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Superior
oblique
Inferior muscular Superior muscle
arteries rectus
Terminal
muscle
Ciliary arteries
branches


Fig. 8.8. Carotid angiogram, lateral projection, to show the ophthalmic artery.
Fig. 8.10. Axial CT scan (superior to Fig. 8.9), to show the superior ophthalmic
veins.



There are two major veins within the orbit. Both are valveless.
The superior ophthalmic vein forms posteromedial to the upper
eyelid, from facial veins. It courses posteriorly, close to the oph-
thalmic artery, to enter the cavernous sinus through the superior
orbital ¬ssure (Fig. 8.10).
The inferior ophthalmic vein forms in the anterior orbital ¬‚oor and
usually joins the superior ophthalmic vein.


The optic pathways
The optic nerves extend posteriorly from the optic canal, ascending
medially at a 45 degree angle. They then then fuse to form the
optic chiasm, which is superior to the pituitary gland and may be
compressed by a large pituitary tumor extending upwards. From the
optic chiasm the two optic tracts pass posterolaterally (refer to
Medial rectus Fig. 8.1(g),(h), see Chapter 7 Figs. 7.17, 7.90). These then merge with
Lacrimal gland
muscle
the hemispheres, becoming indistinguishable on routine CT or MRI.
Visual ¬bers pass posteriorly through the temporal lobes to the visual
Optic nerve
cortex within the occipital lobes, thus running a long intracranial
course.
Ophthalmic
artery
Lateral rectus
muscle

Superior
orbital
fissure



Fig. 8.9. Axial CT scan to show the ophthalmic arteries.



85
Section 4 The head, neck, and vertebral column

Chapter 9 The ear


C L AU D I A K I R S C H




The anatomy of the ear is conveniently described as comprising three in two parts: a smaller, looser and thicker pars ¬‚accida superiorly, and
parts: the external ear, the middle ear, and the inner ear. a larger, tenser, ¬brous pars tensa inferiorly. The scutum represents the
superior tympanic ring to which the tympanic membrane is attached.
It is particularly well seen on coronal thin section CT (Fig. 9.1).
The external ear
The external ear consists of the pinna or auricle and the S-shaped
The middle ear
external auditory canal, extending from the auricle to the tympanic
membrane. The middle ear, or tympanic cavity, is a treasure trove of spaces,
The outer third of the external auditory canal is ¬brocartilagenous bumps, and recesses. The lateral wall of the tympanic cavity is
and contains numerous hairs and glands for producing cerumen. The formed almost completely by the tympanic membrane and is subdi-
inner two-thirds are bony and contains few hairs or cerumen glands. vided into three spaces relative to it: from above down, the epitympa-
The tympanic membrane separates the external auditory canal from num (syn. the attic or epitympanic recess), mesotympanum, and
the middle ear and is embedded in the bone of the tympanic ring. It is hypotympanum.



(a) (b)




Facial nerve (tympanic segment) Facial nerve (tympanic segment)
Facial nerve segments
Tegmen Oval
Superior semicircular canal
tympani window
Tympanic Labyrinthine

Vestibule

IAM
IAM
Scutum
EAM
Cochlea
EAM



Promontory
Basal turn
Styloid process Lateral semicircular canal of cochlea




Fig. 9.1. Coronal HRCT, the petrous bone, (a) is anterior to (b).



Applied Radiological Anatomy for Medical Students. Paul Butler, Adam Mitchell, and Harold Ellis (eds.) Published by Cambridge University Press. © P. Butler,
A. Mitchell, and H. Ellis 2007.

