Infratemporal fossa

Dr. Prathyusha PG ENTNarayana Medical CollegeNellore

• Introduction• Boundaries • Contents• Applied anatomy

Introduction • The infratemporal fossa is a complex and irregularly

shaped space, located deep to the masseter muscle.

• It acts as a conduit for many neurovascular structures that travel between the cranial cavity and other structures of the head.

• A precise knowledge of the structures and boundaries help to reduce intra operative complications

Boundaries • Anterior: the posterior surface of the maxilla

• Posterior: the styloid process, carotid sheath and deep part of the parotid gland.

• Medial: lateral pterygoid plate

• Lateral: the ramus and coronoid process of the mandible

The roof: the infratemporal surface of the greater wing of the

sphenoid.

The infratemporal fossa has NO anatomical floor, being continuous with tissue spaces in the neck.

The infratemporal fossa communicates with the temporal fossa deep to the zygomatic arch

Contents 1. Lateral and medial pterygoid muscles.2. Infratemporal pad of fat 3. Buccal lymph node4. Mandibular nerve5. Chorda tympani nerve6. Maxillary artery7. Pterygoid plexus of veins8. Otic ganglion9. Sphenomandibular ligament

Lateral pterygoid muscle• largest component of the infratemporal fossa.

• This muscle has two heads, upper and lower.

• The upper head is smaller and arises from the greater wing of sphenoid,

• while the larger lower head arises from the lateral aspect of lateral pterygoid plate.

• The fibers of both these heads pass backwards to be inserted into the neck of the mandible.

Medial pterygoid muscle

• The action of lateral pterygoid muscle i.e. protrusion of the lower jaw can easily be tested during clinical examination of the patient.

Medial pterygoid muscle• This muscle is the deepest of the four muscles of

mastication.

• It consists of two heads.

• The bulk of the muscle arises as a deep head from the medial surface of the lateral pterygoid plate.

• Thus, the lateral pterygoid plate of the sphenoid bone gives rise to both pterygoid muscles

• The smaller, superficial head of the medial pterygoid muscle originates from

• the maxillary tuberosity and

• the neighbouring part of the palatine bone

• the fibres pass downwards and backwards to insert into the roughened surface of the angle of the mandible on its medial aspect.

• The medial pterygoid muscle is an elevator of the mandible.

• It assists in lateral and protrusive movements.

• The medial pterygoid muscle is synergistic to the masseter muscle.

2. Infratemporal pad of fat: • Lies between the temporalis muscle and the

infratemporal surface of maxilla.

• The pad of fat helps in outlining the posterior antral tumor spread in CT scans.

• This infratemporal pad of fat continues with the cheek pad of fat passing between the posterior wall of maxilla and the zygoma.

• A mass present behind the maxilla always betrays itself by displacing this pad of fat and causing a puffy sweeling of the cheek (angiofibroma)

3. Buccal lymph node: • Within this infratemporal pad of fat lies the buccal

lymph node. • This node links the infratemporal lymphatics to the

facial lymphatics.

• Lymphatic drainage of the infratemporal fossa region is into the submandibular and upper deep cervical group of nodes• enlargement of the nodes in this region should

alert the clinician to the possibility of infection arising in the infratemporal fossa.• This node should never be left behind during

surgical resection of infratemporal fossa for malignant tumors as it could commonly cause local recurrence.

4. Mandibular nerve• penetrates the roof of the infratemporal fossa

through the foramen ovale.

• It gives rise to inferior alveolar and lingual nerve branches.

Buccal branch of mandibular nerve• Using the medial and lateral pterygoid muscles as

references

• the buccal branch of the mandibular nerve accompanying buccal artery

• The nerve and artery usually pass between the two heads of the lateral pterygoid muscle.

Other branches• the lingual nerve

• inferior alveolar nerve

• These two nerves pass between the medial and lateral pterygoid muscles.

Course of these nerves• Distally, the inferior alveolar nerve enters the

mandibular foramen.

• The lingual nerve lies superior to the inferior alveolar nerve and passes anteriorly to reach the tongue.

• the inferior alveolar nerve, artery, and vein emerge from the mental foramen as

• the mental nerve,• mental artery, • And mental vein .

Auriculo temporal nerve• the auriculotemporal nerve has two roots that

encircle the middle meningeal artery.

• It carries sensory fibers from the skin of the temporal region

• and postganglionic parasympathetic fibers from the otic ganglion to the parotid gland.

5. Chorda tympani • chorda tympani nerve emerges from the

petrotympanic fissure

• passes anteriorly to join the lingual nerve

• This nerve carries special sensory taste fibers from the anterior two-thirds of the tongue and

• preganglionic parasympathetic fibers to the submandibular ganglion.

Maxillary artery • maxillary artery and its branches lies on the

superficial or deep surface of the lateral pterygoid muscle.

