2. • The infratemporal fossa is the space beneath the base of the skull,
between the side wall of the pharynx and ramus of the mandible.
• It communicates with the temporal fossa through a gap deep to the
zygomatic arch.
• It is also referred to as the parapharyngeal space or lateral
pharyngeal space.
3. BOUNDARIES
Roof: Formed by the infratemporal surface of the greater wing of the sphenoid. It is pierced by
foramen spinosum and foramen ovale.
Medial wall: Formed by lateral surface of the lateral pterygoid plate of the sphenoid. It is separated
from the anterior wall by pterygomaxillary fissure.
Lateral wall: Formed by the ramus of the mandible.
Anterior wall: Formed by the infratemporal surface of the maxilla. It is separated from roof by inferior
orbital fissure.
Floor: Open and extends up to the level of the base of the mandible.
Posterior wall: Formed by styloid process of the temporal bone.
4.
5.
6. COMMUNICATIONS
(a) above with the temporal fossa through a gap, deep to
zygomatic arch; and middle cranial fossa through
foramen ovale and foramen spinosum,
(b) below it is continuous with the tissue spaces of the neck
lateral to the pharynx,
(c) with the pterygopalatine fossa through pterygomaxillary
fissure, and
(d) with the orbit through inferior orbital fissure.
7. CONTENTS
The major structures present in the infratemporal fossa are:
1. Muscles: Lateral pterygoid, medial pterygoid, and
tendon of temporalis.
2. Blood vessels: Maxillary artery, maxillary vein, and
pterygoid venous plexus.
3. Neural structures: Mandibular nerve, chorda tympani
nerve, and otic ganglion.
8. MUSCLES
• Lateral Pterygoid
• It is a short, thick conical muscle with its apex pointing backwards. It
passes backwards and slightly laterally from the roof and medial wall
of the fossa to the neck of the mandible.
Muscle(s) Proximal Attachment Distal Attachment Innervation Action on Mandible
Lateral
pterygoid
Triangular two-headed
muscle from (1)
infratemporal
surface and
crest of greater wing of
sphenoid and (2) lateral
surface of lateral
pterygoid plate
Superior head attaches
primarily to joint
capsule
and articular disc
of TMJ; inferior head
attaches primarily to
pterygoid fovea on
anteromedial aspect
of neck of condyloid
process of mandible
Anterior
trunk of
mandibular
nerve
(CN V3)
Via
lateral
pterygoid
nerve
Acting bilaterally,
protracts mandible
and depresses chin;
acting unilaterally, swings
jaw
toward contra lateral
side; alternate
unilateral contraction
produces
larger lateral chewing
movements
9. • The lower head of lateral pterygoid passes between the two
heads of the medial pterygoid muscle.
• It is the only masticatory muscle, which opens the mouth.
• The articular disc of temporomandibular joint is
developmentally a part of tendon of lateral pterygoid muscle.
10.
11. Relations
• The lateral pterygoid is regarded as the key muscle of the
infratemporal region because its relations provide a fair idea about
the layout of structures in this region.
1. Superficial:
1. Ramus of the mandible.
2. Masseter.
3. Tendon of temporalis.
4. Superficial head of medial pterygoid.
5. Maxillary artery and its temporal and masseteric branches.
12. 2.Deep:
1. Mandibular nerve.
2. Middle meningeal artery.
3. Sphenomandibular ligament.
4. Deep head of medial pterygoid
muscle.
3.Structures emerging at the upper
border:
1. Deep temporal nerves (two in
number).
2. Masseteric nerve.
4.Structures emerging at the lower border:
1. Inferior alveolar nerve and artery.
2. Lingual nerve.
3. Middle meningeal artery (it passes up deep
to the lower border).
5.Structures passing through the gap between
the two heads:
1. Maxillary artery, which enters the gap to
reach the
pterygopalatine fossa through pterygomaxillary
fissure.
2. Buccal nerve, a branch of mandibular nerve.
It comes out through the gap to provide
sensory innervation to the skin and mucus
membrane of the cheek.
13.
