Mental foramen

Where is the mental foramen located?

The foramen is located beneath the mucosa on the lateral surface of the body of the mandible (corpus mandibulae), approximately midway between the alveolar and inferior borders of the mandible. The canal opening faces posteriorly, superiorly, and laterally.

The shape of the foramen can be oval or round, with dimensions ranging from 1.5×2 mm to 3×7 mm. The distance from the inferior border of the mandible is 3 to 21 mm. In some cases, there are two foramina on each side.

The topography relative to the tooth roots is variable:

• Below the second premolar — the most common location (54.5% on the right and 42.3% on the left).
• Between the first and second premolars — occurs in 22.5–30.3% of cases.
• Below the first premolar — observed in 11.1–15.9% of cases.
• Posterior to the second premolar or in the canine region — alternative localization variants.

Additionally, the foramen lies on the same vertical facial line as the pupil (when the patient is gazing straight ahead), the angle of the mouth, and the notches on the superior and inferior orbital margins.

What passes through the mental foramen?

The foramen serves as the exit point from the mandibular canal (canalis mandibulae) for the mental neurovascular bundle of the same name (a., v. et n. mentales):

• Mental nerve (n. mentalis) — a large terminal branch of the inferior alveolar nerve. It provides sensory innervation to the skin and mucosa of the lower lip, as well as the skin of the chin.
• Mental artery (a. mentalis) — a branch of the inferior alveolar artery. It supplies blood to the tissues of the chin and lower lip. On the face, it anastomoses with the inferior labial (a. labialis inferior) and submental (a. submentalis) arteries.

Clinical significance in dentistry and surgery

• Administration of anesthesia: The foramen serves as the anatomical landmark for mental nerve block. Both extraoral and intraoral methods are used. To achieve adequate anesthesia of the premolars, canine, incisors, and alveolar process, the needle must be inserted directly into the canal to a depth of 3–5 mm, during which the clinician feels a characteristic "give" or drop. If the needle is not inserted into the canal, only the soft tissues of the lip and chin are anesthetized.
• Surgical interventions: When opening subperiosteal abscesses in the premolar region, the incision should be arcuate with the apex directed superiorly and closer to the gingival margin, and the periosteum must be reflected with utmost care to avoid damaging the exiting neurovascular bundle.
• Neurology: Congenital or acquired narrowing of the mental foramen can be a contributing factor to peripheral trigeminal neuralgia.

Class and exam questions

What else to study on this topic

• Mandibular canal (Canalis mandibulae)
• Mandibular nerve (N. mandibularis)
• Inferior alveolar artery (A. alveolaris inferior)
• Mental nerve block (technique)

Other topics in the "Anatomical Structures" section

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.