24 : The Temporal , Parotid , Infratemporal and Submandibular regions

24.3 Infratemporal region

Boundaries:

Laterally: The ramus fo the mandible.

Medially: Lateral pterygoid plate (B).

Anteriorly: The infratemporal surface of the maxilla (limited by inferior orbital fissure superiorly and the pterygomaxillary fissure medially)

Posteriorly: Anterior surface of the condylar process of the mandible and the styloid process of the temporal bone.

Roof (Superior): Inferior surface of the greater wing of the sphenoid. Foramen ovale is located in the roof of the infratemporal fossa.

Inferiorly: Angle of the mandible (M) and continues in to the sub-mandibular fossa.

Contents:

Muscles:

• Inferior part of temporalis muscle.

• Medial and lateral pterygoids.

Vessels:

Pterygoid venous plexus:

Lies on the lateral pterygoid muscles.

Connections:

Facial vein , via deep facial vein.
Cavernous venous sinus by an emissary vein passing through the foramen ovale.
Inferior opthalmic vein
Pharyngeal venous plexus and muscular veins.

These communications are important for spread of infections and for collateral circulation.

The pterygoid muscles and other muscles of mastication pump the blood from this plexus and are considered a “peripheral heart”. Chewing or yawning increases venous return.

Maxillary artery.

Origin

• Terminal branch of the external carotid artery ,

Course

It commonly lies superficial to the lateral pterygoid muscles but may be deep to it.
It is divided into three parts by the lateral pterygoid muscle.

See table below for parts, branches and distribution

Part	Branch	Distribution

Part 1	Deep auricular (1).	External acoustic meatus
	Anterior tympanic,	Tympanic membrane.
	Middle meningeal(3)	Dura and skull (middle cranial fossa).
	Accessory meningeal	Meninges and skull.
	Inferior alveolar .(2)	Mandibular teeth and gums

*Part 2*	Masseteric:(4)	Masseter muscle.
	Anterior(9) and posterior (10) Deep temporal:	Temporalis.
	Pterygoid:.	Pterygoid muscles
	Buccal:.(5)	Buccinator

*Part 3 Branches:*
	Posterior superior alveolar (7).	Maxillary molars gums
	Middle superior alveolar.	Maxillary Pre-molars and gums
	Infraorbital (8).	Faces
	Descending palatine:	Palate
	Artery of the Pterygoid canal.	Pharynx
	Pharyngeal	Naso-pharynx
	Sphenopalatine:	Nasal cavity and incisive teeth


Mandibular Nerve

These are mainly branches of the Mandibular nerve (V3), together with associated parasympathetic hitch hikers.

a) Branches to the muscles of mastication are named according to the muscles they supply. In addition to the muscle of mastication, the mandibular nerve also supplies: -

• Tensor palati.

• Tensor tympani.

• Mylohyoid and anterior belly of digastric.

b) Sensory branches:

Auricolotemporal	Buccal	Inferior alveolar nerve:	Lingual nerve:
Auricle and temporal region. Auricular fibres to the temporo-mandibular joint. Post-ganglionic parasympathetic fibres to the parotid gland.	Skin and mucous membrane of the cheek. Mandibular buccal gingiva in the molar region.	Teeth and gums in the mandible. Continues as mental nerve (at about 2 nd premolar) Lower lip, chin. Gingiva of mandbular incisors.	General sensation to the anterior two-thirds of the tongue, the floor of the mouth and the gingivae. It is joined by chorda tympani which carries: Preganglionic parasympathetic fibres to the submandibular ganglion. Taste fibres from the anterior two-thirds of the tongue.