The mandibular fossa is a depression within the temporal bone of the skull, forming a crucial part of the jaw joint. It is a component of the temporomandibular joint (TMJ).
Anatomy and Location
The mandibular fossa is an oval-shaped depression in the temporal bone, situated just in front of the external acoustic meatus. It resides in the squamous portion of the temporal bone, providing a smooth surface for articulation.
The fossa is bordered by other temporal bone structures. Anteriorly, it is defined by the articular eminence, which is a bony prominence. Posteriorly, the tympanic part of the temporal bone separates the fossa from the ear canal, with a postglenoid process or tubercle often present in this region. The surface of the fossa is covered with fibrocartilage, facilitating smooth motion.
Role in Jaw Movement
The primary function of the mandibular fossa is to articulate with the mandibular condyle, which is the rounded head of the jawbone. This articulation forms the temporomandibular joint (TMJ), a specialized joint that combines hinging and gliding movements. The fossa allows for a wide range of jaw motions, including opening and closing the mouth, chewing, and speaking.
A significant component facilitating these movements is the articular disc, a thin, oval plate of fibrous connective tissue. This disc is positioned between the mandibular condyle and the mandibular fossa, acting as a cushion and reducing friction. The disc also divides the TMJ into two distinct compartments, enabling different types of movement: the upper compartment allows for gliding or translational movements, while the lower compartment facilitates rotational or hinging actions. When the mouth opens widely, the condyle and the articular disc glide forward and downward along the articular eminence.
Common Conditions Affecting the Mandibular Fossa
Issues related to the mandibular fossa often fall under the umbrella of temporomandibular joint (TMJ) disorders (TMD). These conditions can cause discomfort and affect the normal function of the jaw. Individuals may experience pain or tenderness in the jaw, aching around the ear, or difficulty chewing. Other common indicators include clicking, popping, or grating sounds during jaw movement, as well as limited jaw opening or the jaw locking in certain positions.
The origins of TMD are varied and can include factors such as teeth grinding or clenching, known as bruxism, and physical trauma to the jaw, head, or neck. Certain types of arthritis, like osteoarthritis, can also affect the joint, alongside displacement of the articular disc. Management often begins with conservative approaches, including rest for the jaw, pain relief medications, and physical therapy exercises. Dental splints or mouthguards may be used to address teeth grinding, and stress management techniques can also be beneficial.