Mandible

Last revised by Dr Bahman Rasuli on 26 Feb 2021

The mandible is the single midline bone of the lower jaw. It consists of a curved, horizontal portion, the body, and two perpendicular portions, the rami, which unite with the ends of the body nearly at right angles (angle of the jaw). It articulates with both temporal bones at the mandibular fossa at the temporomandibular joints (TMJ). It bears the lower tooth bearing alveolar process.

Gross anatomy

Osteology
Body

The body of the mandible is curved, somewhat like a horseshoe, with two surfaces and two borders. The mandibular symphysis is located in the midline, a point of fusion. The parasymphysis extends from the midline to past the canine.

  • external surface
    • midline ridge indicating the symphysis
    • mental foramen: inferior to second premolar tooth (with normal variants between the canine and 1st molar), midway between the superior and inferior borders; allows for the passage of the mental vessels and mental nerve
  • internal surface
  • superior (or alveolar) border
    • wider behind than in front
    • hollowed for reception of teeth (normally 16)
    • attachment of buccinator muscle
  • inferior border
    • rounded, longer than the superior border and thicker in front than behind
    • groove for the facial artery may be present at the point it joins the ramus of the mandible
Ramus

The ramus is quadrilateral in shape, and has two surfaces, four borders, and two processes and one canal:

  • lower border
    • thick, straight and continuous with the inferior border of the body of the mandible
  • posterior border
    • thick, smooth, rounded and covered by the parotid gland
    • angle of the mandible is at its junction of the posterior border and the body
  • anterior border
    • thin above and thicker below; continuous with the oblique line
  • upper border
    • thin
    • consists of the coronoid process anteriorly and the condylar process posteriorly separated by the mandibular notch (a.k.a. sigmoid notch)

The mandibular canal runs obliquely downward and forward in the ramus, and then horizontally forward in the body, where it is placed under the alveoli and communicates with them by small openings. On arriving at the incisor teeth, it turns back to communicate with the mental foramen, giving off two small canals which run to the cavities containing the incisor teeth. It contains the inferior alveolar vessels and nerve, from which branches are distributed to the teeth via the incisive nerve

Coronoid process
  • thin, triangular eminence from the upper border of the ramus of the mandible
  • separated from the condylar process posteriorly by the mandibular notch
  • temporalis muscle inserts into its medial and lateral surfaces
  • masseter muscle also inserts into its lateral surface
Condylar process

Please refer to our article on condylar process of the mandible for a specific discussion.

Arterial supply

Anatomy: Head and neck

Anatomy: Head and neck

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Cases and figures

  • Figure 1: mandible - lateral view
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  • Figure 2: skull and facial bones
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  • Figure 3a: mandible at birth (Gray's illustrations)
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  • Figure 3a: mandible in childhood (Gray's illustrations)
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  • Figure 3c: mandible in adulthood (Gray's illustrations)
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  • Figure 3d: mandible in adulthood edentulous (Gray's illustrations)
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  • Figure 4a: mandible muscle attachments (Gray's illustration)
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  • Figure 4b: mandible muscle attachments (Gray's illustration)
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