86
The ear claudia kirsch


promontory is the round window, closed by a secondary tympanic
The epitympanum is located above the tympanic membrane. The
mesotympanum is at the same level as the tympanic membrane and membrane, allowing for counter pulsation of the perilymph ¬‚uid.
From the anterior wall of the tympanic cavity, the pharyngolym-
the hypotympanum is located below it.
The roof of the middle ear cavity is known as the tegmen tympani, panic (Eustachian) tube travels anteromedially to open into the
pharynx (Fig. 9.2). On the posterior wall is a prominent ridge, the
which separates the tympanic cavity below from the middle cranial
pyramidal eminence, in which there is an aperture transmitting the
fossa above. The ¬‚oor also consists of a thin plate of bone below which
stapedius tendon. Lateral to the pyramidal eminence is the facial
is the bulb (superior part) of the internal jugular vein.
nerve recess, medial to it the sinus tympani.
A bony wall separates the tympanic cavity medially from the inner
The posterior wall of the tympanic cavity has a superior opening,
ear. In the epitympanum is a prominence due to the lateral semicircu-
the aditus ad antrum (Fig. 9.3). This leads posteriorly from the epitym-
lar canal and, inferior to this prominence, is the facial nerve canal. On
panic recess into the mastoid air cells and is a pathway for the spread
the medial wall also, but more anterior and just opposite the tym-
of disease between the middle ear and mastoid process.
panic membrane, is the cochlear promontory, created by the large
Within the middle ear cavity is the ossicular chain consisting of the
¬rst turn of the cochlea. The medial wall also contains two small
descriptively named malleus (L. hammer), incus (L. anvil), and stapes
windows. Above the promontory, the oval window is apposed by the
(L. stirrup), each connected by synovial joints (Figs. 9.4 and 9.5).
footplate of the stapes, vibrations from which are transmitted to
the inner ear. Located inferior to the oval window and below the


Head
Body

Anterior process
Short limb

M
I Long limb
Lateral process

Lenticular process

Manubrium
Oval window
S
niche
Eustachian Lateral Medial
tube

Footplate

Head




Fig. 9.2. Axial HRCT to show the eustachian or pharyngotympanic tubes. Fig. 9.4. Diagram of the auditory ossicles.




Incus
Aditus
Facial nerve canal
(vertical segment)
Malleus
Malleus
Incus
Temporomandibular
joint
Stapes
Post. Ant.




Fig. 9.3. HRCT
Fig. 9.5. Axial HRCT
reformatted in the
showing the ossicular
sagittal plane to show
chain.
the aditus ad antrum.


87
The ear claudia kirsch


The malleus has a lateral short process and manubrium embedded
The inner ear
within the tympanic membrane, and head and neck, best seen on thin
section coronal CT images. A small diathrodial joint exists between The inner ear or vestibulocochlear organ is responsible for hearing
the malleus and incus within the attic. and balance. It is well protected and contained within the petrous
The largest ossicle is the incus, posterior to the malleus (Fig. 9.3), portion of the temporal bone. The bony labyrinth of the inner
composed of a body, with a short process extending posteriorly ear encloses the membranous labyrinth, which contains ¬‚uid
acting as a fulcrum allowing the incus to rotate. The incus known as endolymph.
has a lenticular and a long process meeting at about The bony labyrinth comprises the cochlea, vestibule, and semicir-
a 90-degree angle. cular canals and is best appreciated on CT (Figs. 9.1 and 9.6). The
The cup-shaped lenticular process connects to the ball-shaped head cochlea (L. snail shell), is anterior to the vestibule and semicircular
of the stapes (capitulum) via a tiny cartilaginous disc, forming a tiny canals. It is shaped like a spiral seashell, making two and half turns
synovial diathrodial communication. The stapes footplate is attached around its bony central core called the modiolus (L. nave of the
to the oval window via an annular ligament. wheel), which has small openings for blood vessels and nerves. The
The best way to see the ossicular chain is on thin section axial and bony labyrinth encloses the membranous labyrinth, which com-
coronal CT bone windows. prises the saccule and utricle (not visible on imaging), contained
Two important muscles protect the ossicles from loud noises. within the vestibule, three semicircular ducts, located within the
The stapedius muscle, supplied by facial (VIIth cranial) nerve, three semicircular canals, and the cochlear duct located within the
stretches the annular ligament of the stapes. It arises from the pyrami- cochlea. These sacs and ducts contain endolymph and are end
dal eminence and attaches to the stapes footplate. organs for hearing (cochlea) and balance (semicircular canals).
The tensor tympani muscle, supplied by the trigeminal (Vth cranial) Between the bony labyrinth and the membranous labyrinth is ¬‚uid
nerve, dampens sounds by tightening the tympanic membrane. The known as perilymph. Because these are ¬‚uid-containing structures,
tensor tympani muscle lies parallel and medial to the eustachian tube. they are best visualized on MRI, using T2-weighted sequences
It sits in a bony sulcus, extending from the pyramidal eminence ante- (Figs. 9.7 and 9.8).
riorly to attach on to the stapes footplate. The vestibule communicates posteriorly with the semicircular
canals and with the posterior fossa via the vestibular aqueduct. The
vestibular aqueduct contains the endolymphatic duct, which extends
through posterior cranial fossa into a blind pouch, called the



Fig. 9.7. Coronal T2 weighted MRI through the cochleae.




