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Mandibular Molar

Description

The inferior alveolar nerve and artery pass through the mandible through a structure called the mandibular canal. The mandibular canal extends from the mandibular foramen, on the lingual aspect of the ramus, through the body of the mandible under the roots of the molar teeth. 

The mandibular canal appears radiographically as two roughly parallel radiopaque lines traversing the body of the mandible. The radiographic appearance of the mandibular canal is due to the fact that the X-ray beam passes through the denser cortices of the outer edges of the canal to produce radiopaque lines, while the center, without so much superimposition of bone, retains a radiolucent characteristic.

The internal oblique ridge (or mylohyoid line) is an eminence of bone extending along the lingual aspect of the mandible. It serves as the attachment point for the chief muscle of the mouth floor, the mylohyoid muscle. 

The external oblique ridge is a ridge of bone located along the facial aspect of the mandible, which extends from the superior aspect of the posterior body of the mandible down to the necks of the molar teeth. It runs in the same direction as the internal oblique ridge, but is located on the facial or external surface of the mandible. The external oblique ridge serves as the attachment point for the buccinator muscle.

To distinguish radiographically between the internal and external oblique ridges, note that the external ridge is always superior to the internal oblique ridge.

When vertical projection is used the submandibular gland fossa appears as a dark area with indistinct borders just below the shape of the internal oblique ridge.

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