greater wing and pterygoid process). During the first year, the greater upper border behind the third molar as far forwards as the mental
wings and body unite around the pterygoid canals, and the lesser wings symphysis; it is sharp and distinct near the molars but faint further
extend medially above the anterior part of the body, meeting to form forwards. The mylohyoid groove extends downwards and forwards from
the smooth, elevated jugum sphenoidale. By the twenty-fifth year, the ramus below the posterior part of the mylohyoid line and contains
sphenoid and occipital bones are completely fused. An occasional vas- the mylohyoid neurovascular bundle. The area below the line is a
cular foramen, often erroneously termed the craniopharyngeal canal, is slightly concave submandibular fossa and is related to the submandibu-
occasionally seen in the anterior part of the hypophysial fossa. lar gland. The area above the line widens anteriorly into a triangular


Infratemporal and pterygopalatine fossae and temporomandibular joint
537.e1
23
RETPAHC
A plane exists between the pharyngeal side wall and the infratemporal
fossa/masticator space. It is readily identified by palpating the tip of the
styloid process and with gentle blunt finger dissection passing anter-
iorly and medially to the pterygoid hamulus at the lower border of the
medial pterygoid plate. Termed the ‘stylohamular plane’ (Friedman
et al 1981), it defines the medial and superior boundary of the infratem-
poral fossa and is the medial boundary for tumours confined to the
infratemporal fossa. With resections using the stylohamular plane as a
guide, the internal carotid, internal jugular vein and the vagus nerve
should not be at risk because they are deep to the styloid apparatus
(Fig. 32.4).
1
5
4
3
2
Fig. 32.4 The stylohamular plane (dotted line). Key: 1, pterygoid hamulus;
2, styloid process; 3, foramen spinosum; 4, foramen ovale; 5, lateral
pterygoid plate.


InfRATEmPoRAl And PTERygoPAlATInE fossAE And TEmPoRomAndIbulAR joInT
538
4
noITCEs
A BB Condylar process
Condylar process Coronoid process Head
Neck
Oblique line
Lingula
Mylohyoid groove Mandibular foramen
Ramus
Angle
Angle
Mylohyoid line
Mental foramen Mental tubercle Mental protuberance Body Submandibular
fossa
Sublingual fossa Mandibular symphysis
Mental spine
Coronoid process Condylar process Digastric fossa
C D
Mandibular notch
Alveolar arch
Pterygoid fovea
Mentalis Temporalis
Ramus
Mental protuberance Mental foramen Body Angle Depressor Depressor Platysma Buccinator Masseter
labii inferioris anguli oris (part)
E F
Head Coronoid process Body
Condylar process Sublingual fossa
Mandibular notch
Temporalis Geniohyoid
Genioglossus
Ramus Lingula Superior constrictor
Mandibular
foramen Lateral
pterygoid
Mylohyoid groove
Angle
Submandibular fossa
Mylohyoid line Mental spine Medial pterygoid Mylohyoid Digastric, anterior belly
Fig. 32.5 The adult mandible. A, Anterior view. B, Inferior view. C, Lateral view (with muscle attachments in D). E, Internal view (with muscle attachments
in F). (Redrawn with permission from Waschke J, Paulsen F (eds), Sobotta Atlas of Human Anatomy, 15th ed, Elsevier, Urban & Fischer. Copyright 2013.)


Infratemporal fossa
539
23
RETPAHC
sublingual fossa and is related to the sublingual gland; the bone is teeth. The mental nerve may extend anteriorly for 2–3 mm within the
covered by mucosa above the sublingual fossa as far back as the third mandible before curving back to the mental foramen (the ‘anterior
molar. In an edentulous subject, it may be necessary to reduce any loop’ of the mental nerve). Appreciation of the three-dimensional
ridge-like prominence of the mylohyoid line in order for dentures to fit course of the mandibular canal during its passage through the mandible
without traumatizing the overlying oral mucosa. from the mandibular to the mental foramina is essential if damage to
Above the anterior ends of the mylohyoid lines, the posterior sym- the inferior alveolar nerve is to be avoided in third molar surgery, man-
physial aspect bears a small elevation, often divided into upper and dibular osteotomies, dental implant surgery and harvesting of man-
lower parts, the mental spines (genial tubercles). The spines are some- dibular bone grafts.
times fused to form a single eminence, or they may be absent, in which
Coronoid process
case their position is indicated merely by an irregularity of the surface.
The upper part gives attachment to genioglossus, the lower part to The coronoid process projects upwards and slightly forwards as a trian-
geniohyoid. Midline lingual (genial) foramina, above and/or below the gular plate of bone. Its posterior border bounds the mandibular incisure,
genial tubercles, and lateral lingual foramina in the premolar region are and its anterior border continues into that of the ramus.
present in most mandibles and are of importance in the vascular supply
Coronoid hyperplasia
to the symphysis. A rounded elevation of compact bone, the torus
mandibularis, sometimes develops above the mylohyoid line; it is most
prominent in the premolar region, is usually bilateral and only of clini- Available with the Gray’s Anatomy e-book
cal significance if repeatedly traumatized.
Condylar process
Ramus
The mandibular condyle varies considerably in both size and shape.


The mandibular ramus is quadrilateral, and has two surfaces (lateral When viewed from above, the condyle is roughly ovoid in outline, its
and medial), four borders (superior, inferior, anterior and posterior) anteroposterior dimension (approximately 1 cm) being roughly half its
and two processes (coronoid and condylar). The lateral surface is rela- mediolateral dimension. The long axis of the condyle is at right angles
tively featureless and bears the (external) oblique ridge in its lower part. to the mandibular ramus but, due to the flare of the ramus, the lateral
The mandibular foramen, through which the inferior alveolar neuro- pole of the condyle is slightly anterior to the medial; if the long axes
vascular bundle passes to gain access to the mandibular canal (see of the two condyles are extended, they meet at an obtuse angle, varying
below), is sited midway between the anterior and posterior borders of from 145° to 160°, at the anterior border of the foramen magnum. The
the ramus about level with the occlusal surfaces of the teeth. It is over- slender neck of the condyle, which expands transversely upwards, joins
lapped anteromedially by a thin, sharp, triangular spine, the lingula, to the ramus to the articular head. The pterygoid fovea, a small depression
which the sphenomandibular ligament is attached, and which is also situated on the anterior surface of the neck below the articular surface,
the landmark for an inferior alveolar local anaesthetic block injection. receives part of the attachment of lateral pterygoid.
Below and behind the foramen, the mylohyoid groove runs obliquely The condyle consists of a core of cancellous bone covered by a thin
downwards and forwards. outer layer of compact bone whose intra-articular aspect is covered by
The inferior border is continuous with the mandibular base and layers of fibrocartilage. The condyle is one of the most common sites
meets the posterior border at the angle, which is typically everted in for mandibular fractures.
males but frequently inverted in females. The thin superior border
bounds the mandibular incisure (sigmoid or mandibular notch, Condylar hyperplasia


incisura semilunaris), which is surmounted in front by the somewhat
triangular, flat coronoid process and behind by the condylar process. Available with the Gray’s Anatomy e-book
The thick, rounded posterior border extends from the condyle to the
angle, and is gently convex backwards above and concave below. The Accessory foramina of the mandible
anterior border is thin above, where it is continuous with the edge
Accessory mandibular foramina are usually unnamed and infrequently
of the coronoid process, and thicker below, where it is continuous with
described, and yet they are numerous. They may transmit auxiliary
the external oblique line. The temporal crest is a ridge that descends on
nerves to the teeth (from facial, mylohyoid, buccal, transverse cervical
the medial side of the coronoid process from its tip to the bone just
cutaneous, lingual and other nerves), and their occurrence is significant
behind the third molar tooth. The triangular depression between the
in dental anaesthetic blocking techniques. The innervation of the teeth
temporal crest and the anterior border of the ramus is the retromolar
is discussed on page 526. The accessory lingual foramina in the man-
fossa (retromolar trigone).
dibular symphysis are particularly relevant in dental implant surgery
The ramus and its processes provide attachment for the four primary
and osteotomies, e.g. genioplasty, at this site (see below).
muscles of mastication. Masseter is attached to the lateral surface,
medial pterygoid is attached to the medial surface, temporalis is inserted Ossification
into the coronoid process and lateral pterygoid is attached to the The mandible forms in dense fibromembranous tissue lateral to the
condyle. The thickness of the ramus decreases markedly behind the inferior alveolar nerve and its incisive branch, and also in the lower
external oblique line laterally, the temporal crest medially, and above parts of Meckel’s cartilage (first branchial arch). Each half is ossified
the lingula; there may be fusion of the lateral and medial cortical plates. from a centre that appears near the mental foramen at about the sixth


This is of importance in mandibular ramus osteotomies and also influ- week in utero. From this site, ossification spreads medially and postero-
ences the frequency of fractures of the mandibular angle. cranially to form the body and ramus, first below, and then around, the
inferior alveolar nerve and its incisive branch. Ossification then spreads
Antilingula
upwards, initially forming a trough, and later crypts, for the developing
teeth. By the tenth week, Meckel’s cartilage below the incisor rudiments
Available with the Gray’s Anatomy e-book
is surrounded and invaded by bone. The mandibular condyle and coro-
noid process do not develop from the primary (Meckel’s) cartilage but
mandibular canal
from secondary cartilages that appear later (Fig. 32.6). A conical mass,
The mandibular foramen leads into the mandibular canal, which runs the condylar cartilage, extends from the mandibular head downwards
downwards and forwards within the ramus, gently curving inferiorly and forwards in the ramus, and contributes to its growth in height.
within the body under the roots of the molar teeth, with which it com- Although it is largely replaced by bone by midfetal life, its proximal end
municates by small openings, and ascending in the premolar region to persists as proliferating cartilage under the fibrous articular lining until
the mental foramen. The canal is not always easy to define on plain about the third decade. Another secondary cartilage, which soon ossi-
X-rays, especially anterior to the mental foramen. Its walls may be fies, appears along the anterior coronoid border, and disappears before
formed either by a thin layer of cortical bone or, more frequently, by birth. One or two cartilaginous nodules also occur at the symphysis
trabecular bone. Although the buccal–lingual and superior–inferior menti. At about the seventh month in utero, these may ossify as variable
positions of the canal vary considerably between mandibles, in general, mental ossicles in symphysial fibrous tissue; they unite with adjacent
the mandibular canal is situated nearer the lingual cortical plate in the bone before the end of the first postnatal year.
posterior two-thirds of the bone, and closer to the labial cortical plate


in the anterior third. Bilateral symmetry (location of the canal in each Age changes in the mandible
half of the mandible) is reported to be common. Near the mental At birth, the two halves of the mandible are united by a fibrous sym-
foramen, the inferior alveolar nerve branches into the mental nerve, physis menti (Fig. 32.7B). The anterior ends of both rudiments are
which ultimately leaves the mandible via the mental foramen, and the covered by cartilage, separated only by a symphysis. Until fusion occurs,
incisive nerve, which remains within the bone and supplies the anterior new cells are added to each cartilage from symphysial fibrous tissue,