Facial nerve
Posterior cerebral artery
tympanic segment

Cochlea
Incudomallear
Superior cerebellar artery
articulation




Pons
Lateral
semicircular
canal

Cochlea
Anterior inferior cerebellar a.

Vestibule
Fig. 9.6. Axial HRCT
Vestibular aqueduct
showing the bony Vertebrobasilar confluence
(posterior opening)
labyrinth.


88
The ear claudia kirsch


sinus. The horizontal semicircular canal is located just above the facial
nerve canal in the middle ear.



The internal auditory canal
The internal auditory canal or meatus (IAM) is separated laterally
from the inner ear via a thin plate of bone, containing openings
for the facial (VIIth cranial) nerve and the vestibulocochlear (VIIIth
cranial) nerve. The internal auditory canal is a round opening
into the posterior cranial fossa and is divided into quadrants. The
bony crista falciformis divides the IAM horizontally. Bill™s bar
divides the canal vertically. The facial (VIIth cranial) nerve is located
Tentorium cerebelli anteriorly and superiorly. The cochlear division of the eighth nerve
is located anteriorly and inferiorly. Located in the posterior canal
Cerebellopontine
angle cistern
are the superior and inferior quadrants and the remaining
divisions of the eighth nerve, the superior and inferior vestibular
Pons
nerves.
Anterior
Lateral
Semi-
circular
ducts

The facial nerve
Posterior

Vestibule
The facial nerve follows a complex course within the petrous bone. It
may therefore be damaged by trauma to the petrous bone, including
Fig. 9.8. Coronal T2 weighted MRI through the vestibules.
surgery, and by, for example, middle ear infections.
It arises from the brainstem and crosses the cerebellopontine
angle cistern in an anterolateral direction, accompanying the
Anterior semicircular canal
vestibulocochlear (VIIIth cranial) nerve into the internal auditory
meatus (Fig. 9.10). The facial nerve then enters its canal turning
more anteriorly towards the geniculate ganglion (the labyrinthine
portion), (Fig. 9.11). It then turns sharply posterolaterally, at the ¬st
Posterior semicircular canal
Vestibule genu (L. knee) to course along the medial wall of the middle ear
cavity (the tympanic portion) just below the lateral semicircular
Lateral semicircular canal canal and above the oval window niche (Fig. 9.1). At the second genu,
Cochlea
the facial nerve makes a second sharp turn, descending vertically to
exit via the stylomastoid foramen in the mastoid bone (Fig. 9.3) divid-
ing in the parotid gland into ¬ve branches supplying the muscles of
facial expression.




Fig. 9.9. Diagram of the bony labyrinth.




endolymphatic sac, located below the dura mater along the posterior
Cerebellopontine angle cistern
petrous temporal bone. Facial nerve
Basilar artery
The three semicircular canals (Fig. 9.9) are superior and posterior Cochlea
to the vestibule, with which they communicate. They are arranged
at right angles to one another as the superior (anterior), horizontal Vestibule and lat.
(lateral), and posterior semicircular canals. There are only ¬ve semicircular duct

entrances into the vestibule because the superior and posterior canals
Auditory
share a common limb (the common crus). The anterior or superior
nerve Petrosal vein of Dandy
semicircular canal is at a right angle to the long axis of the petrous
temporal bone. The posterior semicircular canal runs parallel to the Fig. 9.10. Axial T2 weighted MRI to show the facial (VIIth cranial) and
axis of the petrous temporal bone in close relation to the sigmoid vestibulocochlear (VIIIth cranial) nerves within the internal auditory meatus.


89
The ear claudia kirsch


Fig. 9.11. Axial HRCT to
The cerebellopontine angle cistern
show the facial nerve
canal. The cerebellopontine angle cistern is one of the large, interconnect-
ing cerebrospinal ¬‚uid spaces (cisterns) at the base of the brain. It is
a subarachnoid space whose medial margin is the pons, and whose
lateral margins include the posterior petrous bone. Traversing the
cistern are the facial (VIIth cranial) and the vestibulocochlear (VIIIth
cranial) nerves. The anterior“inferior cerebellar artery, (AICA), a loop
from which can occasionally enter the IAM, the petrosal vein of
Dandy and the trigeminal (Vth cranial) nerve may also occur within
the cistern.




