The mandible, also known as the lower jaw, is a vital bone in the anatomy of the human body. It is the largest and strongest bone in the face, and it plays a key role in the functioning of the mouth and facial muscles.
Structure
The mandible is a U-shaped bone that is located in the lower part of the face, below the maxilla (upper jaw). It is made up of two symmetrical halves, called ramus, which are connected by a hinge joint known as the mandibular joint or temporomandibular joint (TMJ). The mandible also has two condyles, which are rounded projections located at the end of each ramus. These condyles allow the mandible to move up and down and side to side as we chew, speak, and swallow.
It is composed of a thick outer layer of cortical bone, which is the dense, hard outer layer of bone that is responsible for its strength and durability. Beneath the cortical bone is a spongy layer of trabecular bone, which is lighter and more porous than cortical bone. The trabecular bone is important for supporting the blood vessels and nerves that run through the mandible.
The mandible also has several features that are important for its function, including the following:
Mental foramen
This is a small hole located on the outer surface of the mandible, just below the second premolar tooth. It allows the mental nerve and vessels to pass through the bone and supply the lower lip and chin.
Mandibular canal
This is a long, narrow tunnel that runs through the interior of the mandible, from the mental foramen to the condyles. It contains the inferior alveolar nerve, which supplies sensation to the lower teeth, and the inferior alveolar artery, which supplies blood to the lower teeth and surrounding tissues.
Mandibular angle
This is the point where the body of the mandible meets the ramus. It is an important landmark in anatomy and is used to identify the location of the mandible on X-rays and other images.
Mandibular notch
This is a shallow groove located at the junction of the body and ramus of the mandible. It serves as an attachment site for the masseter muscle, which is responsible for closing the jaw.
Location
The mandible is located in the lower part of the face, below the maxilla and in front of the neck. It is connected to the skull by the temporomandibular joint (TMJ), which allows it to move up and down and side to side. The mandible is also connected to the hyoid bone by the stylohyoid ligament, which helps to stabilize the mandible and prevent it from dislocating during movement.
Function
The mandible plays a key role in the functioning of the mouth and facial muscles. It is responsible for the following functions:
Mastication
The mandible is the main bone involved in chewing and grinding food. As we chew, the mandible moves up and down and side to side, using the teeth to grind and crush the food. This process is called mastication.
Speech
The mandible plays a key role in speech production, as it helps to form the shapes and sounds of words. As we speak, the mandible moves up and down and side to side, allowing us to create different sounds and shapes with our mouth.
Swallowing
The mandible helps to control the movement of food and liquids through the mouth and into the esophagus during swallowing. As we swallow, the mandible moves down and forward, closing the mouth and pushing the food towards the back of the throat.
Facial expression
The mandible is also involved in facial expression, as it helps to move the lower lip and chin. When we smile, frown, or make other facial expressions, the muscles of the mandible contract and relax, pulling on the skin and muscles of the face.