Infratemporal and pterygopalatine fossae and temporomandibular joint
539.e1
23
RETPAHC
The term ‘antilingula’ has been used to describe an inconstant bony
prominence on the lateral aspect of the ramus. This localized bulge,
initially thought to be the result of the entrance of the inferior alveolar
neurovascular bundle into the medial ramus, has been used as a guide
to the position of the mandibular foramen in mandibular osteotomies.
However, there is little correlation between the position of the antilin-
gula and the mandibular foramen. It has been suggested that the promi-
nence (when present) on the lateral ramus could reflect the insertion
of fibres of masseter (Lang 1995, Hogan and Ellis 2006, Park 2014).
The availability of computed tomography (CT), cone beam CT
(CBCT) imaging and computer-assisted intraoperative navigation
permits the assessment of the course of the mandibular canal through-
out its length both prior to and during any surgical procedure that
could place the inferior alveolar nerve and/or the mental nerve at risk
(Aizenbud et al 2012, Wittwer 2012).
Elongation of the coronoid process may be found bilaterally or unilat-
erally, resulting in progressive, painless restriction of mandibular
opening, due to the impingement of the coronoid process on the
medial aspect of the zygomatic arch(es). This rare condition is more
common in males and usually presents in the middle of the third
decade, although it has been reported in neonates. The aetiology is
unknown. Treatment involves the resection of the coronoid process(es)
(Satoh et al 2006, McLoughlin et al 1995, Mulder et al 2012).
Hyperplasia of the mandibular condyle is a rare unilateral condition
that results in facial asymmetry and an altered occlusion (bite). The
condition may occur at any age and, if it occurs prior to puberty, growth
may not cease at the end of the growth period. Reports vary as to
male : female ratio. Although condylar hyperplasia is said to be self-
limiting, removal of the growth site in the condyle may be necessary to


arrest the condition. Correction of the asymmetry of the jaw is usually
performed; however, self-correction of the asymmetry has been reported.
A variety of classification systems have been suggested (Obwegeser and
Make 1986, Nitzan et al 2008, Nitzan 2009, Wolford 2014).


InfRATEmPoRAl And PTERygoPAlATInE fossAE And TEmPoRomAndIbulAR joInT
540
4
noITCEs
A Meckel's cartilage, and ossification on its mandibular side proceeds towards the midline.
Mandibular nerve dorsal end When the latter process overtakes the former and ossification extends
into median fibrous tissue, the symphysis fuses. At this stage, the body
is a mere shell, which encloses the imperfectly separated sockets of
deciduous teeth. The mandibular canal is near the lower border, and
the mental foramen opens below the first deciduous molar and is
directed forwards. The condyle is almost in line with the occlusal plane
of the mandible and the coronoid projects above the condyle. During
the first three postnatal years, the two halves join at their symphysis
from below upwards, although separation near the alveolar margin may
Anterior process persist into the second year. The body elongates, especially behind the
of malleus mental foramen, providing space for three additional teeth. During the
Mental nerve first and second years, as a chin develops, the mental foramen alters
direction; it no longer faces forwards but now faces backwards, as in
B the adult mandible, and accommodates the changing direction of the
Mandibular Lingual Inferior alveolar Meckel's cartilage, emerging mental nerve.
Malleus nerve nerve nerve ventral end In general terms, increase in height of the body of the mandible is
achieved primarily by formation of alveolar bone associated with the
developing and erupting teeth, although some bone is also deposited
on the lower border. Increase in length of the mandible is accomplished
by deposition of bone on the posterior surface of the ramus and con-
comitant compensatory resorption on the anterior surface (accompa-
nied by deposition of bone on the posterior surface of the coronoid
process and resorption on the anterior surface of the condylar process);
a part of the ramus is therefore modelled into an addition to the man-
Chorda Anterior process
dibular body. Increase in width of the mandible is produced by depos-
tympani of malleus
ition of bone on the outer surface of the mandible and resorption on


the inner surface. An increase in the comparative size of the ramus
Nerve to mylohyoid Meckel's Accessory cartilaginous Right half of compared with the body of the mandible occurs during postnatal
cartilage nodules mandible, growth and tooth eruption.
cut The role of the condylar cartilages in mandibular growth remains
Fig. 32.6 The left half of a mandible of a human embryo, 95 mm long. controversial. One view states that continued proliferation of this car-
A, Lateral aspect. B, Medial aspect. Blue: cartilage; yellow: bone. tilage is primarily responsible for the increase in both the mandibular
(Courtesy of A Low.) length and the height of the ramus. Alternatively, there is persuasive
experimental evidence that proliferation of the condylar cartilage is an
adaptive response to function, rather than being genetically determined.
Condylar growth and remodelling have been shown to be influenced
significantly by local factors – notably, movement and loading of the
A Coronoid process Condylar process temporomandibular joint – and to be relatively immune to systemic
influences such as vitamin C and D deficiency. Considering the changes
that occur in the dentition throughout life, continuous adaptation of
the temporomandibular articulation is required in order to maintain
functional occlusal alignment between the upper and lower arches of
teeth; this adaptation is thought to be largely the result of ongoing
condylar remodelling.
In adults, alveolar and subalveolar regions are about equal in depth,
and the mental foramen appears midway between the upper and lower
borders. If teeth are lost, alveolar bone is resorbed, and both the mental
foramen and the mandibular canal come to lie closer to the superior
border (see Fig. 32.7A). The mental foramen is placed higher than the
mandibular canal posterior to it, and so resorption of the alveolus in
edentulous patients exposes the nerve at the foramen, i.e. prior to the
nerve in the mandibular canal (Cawood and Howell 1988, Lang 1995,
Eufinger et al 1997).
Mental foramen Body Ramus
bone resorption in the mandible
Available with the Gray’s Anatomy e-book
Blood supply of the mandible


The blood supply to the body of the mandible is derived from its prin-
B Coronoid process Condylar process cipal nutrient artery, the inferior alveolar artery, and from the vessels
supplying genioglossus, geniohyoid and the anterior belly of digastric
(which are all attached to its lingual aspect between the mental
foramina). The blood supply to these muscles is from the sublingual
branch of the lingual artery and the submental branch of the facial
artery. Branches of these vessels may perforate the lingual cortical plate
Mandibular symphysis
through lateral lingual foramina in the premolar region and genial
Deciduous tooth foramina in the midline, when these foramina are present (Fig. 32.10).
Anastomoses between these vessels are common. A branch of the sub-
Mental foramen mental artery may anastomose with the mental artery, permitting ret-
rograde vascular supply to the body and symphysis (relevant in
mandibular fractures). The vascular supply to the mandibular symphy-
Body Ramus sis is of importance in dental implant surgery. The ramus, including the
Fig. 32.7 A, An edentulous mandible; note the position of the mental mandibular angle, is supplied by the inferior alveolar artery and from
foramen. B, A neonatal mandible. (Redrawn with permission from the vessels supplying masseter and medial pterygoid. Vessels supplying
Waschke J, Paulsen F (eds), Sobotta Atlas of Human Anatomy, 15th ed, temporalis supply the coronoid process. The vascular supply to the
Elsevier, Urban & Fischer. Copyright 2013.) mandibular condyle, temporomandibular joint and the individual


Infratemporal and pterygopalatine fossae and temporomandibular joint
540.e1
23
RETPAHC
The pattern of bone resorption (atrophy) of the mandible following the
loss of teeth is said to be in a centrifugal (‘down and out’) direction,
compared to a centripetal direction in the maxilla. These differences
produce a progressive increase in the incongruity of the alveolar pro-
cesses of the jaws. Bone loss is not limited to the alveolar part; it can
involve the base (basal bone) to varying degrees. Progressive remodel-
ling of the mandible and maxilla accompany the bone loss; it is not
limited to the body of the mandible but also involves the coronoid
process and the mandibular condyle, and reduction in both the height
and width of the ramus. This bone loss has implications in denture
construction, dental implant surgery and mandibular fractures (Figs
32.8–32.9) (Aziz and Najjar 2009, Ellis and Price 2008, Cawood and
Howell 1988, Eufinger et al 1997, Sutton et al 2004).
Fig. 32.9 A bilateral fracture of an edentulous atrophic mandible. There is
complete loss of the alveolar process, extending into the underlying basal
bone. The mental foramen (narrow arrows) and the mandibular canal
(broad arrows) are at the superior border.
Fig. 32.8 The opposing direction (arrows) of resorption (‘atrophy’) of
the mandible and maxilla, resulting in increasing incongruity between
the jaws. The resorption involves the alveolus and the basal bone. Fig. 32.10 A CT image showing the lateral lingual foramina (arrows).
(Image courtesy of Dr Alf Nastri, Royal Melbourne Hospital.) (Courtesy of Dr Koh Nakajima, with permission from Nakajima K, Tagaya
A, Otonari-Yamamoto M, et al. Composition of the blood supply in the
sublingual and submandibular spaces and its relationship to the lateral
lingual foramen of the mandible. Oral Surg Oral Med Oral Pathol Oral
Radiol 2014;117(1):e32–8.)