Facial nerve tympanic segment




Facial nerve “
labyrinthine
segment
Aditus ad antrum




90
Section 4 The head, neck, and vertebral column

Chapter 10 The extracranial head and neck


J U R E E R AT T H A M M A R O J
and J OT I B H AT TAC H A RYA




The facial skeleton and musculature The mandible and temporomandibular joint
For imaging, the skull and facial bones are best considered as a whole The mandible (Fig. 10.6) is the strongest of the facial bones and is par-
(Fig. 10.1). For descriptive purposes, they are usually divided into the ticularly well shown by dental panoramic radiography (or orthopanto-
upper face, consisting of the supraorbital ridge and frontal bone; the mography) (Fig. 10.7). The teeth are borne by the inferior alveolar
midface extending from the supraorbital margin to the upper jaw; process. The mandibular foramen lies on the inner surface of the
and the lower face comprising the mandible. ramus and admits the inferior alveolar nerve (trigeminal) into the
Plain radiographs are still commonly performed. The occipito- mandibular canal, which opens on the outer surface of the mandible
mental or Water™s view (Fig. 10.2), occipito-frontal (Fig. 10.3) and lateral as the mental foramen.
views (Fig. 10.4) are the usual projections. Increasingly, 3-D CT is sup- The muscles of the tongue and ¬‚oor of the mouth are attached to
planting radiographs for facial trauma. CT is also ideal for examining the inner surface of the body of the mandible. The powerful muscles
the skull base, pterygopalatine and infratemporal fossae (Fig. 10.5). of mastication insert on the ramus and angle.




(a) (b)
Bregma
Frontal bone Temporal fossa

Frontal bone


Pterion
Supraorbital
Supraorbital
ridge
foramen
Glabella

Nasion
Greater wing of
sphenoid
Lacrimal
bone
Infraorbital
foramen
Nasal bone


Zygoma
Zygoma

Anterior Temporomandibular
Maxilla nasal spine joint

Pterygoid process
Maxilla
Mental
foramen
Infratemporal fossa

Angle of mandible
Mental
foramen
Fig. 10.1(a),(b). Diagram of skull and facial skeleton. (a) frontal view, (b) lateral view.




Applied Radiological Anatomy for Medical Students. Paul Butler, Adam Mitchell, and Harold Ellis (eds.) Published by Cambridge University Press. © P. Butler,
A. Mitchell, and H. Ellis 2007.

91
jureerat thammaroj and joti bhattacharya
The extracranial head and neck


Fig. 10.2. Occipito-mental
Lateral orbital roof
radiograph (Water™s
Medial orbital roof
view). The petrous
Pituitary fossa
Sphenoid sinus
ridges should be
Posterior wall
projected just below the
of maxillary
maxillary antra. This is sinus
the best single view for
Middle concha
the antra. Note the
Inferior concha
lucency of the canal for
Hard palate
the posterior superior
alveolar nerve in the Soft palate
V-shaped
lateral antral wall. zygomatic
recess of
Prevertebral
maxillary
soft tissues
sinus




Fig. 10.4. Lateral radiograph of facial bones. Note the V-shaped shadows of the
zygomatic recesses of the maxillary antra and the shadows of the middle and
inferior turbinates. The posterior walls of both antra are visible.




(a)


Inferior concha
Pterygopalatine
canal
Medial
and lateral
pterygoid
Lesser wing
Crista galli Frontal sinus
processes
of sphenoid

Greater wing
of sphenoid

Ethmoid sinus
Planum
sphenoidale Innominate
line

Superior Styloid
process
orbital
fissure
Floor of
Occipital Nasopharynx
pituitary Petrous condyle
fossa ridge

Foramen
rotundum

Lateral border
Fig. 10.5(a)“(g). Series of CT images of skull base demonstrating the
of lateral
pterygoid pterygopalatine and infratemporal fossae and related anatomy. Images are
process
contiguous from inferior to superior. The lowest scan (a) shows the
pterygopalatine canal which communicates with the mouth. The
sphenopalatine foramen is seen in (e) opening into the nasal cavity posterior to
Fig. 10.3. Occipito-frontal radiograph (Caldwell view). The petrous ridges should
the middle turbinate. The horizontal canals of the foramen rotundum (g) and the
be projected over the lower third of the orbit. This is the best frontal view for
vidian (pterygoid) canal (e) link the fossa to the middle cranial fossa and the
the ethmoid and frontal sinuses. Note the foramen rotundum always lying
foramen lacerum, respectively. The lateral opening of the pterygopalatine fossa
immediately below the superior orbital ¬ssure.
into the infratemporal fossa is called the pterygomaxillary ¬ssure.


