What is the temporomandibular joint (TMJ) and what bones does it connect?

The TMJ is a bilateral synovial joint that connects the mandible (lower jaw) to the temporal bone of the skull. Both joints function together as a single unit during activities like chewing and speaking.

What makes the TMJ an atypical synovial joint?

Unlike typical synovial joints, the TMJ has fibrocartilage covering its articular surfaces instead of hyaline cartilage. It's classified as a condylar-type joint but is considered atypical due to this unique feature.

How is the TMJ joint cavity structured and what movements does it allow?

A fibrocartilaginous disc divides the joint cavity into two compartments: Upper compartment allows gliding movements, while lower compartment permits both rotational and gliding movements. This structure enables complex jaw motions.

What are the main ligaments that support the TMJ?

The TMJ is supported by several key ligaments including the temporomandibular (lateral) ligament that strengthens the capsule laterally, the sphenomandibular ligament which is important for nerve blocks, and the stylomandibular ligament that limits excessive jaw protrusion.

What nerves and arteries supply the TMJ?

The TMJ receives nerve supply from the auriculotemporal nerve (posterior) and masseteric nerve (anterior), and blood supply from branches of the maxillary and superficial temporal arteries.

What muscles control TMJ movements like jaw opening and closing?

Different muscle groups control specific jaw movements: Depression (opening) involves lateral pterygoid, digastric, geniohyoid, and mylohyoid muscles, while elevation (closing) involves masseter, medial pterygoid, and temporalis muscles.

What are common clinical problems associated with the TMJ?

Common TMJ disorders include TMJ syndrome characterized by facial pain, headaches, and joint clicking, and dislocation where the condyle gets locked in front of the articular eminence. These often result from disc displacement or muscle issues.

TMJ (Temporomandibular Joint) – Anatomy, Movements & Issues

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