Temporomandibular joint
541
23
RETPAHC
masticatory muscles is described below (Janfanza et al 2001, McDonnel arch as the articular tubercle. The roof of the glenoid fossa, by contrast,
et al 1994, Jacobs et al 2007, Romanos et al 2012, Nakajima et al 2014). is thin and often translucent when held to the light, confirmation that
this is not a major load-bearing area of the joint (Hylander 2006). The
Endosseous blood supply to the mandible via
posterior wall is formed by the tympanic plate, which also forms the
lingual foramina anterior wall of the external acoustic meatus.
The anterior articular area of the fossa (articular fossa) is formed
Available with the Gray’s Anatomy e-book entirely from the squamous portion of the temporal bone and lined by
articular tissue that extends anteriorly beyond the articular summit on
to the preglenoid plane. The squamotympanic fissure marks the junc-
TISSUE SPACES tion with the posterior non-articular (tympanic) area. The tegmen
tympani, a bony plate of the petrous temporal, intervenes in the medial
Descriptions of the various ‘spaces’ in the head and neck and the fascial aspect of the fissure, where the squamotympanic fissure becomes the
arrangements of the head and neck in the literature lack clarity, and are petrotympanic fissure. The postglenoid tubercle at the root of the zygo-
variable and open to misinterpretation. There is even controversy as to matic arch, just anterior to the squamotympanic fissure, separates the
what constitutes ‘fascia’ (Guidera et al 2012). No gold standard exists squamotympanic fissure laterally from the tympanic plate.
as to what constitutes cervical fascia; however, the landmark paper by The condylar head, tilted forwards on the neck at an angle of
Grodinsky and Holyoke (1938) is suggested as a useful initial point of approximately 30° (physiological anteversion), articulates with the
reference. fossa on its anterior and superior surfaces. Like the eminence, both its


The contents of the infratemporal fossa are contained within a well- slope and shape are variable, influenced by age, function and dentition.
defined space that is bounded by and incorporates the masticatory In the coronal plane, its shape varies from that of a gable (particularly
muscles; this is termed the masticator space. The masticator space is marked in those whose diet is hard) to roughly horizontal (in the
closed posteriorly by the attachment of the deep cervical fascia, medial edentulous).
pterygoid and masseter (pterygomasseteric sling), and anteriorly, lateral It is probably impossible to measure the pressure developed on the
to the ramus, by the firm attachment of masseter (the submasseteric articular surfaces of the human jaw joint when biting; however, direct
space is a potential space). The masticator space is closed superiorly by measurement of loads across the joint in animals has demonstrated
both the temporal fascia laterally and the firm attachment of temporalis significant intermittent loading during mastication. There is also irrefut-
to the bone of the temporal fossa (the deep temporal space is also only able theoretical evidence based on Newtonian mechanics that the jaw
a potential space). Medial to the ramus of the mandible, the pterygo- joint is a weight-bearing joint. With a vertical bite force of 500 N on
mandibular space (part of the masticator space) communicates freely the left first molar, the right condyle must support a load of well over
with the pterygopalatine fossa, offering little resistance to the spread of 300 N (Osborn 1995). The non-working condyle is more loaded than
infection or tumours. Posteriorly penetrating maxillary tumours directly the condyle on the working side, which may help explain why patients
involve the masticator space/infratemporal fossa and the pterygopala- with a fractured condyle choose to bite on the side of the fracture.
tine fossa. Resection of the masticator space has been termed a ‘com-
partment’ resection of the mandible (McMahon et al 2013, Blanchaert
and Ord 1998) (Fig. 32.12). FIBROUS CAPSULE
Above the level of the zygomatic arch, the temporal fascia provides


both the superior and lateral limits, by its attachments to the superior The lower part of the joint is surrounded by tight fibres, which attach
temporal line and the zygomatic arch, respectively. Below the zygo- the condyle of the mandible to the disc (collateral ligament). The upper
matic arch, the investing layer of deep cervical fascia (superficial layer part of the joint is surrounded by loose fibres, which attach the disc to
of deep cervical fascia) splits into two laminae to enclose masseter, the temporal bone (Fig. 32.13). Thus the articular disc is attached sepa-
the lower part of temporalis and medial pterygoid, further defining rately to the temporal bone and to the mandibular condyle, forming
the boundaries of the masticator space. The superficial (lateral) what could be considered two joint capsules. These attachments stabil-
lamina covers masseter and attaches to the zygomatic arch, and the ize the disc but allow rotation over the condyle. Longer fibres joining
deep (medial) lamina runs on the deep surface of medial pterygoid, the condyle directly to the temporal bone may be regarded as reinfor-
attaching to the skull base medial to the foramen ovale (Guidera et al cing. The capsule is attached above to the anterior edge of the pregle-
2014). This fascial covering of the masticatory muscles is felt to be noid plane, posteriorly to the lips of the squamotympanic fissure,
distinct from the parotid fascia (capsule). The contents of the masti- between these to the edges of the articular fossa, and below to the
cator space are temporalis, masseter, medial and lateral pterygoid, the periphery of the neck of the mandible.
ramus and coronoid process of the mandible, the mandibular nerve
and otic ganglion, the maxillary artery and the pterygoid venous
plexus, and part of the buccal fat pad anterolaterally. The submasse- LIGAMENTS
teric, pterygomandibular, superficial and deep temporal spaces are
contained within. The ligaments of the temporomandibular joint are the temporoman-


The superficial temporal space lies between the temporal fascia lat- dibular (lateral) ligament, the sphenomandibular ligament and the
erally and temporalis medially. The deep temporal space, like the sub- stylomandibular ligament.
masseteric space, is a potential space. It lies between temporalis laterally
and the temporal fossa of the skull medially. Both spaces are in com- Temporomandibular (lateral) ligament
munication with the remainder of the masticator space inferiorly.
There is debate as to the upper limit of the masticator space, with
The broad temporomandibular ligament, reinforcing the joint capsule
the suggestion that it should be at the level of the zygomatic arch. Since
laterally, is attached above to the articular tubercle on the root of the
both temporal spaces communicate with the remainder of the masti-
zygomatic process of the temporal bone (see Fig. 32.13). It extends
cator space, a single masticator space incorporating the temporal fascia,
downwards and backwards at an angle of approximately 45° to the
muscles and temporal spaces is favoured (Guidera et al 2014).
horizontal, to attach to the lateral surface and posterior border of the
neck of the condyle, deep to the parotid gland. A short, almost hori-
TEMPOROMANDIBULAR JOINT zontal, band of collagen connects the articular tubercle in front to the
lateral pole of the condyle behind. It may function to prevent posterior
displacement of the resting condyle and also initiates translation of the
The temporomandibular joint (TMJ) is a synovial joint between the
condyle on mouth opening.
glenoid fossa (mandibular fossa) of the temporal bone above and the
mandibular condyle. It is unusual in that its articular surfaces are lined
Sphenomandibular ligament
by fibrocartilage, rather than hyaline cartilage; fibrocartilage is less sus-
ceptible to degeneration and has a greater repair capacity. The joint
cavity is divided into upper and lower compartments (‘spaces’) by a The sphenomandibular ligament is medial to, and normally separate


fibrocartilaginous articular disc. from, the capsule (see Fig. 32.13). It is a flat, thin band that descends
The anterior limit of the glenoid fossa is the articular eminence. This from the spine of the sphenoid and widens as it reaches the lingula
transverse ridge of dense bone, tilted down at an angle of approximately of the mandibular foramen; it has an average width at its insertion
25° to the occlusal plane, forms most of the articular surface of the into the mandible of about 12 mm. Some fibres traverse the medial end
mandibular fossa. It is strongly convex in the sagittal plane with a slight of the petrotympanic fissure and attach to the anterior malleolar
concavity in the coronal plane. It extends out laterally to the zygomatic process. This part is a vestige of the dorsal end of Meckel’s cartilage.


Infratemporal and pterygopalatine fossae and temporomandibular joint
541.e1
23
RETPAHC
The endosseous supply of the mandibular symphysis via the lingual
foramina, and the rich vascular supply to the anterior floor of the
mouth are of particular importance in dental implant surgery and oste-
otomies, e.g. genioplasty, at this site.
Foramina at the level of, or above, the genial tubercle (superior
genial foramen) and below the genial tubercle (inferior genial foramen)
are almost always found (McDonnel et al 1994, Jacobs et al 2007).
Lateral lingual foramina are usually identified, with an average distance
above the lower border of the mandible of 5 mm (Romanos et al 2012).
The superior genial foramen may contain a branch of the lingual artery
and nerve. The inferior foramen may contain a branch of the sublingual
or submental arteries and a branch of the mylohyoid nerve. The lateral
foramen may contain a branch of the submental artery (Jacobs et al
2007, Nakajima et al 2014). Although the relative contributions from
the individual vessels vary, anastomoses between these perforating
vessels and the inferior alveolar artery, within the mandible, are
common. The soft tissues in the anterior floor of the mouth adjacent Fig. 32.11 A three-dimensional reformatted CT image showing an implant
to the mandible are supplied by contributions from the sublingual, perforating the lingual cortical plate (arrow), leading to haemorrhage in the
submental and mylohyoid arteries; there are considerable anastomoses anterior floor of the mouth. A tracheostomy was required to secure the
between them (Romanos et al 2012, Nakajima et al 2014, Loukas et al airway. (With permission from Dubois L, de Lange J, Baas E, Van Ingen J.
2008, Flanagan 2003). Brisk, potentially life-threatening haemorrhage Excessive bleeding in the floor of the mouth after endosseous implant
has been reported with dental implant placement in the mandibular placement: a report of two cases. Int J Oral Maxillofac Surg


2010;39:412–415.)
symphysis, usually associated with perforation of the lingual cortical
plate of the mandible (Romanos et al 2012, Loukas et al 2008, Woo
et al 2006, Dubois et al 2010) (Fig. 32.11) and death has resulted from
genioplasty, secondary to haemorrhage in the anterior floor of the
mouth (personal communication). The precise source of the haemor-
rhage can be difficult to detect and may arise from both within the
mandible and the soft tissues in the floor of the mouth, from any of
the above-named vessels. The anastomoses between the vessels may
result in haemorrhage on both sides of mylohyoid and thus into the
sublingual and the submental/submandibular spaces bilaterally. As the
lateral and midline lingual foramina are closer to the lower border of
the mandible, caution with longer implants has been recommended in
this region.
Subcutaneous tissue
Masticator fascia
Masticator compartment
Parapharyngeal
compartment
Visceral fascia
Retropharyngeal
Alar fascia
compartment
Parotid fascia
Parotid compartment
Carotid sheath Carotid compartment
Prevertebral compartment
Perivertebral fascia
Perivertebral compartment
Fig. 32.12 A transverse section at the level of the hard palate demonstrating the cranial fascia (left) and associated compartments (right). (With
permission from Guidera, A. K., Dawes, P. J. D., Fong, A., Stringer, M. D. (2014), Head and neck fascia and compartments: No space for spaces. Head
Neck, 36:1058–1068.)