92
jureerat thammaroj and joti bhattacharya
The extracranial head and neck


(b) (c)

Pterygopalatine
fossa
Zygomatic Pterygopalatine
recess fossa Infratemporal
fossa




Head of
mandible
Stylomastoid
foramen
Hypoglossal
canal




(d) (e)


Nasolacrimal Naslacrimal
Inferior orbital
duct duct
fissure
Pterygopalatine
fossa Pterygopalatine
Zygomatic fossa
arch
Sphenopalatine
Infratemporal
foramen
Carotid
fossa
canal
Vidian
Foramen (pterygoid)
spinosum canal

Foramen
ovale
External
auditory
meatus Carotid
canal
Temporo
mandibular
joint Clivus Foramen
lacerum
Jugular
foramen




(f) (g)


Pterygopalatine
Pterygopalatine
fossa
fossa
Foramen
Foramen
rotundum
ovale
Eustachian Temporal
tube fossa
Carotid
canal

Middle
cranial
fossa




External
auditory Internal
meatus auditory
meatus
Petrous portion
of carotid canal




Fig. 10.5(a)“(g). Continued


93
jureerat thammaroj and joti bhattacharya
The extracranial head and neck


communicate via the choanae with the nasopharynx posteriorly,
Fig. 10.6. Diagram of
Condyle/head
mandible. The masseter and laterally with the paranasal sinuses. This region is best demon-
Coronoid
and medial pterygoid strated by CT (Fig. 10.5). The nasal cavity is roofed in its mid-portion by
process Mandibular
muscles insert on the
notch
the cribriform plate of the ethmoid bone which is perforated by about
outer and inner aspects
20 foramina for the olfactory nerve, and ethmoidal vessels. The hard
of the angle. The lateral
Mandibular palate forms the ¬‚oor. The lateral wall is complex bearing the three
pterygoid muscle inserts
foramen
turbinates (or conchae) and their corresponding meatuses (Fig. 10.8).
on the neck and the
Neck
temporalis inserts on
the coronoid process.
The paranasal sinuses and ostiomeatal complex
Alveolar The paranasal sinuses (frontal, maxillary, ethmoid, and sphenoid) arise
process
Angle
as outgrowths of the nasal cavity and communicate with the cavity via
ostia. Although well seen on radiographs (Figs. 10.2“10.4), their anatomy
and pathology is best appreciated on coronal CT images.
Mental Mental
The pyramid-shaped maxillary sinus, or antrum, lies within the
protuberance foramen
body of the maxilla (Fig. 10.9). The roots of the molar and premolar
teeth may project into the sinus but are usually covered by a thin
layer of mucosa. Posteriorly lies the pterygopalatine fossa. The maxil-
lary ostium is in the superior part of the medial wall and opens into
the ethmoid infundibulum, a narrow channel between the uncinate
process and the ethmoid bulla. This in turn opens into a curved
groove in the middle meatus below the ethmoid bulla: the hiatus
semilunaris (Fig. 10.8(b)). The frontal sinus opens into the anterior
end of this groove, with the ethmoid cells opening more posteriorly.
These structures, known as the ostiomeatal complex, form the
drainage pathway for secretions from the sinuses; obstruction here



(a)
Zygomatic Coronoid process
Superior concha Sphenoethmoidal
recess of mandible
Nasal septum
recess
Maxillary Temporo
Hard palate sinus mandibular
joint
Sphenopalatine
foramen
Agger nasi crest

Middle concha


Inferior concha




Orifice of
Eustacian
Styloid tube
process
3rd 2nd 1st
Mandibular
Periodontal canal
Molar 1st Medial
Premolar Incisor membrane
Lateral
2nd
Lamina
dura
Canine
(b)
Posterior ethmoid ostia
Fig. 10.7. Orthopantomography, or dental panoramic radiograph of the mandible
Ethmoid bulla
Frontal recess
and maxilla. This technique in which the X-ray tube and ¬lm cassette rotate
Sphenopalatine
synchronously and reciprocally around the patient™s head gives a good survey
foramen
Anterior
of the upper and lower jaws.
ethmoid
ostia
Middle
ethmoid
ostia
The mandibular condyle articulates with the mandibular fossa of the
temporal bone at the temporomandibular joint (TMJ) (Fig. 10.5 (c)“(e)). Hiatus semilunaris Maxillary
Nasolacrimal and ethmoid sinus
duct ostium infundibulum ostium

Nasal cavity
Fig. 10.8(a),(b). Diagrams of lateral wall of nasal fossa, (a) before and (b) after
The external nose consists of superior bony and inferior cartilaginous removal of the turbinates to expose the underlying meati. Note that only the
portions. The nasal cavity extends from the skull base to the roof of posterior ethmoid cells open into the superior meatus and only the
the mouth and is divided by the nasal septum into two fossae, which nasolacrimal duct opens into the inferior meatus.


