The human skull has many components. In fact, in an average adult human, the skull combines 22 bones. One of these bones is the mandible, more commonly known as the lower jaw.
What Is the Mandible?
Recognized as one of the most prominent bones in the human skull, the mandible is responsible for holding the bottom row of teeth in place and providing the lower face and chin with their shape. The mandible’s primary function is to move the mouth, allowing it to open and close when needed, such as when a person needs to chew food. The mandible is the only bone in the skull that can move and is also the strongest bone in the human face.
Where Is the Mandible Located?
The mandible is located in the lower jaw, directly below the maxilla (upper jaw). The mandible is formed during the developmental stages of pregnancy, when a structure known as the pharyngeal arch develops the coronoid and the condyloid. These eventually join to create the mandible.
The mandible consists of three parts. The first part is the body, a curved and horizontal structure. The second and third parts are the rami, which are vertical structures that join the ends of the body at the angle of the jaw.
The mandible portion known as the body is a horseshoe-like curved fixture consisting of two borders. The borders are called the alveolar border and the base. The alveolar border is on top and contains 16 sockets holding lower teeth. The base is the lower border and is the site where the digastric muscle attaches.
A slight edge of bone, known as the mandibular symphysis, marks the body in the midline.
The rami are located on either side, forming the mandible’s upward angle. Bony landmarks make up each ramus. These landmarks include:
- The head: The head works with the temporal bone to form the temporomandibular joint, or TMJ, and sits posteriorly on the rami.
- The neck: The neck is where the lateral pterygoid muscle connects. It also supports the ramus’ head.
- The coronoid process: The temporalis muscle is connected at the site of the coronoid process.
Aside from the body and the rami, there are also the foramen, which are openings where neurovascular structures can travel. The mandible has two foramina: the mandibular foramen and the mental foramen.
The ramus houses the mandibular foramen, which sits on the internal surface of the ramus. The inferior (lower) alveolar nerve and the inferior alveolar artery are channeled across this foramen, where they travel through the mandibular canal and then leave through the mental foramen.
The mental foramen is located on the external surface of the body of the mandible and directly underneath the second premolar tooth. This is where the alveolar nerve and artery depart from the mandibular canal, traveling through the mental foramen and forming into the mental nerve, which gives your lower lip the ability to feel.
Jaw Bone Problems
Many issues can affect the lower jawbone, including:
- Retrognathia: Retrognathia occurs when the lower jaw is pushed too far back. This can cause the chin to recede and become weak, leading to difficulty biting.
- Prognathia: Prognathia occurs when the jaw is pushed too far forward. This can lead to the protrusion of your chin and may result in the lower teeth overlapping the upper teeth.
- Open bite: An open bite occurs when the upper jaw is too long or the lower jaw is too short. A common cause of open bite is persistent thumb sucking. With an open bite, it becomes difficult and sometimes impossible to close your mouth.
- Asymmetry: Asymmetry happens when the jaw is uneven on one side. This can cause the face to look crooked.
- Other issues: Chewing issues occur when a jaw isn’t aligned correctly. As a result, it may be difficult to bite into food or to keep food in your mouth while chewing. Painful and stiff temporomandibular joint disorders (TMJs) are sometimes present. Additionally, certain sounds may be difficult to make, and you may have trouble speaking clearly. Breathing problems such as sleep apnea can also occur.
Temporomandibular Joint Disorders
Temporomandibular joint disorders (TMJs) are a common jaw issue. TMJs happen when your jaw’s muscles and ligaments become inflamed or irritated. This condition can range from mild to severe and may be short-term or chronic. Injury to the jaw or surrounding tissues can cause a TMJ. Other causes include teeth grinding, arthritis, stress, an improper bite, and acute trauma.
TMJ mainly affects people who are 20 to 40 years old. The most common symptoms include:
- Pain in the jaw
- Neck and shoulder pain
- Trouble opening the mouth wide
- A mouth that locks open or closed
- Sounds of clicking, popping, or grating when you are opening and closing the mouth
- Facial fatigue
- Trouble chewing
- Ringing in the ears
- Tooth pain
- Facial swelling
- Changes in how the teeth fit together
TMD is usually diagnosed during dental checkups. A thorough examination of your jaw and mouth will be performed. Your dentist will examine your mouth’s range of motion and assess your discomfort by pressing on your face and jaw. Your dentist may also order x-rays to be taken to determine how much damage has occurred.
Treatments for a TMJ vary depending on the severity. Some patients can find relief from simple self-care remedies, while others may require injections or surgery. Surgery is often saved as a last resort when other therapies fail.
Osteonecrosis can occur after you receive bone cancer treatment.
Symptoms of osteonecrosis include:
- Gum pain and swelling
- Gum infections
- Loose teeth
- Lack of healing in the gums after dental work
- Numbness in the jaw
- A heavy feeling in the jaw
It’s essential to undergo routine dental checkups to ensure that your jaw is healthy. Discuss any issues with your jaw, teeth, or mouth with your doctor or dentist.