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A articular eminence). The synovium is most abundant in the bilaminar
zone of the articular disc, forming loose folds posteriorly when the
condyle is positioned in the glenoid fossa. These folds disappear when
the condyle is protruded and the synovium is stretched.
Synovial fluid and joint lubrication
The coefficient of friction between the articulating surfaces of the tem-
poromandibular joint is almost zero (Nickel et al 2006), reflecting the
net result of a combination of adequate joint lubrication, the surface
structure of the articulating surfaces and the articular disc. Joint lubrica-
tion depends on the synovial fluid, which also provides protection and
nutrition to the articular surfaces and is the sole supplier of nutrients
to the avascular disc. Surface active phospholipids (SAPLs) and
hyaluronic acid are the key lubricants of the joint and act to protect the
Fibrous capsule articular surfaces. It has been hypothesized that abnormalities of the
joint lubrication system, e.g. changes resulting from uncontrolled oxi-
Lateral ligament dative stress, may play a role in the onset of temporomandibular joint
disorders (Nitzan 2001).
Stylomandibular
ligament ARTICULAR SURFACES
The anterior and superior surfaces of the mandibular condyle, and the
articular eminence and preglenoid plane of the squamous temporal
B bone are the principal articulating surfaces of the joint. This is reflected
in the thickness of the articular tissue covering these surfaces. The fibro-
cartilaginous covering of the condyle is composed of four distinct layers
(De Bont et al 1984). The most superficial layer consists of densely
packed fibres of type I collagen that is arranged mostly parallel to the
articular surface and aligned in an anteroposterior direction (this can
be seen as striation on arthroscopy – Video 32.1). This covers a thin
cellular layer, the proliferative zone that is continuous with the cambial
layer of the periosteum beyond the margins of the joint. The third layer,


of hypertrophic cartilage, is rich in intercellular matrix; it contains
chondrocytes scattered throughout its depth, and randomly orientated
fibres of collagen type II. The fourth layer, immediately above the
subchondral bone, is the zone of calcification. Although the number of
Fibrous capsule chondrocytes within the hypertrophic zone decreases with age, undif-
ferentiated mesenchymal cells have been identified in postmortem
specimens of all ages (Hansson et al 1977). This indicates that a cap-
Sphenomandibular ligament
acity for proliferation and repair persists in condylar cartilage, and may
be the reason why condylar remodelling occurs throughout life
Stylomandibular ligament (Robinson 1993, Toller 1974).
Mylohyoid groove ARTICULAR DISC
The articular disc divides the joint into a superior (discotemporal) space
and an inferior (discomandibular) space, both filled with synovial fluid.
Fig. 32.13 The left temporomandibular joint. A, Lateral aspect. B, Medial The transversely oval disc is composed of avascular dense fibrous con-
aspect. nective tissue with some chondrification in areas of maximum loading
(Fig. 32.14). It has a thick margin, which forms a peripheral anulus
and a central depression in its lower surface that accommodates the
With the jaw closed, there is approximately 5 mm slack within the articular surface of the mandibular condyle. The depression probably
ligament, but it becomes taut when the jaw is about half open. Super- develops as a mechanical response to pressure from the condyle as it
iorly, lateral pterygoid, the auriculotemporal nerve and the maxillary rotates inside the anulus. The disc is stabilized on the condyle in three
artery and vein are lateral to the ligament, the nerve and vessels running ways. Its edges are fused with the part of the capsular ligament that
between the ligament and the condylar neck. The chorda tympani lies tightly surrounds the lower joint compartment and is attached around
medially and occasionally grooves the spine of the sphenoid. Antero- the neck of the condyle; well-defined bands in the capsular ligament


inferiorly, the inferior alveolar nerve and vessels and a parotid lobule attach the disc to the medial and lateral poles of the condyle (collateral
separate the ligament from the ramus of the mandible. The vessels and ligaments), and additionally, the thick anulus prevents the disc sliding
nerves to mylohyoid pierce the ligament adjacent to the lingula. Medial off the condyle (self-centring capability – see below), provided that the
pterygoid is inferolateral. The sphenomandibular ligament is separated condyle and disc are firmly lodged against the articular fossa (as is
from the pharynx by fat and a pharyngeal vein. normally the case).
In sagittal section, the disc has three distinct parts: an anterior band,
Stylomandibular ligament
a thinner intermediate zone and a posterior band. The posterior band
is the thickest. Its upper surface is concavo-convex where it fits against
The stylomandibular ligament is a thickened band of deep cervical the convex articular eminence and the concavity of the articular fossa.
fascia that stretches from the apex and adjacent anterior aspect of the Posteriorly, the disc is attached to a richly vascularized and innervated
styloid process to the angle and posterior border of the mandible (see region, the bilaminar zone (posterior attachment), which splits into
Fig. 32.13). Its position and orientation indicate that it cannot mechan- two laminae; unlike the rest of the disc, its normal function is to provide
ically constrain any normal movements of the mandible and does not attachment rather than intra-articular support. The upper lamina is
seem to warrant the status of a ligament of the joint. composed of fibroelastic tissue and is attached to the squamotympanic
fissure. There is a condensation of elastic fibres in the medial portion
of the upper lamina, which is visible as the posterior oblique protuber-
SYNOVIAL MEMBRANE ance on arthroscopy (see Video 32.1). The lower lamina is composed
of fibrous non-elastic tissue and is attached to the posterior aspect of
The synovial membrane lines the inside of the capsule of the joint but the condyle. The intervening connective tissue between the upper and


does not cover the disc or the articular surfaces (condyle, fossa or lower laminae contains a vascular plexus and is well innervated, but the


Temporomandibular joint
543
23
RETPAHC
A
A Articular layer
Collagen type I fibres aligned parallel
to the articular surface in sagittal and
transverse directions
B Proliferative layer
Mostly cellular
C Hypertrophic zone
Collagen type II fibres in random
orientation– some radial
D Zone of calcification
As per C
E Subchondral bone
B
A
Temporal bone
and cartilage B
Disc
AB Cartilage
C
C
Condylar cartilage
D
E and bone
D
E Bone
Fig. 32.14 Sagittal sections through the right temporomandibular joint. A, Note the relationship of the external acoustic meatus and articular disc to the
mandibular condyle. B, The microstructure of condylar cartilage. (A, Courtesy of Professor Cristina Manzanares Céspedes, Anatomy and Human
Embryology Unit, Bellvitge Campus, University of Barcelona.)
central part of the disc itself is avascular and not innervated. With during movement. The disc moves in an almost congruent manner rela-
anterior movement of the disc–condyle complex, the volume of the tive to the condyle controlled by neuromuscular forces: the upper head
posterior attachment increases as a result of the negative pressures of lateral pterygoid anteriorly and the elastic tissue in the bilaminar
generated, resulting in an influx of blood into the venous plexus. This region posteriorly together pull the disc forwards or backwards. In addi-
pumping mechanism is important in the nutrition of the joint tion, the shape of the disc with its thick, ‘self-seating’ anulus helps to
(Stegenga and de Bont 2006). prevent the disc sliding off the condyle. An alternative view is that a
slippery articular disc doubles the number of virtually friction-free
Upper and lower joint compartments
sliding surfaces, and so destabilizes the condyle in the same way that
The upper joint space contains approximately 1.2 ml of synovial fluid stepping on a banana skin destabilizes the foot. These two roles are
and the lower approximately 0.9 ml. Both spaces may be consider- not mutually exclusive. A deformable disc stabilizes the condyle


ably distended with fluid for diagnostic purposes in temporoman- within the joint whilst, by doubling the friction-free surfaces, the disc–
dibular joint arthrography, for therapeutic purposes in arthrocentesis, condyle assembly slides freely under compressive loading and so is
and to improve access and visibility in arthroscopy. Both joint spaces ‘destabilized’.
have an anterior and posterior recess or pouch, and are lined by syn-
ovium, which has a grey hue when viewed through an arthroscope
(see Video 32.1). RELATIONS
Functions of the articular disc
Superiorly, the thin roof of the glenoid fossa has a mean thickness of
0.9 mm (range 0.2–4 mm) and separates the upper joint space from
The articulating surfaces of the mandibular condyle and the articular the middle cranial fossa. This bony partition is occasionally fenestrated
fossa are highly incongruent. Wear of the articular surfaces may be by inflammatory processes or inadvertently during surgery to the joint,
reduced by the presence of a deformable articular disc, which not particularly for release of ankylosis, and rarely by the condyle being
only distributes compressive joint loading over a larger contact area but driven superiorly by violent trauma to the mandible. The maxillary
also significantly reduces the frictional force on the condyle and the artery and its proximal branches, most notably the middle meningeal
articular fossa by separating slide and rotation into different joint artery, lie medially, just beyond the joint capsule. The uppermost part
compartments. of the parotid capsule enclosing the branches of the facial nerve that
The disc may aid joint lubrication by storing fluid squeezed out from supply the muscles of the upper face, including orbicularis oculi, are
loaded areas to create a weeping lubricant. In addition, its flexibility, lateral to the joint capsule; the thread-like nerves are at risk during surgi-
due to its high water content and viscoelastic properties, allows it to cal approach to the joint. The upper part of the infratemporal fossa,
function almost like a fluid, further reducing friction within the joint which contains the two heads of lateral pterygoid, is anterior to the
and thereby aiding joint lubrication. The friction between the articul- condyle (Fig. 32.15). It is into this space anterior to the articular emi-


ating surfaces in the absence of the disc is 2–3 times greater than with nence that the condyle is displaced in cases of dislocation of the tem-
the disc in situ. poromandibular joint or fracture dislocation of the condylar head due
The role of the disc in relation to joint stability is controversial. One to the vector of pull from lateral pterygoid, which inserts into the anter-
view is that a deformable and viscoelastic disc stabilizes the condyle ior condylar neck. Posteriorly, the tympanic plate and tegmen tympani
within the joint by filling the changing and irregular joint space created separate the joint from the middle ear cavity. Perforation through this


Infratemporal and pterygopalatine fossae and temporomandibular joint
543.e1
23
RETPAHC
The articular disc is designed to withstand compressive and shearing
loads, and has viscoelastic properties, allowing it both to deform when
loaded and to conform to the surfaces causing this deformation.
Removal of the disc increases surface friction within the joint by 2–3
times compared to joints with an intact disc. Long-term follow-up of
patients who have had the disc removed (‘discectomy’) demonstrates
that the joint undergoes significant remodelling similar to that seen in
osteoarthrosis. There is flattening, slight roughening and sclerosis of the
condylar head and articular fossa. These changes, which are believed to
be adaptive responses of the condyle and fossa to the absence of an
intervening disc, collectively produce a broader contact, decreasing the
load per unit area.
The main purpose of collagen in tissue is to resist tensile forces. The
orientation of the collagen fibres in the disc varies in the individual
regions, reflecting the direction of the tensile forces imparted to the disc.
In the intermediate zone, they are predominantly orientated in an
anteroposterior direction. Around the periphery, the collagen forms a
ring-like structure with a three-dimensional framework of collagen
fibrils. In the posterior and anterior bands, the predominant orientation
is lateral–medial and superior–inferior. Type 1 collagen, similar to that
found in the superficial layers of the head of the condyle and the articu-
lar fossa, predominates in the disc.
Chondroitin sulphate and dermatan sulphate are the principal gly-
cosaminoglycans (GAGs) in the intercellular matrix. GAGs are very
hydrophilic and, as such, play an important role in the resistance and
distribution of compressive load applied to the temporomandibular
joint. Their concentration varies with the area of the disc, being highest
in the superficial layer of the intermediate zone (Nickel and McLachlan
1994, Tanaka et al 2006, Miloro and Henrickson 2010, Detamore and
Athanasiou 2003, Obrez and Gallo 2006, Paegle et al 2003).


