Human mandible


Human mandible
This article is about the human jawbone. For the other mandibles, see Mandible.
Bone: Mandible
Gray176.png
Mandible. Outer surface. Side view
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Mandible. Inner surface. Side view
Latin mandibula
Gray's subject #44 172
Precursor 1st branchial arch[1]
MeSH Mandible

The mandible [pronunciation] (from Latin mandibula, "jawbone") or inferior maxillary bone forms the lower jaw and holds the lower teeth in place. The term "mandible" also refers to both the upper and lower sections of the beaks of birds; in this case the "lower mandible" corresponds to the mandible of humans, while the "upper mandible" is functionally equivalent to the human maxilla but mainly consists of the premaxillary bones. Conversely, in bony fish for example, the lower jaw may be termed "lower maxilla".

Contents

Components

The mandible consists of:

  • a curved, horizontal portion, the body. (See body of mandible).
  • two perpendicular portions, the rami, which unite with the ends of the body nearly at right angles. (See ramus mandibulae)
  • Alveolar process, the tooth bearing area of the mandible (upper part of the body of the mandible)
  • Condyle, superior (upper) and posterior projection from the ramus, which makes the temporomandibular joint with the temporal bone
  • Coronoid process, superior and anterior projection from the ramus. This provides attachment to the temporalis muscle

Foramina (singular = foramen)

  • Mandibular foramen, paired, in the inner (medial) aspect of the mandible, superior to the mandibular angle in the middle of the ramus.
  • Mental foramen, paired, lateral to the mental protuberance on the body of mandible.

Nerves

A panoramic radiographic reveals the mandible, including the heads and necks of the mandibular condyles, the coronoid processes of the mandible, as well as the nasal antrum and the maxillary sinuses.

Inferior alveolar nerve, branch of the mandibular division of Trigeminal (V) nerve, enters the mandibular foramen and runs forward in the mandibular canal, supplying sensation to the teeth. At the mental foramen the nerve divides into two terminal branches: incisive and mental nerves. The incisive nerve runs forward in the mandible and supplies the anterior teeth. The mental nerve exits the mental foramen and supplies sensation to the lower lip.

Articulations

The mandible articulates with the two temporal bones at the temporomandibular joints.

Pathologies

One fifth of facial injuries involve mandibular fracture.[2] Mandibular fractures are often accompanied by a 'twin fracture' on the contralateral (opposite) side.

Etiology

Frequency by location
  • Motor vehicle accident (MVA) – 40%
  • Assault – 40%
  • Fall – 10%
  • Sport – 5%
  • Other – 5%

Location

  • Condyle – 30%
  • Angle – 25%
  • Body – 25%
  • Symphesis – 15%
  • Ramus – 3%
  • Coronoid process – 2%

The mandible may be dislocated anteriorly (to the front) and inferiorly (downwards) but very rarely posteriorly (backwards).

Additional images

See also

References

External links

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained within it may be outdated.


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