Temporal & infratemporal fossae Temporal fossa :extends above by the sup.temporal line and below by zygomatic arch. Infratemporal fossa : lies beneath the base of the skull, between the pharynx (medially) & ramus of mandible (laterally). or the space lying below the temporal fossa and behind the maxilla. Muscles of mastication: 1-Temporalis It lies in the temporal fossa. Origin :floor of temporal fossa & temporal fascia. Insertion :by a tendon into the coronoid process of the mandible. N.supply : deep temporal nerves from the ant.division of mandibular N. Action : anterior fibers --elevate the mandible. posterior fibers--- retract the mandible. Muscles of mastication 2-Masseter muscle : Origin : lower border & inner surface of zygomatic arch. Insertion : lateral (outer) surface of ramus of the mandible. N.supply : masseteric N. from anterior division of mandibular N. Action : raises the mandible. Muscles of Mastication attached to mandible : Lateral Surface Medial Surface Contents of the temporal fossa 1-Temporalis muscle. 2-Temporal fascia---covers temporalis muscle, attached above to sup.temporal line and below to upper border of zygomatic arch. 3-Deep temporal nerves : from the ant. division of mandibular N., emerge from upper border of lateral pterygoid, enter the deep surface of temporalis . Contents of the temporal fossa 4-Auriculotemporal nerve : arise from the posterior division of mandibular N. It emerges from upper border of parotid gland , It lies behind superficial temporal artery & TMJ, in front of the auricle. It supplies skin of auricle , ext.auditory meatus and the scalpe over the temporal region. Contents of the temporal fossa 5-Superficial temporal artery : it is a terminal branch of ext.carotid artery. It Emerges from upper border of parotid gland, behind T.M.J. It crosses root of zygomatic arch in front of auriculotemporal N. & auricle ,here its pulsation can be easily felt. Contents of Infratemporal fossa Lateral & medial pterygoid muscles (muscles of mastication) Branches of the mandibular N. Otic ganglion. Chorda tympani. Maxillary artery. Pterygoid venous plexus. Lateral pterygoid Origin :upper head---- from the infratemporal surface of the greater wing of sphenoid. Lower head---- from the lateral surface of lateral pterygoid plate. Insertion :neck of mandible (pterygoid fovea) & articular disc of T.M.J. N.supply :anterior division.of mandibular N. Action: 1-Pulls the neck of mandible forward with the articular disc to depress mandible during opening of mouth. 2-Acting with medial pterygoid of the same side during movement of chewing. 3-Acting with medial pterygoid to protrude the mandible. Medial pterygoid Origin : superficial head----from the tuberosity of the maxilla. Deep head----- from the medial surface of the lateral pterygoid plate. Insertion: angle of mandible (medial surface). N.supply : main trunk of mandibular N. Action : 1-elevates the mandible. 2-Acting with lateral pterygoid during movement of chewing. Tempromandibular joint (TMJ) Articlation : between the articular tubercle & mandibular fossa of temporal bone, and the head of mandible (condyloid process). Type :condyloid synovial joint. Capsule :it surrounds the joint. Synovial membrane--- lines the capsule in upper & lower cavities. Ligaments of Temperomandibular Lateral temporomandibular joint : ligament : lies on the lateral side of joint ,between the tubercle and lateral surface of the neck of mandible. Sphenomandibular ligament : lies on the medial side of the joint ,it connects the spine of sphenoid to the lingula of mandibular foramen. Stylomandibular ligament behind & medial .to the joint. it is a band of thickened deep cervical fascia, from apex of styloid process to angle of mandibule. Intracapsular articular disc It is a plate of fibro-cartilage, it divides the joint into upper & lower cavities. It is attached in front to the tendon of lat. pterygoid , and by fibrous bands to head of mandible. Its upper surface is concavoconvex to fit the articular tubercle & mandibular fossa , while its lower surface is concave to fit the head of mandible. N.supply-auriculotemporal & masseteric branches of mandibular N. Movements: Depression of mandibule : by lat.pterygoid, helped by digastric, geniohyoid & mylohyoid muscles. Elevation :by temporalis, masseter, and medial pterygoid. Protrusion : by lateral + medial pterygoids of both sides. Retraction :by post.fibers of temporalis . Lateral chewing movement: by lat.& med. Pterygoids of both sides Relation of the Temporomandibular joint (TMJ) : Anteriorly : mandibular notch and masseteric N. & artery (structures passing through mandibular notch). Posteriorly : ext.auditory meatus, glenoid process of parotid gland., auriculotemporal N., & superficial temporal artery. Laterally :parotid gland, fascia & skin. Medially : maxillary vessels. Clinical significance of the TMJ : The great strength of the Lat.TM ligament prevents head of mandible from passing backward to cause fracture of the tympanic plate in case of severe blow on the chin. The articular disc may be partially detached causing noisy & audible click, during movements of the joint. Dislocation of the TMJ Sometimes occurs when the mandible is depressed. In case of minor blow on chin or sudden contraction of lateral pterygoids as in yawning, leads to pull the head of mandible & articular disc forward beyond the summit of tubercle. Reduction of disloction : by pressing the thumbs downward on the lower molar teeth and pushing the jaw backward.