Temporomandibular joint and salivary glands overview: Dental assisting

The temporomandibular joint, or TMJ, and the salivary glands work together to support essential functions such as chewing, speaking, swallowing, and maintaining oral health. As a dental assistant, your knowledge of how these structures function is crucial as you assist the dental team with addressing disorders related to TMJ and salivary gland function.

Now, the TMJ

is a bilateral joint, meaning there’s a TMJ on each side of the head.

It’s formed by the mandible, commonly called the lower jaw, and the temporal bone, which makes up the lower side of the head. The TMJ is made up of three bony parts: an oval depression in the temporal bone called the glenoid fossa; a raised part of the temporal bone called the articular eminence; and a protrusion on the mandible called the condyloid process.

Surrounding the TMJ is a fibrous joint capsule called the capsular ligament which provides stability and support for the joint. The articular space is the space between the mandibular condyle and the glenoid fossa within the joint capsule. Within this space, the articular disc, or meniscus, provides a cushion of dense fibrous connective tissue that separates the articular space into upper and lower compartments. These compartments are filled with synovial fluid, which lubricates the joint during movement.

The muscles of mastication are the muscles used to chew. These muscles work with other smaller accessory muscles to allow the TMJ to move the mandible in several different movements. A hinge action involves opening and closing,

while a gliding movement is a forward movement called protrusion; and a backward motion is called retrusion.

Lateral movement allows a side-to-side grinding movement.

These combined movements allow for essential functions like speech, chewing, swallowing, and overall oral function.

Now, some of the patients you care for may experience a temporomandibular disorder, or TMD for short, that can affect one or both TMJs. Causes stem from a variety of factors, including injury to the head, jaw, and neck; stress; genetics; systemic disorders like arthritis; and malocclusion, which is when the upper and lower teeth come together abnormally.