Our jaws are made up of two separate parts: upper jaw (or maxilla), and lower jaw (or mandible). The upper jaw is fused to the skull and does not move. However, we can move our lower jaw, and that allowsfor chewing and talking. The movements of the lower jaw are made possible because of four different muscles. Together, these four muscles constitute the muscles of mastication (or the muscles for chewing). These four muscles are:
- Masseter: These are also known as cheek muscles. They are located on either side of the face.
- Temporalis: Temporalis muscles cover the temples on both sides of the head.
- Medial pterygoid: Medial pterygoid muscles lie deep in the cheek region. They are also known as internal pterygoid muscles.
- Lateral pterygoid: These muscles lie above the internal pterygoid muscles. They are also known as external pterygoid muscles.
These four muscles of mastication help in the following types of jaw movements:
- Closing the mouth: Elevating the lower jaw to meet the upper jaw results in closure of the mouth.
- Backward movement of the jaw: Backwards movement of the lower jaw back is made possible by the concerted actions of these muscles.
- Forward movement of the jaw: Protrusion of the lower jaw.
The combined action of these three movements makes activities such as talking and chewing possible.
Other Signs and Symptoms
Sometimes, the muscles that move the lower jaw become stiff and sore. The stiffness may be mild, in which case it does not affect the routine functions of the mouth. However, the stiffness can become worse. In such cases, the lower jaw is unable to move properly and routine actions such as talking and chewing become very difficult. A stiff jaw also puts a lot of stress on the temporomandibular joint, which might become painfully uncomfortable. Headaches (especially temporal headaches) and clicking jaw might also result from tight jaw muscles.
Causes of Tight Jaw Muscles
Muscular injury in the jaw region can happen in accidents, violent blow to the face, or surgery. Such injuries (either superficial or deep) result in inflammation of the jaw muscles. This leads to stiffness or soreness of the jaw.
Like any other muscle, the jaw muscles tend to become sore after overuse. Chewing hard foods, chewing gum or tobacco for long periods, and talking or laughing excessively can lead to sore jaw muscles. This is perhaps one of the most common causes of tight jaw muscles.
Bruxism refers to a condition in which a person grinds his or her teeth forcefully. This is usually an unconscious act, and can happen when the person is awake or asleep. The person grinding the teeth during sleep is unaware of the act, although the person sleeping next to them can clearly hear the loud grinding noises. Bruxism has been linked to various causes: psychological stress, jaw malocclusion, Parkinson’s disease, reflux of stomach acid, dental pain and certain medications.
Tetanus is an important cause of severely tight jaw muscles. Tetanus is caused by infection with a bacteria called Clostridium tetani. The toxin released by this bacteria causes painful and strong spasms of the muscles in the neck and the jaw. The disease becomes life-threatening once the toxin affects the breathing muscles.
Tetanus is also known as lockjaw, a name inspired by the painfully stiff jaw muscles that prevent the opening of the mouth in affected individuals. Immunization for tetanus exists, and it has been instrumental in reducing the incidence of this disease, especially in developed countries.
In addition to the above mentioned causes, there are other conditions that affect the movement of the lower jaw without primarily affecting the jaw muscles.
- Fracture: A fracture of jaw or cheek bones results in a stiff jaw.
- Infection: Infections of the jaw, gums, and teeth can cause difficulty in moving the jaws.
- Mumps: Mumps is a viral infection that causes painful swelling of the parotid glands. This causes difficulty in jaw movements.
- Trigeminal neuralgia: Trigeminal nerve carries sensations from the face to the brain. Trigeminal neuralgia causes sudden attacks of severe pain, which commonly involves the maxillary and mandibular nerves. The pain attacks tend to occur in cycles with long remission periods in between. There is no cure for this condition, but the symptoms can be managed.
- Ill-fitting dentures: Improperly fitting dentures may also result in stiff jaw muscles and difficult jaw movements.
Treatment for Tight Jaw Muscles
For mild stiffness or soreness in the jaw muscles, following remedies can be considered:
- Rest: Resting the jaw by temporarily ceasing activities such as chewing, talking and laughing can help in relieving the stiffness of the jaw muscles. This may be sufficient to overcome a stiff jaw.
- Application of ice: In case of jaw stiffness due to an injury such as a blow to the face, application of ice packs to the affected areas would help in combating inflammation and relieving soreness of the jaw. Application of ice packs should not exceed 20 minutes at a stretch.
- Application of heat: In case of tight jaw muscles not associated with any apparent injury, heat therapy may help.
- Gentle massage: Light massage of the jaw muscles may help in relieving the stiffness in the jaw.
- Mental relaxation: If tight jaw muscles are accompanied by mental stress, mental relaxation activities might help.
In case of severe jaw muscle stiffness, the exact treatment would depend on the underlying cause. Some of the treatment options are as follows:
- Painkillers: Painful spasms of jaw muscles warrant the use of painkillers to relieve the pain.
- Muscle relaxants: Muscle relaxant medications may be considered to relax the jaw muscles.
- Botox injections: Injections of botulinum toxin (botox) may help in relieving severe muscle spasms.
- Mouth guards: In case of teeth grinding and clenching, use of mouth guards may be suggested.
- Tetanus treatment: Lockjaw needs to be promptly treated since the condition can turn fatal.
- Sedatives: If the patient is not able to relax voluntarily, sedatives may help.
- Surgery: In some severe cases, surgery may be considered.