14. Medial Pterygoid
Muscle(s) Proximal Attachment Distal Attachment Innervation Action on
Mandible
Medial
pterygoid
Quadrangular two
headed
muscle from
(1) medial surface of
lateral pterygoid plate
and pyramidal process
of palatine bone and
(2) tuberosity of
maxilla
Medial surface of
ramus of mandible,
inferior to mandibular
foramen; in essence,
a “mirror image” of
ipsilateral masseter,
two muscles flanking
ramus
Anterior
trunk of
mandibular
nerve
(CN V3)
Via
medial
pterygoid
nerve
Acts synergistically
with masseter
to elevate
mandible;
contributes
to protrusion;
alternate unilateral
activity produces
smaller grinding
movements
15.
16. Relations
Superficial :
1. Lingual nerve.
2. Inferior alveolar nerve.
3. Inferior alveolar vessels.
Deep:
1. Levator palati and tensor palati
muscles.
2. Superior constrictor of pharynx.
3. Styloglossus and stylopharyngeus
muscles.
18. PARTS AND BRANCHES OF MAXILLARY ARTERY
Part Course Branches Distribution
First
(mandibular)
Proximal (posterior) to
lateralpterygoid muscle;
runs horizontally,
deep (medial) to neck of
condylar process of
mandible and lateral to
stylomandibular
ligament
Deep auricular
artery
Supplies external acoustic meatus, external tympanic
membrane, and temporomandibular joint
Anterior tympanic
artery
Supplies internal aspect of tympanic membrane
Middle meningeal
artery
Enters cranial cavity via foramen spinosum to supply
periosteum, bone, red bone marrow, dura mater of
lateral wall and calvaria of neurocranium, trigeminal
ganglion, facial nerve and geniculate ganglion,
tympanic cavity, and tensor tympani muscle
Accessory
meningeal
artery
Enters cranial cavity via foramen ovale; its
distribution is mainly extracranial to muscles of infratemporal
fossa, sphenoid bone, mandibular nerve,
and otic ganglion
Inferior alveolar
artery
Descends to enter mandibular canal of mandible via
mandibular foramen; supplies mandible, mandibular
teeth, chin, mylohyoid muscle
19. PARTS AND BRANCHES OF MAXILLARY ARTERY
Part Course Branches Distribution
Second
(pterygoid)
Adjacent (superficial or deep) to
lateral pterygoid muscle; ascends
obliquely anterosuperiorly, medial
to temporalis muscle
Masseteric artery Traverses mandibular notch,
supplying
temporomandibular
joint and masseter muscle
Deep temporal
arteries
Anterior and posterior
arteries ascend between
temporalis muscle and bone
of temporal fossa,
supplying mainly muscle
Pterygoid branches Irregular in number and
origin; supply pterygoid
muscle
Buccal artery Runs antero-inferiorly with
buccal nerve to supply
buccal fat-pad, buccinator,
and buccal oral mucosa
20. Part Course Branches Distribution
Third
(pterygoidpala
tine)
Distal (anteromedial) to lateral
pterygoid muscle; passes
between heads of lateral
pterygoid and
through pterygomaxillary
fissure into pterygopalatine fossa
Posterior superior
alveolar artery
Descends on maxilla’s infratemporal surface with
branches traversing alveolar canals to supply maxillary molar
and premolar teeth, adjacent gingiva, and mucous
membrane of maxillary sinus
Infra-orbital artery Traverses inferior orbital fi ssure, infra-orbital groove,
canal, and foramen; supplies inferior oblique and
rectus muscles, lacrimal sac, maxillary canines and
incisors teeth, mucous membrane of maxillary sinus,
and skin of infra-orbital region of face
Artery of pterygoid
canal
Passes posteriorly through pterygoid canal; supplies
mucosa of upper pharynx, pharyngotympanic tube,
and tympanic cavity
Pharyngeal branch Passes through palatovaginal canal to supply
mucosa of nasal roof, nasopharynx, sphenoidal air
sinus, and pharyngotympanic tube
Descending palatine
artery
Descends through palatine canal, dividing into
greater and lesser palatine arteries to mucosa and
glands of hard and soft palate
Sphenopalatine artery Terminal branch of maxillary artery, traverses
sphenopalatine foramen to supply walls and septum
of nasal cavity; frontal, ethmoidal, sphenoid, and
maxillary sinuses; and anteriormost palate
21. MAXILLARY VEIN
• It is a short venous trunk, which accompanies the first part of the
maxillary artery.