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ligament that encloses the lower joint compartment is tight, and only
allows the condyle to rotate over the depression inside the anulus of
the articular disc. The normal range of maximum mouth opening
1
measured between the upper and lower incisor tips is 35–50 mm, the
MA
first 15–25 mm of which is due to hinging of the condyle; the remain-
der is due to condylar translation. The adult range of movements is
2 reached at around 10 years in females and 15 years in males. Lateral
9
3 excursions of the chin can normally achieve 8–12 mm of movement at
10 the lower incisors. At the limit of normal opening, the condyle has
4
PNS 11 translated on to the peak or just beyond the peak of the articular emi-
5 12 nence. Translation beyond this results in subluxation and dislocation
6 13 of the joint.
*
7 14
Symmetrical opening
8
Symmetrical jaw opening is associated with preparation for incising. At
15
the start, each mandibular condyle rotates in the lower joint compart-
ment inside the anulus of its disc. After a few degrees of opening, the
condyle continues rotating inside its disc and, in addition, both slide
forwards down the articular eminence of the upper joint compartment.
Without this forward slide or translation, it becomes impossible to
continue opening the jaw beyond a gape of approximately 25 mm.
Opinions differ as to why this forward slide should occur; the fact
that the condyle in a cadaver still slides forwards when the jaw is rotated
Fig. 32.15 An axial T1 weighted MRI at the level of the external acoustic open suggests that it is not a neuromuscular response but rather the
meatus. Key: 1, body of zygoma; 2, pterygopalatine fossa; 3, temporalis; result of mechanical constraints. When the jaw is rotated open, the


4, lateral pterygoid; 5, condyle; 6, parapharyngeal fat stripe; 7, internal temporomandibular ligament rapidly becomes taut (Osborn 1995).
carotid artery; 8, jugular bulb/foramen; 9, coronoid process; 10, lateral The taut ligament acts as a constraint that allows the mandible only
pterygoid plate; 11, torus tubarius; 12, fossa of Rosenmüller; 13, longus two rotary movements: it can swing about the upper attachment of the
colli; 14, external auditory meatus; 15, superficial lobe of parotid gland.
ligament and rotate about the lower attachment. The lower end of the
Abbreviations: MA, maxillary antrum; PNS, postnasal space. *, anterior
taut ligament acts as a moving fulcrum that converts the downward and
arch of atlas.
backward pull of the opening rotary force (created at the front by digas-
tric and geniohyoid) into one that drives the condyle upwards and
forwards into the concavity of the overlying articular disc. This now
thin, bony wall into the middle ear is a recognized complication of
pushes the disc forward. Swing about the upper attachment creates
temporomandibular joint arthroscopy.
space above for the disc to slide further forwards, which is possible
because the upper part of the capsular ligament is loose. The two move-
ments, rotation and swing, are inextricably linked by the taut ligament
VASCULAR SUPPLY AND INNERVATION
and, via the condyle, combine to keep the disc in firm contact with the
articular eminence while the jaw is opened. The disc is stabilized by its
The articular tissues and the dense part of the articular disc have no
tight attachment to the condyle (collateral ligament) and by the thick-
nerve supply. The nerve supply to the temporomandibular joint is from
ened margins of its anulus that prevent it sliding through the thinner
branches from the mandibular division of the trigeminal nerve, mostly
compressed region between the centre of the condyle and the articular
through the auriculotemporal branch, along with branches from
eminence.


the masseteric and deep temporal nerves. Postganglionic sympathetic
As forward slide of the condyle continues, the controlling influence
nerves supply the tissues associated with the capsular ligament and
exerted by the temporomandibular ligament diminishes. The lingula of
the looser posterior bilaminar extension of the disc. The temporoman-
the mandible moves away from the spine of the sphenoid, tautening
dibular joint capsule, lateral ligament and retroarticular tissue contain
the originally slack sphenomandibular ligament, which now acts in the
mechanoreceptors and nociceptors. The input from mechanoreceptors
same way as the temporomandibular ligament, to maintain the condyle
provides a source of proprioceptive sensation that helps control man-
against the articular eminence. Symmetrical opening thus appears to
dibular posture and movement.
consist of at least three separate phases: an early phase controlled by
The joint derives its arterial supply from the superficial temporal
the temporomandibular ligament and articular eminence; a short
artery laterally and the maxillary artery medially. Penetrating vessels
middle phase in which either both temporomandibular and spheno-
that supply lateral pterygoid may also supply the condyle. Veins drain
mandibular ligaments, or neither, act to constrain movements; and a
the anterior aspect of the joint and associated tissues into the plexus
late phase controlled by the sphenomandibular ligament and articular
surrounding lateral pterygoid; posteriorly, they drain into the vascular
eminence.
region that separates the two laminae of the bilaminar region of the
disc. Positive and negative pressure produced by forward and backward Changes in disc position during movement
movement of the condyle shunts blood between these regions. Lym-
With the teeth in occlusion, the condyle is in the glenoid fossa and the
phatics drain deeply to the upper cervical lymph nodes surrounding the
intra-articular disc sits on the condylar head, with its posterior band at
internal jugular vein.
the 12 o’clock position from the centre of the condylar head in the
sagittal plane (Fig. 32.16A). As mouth opening begins (Fig. 32.16B),


the condyle rotates within the lower joint space and the disc remains
JAW MOVEMENTS
stationary. At about mid-opening, the condyle and disc begin to move
forwards together so that their relative position is maintained (Fig.
Movements of the condyle in
32.16C). At maximum gape (Fig. 32.16D), the condylar head slides
the temporomandibular joint
further anteriorly than the disc; the disc is rotated backwards relative to
The major function of the mandible is to exert, via the teeth, the force the condyle by the pull of the elastic superior lamina of the posterior
necessary to break down food into smaller particles and so facilitate attachment, so that the anterior band of the articular disc is above the
digestion. Pure vertical movements of the lower teeth create a crushing summit of the condyle. This differential movement results in the disc
force that is ineffective in breaking up tough fibrous food. Humans use moving only about half the distance of the condyle. Mouth closure
a lateral movement of the lower jaw to create a shear force that enhances involves the disc moving back in tandem with the condyle under the
the effectiveness of the power stroke of mastication. Bodily lateral influence of the elastic fibres in the upper lamina of the bilaminar area
movement of the whole jaw, the Bennett shift, is insignificant. Exten- posterior to the disc itself (Fig. 32.16E), which also reverses its angular
sive lateral movement is only possible when the jaw is rotated horizon- rotation (Fig. 32.16F) to reassume the starting position of the cycle.
tally about one condyle while the other condyle slides backwards and The changes in disc position may become out of phase with the
forwards. The temporomandibular joint is structurally adapted to condyle, causing obstruction to smooth mandibular movement. The
accommodate both sliding/translation and rotation/hinging in a sagit- disc is typically pulled anteromedially by the lateral pterygoid, so pre-
tal plane. Sliding/translation occurs because the capsular ligament that venting forward translation of the condyle. With the disc in this posi-
surrounds the upper joint compartment is loose, whereas the capsular tion, the posterior band of the disc is anterior to the condyle, which


Temporomandibular joint
545
23
RETPAHC
Posterior temporal attachment Bilaminar region Fig. 32.16 Changing
relationships of the condyle of
External auditory meatus Posterior band
the mandible, the articular disc
Posterior mandibular attachment Intermediate zone and the articular surface of the
Anterior mandibular attachment temporal bone during one
complete opening (A → D) and
Anterior band
closing (D → A) cycle of the
Tympanic plate Anterior temporal attachment mouth.
Posterior wall of capsule
Soft tissue pad Lateral pterygoid insertion
A
F
B
C
E
D
causes an obstruction to forward translation of the condyle. As the force potentially shortens the ligaments so that they no longer constrain jaw
from the condyle on the disc increases, the elastic posterior attachments movements. Under these conditions, jaw movements and the positions
of the disc are stretched until the resistance to movement is overcome of the condyles are controlled by neuromuscular processes (within the
and the disc reduces into a normal relationship with the condyle, which limits of constraints imposed by the articular eminence, the occluding
is associated with an audible click (audible to the patient and occasion- surfaces of the teeth and the presence of food between them). Note that
ally to others). Once the normal disc–condyle relation is re-established, the non-working condyle moves the furthest, and is the most heavily
the mouth is free to achieve maximum opening (see Fig. 32.16C,D). loaded, during the power stroke of mastication. The loads on each joint,
The disc may then snap back in front of the condyle on mouth closure. balancing and working, drive each condyle more forcefully into its
This phenomenon is called reciprocal clicking or disc displacement articular eminence.
with reduction. If the disc remains completely anterior to the condylar
The envelope of motion
head and does not reduce into a normal relationship with the condyle
during opening, the condyle is prevented from further forward transla- The envelope of motion is the volume of space within which all move-
tion and mouth opening is restricted. This is a common clinical condi- ments of a point on the mandible have to occur because the limits are


tion and is known appropriately as closed lock or disc displacement set by anatomical features, i.e. by the shape or size of the upper and
without reduction (see below). lower jaws, by tooth contacts, and by the attachment of muscle and
ligaments. The mandibular movements at these extremes are termed
Eccentric jaw opening ‘border movements’.
Jaw movement during mastication can be divided into three parts: In consciously controlled movement of the jaw from the rest posi-
opening, closing and power strokes. Eccentric jaw opening is associated tion to the fully opened position, the trajectory of the mandibular
with preparing for the power stroke of mastication. The mandibular incisal edge is two-phased. The first phase is a hinge-like movement
condyle on the non-working side slides back and forth during lateral during which the condyles are retruded within the mandibular fossae.
movements associated with the power stroke on the working side. When the teeth are opened by approximately 25 mm, the second phase
Although the jaw muscles now have the major control over mandibular of opening occurs by anterior movement or protrusion of the condyles
movements, the temporomandibular and sphenomandibular ligaments down the articular eminences with further rotation.
keep the condyle firmly against its articular eminence during opening. If conscious effort is used, a closure path can then be followed in
which the jaw is closed to an extreme protruded tooth contact position,
Eccentric and symmetrical jaw closing
after which it has to be retruded to the starting position. Similar con-
During closure of the jaw, the masticatory muscles act in combination siderations apply to lateral movements; mandibular rotation around a
to force the joint surfaces together. This compresses the joint tissues and retruding condyle and the protraction of the opposite condyle are


