Anterior division of mandibular nerve

At a glance

English

Anterior division of mandibular nerve

Latin (TA2)

Divisio anterior nervi mandibularis

System

Nerve

Region

Head

Side

Paired, left and right

About the anterior division of mandibular nerve

The mandibular nerve, the third and largest division of the trigeminal nerve, leaves the skull through the foramen ovale and almost at once ends by splitting into two trunks in the infratemporal fossa. The anterior division is the smaller of these. It lies deep to the lateral pterygoid muscle, with tensor veli palatini on the inner side of the parent trunk and lateral pterygoid on the outer side, close to the otic ganglion.

Before the split, the undivided trunk gives two branches from its medial side: the meningeal branch (nervus spinosus), which returns into the skull through the foramen spinosum, and the medial pterygoid nerve. The nerve to medial pterygoid also sends fibres, passing through or beside the otic ganglion, to tensor veli palatini and tensor tympani. These three motor branches therefore belong to the main trunk rather than to either division, although they are sometimes listed with the anterior one.

The anterior division is almost entirely motor. Its masseteric nerve passes outwards above lateral pterygoid and through the mandibular notch to enter the deep surface of masseter, giving a twig to the temporomandibular joint. Two deep temporal nerves, anterior and posterior, climb between the skull and lateral pterygoid to enter the deep surface of temporalis. The lateral pterygoid nerve enters that muscle directly, often sharing a stem with the buccal nerve. The buccal nerve is the division's one sensory branch: it slips between the two heads of lateral pterygoid and runs forward to supply the skin and lining of the cheek and the buccal gum of the lower molars.

Taken together, the division powers three of the four muscles of mastication: masseter, temporalis and lateral pterygoid, while the fourth, medial pterygoid, is served from the main trunk. Injury to it, rare in isolation, weakens biting and side-to-side grinding on the affected side, and the jaw deviates towards the weak side when the mouth opens.

Course and supply

Arises from

The mandibular nerve (V3) just below the foramen ovale, as the smaller of its two terminal trunks, deep to lateral pterygoid.

Ends in

Ends as the masseteric nerve, anterior and posterior deep temporal nerves, a branch for lateral pterygoid and the buccal nerve.

Supplies

Motor to masseter, temporalis and lateral pterygoid; sensory, through the buccal nerve, to the skin and mucosa of the cheek and the buccal gum of the lower molars.