Posterior division of mandibular nerve

The posterior division of mandibular nerve (V3) arises from the main trunk of V3, inside the infratemporal fossa, just inferior to the foramen ovale. It is predominantly sensory and gives off three main branches in the infratemporal fossa. These include the auriculotemporal, inferior alveolar and lingual nerves.

1.       The auriculotemporal nerve originates as two roots from the posterior division of mandibular nerve which encircle the middle meningeal artery. The nerve runs posteriorly on the lateral surface of tensor tympani and levator veli palatini muscles and sphenomandibular ligament. Next, it takes a turn around the neck of mandible to ascend between the temporomandibular joint and external acoustic meatus, deep to the parotid gland.

The auriculotemporal nerve contains general somatic sensory neurons which transmit sensory information from areas including the parotid gland’s fascia and overlying skin, temporomandibular joint, external ear, external acoustic meatus, tympanic membrane and the skin over the temple region. In addition, the nerve contains postganglionic parasympathetic neurons from the glossopharyngeal nerve that provide secretomotor innervation to the parotid gland.

2.       The Inferior alveolar nerve also arises from the posterior division of mandibular nerve and descends on the medial aspect of ramus of mandible. It passes through the mandibular foramen to run inside the mandibular canal within the ramus and body of mandible, where it innervates the teeth in the lower jaw bone. The nerve splits into two terminal branches, the mental and incisive nerves. The mental nerve exits the mental foramen to provide sensory innervation to the skin over the mental region (lower lip and chin), whereas the incisive nerve continues to travel anteriorly inside the mandibular canal and provides sensory innervation to the first premolar, canine and incisor teeth, along with the associated gingival mucosa.

A motor nerve to mylohyoid is given off from the inferior alveolar nerve, prior to it entering the mandibular foramen and canal. This nerve innervates both mylohyoid muscle and the anterior belly of digastric.

3.       Lastly, a lingual nerve arises from the posterior division of mandibular nerve and runs anterior to the inferior alveolar nerve, medial to the ramus of mandible. It slips underneath the inferior border of superior constrictor muscle of pharynx, close to the pterygomandibular raphe, en route to the oral cavity. Here, the lingual nerve can be found underneath the oral mucosa immediately below the lower third molar. This relation is important to be aware of when extracting a wisdom tooth.

The nerve runs further anteriorly on the lateral surface of hyoglossus muscle where it gets connected with the submandibular ganglion. It ends up medially underneath the tongue mucosa as the sublingual nerve.

The lingual nerve contains general somatic afferent and special visceral afferent neurons which transmit general and taste sensations, respectively, from the anterior two-thirds of tongue and associated oral mucosa and gums. The general sensations are conveyed to the trigeminal nucleus whereas the taste sensations are relayed to a facial nucleus (i.e. the superior salivatory nucleus) in the brainstem. The lingual nerve also contains preganglionic parasympathetic efferent neurons from the chorda tympani branch of facial nerve, that are secretomotor to the submandibular and sublingual glands.