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anatomically limiting factors that are again rarely encountered in Masseter
normal function.
Masseter (Fig. 32.18) is a quadrilateral muscle that consists of three
Although all mandibular movement occurs within or along the
layers that blend anteriorly. The superficial layer is the largest. It arises
border movements, knowledge of the extent of border movements pro-
by a thick aponeurosis from the maxillary process of the zygomatic
vides little information on the nature of the movements during chewing
bone and from the anterior two-thirds of the inferior border of the
or on the free (‘empty’), habitual movements during both opening and
zygomatic arch. Its fibres pass downwards and backwards, to insert into
closing, which have a more limited trajectory.
the angle and lower posterior half of the lateral surface of the mandibu-
Disc position and internal derangement lar ramus. The superficial fibres are angled approximately 10° from the
vertical, as is visible in lean individuals. In the coronal (frontal) plane,
Considerable attention has been directed at abnormalities of disc posi-
the muscle forms a 10° angle with the mandibular ramus. Intramuscu-
tion (collectively known as internal derangements) as a cause of joint
lar tendinous septa in this layer are responsible for the ridges on the
noises (clicking), limitation of jaw movement and/or pain. The position
surface of the ramus. The middle layer of masseter arises from the
of the disc is considered to be normal when, with the mandible at rest,
medial aspect of the anterior two-thirds of the zygomatic arch and from
the posterior band is positioned in the 12 o’clock position from the
the lower border of the posterior third of this arch. It inserts into the
centre of the condyle in the sagittal plane. Displacement of the disc
central part of the ramus of the mandible. The deep layer arises from
anteromedially is most common. MRI and arthrography have dem-
the deep surface of the zygomatic arch and inserts into the upper part
onstrated that, although disc position and clinical symptoms are often


of the mandibular ramus and into its coronoid process. The deep fibres
linked, a significant proportion of subjects with apparently normal
run vertically, and are evident just anterior to the temporomandibular
temporomandibular joint function have disc displacement on imaging
joint, where they are not covered by the more superficial layers. There
and, conversely, patients with normally positioned discs may have
is still debate as to whether fibres of masseter are attached to the antero-
severe restriction of mouth opening. Similarly, individuals with dis-
lateral part of the articular disc of the temporomandibular joint. Hyper-
placed discs who have undergone disc repositioning surgery often show
trophy of the masseter may occur either unilaterally or bilaterally. The
functional improvement despite persistent displacement of their intra-
aetiology is uncertain and there may be associated prominence of the
articular disc and vice versa.
mandibular angle. Treatment may involve surgical reduction of the deep
It is appreciated that limited mouth opening is not always related to
aspect of the muscle and contouring of the mandibular angle or injec-
disc displacement or non-reducibility but may be the result of impaired tions of botulinum toxin to paralyse the motor nerves.
joint lubrication and disc mobility. It is also suggested that, in an oth-
erwise asymptomatic jaw with normal movements, an anteriorly ‘dis-
Relations Skin, platysma, risorius, zygomaticus major, the parotid
placed’ disc could be considered a normal variant (Stegenga and de
gland and duct, branches of the facial nerve and the transverse facial
Bont 2006) or, at the least, not an indication for treatment.
branches of the superficial temporal vessels are all superficial relations.
It would appear that the adaptive remodelling capacity of the joint
Temporalis and the ramus of the mandible lie deep to masseter. The
(both the mandibular condyle and articular fossa) and adequate joint
anterior margin of masseter is separated from buccinator and the buccal
lubrication are important for maintaining function of the temporo-
branch of the mandibular nerve by a buccal pad of fat and crossed
mandibular joint.
by the facial vein. The posterior margin of the muscle is overlapped


by the parotid gland. The masseteric nerve and artery reach the
DEVELOPMENT OF THE deep surface of masseter by passing over the mandibular incisure
(mandibular notch).
TEMPOROMANDIBULAR JOINT
Vascular supply Masseter is supplied by the masseteric branch of
The bony components of the secondary jaw joint develop in membrane
the maxillary artery, the facial artery and the transverse facial branch of
as two separate condensations of neural crest mesenchyme between the
the superficial temporal artery.
eighth and twelfth week in utero. This arrangement is different from that
seen with most synovial joints, where a single blastema cavitates to Innervation Masseter is supplied by the masseteric branch of the
form a joint space and the articulating bones are derived from the same
anterior trunk of the mandibular nerve.
condensation of tissue. The separate development of the temporal and
condylar parts of the temporomandibular joint means that the articular
surface of each bone is covered by a persisting layer of proliferative cells Cut temporal fascia Superior temporal line Inferior temporal line
that is continuous with the periosteum surrounding each separate bony
component (Fig. 32.17).
MUSCLES
The four principal muscles of mastication are medial and lateral ptery-
goid, temporalis and masseter; their actions produce movements of the
mandible at the temporomandibular joints.
The infratemporal fossa contains medial and lateral pterygoid and
the tendon of temporalis. Masseter lies on the face, on the lateral surface
of the ramus of the mandible, but will be considered here.
A Joint cavitation Fig. 32.17 A,B,
Development of the
temporomandibular
joint; the temporal and
condylar components
of the joint develop
Temporalis
from two separate
condensations of Zygomatic process, temporal bone
neural crest
B Joint cavitation
mesenchyme.
Masseter
Fig. 32.18 Masseter and temporalis muscles. (Adapted from Drake RL,
Vogl AW, Mitchell A (eds), Gray’s Anatomy for Students, 2nd ed, Elsevier,
Condensation of putative disc Churchill Livingstone. Copyright 2010.)


Temporomandibular joint
547
23
RETPAHC
Actions Masseter elevates the mandible to occlude the teeth in mas- fossa above and the major components of the infratemporal fossa
tication and has a small effect in side-to-side movements, protraction below. Behind the tendon of the muscle, the masseteric nerve and
and retraction. Its electrical activity in the resting position of the man- vessels traverse the mandibular notch. The anterior border is separated
dible is minimal. from the zygomatic bone by a mass of fat.
Submasseteric space infections The submasseteric space is a Vascular supply Temporalis is supplied by deep temporal branches
potential space (see ‘masticator space’, p. 541) produced by the firm from the second part of the maxillary artery, which enter on its deep
attachment of masseter to the ramus. Sometimes, infection around a aspect, and middle temporal branches from the superficial temporal
mandibular third molar tooth tracks backwards, lateral to the mandibu- artery, which enter on its lateral aspect. The anterior deep temporal
lar ramus, and pus localizes deep to the attachment of masseter in the artery supplies 20% of the muscle anteriorly; the posterior deep tem-
submasseteric tissue space. Such an abscess, lying deep to this thick poral artery, entering the mid-portion of the muscle, supplies 40% of
muscle, produces little visible swelling but is accompanied by profound the muscle in the mid-region; and the middle temporal artery, entering
muscle spasm and severe limitation of jaw opening (trismus). the muscle posteriorly, supplies 40% of the muscle in its posterior
region. Considerable vascular anastomoses are present within the
Temporalis
muscle (Cheung 1996).
Temporalis (see Figs 32.18, 32.20) arises from the whole of the tempo-
ral fossa up to the inferior temporal line – except the part formed by Innervation Temporalis is supplied by the anterior, middle and
the zygomatic bone – and from the deep surface of the temporal fascia. posterior deep temporal branches of the anterior trunk of the man-
Its fibres converge and descend into a tendon that passes through the dibular nerve.
gap between the zygomatic arch and the side of the skull. A plane exists


beneath the temporal fascia, which is attached to the superior surface Actions Temporalis elevates the mandible and so closes the mouth
of the zygomatic arch, and the muscle, which passes beneath the arch. and approximates the teeth. This movement requires both the upward
An elevator introduced into this plane through an incision above the pull of the anterior fibres and the backward pull of the posterior fibres
hairline may therefore be placed beneath a fractured zygomatic arch or because the head of the mandibular condyle rests on the articular
bone in order to reduce the fracture (Gillies approach). Temporalis is eminence when the mouth is open. The muscle also contributes to
attached to the medial surface, apex, anterior and posterior borders of side-to-side grinding movements. The posterior fibres retract the man-
the coronoid process and to the anterior border of the mandibular dible after it has been protruded. The posterior fibres of temporalis,
ramus almost up to the third molar tooth. Its anterior fibres are orien- which are almost horizontal, are the only source of mandibular
tated vertically, the most posterior fibres almost horizontally, and the retrusion.
intervening fibres with intermediate degrees of obliquity, in the manner
Lateral pterygoid
of a fan. Fibres of temporalis may occasionally gain attachment to the
articular disc. Though less common than enlargement of masseter, Lateral pterygoid (Fig. 32.20) is a short, thick muscle consisting of two
hypertrophy of temporalis may develop unilaterally or bilaterally, pro- parts. The upper head arises from the infratemporal surface and
ducing prominence of the temporal fossa, which may be considered infratemporal crest of the greater wing of the sphenoid bone. The lower
unsightly; botulinum toxin to paralyse the motor nerves is the preferred head arises from the lateral surface of the lateral pterygoid plate. From
treatment for this condition. the two origins, the fibres converge, and pass backwards and laterally,
to be inserted into a depression on the front of the neck of the mandible
Relations Skin, auriculares anterior and superior, temporal fascia, (the pterygoid fovea). A part of the upper head may be attached to the


superficial temporal vessels, the auriculotemporal nerve, temporal capsule of the temporomandibular joint and to the anterior and medial
branches of the facial nerve, the zygomaticotemporal nerve, the epi- borders of its articular disc. Unlike the other muscles of mastication,
cranial aponeurosis, the zygomatic arch and the masseter muscle are all lateral pterygoid is not pennate, nor does it have a significant number
superficial relations. Posterior relations of temporalis are the temporal of Golgi tendon organs associated with its attachments.
Temporalis Fig. 32.20 Arteries and
Posterior deep temporal artery; deep temporal nerve
nerves of the head; deeper
Middle temporal artery
Lateral pterygoid lateral regions. Most of the
Superficial temporal artery,
Anterior deep temporal artery zygomatic arch and the ramus
parietal branch
and body of the mandible
Supraorbital nerve, lateral branch
have been removed; masseter
Supraorbital nerve, medial branch Zygomatico-orbital artery has been cut and reflected
Temporomandibular joint, laterally. (With permission
Supratrochlear artery lateral ligament from Waschke J, Paulsen F
Transverse facial artery (eds), Sobotta Atlas of Human
Supratrochlear nerve Anatomy, 15th ed, Elsevier,
Infraorbital nerve Urban & Fischer. Copyright
Angular artery 2013.)
Vagus nerve,
Infratrochlear nerve auricular branch
Infraorbital artery
External nasal branch of
anterior ethmoidal nerve Auriculotemporal nerve
Infraorbital nerve Facial nerve
Stylomastoid artery
Deep auricular artery
Anterior tympanic artery
Posterior superior alveolar artery Occipital artery
Buccal nerve Maxillary artery
Middle meningeal artery
Masseter, cut and reflected
Buccal artery
Masseteric nerve; masseteric artery
Mental nerve
Lingual nerve
Medial pterygoid
Mylohyoid nerve
Facial artery


