What Are the Different Shapes of the Lower Human Bones in the Jaw?

A human's lower jaw is also called the mandible. According to Theodora, it is both the largest and strongest set of bones in the skull; the mandible consists of three portions: one called "the body" and two called "rami".

The Body

• The Body portion of the mandible is the curved, horizontal portion that forms the jawline and holds a human's bottom row of teeth. Its curvature resembles a horseshoe, which gives it two surfaces and two borders.

  The external surface is a ridge, the internal surface is concave. The two borders are named superior and inferior: the superior is wide and hollow, the inferior is round, longer and stronger.

The Perpendicular Rami

• The two Perpendicular Rami are quadrilateral shaped, with two surfaces, the lateral and the medial, and four borders: lower, upper, anterior and posterior.

  The surfaces range in shape from flat to notched, slanted and grooved. The lower border is thick and straight and the upper is thin; the anterior is thin on top and thick below, the posterior is thick, rounded and smooth.

Lesser Bones and Bone Growth

• The mandible articulates with two temporal bones that are oblong and shrouded with nerves. As the human body grows, so do the bones of the mandible.

  The two sides of the mandible, each ramus, are not joined together until birth. After birth, the body elongates to its full length, and as the child grows, the bone adjusts to allow teeth to grow.