6. Pterygoid venous plexus• venous plexus of considerable size,

• situated between the temporalis muscle and lateral pterygoid muscle,

• partly between the two pterygoid muscle

• These plexus could cause troublesome bleeding during total maxillectomy surgery.

Veins contributing for plexus• sphenopalatine• middle meningeal• deep temporal (anterior & posterior)• pterygoid• masseteric• buccinator• alveolar• some palatine veins (palatine vein which divides into the greater and

lesser palatine v.)• a branch which communicates with the ophthalmic vein through

the inferior orbital fissure• infraorbital vein

• The pterygoid venous plexus communicates with the cavernous sinus via two routes.

• One is via emissary veins passing through the foramen ovale, foramen spinosum.

• Another route is via the deep facial vein, which links the pterygoid venous plexus with the facial vein.

• The facial vein connects with the superior ophthalmic vein, which drains into the cavernous sinus.

• Due to its communication with the cavernous sinus, infection of the superficial face may spread to the cavernous sinus, causing cavernous sinus thrombosis.

Cavernous sinus thrombosis

• Complications may include • edema of the eyelids,

conjunctivae of the eyes, • paralysis of cranial

nerves which course through the cavernous sinus.

7. Otic ganglion• located inferiorly to the foramen ovale,

• medial to the mandibular nerve

• preganglionic fibres from inferior salivatory nucleus (associated with the glossopharyngeal nerve).

• Parasympathetic fibres travel within a branch of the glossopharyngeal nerve, the lesser petrosal nerve, to reach the otic ganglion.

• Post ganglionic fibres along the auriculotemporal nerve (branch of the mandibular division of the trigeminal nerve).

• provide secretomotor innervation to the parotid gland.

• Sympathetic fibres from the superior cervical chain pass through the otic ganglion.

• They travel with the middle meningeal artery to innervate the parotid gland.

7. Sphenomandibular ligament• a flat, thin band which is attached superiorly to the

spine of the sphenoid bone, and, becoming broader as it descends,• It is fixed to the lingula of the mandibular foramen. • it limits distension of the mandible in an inferior

direction. • It is slack when the TMJ is in closed position.• It is taut as the condyle of the mandible is in front

of the temporomandibular ligament.

Communications • The infratemporal fossa communicates superiorly

with middle cranial fossa by the neurovascular formina like• carotid canal,• jugular foramen, • foramen spinosum,• foramen ovale • foramen lacerum.

• Medially the infratemporal fossa communicates with pterygopalatine fossa through the pterygomaxillary fissure.

• With orbit through infra orbital fissure

• The pterygomaxillary fissure is contiguous with that of the infraorbital fissure.

• The roof of the infratemporal fossa is open to the temporal fossa lateral to the greater wing of sphenoid, deep to the zygomatic arch.

• Benign tumors involving the infratemporal fossa always respect these boundaries

• They expand in the direction of soft tissue planes, or follow preexistant pathways and foramen described above.

• Maxillofacial trauma , maxillary osteotomies, have the potential to disrupt the soft tissue contents of the infratemporal fossa

• These fractures frequently extend to involve the bones immediately adjacent to them

• Infection of the infratemporal fossa is most

commonly associated with a pericoronitis of mandibular third molar tooth

• dental abscess of this tooth, or as a result of infection following tooth extraction

• Rarely, it may result from an infected needle used during an inferior alveolar nerve block.

• Infection of the infratemporal region may be secondary due to spread from an adjacent infected tissue space.

• The main symptom is trismus (though a common symptom of parapharyngeal abscess)generally affecting the medial pterygoid muscle

• Externally there is usually little evidence of tissue

swelling.

• Spread of infection from the infratemporal fossa region to involve the buccal space is characterised by the presence of a swelling of the cheek

• The swelling is bounded above by the zygomatic arch and below by the lower border of the mandible, both landmarks being palpable.

• Infection from the infratemporal fossa may spread

• directly around the back of the maxillary tuberosity • into the orbit via the inferior orbital fissure.

• This may result in cavernous sinus thrombosis • Once in the orbit, further direct spread of infection

through the superior orbital fissure will gain entrance into the cranial cavity.

• Spread from the infratemporal fossa via the pterygomaxillary fissure may also involve the pterygopalatine fossa,• which contains the maxillary nerve,• maxillary artery • pterygopalatine ganglion

• From the pterygopalatine fossa a number of small canals lead into • nose, • pharynx • palate.

Take home message• Numerous structures in this deep irregular space expects us

to be anatomically oriented

• Potential communication to cavernous sinus, middle cranial fossa and orbit makes this area a potential high risk space

• Highly vascular area due to pterygoid plexus and maxillary artery warns surgeons to be alert to prevent bleeding

• Appearance of infections in other tissue spaces like orbit, pterygopalatine fossa, and in the maxillary antrum should prompt a primary site in infratemporal fossa