fusco M, Samii M 2003 The sphenopetroclival venous gulf: a dural collar (carotid collar) and rings around the clinoid segment of the
microanatomical study. J Neurosurg 99:366–75. internal carotid artery. Neurosurgery 42:869–84.
A detailed anatomical study of the abducens nerve, Dorello’s canal and the Sheu M, Fauteux G, Chang H et al 2002 Sinus pericranii: dermatologic
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Kakizawa Y, Abe H, Fukushima Y et al 2007 The course of the lesser petrosal Tauber M, van Loveren HR, Jallo G et al 1999 The enigmatic foramen
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cavernous cranial nerves: an anatomic study. Neurosurgery 34:275–9.


CHAPTER
29
Neck
The neck extends from the base of the cranium and the inferior border contribute). It first passes anterior to the plane of the accessory nerve
of the mandible to the thoracic inlet. (previously called the spinal accessory nerve; p. 310) before winding
around it and becoming anterior to it. It next ascends along the pos
terior margin of sternocleidomastoid. Near the cranium it perforates
SKIN
the deep fascia and passes up on to the scalp behind the auricle to
supply the skin and connect with the great auricular and greater occipi
The skin in the neck is normally under tension. Lines of greatest tension tal nerves and the auricular branch of the facial nerve. Its auricular
have been termed ‘relaxed skin tension lines’; surgical incisions made branch supplies the skin on the upper third of the medial aspect of the
along these lines are said to heal with minimal postoperative auricle and connects with the posterior branch of the great auricular
scarring. nerve. The auricular branch is occasionally derived from the greater
occipital nerve. It has been suggested that compression or stretching of
Cutaneous vascular supply and the lesser occipital nerve contributes to cervicogenic headache (Lucas
lymphatic drainage et al 1994).
Great auricular nerve
The blood vessels supplying the skin of the neck are derived principally The great auricular nerve is the largest ascending branch of the cervical
from the facial, occipital, posterior auricular and subclavian arteries. plexus. It arises from the second and third cervical rami, encircles the
They form a rich network within platysma and in the subdermal plexus, posterior border of sternocleidomastoid, perforates the deep fascia and
which accounts for the viability of the various skin flaps raised during ascends on the muscle beneath platysma with the external jugular vein.
block dissection of the neck, irrespective of whether they include On reaching the parotid gland, it divides into anterior and posterior
platysma. Great care must be taken in their design to avoid threepoint branches. The anterior branch is distributed to the facial skin over the
junctions if the area has been irradiated previously and its viability parotid gland and connects in the gland with the facial nerve. This


compromised. crossinnervation between somatic sensory supply (great auricular) and
The anterior cervical skin is supplied mainly by the superior thyroid parasympathetic secretomotor fibres to the parotid is considered to be
artery and the transverse cervical branch of the subclavian artery. The
posterior skin is supplied by branches from the occipital artery and the
deep cervical and transverse cervical branches of the subclavian artery.
The superior skin is supplied by the occipital artery and its upper sterno
cleidomastoid branch, and the submandibular and submental branches
of the facial artery. Inferiorly, the skin is supplied by the transverse cervi
cal and/or suprascapular branches of the subclavian artery. Transverse cervical nerve
The pattern of venous drainage of the skin of the neck mirrors the
arterial supply: the veins drain into the jugular and facial veins.
Many lymphatic vessels draining the superficial cervical tissues skirt
the borders of sternocleidomastoid to reach the superior or inferior
deep cervical nodes. Some pass over sternocleidomastoid and the pos
terior triangle to drain into the superficial cervical and occipital nodes
(see Fig. 29.15). Lymph from the superior region of the anterior triangle Lesser occipital nerve
drains to the submandibular and submental nodes. Vessels from the
anterior cervical skin inferior to the hyoid bone pass to the anterior Great auricular nerve
cervical lymph nodes near the anterior jugular veins, and their efferents
go to the deep cervical nodes of both sides, including the infrahyoid,
prelaryngeal and pretracheal groups. An anterior cervical node often Accessory nerve
occupies the suprasternal space.
Cutaneous innervation
Sternocleidomastoid Trapezius
The cervical skin is innervated by branches of cervical spinal nerves, via
both dorsal and ventral rami (see Fig. 45.8). The dorsal rami supply
skin over the back of the neck and scalp, and the ventral rami supply
skin covering the lateral and anterior portions of the neck, and the angle
of the mandible (Fig. 29.1). The dorsal rami of the first, sixth, seventh
and eighth cervical nerves have no cutaneous distribution in the neck.


The greater occipital nerve mainly supplies the scalp; it comes from the
medial branch of the dorsal ramus of the second cervical nerve. The
medial branches of the dorsal rami of the third, fourth and fifth cervical
nerves pierce trapezius to supply skin over the back of the neck sequen
tially. The ventral rami of the second, third and fourth cervical nerves
supply named cutaneous branches (the lesser occipital, great auricular,
transverse cutaneous and supraclavicular nerves), via the cervical plexus Area supplied by supraclavicular nerves
(see Fig. 29.1) (see p. 463 for details of the motor branches of the cervi Fig. 29.1 The cutaneous branches of the cervical plexus. The accessory
cal plexus). nerve is also shown as it crosses the posterior triangle to supply
trapezius. Note that the interval between the upper attachments of
Lesser occipital nerve
sternocleidomastoid and trapezius is not normally as extensive as shown
The lesser occipital nerve is derived mainly from the second cervical here. (Adapted from Drake RL, Vogl AW, Mitchell A (eds), Gray’s Anatomy
442 nerve (although fibres from the third cervical nerve may sometimes for Students, 2nd ed, Elsevier, Churchill Livingstone. Copyright 2010.)