• It is formed by the confluence of veins from the pterygoid venous
plexus and passes backwards between the sphenomandibular
ligament and the neck of the mandible.
• Within the parotid gland it unites with the superficial temporal vein
to form the retromandibular vein.
22. Pterygoid Venous Plexus
• It is a network of very small veins that lie
around and within the lateral pterygoid
muscle.
• The pterygoid venous plexus
communicates:
(a) with inferior ophthalmic vein via inferior
orbital fissure,
(b) with cavernous sinus by emissary veins
via foramen ovale or foramen of Vesalius,
and
(c) with facial vein through the deep facial
vein.
• The plexus is drained by maxillary vein
which is formed at the lower border of
the lateral pterygoid muscle.
• The pterygoid venous plexus is
sometimes referred to as a peripheral
heart for during yawning when the mouth
is widely open due to contraction of
lateral pterygoid muscle, the stagnant
venous blood is pumped up into the
cavernous sinus and maxillary vein.
23. MANDIBULAR NERVE
The mandibular nerve is the largest of the three divisions of the
trigeminal nerve. It is a mixed nerve, consisting of both sensory and
motor fibres. It is a nerve of the first pharyngeal arch, hence supplies all
the structures derived from this arch,e.g., muscles of mastication.
24. Course and Relations
• The mandibular nerve is the largest of three divisions of trigeminal nerve. It
begins in the middle cranial fossa as two roots: a larger sensory root and a
smaller motor root.
• The large sensory root arises from lateral convex part of the trigeminal
ganglion and immediately leaves the cranial cavity by passing through
foramen ovale to enter the infratemporal fossa. The small motor root
arises from the pons, lies deep to the trigeminal ganglion and the sensory
root.
• It also passes through foramen ovale to join the sensory root just below
the foramen ovale in the infratemporal fossa, thus forming the main trunk.
• The mandibular nerve trunk is short and after a short course divides into a
small anterior and large posterior division.
25. Relations of Trunk of Mandibular Nerve in the
Infratemporal Fossa
• Medial: Tensor palati muscle and otic ganglion.
• Lateral: Upper head of lateral pterygoid muscle.
• Posterior: Middle meningeal artery.
• Anterior: Posterior border of lateral pterygoid plate.
26. Branches
From the Main Trunk
Two branches arise from the main trunk, a sensory branch (nervus spinosus)
and a motor branch (nerve to medial pterygoid):
1. Nervus spinosus (meningeal branch): It takes a recurrent course to enter
the cranial cavity through foramen spinosum with middle meningeal artery
and supplies the dura mater of the middle cranial fossa.
2. Nerve to medial pterygoid: It arises from the medial aspect of the main
trunk, close to the otic ganglion traverses through the ganglion and supplies
the medial pterygoid from its deep aspect. In addition to medial pterygoid it
also supplies tensor palati and tensor tympani muscles.
27. From the Anterior Division
The anterior division is mainly motor and gives branches to all muscles of mastication except
medial pterygoid, which is supplied by nerve to medial pterygoid from the main trunk. The
branches from the anterior divisions are as follows:
1. Masseteric nerve: It emerges at the upper border of the lateral pterygoid, just in front of the
temporomandibular joint, passes laterally through the mandibular notch, along with
masseteric artery to supply the masseter from its deeper aspect. It also supplies the
temporomandibular joint.
2. Deep temporal nerves: These are usually two in number, anterior and posterior. The
anterior and posterior temporal nerves emerge at the upper border of the lateral pterygoid
and ascend up in the temporal fossa to supply the temporalis muscle from its deep aspect.
3. Nerve to lateral pterygoid: It runs with the buccal nerve and enters the deep surfaces of
both the heads of lateral pterygoid muscle, which it supplies.
4. Buccal nerve: It contains all the sensory fibres of the anterior division. It emerges between
the two heads of the lateral pterygoid and courses downwards and forwards onto the
buccinator muscle, giving branches to the skin of the cheek. It then pierces the buccinator
muscle and supplies the mucus membrane of the cheek and gum of the lower jaw opposite the
molars and second premolar teeth.
• All the branches of anterior division of the mandibular nerve are motor except buccal nerve
which is sensory.