Infratemporal and pterygopalatine fossae and temporomandibular joint
547.e1
23
RETPAHC
The arterial supply is axial, i.e. the vessels run the entire length of long axis), retaining its axial supply from individual arteries; the vessels
the muscle. It is this vascular arrangement that permits the use of tem- are identified at operation if necessary, with a Doppler. A further vas-
poralis as an inferiorly based pedicled flap, either dynamic or static cular advantage is that the arterial supply is disposed medially (deep
(increased length being obtained with division of the coronoid process), temporal) and laterally (middle temporal), and there are few vessels in
for the reconstruction of a variety of local facial and oral defects and in the mid-sagittal plane, which means that splitting of the muscle flap in
the treatment of facial paralysis. The temporalis fascia can be incorpo- the sagittal plane is possible (Fig. 32.19) (Cheung 1996).
rated with the flap. The muscle may be split longitudinally (along its
Fig. 32.19 The arterial network of the human
temporalis. A, Lateral plane. B, Coronal plane. In
the lateral plane, the muscle is supplied by the
three primary arteries: the anterior deep temporal
artery in the anterior portion, the posterior deep
temporal artery in the mid-portion and the middle
deep temporal artery in the posterior portion. In
the coronal plane, the arterial distribution is
concentrated mainly lateral (L) and medial (M) with
less vascular density in the mid-sagittal region of
the muscle. (With permission from Cheung LK.
The vascular anatomy of the human temporalis
muscle: implications for surgical splitting
techniques. Int J Oral Maxillofac Surg
M L 1996;25:414–421.)
A B


InfRATEmPoRAl And PTERygoPAlATInE fossAE And TEmPoRomAndIbulAR joInT
548
4
noITCEs
Relations The mandibular ramus and masseter, the maxillary artery, lateral pterygoid, the sphenomandibular ligament, the maxillary artery,
which crosses either deep or superficial to the muscle, and the super- the inferior alveolar vessels and nerve, the lingual nerve and a process
ficial head of medial pterygoid and the tendon of temporalis are all of the parotid gland. The medial surface is related to tensor veli palatini
superficial relations. Deep to the muscle are the deep head of medial and is separated from the superior pharyngeal constrictor by styloglos-
pterygoid, the sphenomandibular ligament, the middle meningeal sus and stylopharyngeus and by some areolar tissue.
artery and the mandibular nerve. The upper border is related to the
Vascular supply Medial pterygoid derives its main arterial supply
temporal and masseteric branches of the mandibular nerve and the
from the pterygoid branches of the maxillary artery.
lower border is related to the lingual and inferior alveolar nerves. A
deeply placed posterior superior alveolar nerve block has been known
Innervation Medial pterygoid is innervated by the medial pterygoid
also to anaesthetize the lingual nerve. The buccal nerve and the maxil-
branch of the mandibular nerve.
lary artery pass between the two heads of the muscles. In temporoman-
dibular joint dysfunction syndrome, spasm of lateral pterygoid can give Actions The medial pterygoid muscles assist in elevating the man-
rise to tenderness when palpating behind the maxillary tuberosity high dible. Acting with the lateral pterygoids, they protrude it. When the
in the buccal sulcus (the pterygoid sign). medial and lateral pterygoids of one side act together, the correspond-
ing side of the mandible is rotated both forwards and to the opposite
Vascular supply Lateral pterygoid is supplied by pterygoid branches side, with the opposite mandibular head as a vertical axis. Alternating


from the maxillary artery that are given off as the artery crosses the activity in the left and right sets of muscles produces side-to-side move-
muscle and from the ascending palatine branch of the facial artery. ments, which are used to triturate food.
Innervation The nerves to lateral pterygoid (one for each head) arise Pterygospinous ligament
from the anterior trunk of the mandibular nerve, deep to the muscle. The pterygospinous ligament, which is occasionally replaced by muscle
The upper head and the lateral part of the lower head receive their fibres, stretches between the spine of the sphenoid bone and the pos-
innervation from a branch given off from the buccal nerve. However, terior border of the lateral pterygoid plate near its upper end. It is
the medial part of the lower head has a branch arising directly from the sometimes ossified, and then completes a foramen that transmits the
anterior trunk of the mandibular nerve. branches of the mandibular nerve to temporalis, masseter and lateral
pterygoid.
Actions Lateral pterygoid has assumed a specialized role in mandibu-
lar opening that is mediated by its horizontally orientated fibres. When
left and right muscles contract together, the condyle is pulled forwards VASCULAR SUPPLY AND LYMPHATIC DRAINAGE
and slightly downwards. This protrusive movement alone has little or
no function except to assist in opening the jaw. Digastric and genio- Maxillary artery
hyoid are the main jaw opening muscles; unlike lateral pterygoid, when
acting alone, they rotate the jaw open, provided other muscles attached The maxillary artery, the larger terminal branch of the external carotid
to the hyoid prevent it from being pulled forwards. If only one lateral artery, arises behind the neck of the mandible and is at first embedded
pterygoid contracts, the jaw rotates about a vertical axis passing roughly in the parotid gland. It then crosses the infratemporal fossa to enter the
through the opposite condyle and is pulled medially towards the oppo- pterygopalatine fossa through the pterygomaxillary fissure. The artery
site side. This contraction, together with that of the adjacent medial is widely distributed to the mandible, maxilla, teeth, muscles of masti-


pterygoid (both attached to the lateral pterygoid plate), provides most cation, palate, nose and cranial dura mater (see Fig. 32.20; Fig. 32.21).
of the strong medially directed component of the force used when It will be described in three parts: mandibular, pterygoid and
grinding food between teeth of the same side. It is arguably the most pterygopalatine.
important function of the inferior head of lateral pterygoid. The mandibular part runs horizontally by the medial surface of the
It is often stated that the upper head is used to pull the articular disc ramus. It passes between the neck of the mandible and the spheno-
forwards when the jaw is opened. However, electromyographic studies mandibular ligament, parallel with and slightly below the auriculotem-
(e.g. McNamara 1973, Juniper 1981) have demonstrated that the upper poral nerve. It next crosses the inferior alveolar nerve and skirts the
and lower heads are reciprocally innervated, so that the lower head lower border of lateral pterygoid. The pterygoid part ascends obliquely
contracts during mouth opening whilst the upper head relaxes, the situ- forwards medial to temporalis and is usually superficial to the lower
ation reversing during closure. An explanation for this surprising activ- head of lateral pterygoid. When it runs deep to lateral pterygoid, it lies
ity is as follows (Osborn 1995). Most of the power of a clenching force between the muscle and branches of the mandibular nerve, and may
is due to contractions of masseter and temporalis. The associated back- project as a lateral loop between the two parts of lateral pterygoid.
ward pull of temporalis is greater than the associated forward pull of Asymmetry in this pattern of distribution may occur between the right
(superficial) masseter, and so their combined jaw-closing action poten- and left infratemporal fossae, and ethnic differences have been reported.
tially pulls the condyle backwards. This is prevented by the simultan- Where the maxillary artery runs superficial to the lower head of lateral
eous contraction of the upper head of lateral pterygoid, which stabilizes pterygoid, the most common pattern is that the artery passes lateral to


the condylar head against the articular eminence during closure, par- the inferior alveolar, lingual and buccal nerves. Less frequently, only the
ticularly during biting and mastication. buccal nerve crosses the artery laterally, and rarely the artery passes deep
to all the branches of the mandibular nerve. The pterygopalatine part
Medial pterygoid
passes between the two heads of lateral pterygoid to reach the pterygo-
Medial pterygoid (see Fig. 32.20) is a thick, quadrilateral muscle with
maxillary fissure before it passes into the pterygopalatine fossa, where
two heads of origin. Mirroring masseter (which lies laterally), its fibres
it terminates as the third part of the maxillary artery.
descend posteroinferiorly at an angle of about 10° to the vertical. In
The mandibular part of the maxillary artery has five branches that
the coronal plane, it forms a 30° angle with the ramus. The major
all enter bone, namely: deep auricular, anterior tympanic, middle
component is the deep head that arises from the medial surface of the
meningeal, accessory meningeal and inferior alveolar arteries. The
lateral pterygoid plate of the sphenoid bone and is therefore deep to
pterygoid part of the maxillary artery has five branches that do not enter
the lower head of lateral pterygoid. The small, superficial head arises
bone but supply muscle, and include deep temporal, pterygoid, mas-
from the maxillary tuberosity and the pyramidal process of the palatine
seteric and buccal arteries. The branches of the pterygopalatine part of
bone, and therefore lies on the lower head of lateral pterygoid. The
the artery accompany similarly named branches of the maxillary nerve
fibres of medial pterygoid descend posterolaterally and are attached by
(including those associated with the pterygopalatine ganglion) and are
a strong tendinous lamina to the posteroinferior part of the medial
described on page 552.
surface of the ramus and angle of the mandible, as high as the man-


dibular foramen and almost as far forwards as the mylohyoid groove. Deep auricular artery
This area of attachment is often ridged. Inferior alveolar nerve block The deep auricular artery pierces the osseous or cartilaginous wall of
injection can occasionally cause haemorrhage into the muscle, which the external acoustic meatus and supplies the skin of the external acous-
may give rise to painful trismus. Medial pterygoid and masseter act tic meatus and part of the tympanic membrane. A small branch con-
together to support the angle of the mandible as the pterygomasseteric tributes to the arterial supply of the temporomandibular joint.
sling. Their strong muscle attachments resist lengthening of the man-
Anterior tympanic artery
dibular ramus surgically.
The anterior tympanic artery passes through the petrotympanic fissure
Relations The lateral surface of medial pterygoid is related to the to supply part of the lining of the middle ear and accompanies the
mandibular ramus, from which it is separated above its insertion by chorda tympani nerve.