Triangles of the neck
443
92
RETPAHC
part of the anatomical basis for the phenomenon of gustatory sweating A B
(Frey’s syndrome), seen after parotidectomy with its inherent disrup
tion of the secretomotor nerve supply. The posterior branch supplies
Greater cornu
the skin over the mastoid process and on the back of the auricle (except Chondroglossus Middle
its upper part); a filament pierces the auricle to reach the lateral surface, constrictor
where it is distributed to the lobule and concha. Efforts are made to Geniohyoid
Hyoglossus
preserve the posterior branch at parotid surgery in order to avoid a Body
Genioglossus
sensory deficit of the pinna. The posterior branch communicates with
the lesser occipital nerve, the auricular branch of the vagus and the
posterior auricular branch of the facial nerve.
Stylohyoid
Transverse cervical cutaneous nerve
Omohyoid
The transverse cervical cutaneous nerve arises from the second and third Lesser cornu
cervical rami. It curves round the posterior border of sternocleidomas Sternohyoid Mylohyoid
toid near its midpoint and runs obliquely forwards, deep to the external C Lesser cornu
jugular vein, to the anterior border of the muscle. It perforates the deep
cervical fascia, and divides under platysma into ascending and descend
ing branches that are distributed to the anterolateral areas of the neck.
The ascending branches ascend to the submandibular region, forming
a plexus with the cervical branch of the facial nerve beneath platysma. Body
Some branches pierce platysma and are distributed to the skin of the Greater cornu
upper anterior areas of the neck. The descending branches pierce
Fig. 29.2 The hyoid bone. A, Anterosuperior aspect. B, Anterosuperior
platysma and are distributed anterolaterally to the skin of the neck, as
aspect, showing the positions of muscular attachments. C, Lateral aspect.
low as the sternum.
Supraclavicular nerves Greater cornua
The supraclavicular nerves arise from a common trunk formed from
rami from the third and fourth cervical nerves, and emerge at the pos


In early life, the greater cornua are connected to the body by cartilage,
terior border of sternocleidomastoid. Descending under platysma and
but after middle age they are usually united by bone. They project
the deep cervical fascia, the trunk divides into medial, intermediate and
backwards (curving posterolaterally) from the lateral ends of the body.
lateral (posterior) branches, which diverge to pierce the deep fascia a
They are horizontally flattened and taper posteriorly, and each ends in
little above the clavicle. The medial supraclavicular nerves run infero
a tubercle. When the throat is gripped between finger and thumb above
medially across the external jugular vein and the clavicular and sternal
the thyroid cartilage, the greater cornua can be identified and the bone
heads of sternocleidomastoid to supply the skin as far as the midline
can be moved from side to side.
and as low as the second rib. They also supply the sternoclavicular joint.
The middle pharyngeal constrictor and, more laterally (i.e. super
The intermediate supraclavicular nerves cross the clavicle to supply the
ficially), hyoglossus are attached along the whole length of the upper
skin over pectoralis major and deltoid down to the level of the second
surface of each greater cornu. Stylohyoid is attached near the junction
rib, next to the area of supply of the second thoracic nerve. Overlap
of the cornu with the body. The fibrous loop for the digastric tendon
between these nerves is minimal. The lateral supraclavicular nerves
is attached lateral and a little posterior to hyoglossus. The thyrohyoid
descend superficially across trapezius and the acromion, supplying the
membrane is attached to the medial border and thyrohyoid is attached
skin of the upper and posterior parts of the shoulder.
to the lateral border. The oblique inferior surface is separated from the
thyrohyoid membrane by fibroareolar tissue.
BONES, JOINTS AND CARTILAGES
Lesser cornua
The bones and cartilages of the neck are the cervical vertebrae and the
The lesser cornua are two small conical projections at the junctions of


hyoid bone, and the cartilages of the upper respiratory tract, including
the body and greater cornua. At its base, each is connected to the body
the larynx. The cervical vertebrae, the occipital bone and the atlanto
by fibrous tissue and occasionally to the greater cornu by a synovial
occipital and atlantoaxial joints are described in Chapter 43, and the
joint that occasionally becomes ankylosed.
laryngeal cartilages are described in Chapter 35.
The middle pharyngeal constrictors are attached to the posterior and
lateral aspects of the lesser cornua. The stylohyoid ligaments are
HYOID BONE attached to their apices and are often partly calcified, and the chon
droglossi are attached to the medial aspects of their bases.
The Ushaped hyoid bone (Fig. 29.2) is suspended from the tips of the
Ossification
styloid processes by the stylohyoid ligaments. It has a body and two
greater and two lesser horns, or cornua.
The hyoid bone develops from cartilages of the second and third pha
Body ryngeal arches, the lesser cornua from the second, the greater cornua
from the third, and the body from the fused ventral ends of both.
Chondrification begins in the fifth fetal week in these elements and is
The body is irregular, elongated and quadrilateral. Its anterior surface
completed in the third and fourth months. Ossification proceeds from
is convex, faces anterosuperiorly, and is crossed by a transverse ridge
six centres, i.e. a pair for the body and one for each cornu. Ossification
with a slight downward convexity. A vertical median ridge often bisects
begins in the greater cornua towards the end of intrauterine life, in the
the upper part of the body but rarely extends to the lower part. The
body shortly before or after birth, and in the lesser cornua around
posterior surface is smooth and concave, faces posteroinferiorly, and is
puberty. The greater cornual apices remain cartilaginous until the third
separated from the epiglottis by the thyrohyoid membrane and loose