94
jureerat thammaroj and joti bhattacharya
The extracranial head and neck


(a) (b) Fig. 10.9(a)“(f). Coronal CT
series on bone window
settings demonstrating
the anatomy of the
paranasal sinuses and
ostiomeatal complex
Anterior
from anterior (a) to
ethmoid
air cells posterior (f).
Crista galli




Septal
Frontal sinus Lacrimal
swell
fossa
body

Nasal bone




(d)
(c)




Superior
Bulla Cribriform turbinate
ethmoidalis palate




Zygomatic
Middle
process
turbinate
Ethmoid
infundibulum



Uncinate
process

Ostium of
maxillary sinus Ethmoid infundibulum
Orifice of
openng into hiatus
nasolacrimal
Middle
semilunaris
duct
turbinate
Maxillary
antrum
Uncinate
Inferior
process
turbinate
Inferior meatus Inferior turbinate Lacrimal duct

(e) (f)

Sphenoid sinus
Superior
Sphenoethmoidal turbinates
Dorsum sellae
Middle
Anterior Planum
recess
clinoid process sphenoidale
Pituitary fossa
Sphenopalatine
foramen
Superior
orbital fissure Temporal
fossa

Coronoid
Inferior process
orbital fissure


Infratemporal
Middle fossa
turbinate
Zygomatic
recess
Uncinate Zygomatic
process process
Inferior
turbinate
Maxillary
antrum
Maxillary antrum
Hard palate Zygomatic recess
Inferior turbinate




95
jureerat thammaroj and joti bhattacharya
The extracranial head and neck


thus has a pivotal role in the development of sinusitis and endoscopic portion curling around the mandible. It is traversed by the facial nerve
sinus surgery seeks to clear these obstructions. which divides here into its ¬ve terminal branches. The course of the
nerve divides the gland into super¬cial and deep lobes. The facial
nerve is seldom visible on imaging studies, although its course can be
The oral cavity tongue and salivary glands
traced. The fatty structure of the parotid gives it a CT density between
The oral cavity contains the teeth, tongue and salivary glands, while that of muscle and fat. On MRI scans, the gland is hyperintense to
muscle.
posteriorly lies the pharynx. The mylohyoid muscles (originating from
the mandible and inserting on the hyoid bone) form the “diaphragma- The submandibular gland is the principal structure in the sub-
mandibular space. Because the gland wraps around the posterior
oris,” which divides the ¬‚oor of the mouth into a sublingual space
border of the mylohyoid, its deep portion lies in the sublingual space.
superomedially and a submandibular space inferolaterally (Fig. 10.10).
The tongue is a muscular organ, supplied by the hypoglossal nerve Its CT density is approximately that of muscle and higher than that of
the parotid gland. It shows strong contrast enhancement.
and readily identi¬ed on CT and MRI.
The sublingual gland is the smallest of the major salivary glands
The parotid gland is the largest of the three, and lies over the
lying anterior to the submandibular gland.
ramus of the mandible and masseter muscle (Fig. 10.11) with its deep


(a) (b)
Hard palate


Longitudinal fibres Soft palate
Intrinsic of tongue
tongue
muscle



Genioglossus
muscle




Masseter
muscle



Sublingual
Teeth
gland
Genioglossus
muscle
Mandible
Transverse fibres
Mylohyoid
of tongue
muscle Hyoid bone
Hyoid bone

Lingual septum


Fig. 10.10. T1W MRI of the head coronal (a) and sagittal (b) demonstrating the structures of the ¬‚oor of the mouth and tongue.




(a) (b)
Parapharyngeal
space
Parapharyngeal space Medial pterygoid
muscle

Masseter
muscle

Parotid gland
Mandible

Posterior facial vein
(lateral) and external
carotid artery (medial)

Posterior facial vein
Parotid gland

External carotid artery
Internal jugular
vein

Carotid sheath Internal carotid
artery



Fig. 10.11(a),(b). Contrast-enhanced axial CT through the parotid gland. Note the typical attenuation of the adult parotid gland in (a), intermediate between fat and
muscle density. In children and some adults the parotid can almost be isodense with muscle (b) which can make identi¬cation of mass lesions dif¬cult.


