Posterior division of mandibular nerve

At a glance

English

Posterior division of mandibular nerve

Latin (TA2)

Divisio posterior nervi mandibularis

System

Nerve

Region

Head

Side

Paired, left and right

About the posterior division of mandibular nerve

Soon after the mandibular nerve leaves the skull through the foramen ovale, it ends by splitting into two trunks below lateral pterygoid. The posterior division is the larger. Apart from a small motor contribution it is sensory, serving a wide strip of the lower face and side of the head: the skin in front of the ear and over the temple, the lower teeth and gums, the lower lip and chin, the front of the tongue and the floor of the mouth.

It lies deep to lateral pterygoid with tensor veli palatini to its inner side, near the otic ganglion and the middle meningeal artery. Before the split, the parent trunk gives off, from its inner side, the nervus spinosus and the medial pterygoid nerve, so these do not belong to either division. The posterior division then breaks up into three large nerves.

The auriculotemporal nerve usually starts as two roots that encircle the middle meningeal artery and then join. It passes back behind the neck of the mandible, gives twigs to the temporomandibular joint and the ear, and then turns up over the root of the zygoma with the superficial temporal vessels to the skin of the temple. It also carries secretory fibres from the otic ganglion to the parotid gland. The lingual nerve runs down in front of the inferior alveolar nerve, receives the chorda tympani, and curves into the floor of the mouth to supply the body of the tongue. The inferior alveolar nerve descends to the mandibular foramen, gives the mylohyoid nerve, the only motor branch of this division, to mylohyoid and the front belly of digastric, and then runs through the jaw to the lower teeth before ending as the mental and incisive nerves.

Most dental anaesthesia of the lower jaw targets this division. The inferior alveolar block reaches the inferior alveolar and lingual nerves together. The auriculotemporal nerve explains why parotid swelling or temporomandibular joint disease can cause pain in the ear and temple, and why, after parotid surgery, regrowing secretory fibres may enter sweat glands in the skin and cause sweating of the cheek while eating (Frey syndrome).

Course and supply

Arises from

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

Ends in

Ends by dividing into three nerves: the lingual, the inferior alveolar and the auriculotemporal.

Supplies

Sensory to the temple and front of the ear, the temporomandibular joint, the lower teeth and gums, the lower lip, chin, front of the tongue and floor of the mouth; motor, via the mylohyoid nerve, to mylohyoid and the anterior digastric belly; carries parasympathetic fibres to the parotid and, via the chorda tympani, to the submandibular and sublingual glands.