28. From the Posterior Division
The posterior division is mainly sensory. It gives the following three branches:
1. Auriculotemporal nerve: This nerve arises by two roots, which after
encircling the middle meningeal artery unite to form the single trunk. It runs
backwards between the neck of the mandible and the sphenomandibular
ligament. Behind the neck of the mandible, it turns upwards and ascends over
the root of zygoma to enter the temple behind the superficial temporal vessels
Distribution:
(a) Its auricular branches supply skin of the tragus, upper part of the pinna,
external auditory meatus and tympanic membrane. The lower parts of these
regions are supplied by great auricular nerve and auricular branch of the vagus
nerve.
(b) Its articular branches supply the temporomandibular joint.
(c) Its superficial temporal branches supply the skin of the temple.
(d) It also supplies secretomotor fibres to the parotid gland.
29. 2. Lingual nerve: It is the smaller terminal branch of posterior division of the
mandibular nerve. It is sensory to the mucus membrane of anterior two-third
of the tongue except vallate papillae.
• Course and relations:
• It begins about 1 cm below the skull. It runs first between tensor palati and
lateral pterygoid and then between lateral and medial pterygoids. About 2
cm below the skull it is joined by the chorda tympani nerve. After emerging
at the lower border of the lateral pterygoid, it first run downwards and
forwards between the ramus of the mandible and medial pterygoid, comes
in direct contact with the mandible where the bone is thinned to form a
shallow groove below and medial to the last molar tooth, just above the
posterior end of the mylohyoid line. This groove separates the attachments
of pterygomandibular raphe above and mylohyoid muscle below. It enters
the mouth on the superior surface of the mylohyoid, and then it crosses
the styloglossus to reach the lateral surface of the hyoglossus. Finally it lies
on the surface of the genioglossus. Here it winds round the submandibular
duct (first above, then lateral, then below and finally medial to the duct)
and divides into its terminal branches.
30. • Distribution:
• (a) Provides sensory supply to floor of mouth, lingual surface of the gum and anterior two-third of the tongue;
• (b) Carries preganglionic secretomotor fibres to submandibular and sublingual salivary glands.
3. Inferior alveolar nerve:
It is the larger terminal branch of the posterior division of mandibular nerve. It is a mixed nerve. It receives all the motor fibres of
the trigeminal nerve.
Course:
It emerges below the lower head of the lateral pterygoid and passes vertically downwards and forward on the medial pterygoid.
The nerve lies anterior to inferior alveolar vessels between the sphenomandibular ligament and the ramus of the mandible. Then
enters the mandibular foramen in company with inferior alveolar artery, traverses the mandibular canal as far as mental foramen,
where it terminates by dividing into mental and incisive branches.
Branches:
(a) Nerve to mylohyoid arises from the inferior alveolar nerve before it enters the mandibular canal. It pierces the
sphenomandibular ligament to reach the mylohyoid groove. It supplies mylohyoid and anterior belly of digastric muscle.
(b) Dental branches supply molar and premolar teeth.
(c) Mental nerve emerges out through mental foramen to supply skin of the chin and skin and mucus membrane of the lower lip.
(d) Incisive branch, supplies canine and incisor teeth.
31.
32. Branches of the mandibular nerve
From main trunk From anterior
division
From posterior
division
1. Nervus spinosus (meningeal branch)
2. Nerve to medial pterygoid
1. Masseteric nerve
2. Deep temporal nerves
3. Nerve to lateral pterygoid
4. Buccal nerve
1. Auriculotemporal nerve
2. Lingual nerve
3. Inferior alveolar nerve
All the branches of posterior division of the mandibular nerve are sensory except nerve to mylohyoid, which
is motor
All the branches of anterior division of the mandibular nerve are motor except buccal nerve which is sensory.
33. • Inferior alveolar nerve block (generally called inferior alveolar block or 1A
block): It is the most common nerve block performed in dentistry to carry
out dental procedures on the mandibular teeth.
• The anesthetic agent is injected slightly superior to the entry of inferior
alveolar nerve into the mandibular foramen being overhung by the lingula.
While performing inferior alveolar nerve block, if needle is inserted too far
posteriorly, it may enter the parotid gland and damage the facial nerve
leading to transient facial palsy.
