Chapter 38: Infratemporal & Pterygopalatine Fossae & TMJ

The ITF is situated deep to the ramus of the mandible, lacking an anatomical floor but communicating broadly with regions such as the temporal fossa superiorly, the orbit anteriorly via the inferior orbital fissure, and the middle cranial fossa through the foramina ovale and spinosum. Key contents of the ITF include the lateral and medial pterygoid muscles, the mandibular division of the trigeminal nerve, the chorda tympani, the otic ganglion, the maxillary artery, and the clinically significant pterygoid venous plexus, which is important for understanding the spread of infection. The skeletal framework of these regions is derived primarily from the sphenoid bone (with its greater wings, lesser wings, and pterygoid processes) and the mandible. The mandible, the largest and strongest facial bone, is described in terms of its body, supporting the teeth within the alveolar process, and its two rami, which bear the coronoid and condylar processes. Clinically, bone loss in edentulous patients leads to resorption of alveolar bone, causing the mandibular canal and mental foramen to lie closer to the superior border. The PPF is a small, pyramidal neurovascular conduit positioned below the orbital apex, bounded laterally by the pterygomaxillary fissure and anteriorly by the posterior wall of the maxilla. It houses the third part of the maxillary artery, the maxillary nerve (V2), and the pterygopalatine ganglion. The maxillary artery is divided into three parts—mandibular, pterygoid, and pterygopalatine—supplying structures including the masticatory muscles, teeth, and cranial dura mater. The muscles of mastication—masseter, temporalis, and the medial and lateral pterygoids—control mandibular movement. Notably, the lateral pterygoid is key to understanding the ITF's deep relationships, and its two heads perform specialized roles, with the upper head stabilizing the condyle during jaw closure. The TMJ is a synovial joint featuring fibrocartilage-lined surfaces and an articular disc that divides the joint cavity into upper (discotemporal) and lower (discomandibular) compartments. Jaw function involves both condylar rotation within the lower compartment and sliding/translation across the articular eminence in the upper compartment, movements constrained by ligaments like the temporomandibular and sphenomandibular ligaments. Abnormalities in disc position, such as disc displacement with or without reduction, are categorized as internal derangements and often result in clicking or limited mouth opening.