Reading

Body Surface

The primary surface landmarks of the infratemporal fossa are associated with the mandible (angle), zygomatic arch and ear (external auditory meatus). Branches of the trigeminal nerve (auriculotemporal, zygomaticotemporal, zygomaticofacial and buccal) and cervical plexus (great auricular) innervate the skin overlying the infratemporal fossa.

Skeleton and Joints

The bones associated with the infratemporal fossa are the temporal, zygomatic, sphenoid, maxilla and mandible. The head of the mandible articulates with the mandibular fossa of the temporal bone at the temporomandibular joint (TMJ). An articular disc divides the joint into two compartments, an upper gliding and lower hinge articulation. The temporomandibular joint is supported by a fibrous joint capsule, the lateral temporomandibular ligament (thickening of the capsule) and the sphenomandibular ligament. The two compartments of the joint allow for depression, elevation, protrusion, retrusion and medial deviation of the mandible.

Organization

In this dissection exercise you will study the temporal fossa, the infratemporal fossa and the temporomandibular joint. The temporal fossa is bounded by the zygomatic arch, the superior temporal line and the frontal process of the zygomatic bone. The temporal fossa contains the temporalis muscle. The infratemporal fossa is bounded by the zygomatic arch, ramus of the mandible, pterygoid process of the sphenoid, infratemporal surface of the maxilla, and styloid process and tympanic region of the temporal bone. It contains the medial and lateral pterygoid muscles, a portion of the temporalis muscle, and branches of the maxillary artery and mandibular nerve. The infratemporal fossa communicates with the temporal and pterygopalatine fossae. The tempormandibular joint is described above.

Muscles

The muscles of the infratemporal fossa include muscles that elevate ( temporalis, masseter and medial pterygoid), depress ( lateral pterygoid assisted by gravity), protrude (lateral pterygoid), retrude (posterior temporalis) and medially deviate (ipsilateral medial and lateral pterygoid) the mandible. The lateral pterygoid also acts to anteriorly translate the TMJ articular disc during jaw depression and protrusion.

Innervation

Branches of the mandibular (trigeminal, cranial nerve V) nerve innervate (motor, sensory and postganglionic sympathetic) the temporalis, masseter, medial pterygoid and lateral pterygoid muscles. Sensory branches (long buccal, lingual, inferior alveolar and auriculotemporal) of the mandibular nerve traverse the infratemporal fossa on their routes to their distal sites of innervation.

Blood Supply

Branches of the maxillary artery supply the structures of the infratemporal region. The corresponding tributaries of the pterygoid venous plexus drain the infratemporal region before emptying into the maxillary vein.