Mandibular canal

Where is the canal located and what is its structure?

The mandibular canal begins in the ramus (ramus mandibulae) and runs through the body (corpus mandibulae) of the mandible.

• Start: On the medial (internal) surface of the mandibular ramus, below the mandibular notch, lies the mandibular foramen (foramen mandibulae). Inferiorly, it is bounded by a bony prominence — the lingula of mandible (lingula mandibulae). The canal begins from this foramen.
• Course: The canal runs within the body of the mandible.
• Termination: On the lateral (outer) surface of the mandibular body opens the mental foramen (foramen mentale), which marks the termination of the mandibular canal (canalis mandibulae).

Anteriorly and inferiorly to the lingula of the mandible, along the inner surface of the bone, runs the mylohyoid groove (sulcus mylohyoideus).

What passes through the mandibular canal?

The canal contains a neurovascular bundle, which includes:

• Inferior alveolar nerve (n. alveolaris inferior) — the largest mixed branch of the mandibular nerve. In most cases (about 80%), it runs through the canal as a single trunk. In approximately 20% of cases, the nerve forms a dental plexus in the proximal portion of the canal. Branches to the teeth, gingiva, and bone arise from the trunk or plexus.
• Inferior alveolar artery and vein — vessels accompanying the nerve in the mandibular canal.

Nerve branches associated with the canal

• Mylohyoid nerve (n. mylohyoideus) — a motor branch that arises from the inferior alveolar nerve before its entry into the mandibular canal. It innervates the mylohyoid muscle and the anterior belly of the digastric muscle.
• Mental nerve (n. mentalis) — a major branch and the extracanalicular continuation of the inferior alveolar nerve after exiting the mental foramen. It emerges through the mental foramen and innervates the skin and mucous membrane of the lower lip, as well as the skin of the chin.
• Incisive branch (ramus incisivus nervi alveolaris inferioris) — the segment of the nerve within the bone in the canine and incisor region after the departure of the mental nerve.

Clinical significance in dentistry and surgery

• Conduction anesthesia: When performing an inferior alveolar nerve block, the needle is advanced 2 cm to the bony sulcus — the location of the nerve prior to its entry into the mandibular canal.
• Mental nerve block: To anesthetize the premolars, canine, and incisors, the needle must be inserted into the canal through the mental foramen to a depth of 3–5 mm. The landmark is the sensation of a "drop" or "yielding". If the needle is not introduced into the canal, anesthesia is limited to the soft tissues of the chin and lower lip.
• Periodontal anesthesia: Due to high injection pressure, the solution penetrates into intraosseous arteries and pulpal vessels both anterograde and retrograde. This causes near-complete ischemia of the pulp and periodontal tissues.

Class and exam questions

What else to study on this topic

• Inferior alveolar nerve (n. alveolaris inferior)
• Mandibular foramen (foramen mandibulae)
• Mental foramen (foramen mentale)
• Mandibular anesthesia

Other topics in the "Anatomical Structures" section

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