What is the temporomandibular joint (TMJ) and what is its function?

The Temporomandibular Joint, or TMJ, is a vital joint that connects the mandible (the movable lower jaw) to the skull. There are two temporomandibular joints, one on each side of the head, located directly in front of the ears. These complex joints allow for the varied jaw movements essential for many daily functions, such as speaking, chewing, yawning, and swallowing food [2].

The TMJ consists of several key components that work together smoothly: the head of the lower jaw (the condyle), the temporal fossa of the skull bone, and a cartilage disc (articular disc) that separates the two bones. This disc acts as a cushion to absorb shock and allows for smooth movement between the bones, preventing direct friction [2].

Functions of the Temporomandibular Joint

The primary function of the TMJ is to facilitate the movement of the lower jaw. These movements include:

• Opening and closing: This basic movement allows the mouth to open for eating and speaking and to close for chewing and swallowing.
• Lateral movement: This enables the jaw to move from side to side, which is essential for grinding food during chewing.
• Forward and backward movement: This allows the lower jaw to move forward and backward, which helps in biting food with the front teeth and adjusting jaw positioning.

These functions depend on complex coordination between the muscles, ligaments, and nerves surrounding the joint [2].

Temporomandibular Joint Disorders (TMDs)

TMJ function can be affected by a variety of conditions known collectively as temporomandibular joint disorders (TMDs). These disorders include:

• Fractures: Fractures of the jawbones can occur due to direct injuries [2].
• Dislocation: When the ends of the joint bones move out of their normal position [2].
• Articular disc problems: The disc may slip out of place or wear down, causing pain and difficulty with movement.
• Arthritis: Arthritis can affect the TMJ, leading to pain and stiffness.
• Muscular problems: Tightness or spasms of the muscles surrounding the jaw can cause pain and limit jaw movement.

Some rare genetic conditions, such as Auriculocondylar syndrome, can lead to deformities of the lower jaw, including underdevelopment of the upper part of the jaw (the condyle), which affects TMJ function and makes opening and closing the mouth difficult [1].

Symptoms of Temporomandibular Joint Disorders

Symptoms vary based on the type and severity of the disorder, but may include:

• Pain in the jaw, face, ear, or neck.
• Difficulty or pain when chewing or speaking.
• A clicking or popping sound when moving the jaw.
• Difficulty opening the mouth wide.
• A feeling that the jaw is "stuck" or "locked."
• Swelling on one side of the face.

Diagnosis and Treatment

Diagnosis of TMDs is often based on a clinical examination, the patient's medical history, and may require imaging tests such as panoramic X-rays or magnetic resonance imaging (MRI) [2]. Treatment depends on the specific cause of the problem. Treatment options can range from conservative measures like rest, compresses, pain relievers, and jaw exercises, to more invasive treatments like oral splints or surgery in some complex cases [2]. For more information on jaw injuries and disorders, you can visit Jaw injuries and disorders: causes, symptoms, and treatment options (Arabic).

When should you seek medical help?

If you suffer from persistent jaw pain, difficulty opening or closing your mouth, or any other symptoms that affect your ability to eat or speak, it is important to consult a dentist or an oral and maxillofacial surgeon. In cases of severe injuries that may lead to a jaw fracture or dislocation, immediate medical care must be sought [2].

Medical references

• Jaw Injuries and Disorders
• Auriculocondylar syndrome