Temporomandibular disorder (TMD) refers to a group of conditions involving the orofacial region divided into those affecting the masticatory muscles and those affecting the temporomandibular joint (TMJ). The typical features include pain in TMJ, restriction of mandibular movement, and TMJ sounds.
Temporomandibular Joint Anatomy
The temporomandibular joint (TMJ) is a ginglymoarthrodial joint formed by the glenoid fossa of the temporal bone and the mandibular condyle. An articular disc separates the joint into two synovial cavities with distinctive movement patterns. Gliding or translatory movement occurs in the superior joint (between the articular disc and the glenoid fossa). Rotary or hinge movement takes place in the inferior joint (between the articular disc and the condyle).
The muscles involved in temporomandibular disorders are the muscles of the mastication: temporalis, masseter, medial and lateral pterygoid muscles. Three major ligaments stabilize the TMJ: temporomandibular, stylomandibular, and sphenomandibular ligaments.
The primary blood supply of the TMJ comes from the superficial temporal and maxillary branches of the external carotid artery.
Other contributing branches include the anterior tympanic, deep auricular, and ascending pharyngeal arteries. The TMJ receives its sensory innervation from the auriculotemporal and masseteric branches of the mandibular nerve (V3), a branch of the trigeminal nerve.
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