decade and epiphyses may occur here. They fuse with the body. Synovial
areolar tissue. There is a bursa between the hyoid bone and the
joints between the greater and lesser cornua may be obliterated by
membrane.
ossification in later decades.
Geniohyoid is attached to most of the anterior surface of the body,
above and below the transverse ridge; the medial part of hyoglossus
invades the lateral geniohyoid area. The lower anterior surface gives JOINTS
attachment to mylohyoid, the line of attachment lying above sterno
hyoid medially and omohyoid laterally. The lowest fibres of genioglos The atlantooccipital and atlantoaxial joints are described in Chapter 43.
sus, the hyoepiglottic ligament and (most posteriorly) the thyrohyoid
membrane are all attached to the rounded superior border. Sterno
TRIANGLES OF THE NECK
hyoid is attached to the inferior border medially and omohyoid is
attached laterally. Occasionally, the medial fibres of thyrohyoid and,
when present, levator glandulae thyroideae, are attached along the Anterolaterally, the neck appears as a somewhat quadrilateral area,
inferior border. limited superiorly by the inferior border of the mandible and a line


NECk
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NOITCES
Splenius capitis Submental triangle
The single submental triangle is demarcated by the anterior bellies of
Sternocleidomastoid both digastric muscles. Its apex is at the chin, its base is the body of the
hyoid bone and its floor is formed by both mylohyoid muscles. It con
tains lymph nodes and small veins that unite to form the anterior
jugular vein. The structures within the digastric and submental triangles
are described in more detail with the floor of the mouth.
Muscular triangle
Levator scapulae
The muscular triangle is bounded anteriorly by the median line of
Trapezius
the neck from the hyoid bone to the sternum, inferoposteriorly by the
anterior margin of sternocleidomastoid and posterosuperiorly by the
Scalenus
Scalenus medius posterior superior belly of omohyoid. The triangle contains omohyoid, sterno
hyoid, sternothyroid and thyrohyoid.
Scalenus anterior Inferior belly of
omohyoid Carotid triangle
The carotid triangle is limited posteriorly by sternocleidomastoid, an
Clavicle
teroinferiorly by the superior belly of omohyoid and superiorly by
stylohyoid and the posterior belly of digastric. In the living (except the
obese), the triangle is usually a small visible triangular depression,
sometimes best seen with the head and cervical vertebral column
Fig. 29.3 The anterior and posterior triangles of the neck, left lateral slightly extended and the head contralaterally rotated. The carotid tri
aspect. See the note in the caption to Figure 29.1. (Adapted from Drake angle is covered by the skin, superficial fascia, platysma and deep fascia
RL, Vogl AW, Mitchell A (eds), Gray’s Anatomy for Students, 2nd ed, containing branches of the facial and cutaneous cervical nerves. The
Elsevier, Churchill Livingstone. Copyright 2010.)
hyoid bone forms its anterior angle and adjacent floor; it can be located
on simple inspection and verified by palpation. Parts of thyrohyoid,
hyoglossus and inferior and middle pharyngeal constrictor muscles


form its floor. The carotid triangle contains the upper part of the
continued from the angle of the mandible to the mastoid process,
common carotid artery and its division into external and internal
inferiorly by the upper border of the clavicle, anteriorly by the anterior
carotid arteries. Overlapped by the anterior margin of sternocleidomas
median line, and posteriorly by the anterior margin of trapezius. This
toid, the external carotid artery is first anteromedial, then anterior to
quadrilateral area can be further divided into anterior and posterior
the internal carotid artery. Branches of the external carotid artery are
triangles by sternocleidomastoid, which passes obliquely from the
encountered in the carotid triangle. Thus the superior thyroid artery
sternum and clavicle to the mastoid process and occipital bone (Fig.
runs anteroinferiorly, the lingual artery anteriorly with a characteristic
29.3). It is true that these triangles and their subdivisions are somewhat
upward loop, the facial artery anterosuperiorly, the occipital artery pos
arbitrary because many major structures – arteries, veins, lymphatics,
terosuperiorly and the ascending pharyngeal artery medial to the in
nerves and some viscera – transgress their boundaries without interrup
ternal carotid artery. Arterial pulsation greets the examining finger. The
tion; nevertheless they have a topographical value in description. More
superior thyroid, lingual, facial, ascending pharyngeal and sometimes
over, some of their subdivisions are easily identified by inspection and
the occipital veins correspond to the branches of the external carotid
palpation, and provide invaluable assistance in surface anatomical and
artery, and all drain into the internal jugular vein. The hypoglossal nerve
clinical examination.
crosses the external and internal carotid arteries. It curves round the
origin of the lower sternocleidomastoid branch of the occipital artery,
and at this point the superior root of the ansa cervicalis leaves it to
ANTERIOR TRIANGLE OF THE NECK descend anteriorly in the carotid sheath. The internal laryngeal nerve
and, below it, the external laryngeal nerve lie medial to the external