96
jureerat thammaroj and joti bhattacharya
The extracranial head and neck


(a)
The pharynx
The pharynx is a ¬bromuscular tube, which forms the upper part Temporalis Buccal space

of the aerodigestive tract and extends from the skull base to the
lower border of the cricoid cartilage where it becomes continuous Masticator
with the oesophagus. It is divided into the nasopharynx, oropharynx, space

and laryngopharynx (Fig. 10.12) and consists of mucosal, submucosal,
and muscular layers. Posteriorly lies the prevertebral fascia. The major Pharyngeal
Masseter
mucosal space
function of the pharynx is swallowing, which can be studied by
video¬‚uoroscopy.
Pharyngeal morphology and adjacent structures are well shown by
Parotid
cross-sectional techniques. The nasopharynx is closely related to the space
foramina of the central skull base, accounting for the frequency of
neurological involvement in invasive nasopharyngeal carcinomas Parapharyngeal
space
(Fig. 10.13).
Parotid
Carotid sheath
Medial Internal
pterygoid cartoid artery Retropharyngeal
Fig. 10.12. Diagram of
space
subdivisions of pharynx. Internal
jugular vein Prevertebral space

Fig. 10.14. Parapharyngeal and other deep spaces of the face and upper neck:
(a) schematic diagram through the nasopharynx showing the deep spaces of
Nasopharynx
the face on the right and some of their contents on the left. The central position
of the parapharyngeal space (shaded) is emphasised. (b)“(d) contiguous axial
Uvula T1W MRI superior to inferior demonstrating the high-signal fatty triangle of the
parapharyngeal space.
Tonsil
(b)
Oropharynx Hard palate

Epiglottis
Nasopharynx
Laryngopharynx


Medial pterygoid




Parapharyngeal
space




Fig. 10.13. Coronal CT through nasopharynx showing the pharyngeal recesses. Parotid
Also demonstrated are the foramen rotundum superolaterally, and the vidian
canal linking the pterygopalatine fossa and the foramen lacerum,
inferomedially.
(c)
Sphenoid sinus
Temporalis Medial pterygoid
Foramen
rotundum
Masseter Lateral
Vidian pterygoid
(pterygoid)
canal
Levator
veli palatini
Parotid gland
Pterygoid
processes
Parapharyngeal
space
Lateral
pterygoid
muscle

Medial
pterrygoid
muscle Carotid sheath

Fossa of
Torus tubarius
Rosenmuller Longus colli



97
jureerat thammaroj and joti bhattacharya
The extracranial head and neck


(d) The oropharynx extends from the nasopharynx to the upper border
of the epiglottis inferiorly which, in turn, marks the upper limit of the
Maxillary alveolus
laryngopharynx. The tonsils appear as symmetrical soft tissue densi-
ties on either side of the airway on CT. Both tonsils and adenoids are
Medial pterygoid
also well seen on MRI.
The laryngopharynx extends from the tip of the epiglottis to the
Parapharyngeal esophagus at the level of the sixth cervical vertebra. The pharyngeal
space
lumen is narrowest at its junction with the oesophagus where the
cricopharyngeus forms the upper esophageal sphincter.


The fascial layers of the neck and the parapharyngeal
space
Traditional anatomy describes several muscular triangles of the neck
Parotid

but cross-sectional imaging in contrast emphasizes the importance of
the deep, fascia-lined spaces (Fig. 10.14) The fascia of the neck are
divided into super¬cial and deep layers. The deep fascia de¬ne the
deep spaces of the head and neck. These fascial layers form a barrier
Fig. 10.14. Continued
against the spread of in¬‚ammatory or neoplastic disease. The parapha-
ryngeal space is easily recognized on both CT and MRI as a fatty trian-
(a) Fig. 10.15(a),(b). Diagram gle (Fig. 10.14) whose diagnostic importance is in the characteristic
Tip of epiglottis
of the cartilaginous
manner in which it is in¬ltrated, displaced or distorted by surround-
Lesser cornu
skeleton of the larynx:
ing masses.
Greater (a) external view,
Hyoid bone cornu
(b) cutaway view.

