The Mandible: Anatomy, Structure, Function | Kenhub

Anatomy

The mandible is a horseshoe shaped bone of the viscerocranium. It consists of the body and two rami, connected at the angle of mandible.

Body

The body of mandible is its horizontal portion. It consists of two parts: 

• The alveolar part
• The base of mandible

The alveolar part is the upper portion of the body. It consists of two bony lamellae: a thick buccal lamella, and a thin lingual lamella. They are parallel to each other, forming a shallow trench on the upper surface of the alveolar part. The lamellae are connected by interalveolar septa, which cut the trench into sockets which house the mandibular teeth. 

Mental protuberance of mandible Protuberantia mentalis mandibulae 1/5 Synonyms: none

The base is the inferior part of the body that features several anatomical landmarks. On its external surface, we can identify:

• The mandibular symphysis: Fibrous tissue in the midline of the mandibular body, which ossifies by the first year of life. It unites the left and right halves of the mandible in order to form a single, symmetrical bone. 
• The mental protuberance: A bony prominence at the midline of the body.
• The mental tubercle: A paired bony prominence on each side of the mental protuberance.
• The oblique line: A crest extending from the ramus to the body of mandible. It provides the insertion point for the depressor anguli oris muscle.

The mental foramen: An opening located inferior to the second mandibular premolar tooth which provides the passage for the mental nerve and vessels.

Try out our free labeling diagrams about the bones of the skull to enhance your learning

The internal surface of the base of mandible features the following landmarks:

• The digastric fossa: A paired depression on the lower margin of the mandibular body, located on each side of the midline.
• The superior and inferior mental spines: Paired bony eminences on the midline of the internal surface of the body. They provide the attaching point for the genioglossus and geniohyoid muscles.
• The submandibular fossa: A paired depression on each side of the mental spines which houses the submandibular gland.
• The sublingual fossa: A depression located superior to the mental spines which hosts the sublingual gland.
• The mylohyoid line: A paired oblique crest on the sides of the body to which the mylohyoid muscle attaches.

Ramus

Ramus of mandible Ramus mandibulae 1/5 Synonyms: none

The ramus is the vertical part of the mandible. The point at which it unites with the body is called the angle of mandible (i.e. gonial angle). The angle can range from 110° to 130° and can vary depending on the age, sex and etnicity. Usually, the angulation is larger in men.

The superior part of the ramus consists of two processes: the coronoid process (anterior process) and the condylar process (posterior process). The incisure between them is called the mandibular notch and it is crossed by the masseteric nerve and vessels. 

The coronoid process features the temporal crest, which serves as an attachment point for the temporalis muscle. The condylar process has an articular surface (the condyle), via which the mandible articulates with the articular tubercle of the temporal bone to form the temporomandibular joint. 

On the posterolateral aspect of the ramus there is a single landmark called the masseteric tuberosity, a rough surface that serves for the insertion of the masseter muscle. 

The medial surface of the rami harbours the following landmarks:

• The pterygoid tuberosity: A rough area for the insertion of the medial pterygoid muscle.
• The inferior alveolar (a.k.a. mandibular) foramen: The starting point of the mandibular canal which is traversed by the inferior alveolar nerve and its branches.
• The mylohyoid sulcus: A small sulcus which contains the mylohyoid artery and nerve.