The anterior triangle of the neck is bounded anteriorly by the median carotid artery below the hyoid bone. Many structures in this region,
line of the neck and posteriorly by the anterior margin of sternocleido such as all or part of the internal jugular vein, associated deep cervical
mastoid. Its base is the inferior border of the mandible and its projec lymph nodes, and the vagus nerve, may be variably obscured by sterno
tion to the mastoid process, and its apex is at the manubrium sterni. It cleidomastoid, and, pedantically, are thus ‘outside the triangle’.
can be subdivided into suprahyoid and infrahyoid areas above and
below the hyoid bone, and into digastric, submental, muscular and
POSTERIOR TRIANGLE OF THE NECK
carotid triangles by the passage of digastric and omohyoid across the
anterior triangle (see Fig. 29.5).
The posterior triangle is delimited anteriorly by the posterior edge of
sternocleidomastoid, posteriorly by the anterior edge of trapezius, and
Digastric triangle inferiorly by the middle third of the clavicle (see Fig. 29.3). Its apex is
between the attachments of sternocleidomastoid and trapezius to the
The digastric triangle is bordered above by the lower border of the occiput and is often blunted, so that the ‘triangle’ becomes quadrilat
mandible and its projection to the mastoid process, posteroinferiorly eral. The roof of the posterior triangle is formed by the investing layer
by the posterior belly of digastric and by stylohyoid, and anteroinferi of the deep cervical fascia. The floor of the triangle is formed by the
orly by the anterior belly of digastric. It is covered by the skin, superficial prevertebral fascia overlying splenius capitis, levator scapulae and the
fascia, platysma and deep fascia, which contain branches of the facial scalene muscles. It is crossed, approximately 2.5 cm above the clavicle,
and transverse cutaneous cervical nerves. Its floor is formed by mylo by the inferior belly of omohyoid, which subdivides it into occipital


hyoid and hyoglossus. The anterior region of the digastric triangle con and supraclavicular triangles. The contents of the posterior triangle
tains the submandibular gland, which has the facial vein superficial to include fat, lymph nodes (level V), the accessory nerve, cutaneous
it and the facial artery deep to it. The submental and mylohyoid arteries branches of the cervical plexus, inferior belly of omohyoid, branches of
and nerves lie on mylohyoid. The submandibular lymph nodes are the thyrocervical trunk (transverse cervical and suprascapular arteries),
variably related to the submandibular gland. The posterior region the third part of the subclavian artery, and the external jugular vein. The
of the digastric triangle contains the lower part of the parotid gland. anterior and lateral groups of prevertebral muscles form the floor of the
The external carotid artery, passing deep to stylohyoid, curves above posterior triangle.
the muscle, and overlaps its superficial surface as it ascends deep to the
Occipital triangle
parotid gland before entering it. The internal carotid artery, internal
jugular vein and vagus nerve lie deeper and are separated from the
external carotid artery by styloglossus, stylopharyngeus and the glos The occipital triangle constitutes the upper and larger part of the pos
sopharyngeal nerve. terior triangle, with which it shares the same borders, except that


Cervical fascia
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RETPAHC
inferiorly it is limited by the inferior belly of omohyoid. Its floor, from fan out in this layer and either become skin ligaments or continue into
above down, is formed by splenius capitis, levator scapulae, and scaleni the fascia covering pectoralis major and deltoid (Nash et al 2005).
medius and posterior; semispinalis capitis occasionally appears at the
apex. The triangle is covered by skin, superficial and deep fasciae, and DEEP CERVICAL FASCIA
inferiorly by platysma. The accessory nerve pierces sternocleidomastoid
and crosses levator scapulae obliquely downwards and backwards to
Descriptions of the organization of the deep cervical fascia are largely
reach the deep surface of trapezius. The surface marking of its course is
based on the classic work of Grodinsky and Holyoke in 1938. Con
in a line from the junction of the superior third and inferior twothirds
ventionally, three layers – superficial investing, middle and deep – are
of sternocleidomastoid, to the junction of the inferior third and su
recognized (Fig. 29.4). Details of their precise attachments and con
perior twothirds of trapezius. Cutaneous and muscular branches of the
tents vary between authors. (For further reading, see Som and Curtin
cervical plexus emerge at the posterior border of sternocleidomastoid.
(2011).)
Inferiorly, supraclavicular nerves, transverse cervical vessels and the
uppermost part of the brachial plexus cross the triangle. Lymph nodes Investing layer of deep cervical fascia
lie along the posterior border of sternocleidomastoid from the mastoid
process to the root of the neck.
The investing or superficial layer of the deep cervical fascia encircles the
neck, ensheathing trapezius and sternocleidomastoid. The portions
Supraclavicular triangle
between trapezius and sternocleidomastoid, and in the anterior triangle
of the neck, are formed of areolar tissue, indistinguishable from that in
The supraclavicular triangle is the lower and smaller division of the the superficial cervical fascia and deep potential tissue spaces. Superi


posterior triangle, with which it shares the same boundaries, except that orly, the deep fascia fuses with periosteum along the superior nuchal
superiorly it is limited by omohyoid. It corresponds in the living neck line of the occipital bone, over the mastoid process and along the entire
with the lower part of a deep, prominent hollow, namely: the greater base of the mandible. Between the angle of the mandible and the an
supraclavicular fossa. Its floor contains the first rib, scalenus medius and terior edge of sternocleidomastoid, it is particularly strong. Between the
the first slip of serratus anterior. Its size varies with the extent of the mandible and the mastoid process, it is related to the parotid gland,
clavicular attachments of sternocleidomastoid and trapezius, and also extending beneath it to become attached to the zygomatic arch. From
the level of the inferior belly of omohyoid. The triangle is covered by this region, the strong stylomandibular ligament ascends to the styloid
skin, superficial and deep fasciae, and platysma, and crossed by the process. Inferiorly, along trapezius and sternocleidomastoid, the invest
supraclavicular nerves. Just above the clavicle, the third part of the ing layer of the deep cervical fascia is attached to the acromion, clavicle
subclavian artery curves inferolaterally from the lateral margin of sca and manubrium sterni, fusing with their periostea. A short distance
lenus anterior across the first rib to the axilla. The subclavian vein is above the manubrium, the investing layer interweaves with aponeurotic
behind the clavicle and is not usually in the triangle, but it may rise as fibres of platysma and the fascia investing the strap muscles. It is organ
high as the artery and even accompany it behind scalenus anterior. The ized into superficial and deep layers, which are attached to the anterior
brachial plexus is partly superior, and partly posterior, to the artery and border of the manubrium, and to the posterior border and the inter