• The lingual nerve is at great risk (10%) during surgical removal of the
impacted third molar teeth. The nerve is also at risk during surgical
removal of the submandibular salivary gland, during which the
submandibular duct must be dissected out carefully from the nerve
34. • Referred Pain:
• It is the pain frequently referred from one branch of mandibular
nerve to the other. Thus in patients suffering from tongue cancer, the
pain radiates to the ear and to the temporal fossa in the area of
distribution of auriculo-temporal nerve. The pain is relieved by
dividing the lingual nerve below and behind the last molar tooth. At
this site the nerve is in contact with the mandible and covered only by
mucus membrane. Similarly, pain from teeth is also referred to the
ear and temporal region.
35. CHORDA TYMPANI NERVE
The chorda tympani nerve is the slender
branch of facial nerve. It is so named
because of its intimate relationship to
the middle ear (tympanum).
Function Components
The chorda tympani nerve contains:
1 General visceral efferent fibres: These
are preganglionic parasympathetic
(secretomotor) fibres to submandibular
and sublingual salivary glands.
2 Special visceral afferent fibres: These
fibres carry taste sensations from
anterior 2/3rd of tongue (except vallate
papillae).
36. Origin, Course, and Relations
• It arises from facial nerve in the facial canal about 6 mm above the
stylomastoid foramen, within the posterior wall of the tympanic (middle
ear) cavity. It enters the middle ear through the posterior canaliculus of
chorda tympani in the posterior wall, runs across the lateral wall (tympanic
membrane). Here it crosses medial aspect of handle of malleus and lateral
aspect of long process of incus.
• At the anterior margin of tympanic membrane it enters anterior canaliculus
in the anterior wall of the middle ear passes through canaliculus and
emerges at the base of skull through medial end of petrotympanic fissure.
• It then goes medially, forwards and downwards, grooves the medial side of
the spine of the sphenoid, running anteroinferiorly deep to lateral
pterygoid to join the posterior aspect of the lingual nerve about 2 cm
below the base of the skull.
37.
38. Distribution
1. It supplies secretomotor fibres to submandibular and sublingual
glands through the submandibular ganglion.
2. It carries taste sensations from anterior two-third of the tongue
(except vallate papillae).
39. OTIC GANGLION
It is a small parasympathetic ganglion connected to the mandibular division of
trigeminal nerve and provides a relay station to the secretomotor fibres to the
parotid gland.
Topographically, it is intimately related to the mandibular nerve but functionally it
is related to glossopharyngeal nerve.
Size Pinhead (2–3 mm in size).
Location Infratemporal fossa, just below the foramen ovale.
Relations
Lateral: Mandibular nerve.
Medial: Tensor palati muscle.
Posterior: Middle meningeal artery.
Anterior: Medial pterygoid muscle.
40. Roots or Connections
• 1. Parasympathetic motor (secretomotor):
• From lesser petrosal nerve. Preganglionic parasympathetic fibres arise from inferior
salivatory nucleus; pass successively through glossopharyngeal nerve, tympanic branch
of glossopharyngeal nerve (Jacobson’s nerve), tympanic plexus, and lesser petrosal nerve
to relay in the ganglion.
• Postganglionic parasympathetic fibres from ganglion cells pass through auriculo-
temporal nerve to supplynparotid gland.
• 2. Sympathetic: From sympathetic plexus around the middle meningeal artery.
• Preganglionic sympathetic fibres arise from T1 and T2 spinal segments, enter the cervical
sympathetic chain at the level of its inferior ganglion and then ascend to relay in the
superior cervical sympathetic ganglion. The postganglionic fibres arise from this ganglion
and form plexus around the middle meningeal artery. They then pass through the
ganglion without relay to reach the parotid gland via auriculotemporal nerve. They are
vasomotor in nature and responsible for thick salivary secretion.
41. 3. Sensory: From auriculotemporal nerve.
4. Somatic motor: Nerve to medial pterygoid. It passes through
ganglion to supply medial pterygoid, tensor palati, and tensor tympani
muscles.
42. Branches
1. Postganglionic parasympathetic
2. Postganglionic sympathetic
3. Sensory
• In humans, the chorda tympani nerve is connected to the otic
ganglion and nerve to pterygoid canal. These connections provide an
alternative pathway of taste sensations from anterior two-third of the
tongue.
• Clinical evidence suggests that in humans the parotid gland also
receives secretomotor fibres through chorda tympani nerve.
All supply parotid gland
through auriculotemporal nerve
