Jaw

It is a unique bone that contains the lower dental arch. It consists of a horizontal portion, the body, and two perpendicular portions, the branches, which join the body at an almost right angle.

Body

Outer Face

Mentonian protuberance – triangular eminence
Mentonian Symphysis (Anthropometric Point) – smooth crest on midline
Mental foramen – depression on either side of the symphysis. Passage of vessels and mental nerve
External Oblique Line

Inner face

Mentonian Spine – pair of spines near the symphysis
Digastric fossa – just below the mental spines
Sublingual fossa – above the mylohyoid line
Submandibular fossa – below the mylohyoid line
Mylohyoid Line (Internal Oblique) – beside the symphysis and running backwards

edges

Superior or Alveolar – receives the sixteen teeth of the lower dental arch
Bottom

branches

They have two faces, four edges and two processes:

Lateral surface – presents oblique ridges for insertion of the masseter muscle
Medial Face – has the following structures:
Mandibular foramen - passage of inferior alveolar vessels and nerve
Mylohyoid sulcus
Mandibular lingula – prominent ridge above the mylohyoid groove

Lower Edge – meets the angle of the mandible

Posterior Border – is covered by the parotid gland

Anterior Edge – continues with the oblique line

Superior Border – has two very important processes: Coronoid Process and Condylar Process (articulates with the articular disc of the temporomandibular joint – TMJ). Between these two processes we find the mandibular notch.

The Mandible articulates with two bones: Temporal (2).

JAW - BACK VIEW