is always closely related to it. The trunks of the brachial plexus may clavicular ligament, respectively. Between these two layers, a slitlike
easily be palpated here if the neck is contralaterally flexed and the interval, the suprasternal space, contains a small amount of areolar
examining finger is drawn across the trunks at right angles to their tissue, the lower parts of the anterior jugular veins and the jugular
length. With the musculature relaxed, pulsation of the subclavian artery venous arch, the sternal heads of the sternocleidomastoid muscles and
may be felt and the arterial flow can be controlled by retroclavicular sometimes a lymph node.
compression against the first rib. The suprascapular vessels pass trans
versely behind the clavicle, below the transverse cervical artery and vein. Middle layer of deep cervical fascia
The external jugular vein descends behind the posterior border of ster
nocleidomastoid to end in the subclavian vein. It receives the transverse Many of the variations in the descriptions of cervical fascia concern the
cervical and suprascapular veins, which form a plexus in front of the middle layer. (For a detailed discussion, see Som and Curtin (2011).) It
third part of the subclavian artery; occasionally, it is joined by a small is usually subdivided into a muscular layer that surrounds the infra
vein that crosses the clavicle anteriorly from the cephalic vein. Other hyoid strap muscles and a visceral layer that includes both the pretrach
structures within the triangle include the nerve to subclavius, which eal and buccopharyngeal fasciae. The visceral layer extends inferiorly
crosses the triangle, and lymph nodes. from the base of the skull posteriorly and the hyoid bone and thyroid
cartilage anteriorly and laterally, and provides fascial sheaths of varying
thickness for the thyroid gland, larynx, trachea, pharynx and oesopha
CERVICAL FASCIA
gus. Inferiorly, it continues into the superior mediastinum along the
great vessels and fuses with the fibrous pericardium. Laterally, it merges
The organization of the layers of the cervical fascia, and of the tissue with the investing layer of deep cervical fascia and with the carotid


‘spaces’ they enclose, may determine the spread of disease in sheath (see Fig. 29.4).
the head and neck, and facilitates both the differential diagnosis and
the surgical management of that disease, particularly in the suprahyoid Deep layer of deep cervical fascia
neck. Descriptions of the detailed anatomy of these layers and their
associated spaces have a long and chequered history: Malgaigne (1838) The deep layer of cervical fascia consists of dorsal and ventral layers:
commented that ‘the cervical fasciae appear in a new form under the the prevertebral and alar fasciae, respectively. In some descriptions, the
pen of each author who attempts to describe them.’ The situation seems prevertebral layer is synonymous with the deep layer.
to have changed very little in the intervening years, and details of the The prevertebral fascia lies closest to the vertebral bodies, covering
attachments and distribution of the layers and spaces still vary in the anterior surface of longus capitis and longus colli. It extends infer
modern surgical, radiological, oncological and anatomical literature iorly from the skull base, descending in front of longus colli into the
(Som and Curtin 2011, Guidera et al 2012). Interestingly, there is more superior mediastinum, where it blends with the anterior longitudinal
consensus on why the confusion persists, e.g. the difficulties of defining ligament. It passes laterally and posteriorly as the scalene fascia, which
what constitutes fascia, or the limits of layers that split to ensheathe covers the scalene muscles, splenius capitis and levator scapulae. All the
muscles and neurovascular bundles and then merge with other fascial ventral rami of the cervical nerves are initially behind the prevertebral
layers. fascia. The nerves to the rhomboids and serratus anterior and the proxi
mal portions of the phrenic nerve retain this position throughout their
course in the neck, but the accessory nerve lies superficial to the prever
SUPERFICIAL CERVICAL FASCIA tebral fascia. As the subclavian artery and the brachial plexus emerge
from behind scalenus anterior, they carry the prevertebral fascia down
Like superficial fascia elsewhere in the body, the superficial cervical wards and laterally behind the clavicle as the axillary sheath. The pre


fascia is not a separate stratum but a zone of loose connective tissue vertebral fascia is attached to the spinous processes of the vertebrae and
between dermis and deep fascia, and is joined to both. It covers platysma forms a fascial floor for the posterior triangle of the neck.
but is hardly demonstrable as a separate layer. It may contain consider The alar fascia is a coronally orientated sheet, attached to the trans
able amounts of adipose tissue, especially in females, which presuma verse process of the cervical vertebrae. It lies anterior to the prevertebral
bly explains why it is sometimes referred to simply as subcutaneous fat. fascia, from which it is separated by loose connective tissue that fills
In the lower cervical region, aponeurotic fibres of platysma gradually the socalled danger space (see below), and posterior to the pharynx/