The larynx
Thyrohyoid
membrane
The larynx forms the superior part of the lower respiratory tract
and lies anterior to the laryngopharynx. Its cartilaginous skeleton
Thyroid
Laryngeal
(Fig. 10.15) contains the intrinsic muscles and the vocal folds. Laryngeal
cartilage
prominence
structures are well demonstrated by axial CT (Fig. 10.16) anteriorly lies
the epiglottis, which arises from the posterior surface of the thyroid
cartilage and is separated from the back of the tongue by paired
depressions, the valleculae. The piriform fossae of the laryngopharynx
Cricoid cartilage
Median
cricothyroid lie between the laryngeal opening and the thyroid cartilage on
ligament
each side.
Tracheal rings




(a)
Glossoepiglottic
Hyoid bone
fold


(b) Vallecula
Epiglottis

Cartilago
triticea

Superior
cornu



Ventricular
ligament
Aperture for internal
branch of recurrent
laryngeal nerve
Vocal Epiglottis
Arytenoid
ligament
cartilage


Inferior cornu


Fig. 10.16(a)“(i). Axial CT of the larynx from superior to inferior: (a) CT at level of
hyoid bone showing tip of epiglottis and the valleculae anteriorly. Note the
piriform fossae are below the level of the valleculae and are prominent laterally
on (c)“(f). Note also the normally fatty preepiglottic and paraglottic spaces and
that the fat is replaced by the glottic muscles at the level of the glottis.


98
jureerat thammaroj and joti bhattacharya
The extracranial head and neck


(b) (c)


Vallecula Mandible Preepiglottic
Thyroid cartilage
space

Hyoid bone

Epiglottis
Pyriform fossa
Epiglottis Submandibular
gland




Sternocleido
mastoid




(d) (e)

Thyroid cartilage

Fat in paraglottic Aryepiglottic fold
space
Preepiglottic space



Aryepiglottic fold
Pyriform fossa




Pyriform fossa




(f) (g)
Vocal fold

Fat in paraglottic Thyroid cartilage
space Arytenoid cartilage
Arytenoid cartilage




Upper border of
cricoid cartilage




99
jureerat thammaroj and joti bhattacharya
The extracranial head and neck


(i)
(h)
Trachea
Vocal fold
Cricoid cartlage
Thyroarytenoid muscle
in paraglottic space
Thyroid gland

Arytenoid
Thyroid cartlage
cartilage




Ci id til

Fig. 10.16(a)“(i). Continued


Fig. 10.17(a),(b). Coronal
(b)
(a)
views of the larynx:
(a) soft tissue
radiograph and
(b) coronal MRI.




Uvula



Vestibule Vestibular
fold

Pyriform
Ventricle
Vestibular fossa
fold

Vocal fold
Thyroid cyst
Thyroid
Ventricle cartilage

Trachea
Vocal fold Cricoid
cartilage Thyroid
gland




Trachea




is marked by the parallel bands of the true vocal cords inferiorly, and
The inferior limit of the larynx is formed by the lower border of the
the vestibular folds or false cords superiorly. Between these is the slit-
cricoid cartilage, which articulates with the arytenoid cartilages. The
like cavity of the laryngeal ventricle. These structures are well seen
arytenoids are capable of rotational and gliding movements, which
in the coronal plane, on soft tissue radiographs, and on MRI scans
alter the tension of the vocal cords.
(Fig. 10.17).
The vocal cords are attached to the arytenoids, which are useful
landmarks on CT to identify the vocal folds. The interior of the larynx

100
jureerat thammaroj and joti bhattacharya
The extracranial head and neck


(a)
Trachea
Common
Hyoid
carotid artery Thyroid gland

Vertebral artery
Sternocleidomastoid
Thyroid
Thyroid and vein
muscle
cartilage
muscle

Internal
jugular
Sternothyroid
vein
muscle
External
jugular
vein

Cricoid Oesophagus C7 vertebral
Cricothyroid
cartilage body
muscle



Thyroid Fig. 10.19. Contrast-enhanced CT of the neck at the level of the C7 vertebra. The
gland
thyroid gland shows intense enhancement. Posterolaterally lie the carotid
sheaths. The vertebral vessels have not yet entered the foramen
transversarium.
Isthmus Trachea


Oesophagus




Tracheal ring


(b)
Sternocleidomastoid
Trachea
Common carotid artery Thyroid gland

Sternocleidomastoid
Thyroid gland
Internal jugular vein
Phrenic nerve

Scalenus
anterior

Brachial
plexus

Oesophagus

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