The mandible is the only movable cranial bone. It is a single bone connected to the skull at the temporomandibular joint on each side. The same as the maxilla, it is also a part of the viscerocranium. It forms the lower jaw.

The mandible has three parts:

Body of the mandible
Ramus of the mandible (paired)

Body of the mandible

The body of the mandible is located in the anterior part of the lower jawbone.

It has a curved shape and can be subdivided into two smaller parts:

The body of the mandible has two surfaces (external and internal) and two borders (superior or alveolar and inferior).

Base of the mandible

The base is the lowest, thickened part of the body of the mandible, excluding the alveolar part of the mandible, and it has an external and an internal surface.

The features on the external surface of the mandibular base are:

Mental protuberance - a prominence on the outer surface of the mandible forming the chin;
Mental tubercle (2) - a prominence on either side of the mental protuberance;
Mental foramen (2) - an opening in the mandible located below the second premolar; it is the passage for the mental nerve (a branch of the inferior alveolar nerve, which arises from the mandibular nerve (CN V3)), as well as a pressure point for the mandibular nerve - mandibular branch of the trigeminal nerve (CN V); besides nerves, through the canal also goes the mental artery which is a branch of the inferior alveolar artery (from the maxillary artery).

The features found on the internal surface of the mandibular base are:

Mental spine - a bony elevation projecting toward the tongue; the origin site of the genioglossus and geniohyoid muscles;
Digastric fossa (2) - an oval depression on the lower part of the internal surface of the mandibular body on either side of the mental spine for attachment of the anterior belly of the digastric muscle;
Mylohyoid line (2) - an oblique ridge extending from the posterosuperior to anteroinferior aspect of the inner surface of the body of the mandible; the origin site of the mylohyoid muscle, its posterior part is the origin of the mylopharyngeal part of the superior constrictor muscle of the pharynx;
Sublingual fossa (2) - a depression on the sides of the mental spine above the medial end of the mylohyoid line; the sublingual gland lies in it;
Submandibular fossa (2) - a depression located on the sides of the body below the mylohyoid line; the submandibular gland lies in it.

Alveolar process of the mandible

The alveolar process of the mandible is the superior portion of the body of the mandible that surrounds and supports the lower teeth. An alveolar process is a crested process of upper or lower jaw that houses the teeth.

The curved free margin of the alveolar process is called the alveolar arch.

The alveolar arch of the mandible (as the alveolar arch formed by the maxillae) features the following structures:

Ramus of the mandible

The rami of the mandible are situated on the right and left side of the mandible. They go upwards from the body of the mandible.

Each ramus of the mandible features several landmarks:

Angle of the mandible - the angle forming between the body and ramus of the mandible;

The superior part of the ramus has two processes:

Condylar process - an articular process, which has three landmarks:
- Head of the mandible - the articular part of the ramus;
- Neck of the mandible - a narrow segment below the head of the mandible;
- Pterygoid fovea - an anteromedial pit below the head of the mandible, where the lateral pterygoid muscle attaches;
Coronoid process - a flattened process located anteriorly to the condylar process.

Both processes are separated by the mandibular notch; the temporal muscle inserts into the coronoid process.

The ramus of the mandible also has an internal and an external surface.

The internal surface of the ramus of the mandible features:

Mandibular foramen - an opening leading into the mandibular canal - a bony passage that transmits the inferior alveolar artery, vein and nerve;
Lingula - it is also known as the Spix spine; a triangular-shaped bony ridge extending superior from the mandibular foramen;
Mylohyoid groove - a groove on the internal surface of the mandible extending forward and downward from the mandibular foramen; it is the passage for the mylohyoid nerve (a branch of the inferior alveolar nerve) and the mylohyoid branch of the inferior alveolar artery (from the maxillary artery);
Pterygoid tuberosity - a roughened area occasionally present on the internal surface of the mandibular ramus near the angle of the mandible; it serves as the attachment site for the medial pterygoid muscle.

The external surface of the ramus presents the masseteric tuberosity - a roughened area occasionally present near the angle of the mandible. This tuberosity is the attachment site for the masseter muscle.

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Mandible