NECk
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4
NOITCES
A Superficial cervical fascia
Subcutaneous tissue/platysmal layer/SMAS
Superficial layer of deep cervical fascia (SLDCF)
Investing fascia/investing layer DCF/parotidomasseteric fascia
Carotid sheath
Middle layer of deep cervical fascia (MLDCF)
Pretracheal fascia/visceral fascia/buccopharyngeal fascia
± Muscular layer
Deep layer of deep cervical fascia (DLDCF)
Prevertebral fascia
(± Separate component of alar fascia)
B Superficial space
Central compartment Visceral space or compartment
Pretracheal space
± Oesophageal compartment
Carotid space Carotid sheath
Retropharyngeal space
± Retrovisceral or retro-oesophageal space
‘Danger’ space
Third space
Posterior compartment of retropharyngeal space
Prevertebral space
Perivertebral space
± Paraspinal space
Fig. 29.4 A, The layers of cervical fascia. Abbreviation: SMAS, superficial musculo-aponeurotic system. B, The deep ‘spaces’ in the neck. (A and B,
Infrahyoid transverse section of the neck, adapted from McMinn RMH, Last’s Anatomy. Redrawn with permission from Guidera AK, Dawes PJD, Stringer
MD 2012 Cervical fascia: a terminological pain in the neck. ANZ Surg 82:786–791.)
oesophagus and the visceral layer of the middle deep cervical fascia, Tissue spaces and the spread of infection
from which it is separated by loose connective tissue that fills the retro and injectate
pharyngeal space (see Fig. 29.4). It passes anterolaterally to fuse with
the prevertebral fascia and extends inferiorly from the skull base to
The fascial layers of the neck define a number of potential tissue ‘spaces’
about the level of the seventh cervical vertebra (it varies between C6
above and below the hyoid bone. In health, the tissues within these
and T4), where it fuses with the visceral layer of middle cervical fascia,
spaces are closely applied to each other or are filled with relatively loose
thereby delimiting the lowest extent of the retropharyngeal and danger
connective tissue. However, infections arising superiorly, such as dental,


spaces.
tonsillar, vertebral or intervertebral discrelated infections, can alter
Carotid sheath
these relationships. The organisms responsible are often βhaemolytic
streptococci or a variety of anaerobes. Streptococci produce proteolytic
enzymes that digest the loose connective tissue and so open up the
The conventional description of the carotid sheath is that it is a con tissue spaces. Since there are no tissue barriers running horizontally in
densation of deep cervical fascia around the common and internal the neck, infections that are not treated promptly can rapidly spread
carotid arteries, internal jugular vein, vagus nerve and ansa cervicalis. It from the infratemporal fossa down to the mediastinum below, cross
is thicker around the arteries than the vein, an arrangement that allows the midline through the sublingual and submental spaces, and even
the vein to expand. Peripherally, the sheath is connected to adjacent track into the axilla.
fascial layers by loose areolar tissue. There is disagreement about Understanding the configuration of the cervical fasciae and spaces
whether the carotid sheath is formed by all three layers of the deep is essential for the placement of local anaesthetic cervical plexus blocks
cervical fascia, or exclusively by the deep or the superficial layer, or even in the neck to facilitate operations such as thyroidectomy, parathyroid
that it lacks a demonstrable fascial ensheathment (Guidera et al 2012). ectomy and carotid endarterectomy (Pandit et al 2000).
The spaces are best conceptualized in terms of their location, remem
Suprapleural membrane (Sibson’s fascia)
bering that some communicate with each other and/or with the axilla
or thorax, and that some contain only loose areolar tissue whilst others
The suprapleural membrane (Sibson’s fascia) serves as a plane of contain dense connective tissue. Thus, spaces may be associated with
separation between the lower neck and the thorax. It is attached ante the face (buccal, canine, masticator, parotid), suprahyoid (peritonsillar,
riorly to the inner border of the first rib, and posteriorly to the anterior submandibular, sublingual, parapharyngeal) or infrahyoid (anterior


border of the transverse process of the seventh cervical vertebra and is visceral), or extend the length of the neck (retropharyngeal, danger,
covered and strengthened by a few spreading muscular fibres derived prevertebral, carotid). (For further reading, see Oliver and Gillespie
from the scaleni. (2010).) Tissue spaces associated with the face are described in Chapter


Muscles
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RETPAHC
31. Tissue spaces around the pharynx and larynx are described on pages Cellulitis in the neck
578 and 594, respectively.
The most common causes of cellulitis of the neck are infections arising
from the region of the mandibular molar teeth and the palatine tonsils.
Visceral space or compartment
Several fascial spaces are accessible from this area, and several anatomi
The visceral space or compartment contains the pharynx, cervical cal factors contribute to the spread of infection. Thus, the apices of the
oesophagus, larynx, trachea, thyroid and parathyroid glands, recurrent second and, more especially, the third, mandibular molar teeth are
laryngeal nerves, and the cranial sympathetic trunk. It is bounded anter often close to the lingual surface of the mandible. The apices of the
iorly by the fascia that encloses the infrahyoid strap muscles (muscular roots of the third mandibular molars are usually, and the second molars
layer of middle deep cervical fascia), posteriorly by the alar fascia, and are often, below the attachment of mylohyoid on the inner aspect of
laterally by the carotid sheath on either side. It may be subdivided into the mandible and so drain directly into the submandibular tissue space.
an anterior visceral (pretracheal) space and a posterior visceral space; The posterior free border of mylohyoid is close to the sockets of the
these spaces communicate freely between the levels of the midthyroid third mandibular molars, and at this point, the floor of the mouth
cartilage and the inferior thyroid artery, but are separated inferiorly by consists only of mucous membrane covering part of the submandibular
the fascia associated with the artery. salivary gland. Any virulent periapical infection of the mandibular third
molar teeth may therefore penetrate the lingual plate of the mandible
Anterior visceral (pretracheal) space
and is then at the entrance to the submandibular and sublingual spaces
The visceral division of the middle layer of deep cervical fascia encloses anteriorly, and the parapharyngeal and pterygoid spaces posteriorly.