Temporomandibular joint
549
23
RETPAHC
A Fig. 32.21 A, Vessels and nerves
of the head, exposed at a level
Ramus of mandible (reflected upwards)
deeper than that shown in Figure
Middle temporal artery, frontal branch Masseteric nerve; masseteric artery 32.20. Note the pterygoid venous
Superficial temporal artery,
plexus. B–E, Variations in the
parietal branch
Supraorbital nerve, lateral branch Auriculotemporal nerve course of the maxillary artery.
B, The maxillary artery passes
medial to lateral pterygoid, and to
Supraorbital nerve, medial branch
the lingual and inferior alveolar
Supratrochlear nerve nerves. C, The artery passes
Angular artery Auriculotemporal nerve between the lingual and inferior
Infratrochlear nerve alveolar nerves. D, The artery
Superficial temporal vein
passes through a loop formed by
the inferior alveolar nerve. E, The
middle meningeal artery branches
off distal to the inferior alveolar
artery. (With permission from
Posterior auricular nerve Waschke J, Paulsen F (eds),
Sobotta Atlas of Human
Facial nerve
Anatomy, 15th ed, Elsevier,
Superficial temporal artery Urban & Fischer. Copyright 2013.)
Pterygoid plexus Posterior auricular artery
Deep facial vein Maxillary artery
Buccal nerve Occipital artery
Maxillary vein
Buccal artery External carotid artery
Retromandibular vein
Sphenomandibular ligament
Facial vein
Inferior alveolar nerve and artery
Mental nerve Lingual nerve
Inferior dental plexus Internal carotid artery
External carotid artery
Mylohyoid nerve
Submental vein Lingual artery
Facial artery
6% 3% 4% 18%
B C D E
Middle meningeal artery Inferior alveolar artery
The middle meningeal artery is the main source of blood to the bones The inferior alveolar artery descends in the infratemporal fossa pos-
of the vault of the skull (Fig. 32.22). It may arise either directly from terior to the inferior alveolar nerve, between the ramus laterally and the


the first part of the maxillary artery or from a common trunk with the sphenopalatine ligament medially. Two anterior branches are given off
inferior alveolar artery. When the maxillary artery lies superficial to the artery prior to its entry into the mandibular foramen. The further
lateral pterygoid, the middle meningeal artery is usually the first branch course of the artery is described on page 526.
of the maxillary artery. However, when the maxillary artery takes a deep
Deep temporal arteries
course in relation to the muscle, this is not usually the case. The middle
meningeal artery ascends between the sphenomandibular ligament and The arterial supply to the temporalis in the coronal plane is concen-
lateral pterygoid, passes between the two roots of the auriculotemporal trated mainly on its medial and lateral aspects. The anterior and
nerve, and leaves the infratemporal fossa through the foramen spino- posterior branches of the deep temporal arteries pass between
sum to enter the cranial cavity medial to the midpoint of the zygomatic temporalis and the pericranium, producing shallow grooves in the
bone. Its further course is described on page 439. bone. They anastomose with the middle temporal branch of
the superficial temporal artery situated laterally (Cheung 1996). The
Accessory meningeal artery
anterior deep temporal artery connects with the lacrimal artery by
The accessory meningeal artery runs through the foramen ovale into the small branches which perforate the zygomatic bone and greater wing
middle cranial fossa and may arise directly from the maxillary artery or of the sphenoid.
as a branch of the middle meningeal artery itself. In its course in the
infratemporal fossa, the accessory meningeal artery is closely related to Masseteric artery
tensor and levator veli palatini and usually runs deep to the mandibular The masseteric artery, which is small, accompanies the masseteric
nerve. Although it runs intracranially, its main distribution is extra- nerve as it passes behind the tendon of temporalis through the man-
cranial, principally to medial pterygoid, lateral pterygoid (upper head), dibular incisure (notch) to enter the deep surface of masseter (see Fig.


tensor veli palatini, the greater wing and pterygoid processes of the 32.20). Its branches can also supply the temporomandibular joint.
sphenoid, branches of the mandibular nerve and the otic ganglion. The The masseteric artery anastomoses with the masseteric branches of
accessory meningeal artery is sometimes replaced by separate small the facial artery and with the transverse facial branch of the superfi-
arteries. cial temporal artery.


InfRATEmPoRAl And PTERygoPAlATInE fossAE And TEmPoRomAndIbulAR joInT
550
4
noITCEs
A
Superficial temporal artery Middle meningeal artery
Articular disc Lateral pterygoid
Condylar process B C
Coronoid process
Posterior auricular
artery
Inferior alveolar nerve
Maxillary artery
Lingual nerve
Occipital artery
3% 3%
Inferior alveolar artery
External carotid artery
Fig. 32.22 Variations in the origin of the middle meningeal artery. A, The middle meningeal artery branches off proximal to the inferior alveolar artery.
B, The artery branches off opposite the inferior alveolar artery. C, The artery branches off distal to the inferior alveolar artery. (With permission from
Waschke J, Paulsen F (eds), Sobotta Atlas of Human Anatomy, 15th ed, Elsevier, Urban & Fischer. Copyright 2013.)
Pterygoid arteries the skin in the temporal region, part of the auricle – including the
external meatus and tympanic membrane – and the lower lip, the lower
The pterygoid arteries are irregular in number and origin, and are dis-
part of the face and the mucosa of the anterior two-thirds (presulcal
tributed to lateral and medial pterygoid.
part) of the tongue and the floor of the oral cavity (see Figs 32.20,
Buccal artery 32.21A; Fig. 32.23). The motor branches innervate the muscles of mas-
The buccal artery runs obliquely forwards between medial pterygoid tication. The large sensory root emerges from the lateral part of the
and the attachment of temporalis, and supplies the skin and mucosa trigeminal ganglion and exits the cranial cavity through the foramen
over buccinator, accompanying the lower part of the buccal branch of ovale. The small motor root passes under the ganglion and through the
the mandibular nerve (see Fig. 32.21A). It anastomoses with branches foramen ovale to unite with the sensory root just outside the skull. As


of the facial and infraorbital arteries. A small lingual branch may be it descends from the foramen ovale, the nerve is usually around 4 cm
given off to accompany the lingual nerve and supply structures in the from the surface and a little anterior to the neck of the mandible. The
floor of the mouth. mandibular nerve immediately passes between tensor veli palatini,
which is medial, and lateral pterygoid, which is lateral, and gives off a
Maxillary veins and the pterygoid meningeal branch and the nerve to medial pterygoid from its medial
venous plexus side. The nerve then divides into a small anterior and large posterior
trunk. The anterior division gives off branches to the four main muscles
of mastication and a buccal branch that is sensory to the cheek. The
Maxillary vein
posterior division gives off three main sensory branches – the auriculo-
The maxillary vein is a short trunk that accompanies the first part of the temporal, lingual and inferior alveolar nerves – and motor fibres that
maxillary artery (see Fig. 32.21A). It is formed from the confluence of supply mylohyoid and the anterior belly of digastric.
veins from the pterygoid plexus and passes back between the spheno- As is the case with the extraocular muscles, the masticatory muscles
mandibular ligament and the neck of the mandible, to enter the parotid function as a group; only when pathology intervenes do their individual
gland. It unites within the substance of the gland with the superficial actions, or lack of action, become apparent. Wasting of the masticatory
temporal vein to form the retromandibular vein. muscles, most evident in the temporal fossa, happens when tumours
affect the motor root of the mandibular nerve. The mandible deviates
Pterygoid venous plexus
to the side of the pathology as a result of the unopposed action of the
The pterygoid plexus of veins consists of copious large-calibre veins contralateral lateral and medial pterygoids.
surrounding the pterygoid segment of the maxillary artery. It is found
Meningeal branch (nervus spinosus)
partly between temporalis and lateral pterygoid, and partly between the


two pterygoid muscles. Sphenopalatine, deep temporal, pterygoid, mas- The meningeal branch re-enters the cranium through the foramen
seteric, buccal, alveolar (dental), greater palatine and middle meningeal spinosum with the middle meningeal artery. It divides into anterior and
veins and a branch or branches from the inferior ophthalmic vein are posterior branches, which accompany the main divisions of the middle
all tributaries. The plexus connects with the facial vein via the deep meningeal artery and supply the dura mater in the middle cranial fossa
facial vein, with the cavernous sinus through veins that pass through and, to a lesser extent, in the anterior fossa and calvarium.
the sphenoidal emissary foramen (of Vesalius), foramen ovale and Nerve to medial pterygoid
foramen lacerum and with the orbit via the inferior ophthalmic vein(s).
The nerve to medial pterygoid is a slender ramus that enters the deep
Its deep temporal tributaries often connect with tributaries of the
aspect of the muscle. It supplies one or two filaments that pass through
anterior diploic veins and thus with the middle meningeal veins.
the otic ganglion without interruption to supply tensor tympani and
tensor veli palatini.
Lymphatic drainage
Anterior trunk of mandibular nerve
Lymphatic drainage of the infratemporal fossa (and the temporal fossa) The anterior trunk of the mandibular nerve gives rise to the buccal
is to the superior deep cervical nodes. nerve, which is sensory, and the masseteric, deep temporal and lateral
pterygoid nerves, which are all motor.
buccal nerve
INNERVATION
The buccal nerve passes between the two heads of lateral pterygoid (see
Fig. 32.23). It descends deep to the tendon of temporalis, passes later-
The infratemporal fossa contains the major subdivisions of the man-
ally in front of masseter, and anastomoses with the buccal branches of
dibular branch of the trigeminal nerve, together with the chorda tym-
the facial nerve. It carries the motor fibres to lateral pterygoid, and these


pani, which enters the fossa and joins the lingual nerve, and the otic
are given off as the buccal nerve passes through the muscle. It may also
ganglion, which is functionally related to the parotid gland. The main
give off the anterior deep temporal nerve. The buccal nerve supplies
sensory branches of the mandibular nerve extend beyond the infratem-
sensation to the skin over the anterior part of buccinator and the buccal
poral fossa and their distribution to the face is described on page 502.
mucous membrane, together with the posterior part of the buccal gin-
givae adjacent to the second and third molar teeth.
Mandibular nerve
nerve to masseter
The mandibular nerve is the largest trigeminal division and is a mixed The nerve to masseter passes laterally above lateral pterygoid, on to the
nerve. Its sensory branches supply the teeth and gums of the mandible, skull base, anterior to the temporomandibular joint and posterior to


Temporomandibular joint
551
23
RETPAHC
Middle temporal artery Fig. 32.23 Arteries and nerves of
the head, deepest lateral regions.
Posterior deep temporal artery; deep temporal nerve
Compare with Figures 32.20 and
Mandibular nerve (V/3)
32.21A. (With permission from
Lateral pterygoid and nerve Waschke J, Paulsen F (eds), Sobotta
Auriculotemporal nerve
Maxillary artery Atlas of Human Anatomy, 15th ed,
Elsevier, Urban & Fischer. Copyright
2013.)
Posterior auricular
artery and nerve
Sphenopalatine artery Superficial
temporal artery
Facial nerve
Auriculotemporal nerve
Posterior superior
alveolar branches Occipital artery
Anterior tympanic artery
Middle meningeal artery
Masseteric nerve
Buccal nerve
Chorda tympani
Buccinator
Buccal nerve and artery Inferior alveolar artery
Inferior alveolar nerve Hypoglossal nerve
Lingual artery
Lingual nerve
Ascending palatine artery
Sublingual gland
Vagus nerve
Submandibular duct
Sublingual artery
Facial artery
Hypoglossal nerve
Submandibular ganglion
Submental artery Submandibular gland
Mylohyoid nerve
the tendon of temporalis. It crosses the posterior part of the mandibular lingual nerve
notch with the masseteric artery and ramifies on and enters the deep The lingual nerve is sensory to the mucosa of the anterior two-thirds of
surface of masseter. It also provides articular branches that supply the the tongue, the floor of the mouth and the mandibular lingual gin-
temporomandibular joint. givae. It arises from the posterior trunk of the mandibular nerve and at
first runs beneath lateral pterygoid and superficial to tensor veli pala-
deep temporal nerves
tini, where it is joined by the chorda tympani branch of the facial nerve,
The deep temporal nerves usually consist of two branches, anterior and and often by a branch of the inferior alveolar nerve. Emerging from
posterior, although there may be a middle branch. They pass above under cover of lateral pterygoid, the lingual nerve then runs downwards