Temporal and Infratemporal Fossae: Mastication and the Temporomandibular Joint

Overview

The temporal and infratemporal fossae together form the deep lateral compartment of the skull that houses the muscles of mastication, the mandibular division of the trigeminal nerve, the maxillary artery, and the temporomandibular joint (TMJ) — structures central to dental anesthesia, oral surgery, and TMJ disorders.

Temporal Fossa

• Bounded by the superior and inferior temporal lines superiorly, the zygomatic arch inferiorly, and floored by parts of the frontal, parietal, temporal, and greater wing of sphenoid (the pterion, a clinically important thin region, lies within this fossa).
• Occupied by the temporalis muscle, which converges through the zygomatic arch to insert on the coronoid process and anterior ramus of the mandible.

Infratemporal Fossa

An irregular space deep to the ramus of the mandible, continuous with the temporal fossa above.

Boundaries:

• Roof: infratemporal surface of the greater wing of sphenoid.
• Medial wall: lateral pterygoid plate.
• Lateral wall: ramus of the mandible.
• Anterior wall: posterior surface of the maxilla.

Contents:

• Lower part of temporalis, lateral and medial pterygoid muscles.
• Maxillary artery and its branches, including the inferior alveolar artery (accompanies the nerve of the same name into the mandibular canal) and middle meningeal artery (ascends through the foramen spinosum).
• Mandibular nerve (CN V3) and its branches: inferior alveolar, lingual, buccal, auriculotemporal.
• Otic ganglion, suspended from the mandibular nerve, relaying parasympathetic secretomotor fibers to the parotid gland.
• Chorda tympani, joining the lingual nerve to carry taste fibers (CN VII) and parasympathetic fibers to the submandibular and sublingual glands.
• Pterygoid venous plexus, an important route for spread of dental infection toward the cavernous sinus.

Muscles of Mastication

All four are innervated by the mandibular nerve (CN V3):

• Masseter: elevates the mandible (closes the jaw); superficial and deep heads span from the zygomatic arch to the ramus and angle.
• Temporalis: elevates and retracts the mandible; its posterior fibers are key for retrusion.
• Lateral pterygoid: the only muscle that opens the jaw (via its inferior head) and protrudes the mandible; its superior head attaches to the TMJ articular disc, and its overactivity is implicated in disc displacement.
• Medial pterygoid: elevates the mandible and, acting with the contralateral lateral pterygoid, contributes to side-to-side grinding movements.

Temporomandibular Joint (TMJ)

A synovial joint between the mandibular condyle and the mandibular fossa/articular tubercle of the temporal bone, unique in the body for combining hinge and gliding movements.

• Articular disc: a fibrocartilaginous disc divides the joint into upper (gliding — protrusion/retrusion) and lower (hinge — depression/elevation) synovial cavities.
• Capsule and ligaments: the lateral (temporomandibular) ligament reinforces the joint laterally; the sphenomandibular and stylomandibular ligaments act as accessory suspensory ligaments.
• Movements: depression, elevation, protrusion, retrusion, and lateral excursion (grinding), the last requiring asymmetric rotation and translation of the two condyles.

Clinical Relevance

• Inferior alveolar nerve block: the most common dental local anesthetic technique, targeting the nerve as it enters the mandibular foramen on the medial ramus — the pterygomandibular raphe and occlusal plane are key intraoral landmarks.
• TMJ dysfunction (TMD): often linked to lateral pterygoid hyperactivity or disc displacement, presenting with clicking, pain, or limited opening.
• Trismus (limited mouth opening) can result from masticatory muscle spasm, infection spreading through the infratemporal fossa, or mandibular fracture.
• Odontogenic infection spread: because the infratemporal fossa communicates with the pterygoid venous plexus and, via emissary veins, the cavernous sinus, untreated dental abscesses can rarely progress to cavernous sinus thrombosis.
• Mandibular condyle fractures are common after trauma and can be complicated by TMJ ankylosis if untreated in growing patients.