the anterior visceral space, a surgical and radiological term also trad Infection in this area may also spread from an acute pericoronitis, par
itionally (and confusingly) called the ‘pretracheal’ space. It contains the ticularly when the deeper tissues are opened to infection by extraction
trachea, as well as the thyroid and parathyroid glands, larynx, cervical of the tooth during the acute phase.
oesophagus, recurrent laryngeal nerves and the cranial sympathetic In general, cellulitis around the jaw is only likely to develop when
trunks. The space extends superiorly from the hyoid bone and the the tissues are infected by virulent and invasive organisms at a point
attachments of the strap muscles and their fasciae to the hyoid bone where there is access to the fascial spaces; the predisposing causes do
and thyroid cartilage down into the anterior portion of the superior not often coincide, and cellulitis is therefore uncommon. Cellulitis in
mediastinum. It communicates freely with the posterior visceral space the region of the maxilla is even more uncommon, but fascial space
around the sides of the larynx, the caudal portion of the pharynx and infections may develop in various sites as the result of infected local
the upper cervical oesophagus, but becomes separated from the pos anaesthetic needles. Since there are no barriers running horizontally
terior visceral space at lower levels by dense connective tissue associated with respect to the tissue spaces in the neck, infection entering in this
with the inferior thyroid artery as the latter approaches the thyroid site can rapidly spread more or less unhindered down the neck and may
gland. Infection usually spreads into the anterior visceral space by either enter the mediastinum.
perforation of the anterior wall of the oesophagus by endoscopic instru All forms of cellulitides of the neck or deep neck space infections
mentation, foreign bodies or trauma or from the posterior visceral are potentially very serious. Obstruction of the upper airway develops
space. Radiologically, the portion of the anterior visceral space between as a result of inflammation and oedema, compounded by salivary
the strap fascia and the fascia of the thyroid gland is referred to as the pooling consequent on dysphagia, and this can be quite catastrophic.
anterior cervical space; its posterolateral border is either the carotid This situation is very difficult to manage by conventional techniques.


sheath or the fascia covering sternocleidomastoid. The anterior cervical Increased rigidity and reduced compliance of the tissues make manœu
space often provides a symmetric landmark on transverse imaging vres such as manual anterior jaw thrust or laryngoscopy almost impos
(Smoker and Harnsberger 1991). sible. Specialized techniques, e.g. flexible fibreopticassisted tracheal
intubation or surgical tracheostomy under local anaesthesia, are usually
Posterior visceral space
required to provide safe general anaesthesia to facilitate the surgical
The posterior visceral space lies posterior to the pharynx and cervical drainage and treatment of the cellulitis or deep space abscess. (For
oesophagus, extending from the skull base down to the superior medi further reading see Hedge et al (2012), Maroldi et al (2012).)
astinum, its caudal limit being the level of fusion between the alar and
visceral layers of fascia. The posterior visceral space is often referred to
as the retropharyngeal space in the upper neck.
MUSCLES
Prevertebral space
The prevertebral tissue space is the potential space lying between the The superficial muscles of the neck are platysma, which lies in the
prevertebral fascia and the vertebral column. It extends from the skull subcutaneous tissue of the neck, and sternocleidomastoid and trapez
base to the coccyx, and encloses the prevertebral muscles. Almost all of ius. Sternocleidomastoid is a key landmark because it divides the neck
the pathology that affects the prevertebral space arises from either the into anterior and lateral regions (anterior and posterior triangles,
adjacent vertebrae or their intervertebral discs, or the spinal cord and respectively); the anterior region may be further subdivided into several
associated nerve roots and spinal nerves. Tuberculosis of the spine may smaller named triangles (see above). Muscles in the anterior region are
breach the space and form a Pott’s abscess. organized into supra and infrahyoid groups, and, with one exception,
are all attached to the hyoid bone. The suprahyoid muscles, which
Danger space connect the hyoid bone to the mandible and the base of the skull,


The danger space lies between the alar and prevertebral fascia, and include mylohyoid, geniohyoid, stylohyoid and digastric. The infra
extends from the skull base down to the posterior mediastinum, where hyoid (strap) muscles, which connect the hyoid, sternum, clavicle and
the alar, visceral and prevertebral layers of deep cervical fascia fuse. scapula, are arranged in two planes: a superficial plane consisting of
The potential space so created is closed superiorly, inferiorly and lat sternohyoid and omohyoid, and a deep plane consisting of sterno
erally; infections can only enter by penetrating its walls. The danger thyroid and thyrohyoid.
space is so called because its loose areolar tissue offers a potential route The muscles that form part of the musculoskeletal column in the
for the rapid downward spread of infection, primarily from the retro neck are described in Chapter 43. They can be considered in three
pharyngeal, parapharyngeal or prevertebral spaces, to the posterior groups – anterior, lateral and posterior; very broadly speaking, the
mediastinum. muscles in these groups lie anterior, lateral or posterior to the cervical
vertebrae. The anterior and lateral groups include longi colli and capitis;
Carotid space recti capitis anterior and lateralis; and scaleni anterior, medius, poste
The carotid sheath is a layer of loose connective tissue demarcated by rior and minimi (when present). The posterior muscle group is com
adjacent portions of the investing layer of deep cervical fascia, the pre posed of the cervical components of the intrinsic muscles of the back,
tracheal fascia and the prevertebral fascia. The literature about the overlaid by some of the extrinsic ‘immigrant’ muscles of the back that
existence of a carotid space is confusing: some authors dispute that a run between the upper limb and the axial skeleton (trapezius, levator
potential cavity exists within the carotid sheath that could permit the scapulae; Chapter 48). The intrinsic muscles are arranged in superficial
spread of infections from the upper neck down into the lower neck and deep layers. The superficial layer contains splenius capitis and cer


and mediastinum, while others consider that the suprahyoid sheath vicis. The deeper layers include the transversospinal group (semispi
should be regarded as part of the parapharyngeal space (see discus nales cervicis and capitis, multifidus and rotatores cervicis), interspinales
sion in Som and Curtin (2011)). Infections around the carotid sheath and intertransversarii, and the suboccipital group (recti capitis posterior
may be restricted because, superiorly (near the hyoid bone) and inferi major and minor, and obliquus capitis superior and inferior).
orly (near the root of the neck), the connective tissues adhere to the The muscles associated with the pharynx and larynx are described
vessels. in Chapters 34 and 35, respectively.


