The only bone of the skull that can move, hinging at the joint in front of each ear
Mandible — it articulates with the temporal bone at the temporomandibular joint.
Anatomy · Bones
Mandible
Largest and strongest bone of the face
Skull · facial bones
The mandible is the lower jaw, the largest and strongest bone of the face and the only movable bone of the skull. A horseshoe-shaped body carries the lower teeth, and a vertical ramus on each side rises to meet the temporal bone at the jaw joint. The two halves are separate at birth and fuse during the first year of life.
How to spot them
- ▸A single U- or horseshoe-shaped bone forming the lower jaw, with a projecting chin
- ▸A horizontal body carrying the lower teeth, and on each side a vertical ramus meeting it at the angle of the jaw
- ▸Each ramus ends in two processes: a flat coronoid process in front and a condylar process behind that forms the joint
- ▸A hole, the mental foramen, on each side of the body below the second premolar
What to know
The largest and strongest bone of the face, forming the lower jaw and holding 16 tooth sockets
Mandible — 16 alveoli in its alveolar border.
At birth it is two halves; they fuse at the midline symphysis in the first year, leaving the chin
Mandible — the mental protuberance forms the chin.
A foramen below the second premolar transmits the nerve that supplies the skin of the lower lip and chin
Mandible — the mental foramen, carrying the mental branch of the inferior alveolar nerve.
A flattened process on the ramus provides attachment for the temporalis muscle, while the process behind it carries the joint surface
Mandible — coronoid process and condylar process.
A fracture of one side of this bone is usually accompanied by a second on the opposite side, like a ring
Mandible — fractures rarely occur in isolation.
The inferior alveolar nerve and artery enter its inner surface through a foramen on the ramus and travel in a canal to the chin
Mandible — the mandibular foramen and mandibular canal.
Key ideas
- Muscles of mastication act on it: temporalis on the coronoid process, masseter on the ramus, medial pterygoid near the angle and lateral pterygoid at the neck of the condyle.
Quick-fire facts
- •The only movable bone of the skull; the other 21 are immobile
- •The two halves fuse in the first year of life
- •The alveolar border contains 16 sockets for the lower teeth
- •The mental foramen lies below the second premolar tooth on each side
- •Fractures of the neck of the condyle are often transverse and accompany dislocation of the jaw joint
- •Fractures of the body often pass through the canine tooth; fractures at the angle may involve the socket of the third molar
- •Mylohyoid line: a ridge on the inner surface where the floor-of-mouth muscle attaches
- •Lingula: a small flap of bone by the mandibular foramen anchoring the sphenomandibular ligament
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Sources
- TeachMeAnatomy — The Mandible
- OpenStax — Anatomy and Physiology 2e, 7.2 The Skull