The temporomandibular joint (TMJ) is the key joint of the head. It is a bilateral articulation formed by the temporal bones and the mandible. The articulating bony structures are lined with fibrocartilage and there is an articular disc between them, which creates two synovial joint cavities. To stabilise the joint, ligaments provide further support. Muscles of mastication cause movements of the TMJ such as protraction, retraction, elevation and depression.
The main arterial supply to the TMJ comes from the superficial temporal artery of the external carotid artery. Nerve supply is provided by the mandibular nerve (CN3).
The muscles of mastication allow for several different types of movement of the TMJ. These are important for different kinds of activities such as eating, speaking and yawning. Protraction and retraction refer to the forward and backward movements of the mandible. Elevation and depression refer to the up and down movements of the mandible.
Protraction occurs when the mandible moves away from the joint, allowing the movement of the tongue and lips necessary for speaking, eating and yawning. Retraction occurs when the mandible returns back to the original position. Elevation and depression refer to the up and down movements of the mandible. Elevation occurs when the mandible is brought upwards, usually during closure of the mouth. Depression occurs when the mandible is brought downwards, usually during opening of the mouth.
The main arterial supply to the TMJ is the superficial temporal branch of the external carotid artery, which provides oxygenated blood to this important joint. The mandibular nerve (CN3) is responsible for its nerve innervation, providing nerves to the muscles in the area.
The TMJ is stabilised by ligaments which attach the articular disc to the mandible. These ligaments are the sphenomandibular, the temporomandibular and the stylomandibular ligaments. The sphenomandibular ligaments attach the medial aspect of the mandible to the spine of the sphenoid bone while the temporomandibular ligaments attach the mandible to the temporal bone. The stylomandibular ligament is the most important ligament, attaching the angle of the mandible to the styloid process of the temporal bone.
In addition to these structural ligaments, the TMJ is also supported by active muscles which are responsible for the movements of the joint. These muscles of mastication are the temporal, masseter, lateral and medial pterygoid muscles, which provide a dynamic stability to the joint.
The temporomandibular joint (TMJ) is an important joint of the head. It is stabilised by ligaments and the muscles of mastication and it is supplied with blood from the superficial temporal branch of the external carotid artery, while its nerve innervation is provided by the mandibular nerve (CN3). The TMJ is involved in a range of different functions including speaking, eating and yawning, and it is important to have a good understanding of the anatomy and function of this joint in order to keep it healthy and functioning properly.
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