TMJ Ligaments3 ligaments associated with the TMJ: 1) Temporomandibular ligament (Major) is really the thickened lateral portion of the capsule, and it has two parts: an outer oblique portion (OOP) and an inner horizontal portion (IHP)Lower border of zygomatic arch to posterior border of the neck and ramus Temporomandibular JointAtypical synovial joint separated into upper and lower cavities by a fibrocartilaginous discNo hyaline cartilageCapsule attached high on neck of mandible around articular margin, then to transverse prominence or articular tubercle and as far posteriorly as squamotympanic fissureFibrocartilage attached around periphery to capsuleAnteriorly near head of mandible, so mobilePosteriorly near temporal bone, so more fixedThinner in middle than periphery, crinkled fibres to allow movement and contouringLateral TM ligament is a stout fibrous band passing from zygomatic arch to posterior border of neck and ramus, blending with capsuleTightens with movements away from restSphenomandibular ligament runs between sphenoid spine and lingula of mandibleRemains constant tension through range of motion as the lingula is the axis of rotation of the mandibleSensation supplied by auriculotemporal nerve with some supply from nerve to masseter (Hiltons law) (opening and closing movements)Superior compartment involved in translational movements sliding the lower jaw forward or side to sideTemporomandibular Joint Temporomandibular JointArticulationSynovial joint between the condyle of the mandible and the mandibular fossa in the squamous part of the temporal boneBoth bone surfaces covered with layer of fibrocartilage identical to the discNo hyaline cartilage, therefore an atypical jointTemporomandibular JointUnique feature of the TMJs is the articular disc.Composed of fibrocartilaganeous tissue Divides each joint into 2:Inferior compartmentSuperior compartmentTemporomandibular JointInferior compartment Allows for pure rotation of the condylar head,corresponds to the first 20 mm or so of the opening of the mouth.
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Lateral pterygoid2 heads:Superior:Infratemporal fossa Inferior:Lateral surface of the lateral pterygoidFuse into a short thick tendon that inserts into pterygoid foveathe upper fibres passing into articular disc and anterior part of the capsuleAction: side-to-side plus only muscle to open jaw Medial pterygoid2 heads:Deep:Larger Medial surface of the lateral pterygoid plate and the fossa between 2 platesSuperficial :Tuberosity of the maxilla and pyramidal process of palatine bonesInsert lower and posterior part of angle (with masseter)Action: upwards and forwards and medially TemporalisArises temporal fossa between inferior temporal line and infratemporal crestInserts at posterior border of the coronoid process and ascending ramusUpper and anterior fibres elevate the mandiblePosterior fibres (horizontal) retract the mandible (only muscles that do so) MasseterDivided into 3 headsSuperficial: largest headArises anterior 2/3rds of the lower border of the zygomatic archWide insertion to angle, forwards along lower border and upwards to lower part of ramusIntermediate:Middle 1/3 of the archDeep:Deep surface of the archAction: elevator and drawing forward the angleMasseterIntermediate and deep fuse and pass vertically downwards to fuse with ramusNerve and artery divide muscle incompletely into 3 partsMasseteric nerve (Br of anterior division of V3) runs between deep and intermediateBr of superficial temporal and transverse facial runs between superficial and intermediate Muscles of Mastication4 muscles of masticationMasseter TemporalisMedial pterygoid Lateral pterygoid Supplied by V3, testament to same embryologic origin as the mandible from the 1st branchial arch