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NOITCES
Platysma mastoid process; the sternal fibres are more oblique and superficial, and
extend to the occiput. The direction of pull of the two heads is therefore
Platysma is a broad sheet of muscle of varying prominence that arises
different, and the muscle may be classed as ‘cruciate’ and slightly
from the fascia covering the upper parts of pectoralis major and deltoid.
‘spiralized’.
Its fibres cross the clavicle and ascend medially in the side of the neck.
Anterior fibres interlace across the midline with the fibres of the con
tralateral muscle, below and behind the symphysis menti. Other fibres Relations The superficial surface of sternocleidomastoid is covered by
attach to the lower border of the mandible or to the lower lip, or cross skin and platysma, between which lie the external jugular vein, the great
the mandible to attach to skin and subcutaneous tissue of the lower auricular and transverse cervical nerves, and the superficial lamina of
face. Careful elevation of a myocutaneous flap in the subplatysmal the deep cervical fascia. Near its insertion, the muscle is overlapped by
plane as part of a neck dissection will include this muscle and its associ a small part of the parotid gland. The deep surface of the muscle near
ated blood supply, thereby minimizing the risk of skin necrosis and its origin is related to the sternoclavicular joint and sternohyoid, sterno
wound breakdown. thyroid and omohyoid. The anterior jugular vein crosses deep to it
but superficial to the infrahyoid muscles, immediately above the clavi
Vascular supply Platysma is supplied by the submental branch of cle. The carotid sheath and the subclavian artery are deep to these
the facial artery and by the suprascapular artery (from the thyrocervical muscles. Between omohyoid and the posterior belly of digastric, the
trunk of the subclavian artery). anterior part of sternocleidomastoid lies superficial to the common,
internal and external carotid arteries, the internal jugular, facial and
Innervation Platysma is innervated by the cervical branch of the facial lingual veins, the deep cervical lymph nodes, the vagus nerve and the


nerve, which descends on the deep surface of the muscle close to the rami of the ansa cervicalis. The sternocleidomastoid branch of the
angle of the mandible. superior thyroid artery crosses deep to the muscle at the upper border
of omohyoid. The posterior part of sternocleidomastoid is related on
Actions Contraction diminishes the concavity between the jaw and its internal surface to splenius capitis, levator scapulae and the scalene
the side of the neck, and produces tense, oblique ridges in the skin of muscles, the cervical plexus, the upper part of the brachial plexus, the
the neck. Platysma may assist in depressing the mandible, and, via its phrenic nerve and the transverse cervical and suprascapular arteries.
labial and modiolar attachments, it can draw down the lower lip and The occipital artery crosses deep to the muscle at, or under cover of, the
corners of the mouth in expressions of horror or surprise. lower border of the posterior belly of digastric. At this point, the acces
sory nerve passes deep to sternocleidomastoid, then pierces and sup
Sternocleidomastoid plies the muscle, before it reappears just above the middle of the
Sternocleidomastoid (Fig. 29.5) descends obliquely across the side of posterior border. At its insertion, the muscle lies superficial to the
the neck and forms a prominent surface landmark, especially when mastoid process, splenius capitis, longissimus capitis and the posterior
contracted. It is thick and narrow centrally, and broader and thinner at belly of digastric.
each end. The muscle is attached inferiorly by two heads. The medial
or sternal head is rounded and tendinous, arises from the upper part Vascular supply Sternocleidomastoid receives its blood supply from
of the anterior surface of the manubrium sterni, and ascends postero branches of the occipital and posterior auricular arteries (upper part of
laterally. The lateral or clavicular head, which is variable in width and muscle), the superior thyroid artery (middle part of muscle) and the


contains muscular and fibrous elements, ascends almost vertically from suprascapular artery (lower part of muscle). A superiorly based flap can
the superior surface of the medial third of the clavicle. The two heads be raised on sternocleidomastoid to include a paddle of skin supplied
are separated near their attachments by a triangular interval that cor by perforator vessels (Froes et al 1999), and has been used to recon
responds to a surface depression, the lesser supraclavicular fossa. As struct the lips, floor of mouth and inner aspect of the cheeks. It is not
they ascend, the clavicular head spirals behind the sternal head and a very reliable flap and its use has been superseded by microvascular
blends with its deep surface below the middle of the neck, forming a free transfer flaps or by conventional myocutaneous flaps such as the
thick, rounded belly. Sternocleidomastoid inserts superiorly by a strong pectoralis major flap.
tendon into the lateral surface of the mastoid process from its apex to
its superior border, and by a thin aponeurosis into the lateral half of Innervation Sternocleidomastoid is supplied by the accessory nerve.
the superior nuchal line. The clavicular fibres are directed mainly to the Branches from the ventral rami of the second, third, and sometimes
Hyoid bone Fig. 29.5 Muscles of the neck. Note
that the head is slightly extended in
Mylohyoid
order to expose the suprahyoid
Stylohyoid
muscles. (With permission from
Waschke J, Paulsen F (eds), Sobotta
Atlas of Human Anatomy, 15th ed,
Elsevier, Urban & Fischer. Copyright
2013.)
Posterior belly of digastric
Levator scapulae Sternohyoid
Thyrohyoid Longus capitis
Sternothyroid
Scalenus medius
Cricothyroid
Tendon of omohyoid
Scalenus anterior
Trapezius Sternocleidomastoid