Mandibular Nerve

Origin

The mandibular nerve originates at the trigeminal ganglion as the inferior most of the three branches of the trigeminal nerve. It projects inferiorly through the foramen ovale.

The sensory neurons that make up the mandibular nerve are found in the trigeminal ganglion. Those conveying general sensory information project to the main sensory nucleus of trigeminal nerve and the spinal nucleus of trigeminal nerve, both in the pons. Proprioception fibers from the muscles of mastication project to the mesencephalic nucleus.

Motor neurons reach the mandibular nerve just distal to the trigeminal ganglion via the motor root of the trigeminal nerve. These fibers originate in the motor nucleus of the trigeminal nerve.

Course

The mandibular nerve runs from its origin at the base of the trigeminal ganglion inferiorly through the foramen ovale. It emerges in the superior roof of the infratemporal fossa. It quickly splits into anterior and posterior divisions, and these divisions in turn soon divide into multiple nerves (Norton, 2016).

Branches

The first branch of the mandibular nerve is the meningeal branch, which occurs just inferior to the foramen ovale. This ascends into the skull via the foramen spinosum and follows the middle meningeal artery to supply cranial dura mater. The nerve to medial pterygoid muscle also splits off the mandibular nerve very close to the foramen ovale. It sends a branch to the medial pterygoid muscle and another branch to innervate both the tensor veli palatini and the tensor tympani muscles.

Shortly after these two branches, the mandibular nerve divides into anterior and posterior divisions. The anterior division primarily gives rise to motor nerves, while the posterior division primarily gives rise to sensory nerves.

The branches of the anterior division are:

—deep temporal nerves;

—nerve to lateral pterygoid muscle;

—masseteric nerve;

—buccal nerve.

The branches of the posterior division are:

—auriculotemporal nerve;

—lingual nerve;

—inferior alveolar nerve.

Supplied Structures

The mandibular nerve conveys general sensory information from portions of the skin and mucosal linings of the lower face, oral cavity, and ear as well as the mandibular teeth. It transmits branchial motor fibers to muscles of mastication and several other muscles of the head and upper neck. Finally, although the mandibular nerve does not contain any parasympathetic fibers, several of its branches help guide the parasympathetic fibers of other cranial nerves to their targets. The targets of each branch of the mandibular nerve are listed below.

—The meningeal branch of the mandibular nerve conveys general sense fibers from cranial dura mater, typically in the posterior half of the middle cranial fossa.

—The nerve to medial pterygoid muscle innervates the medial pterygoid, the tensor veli palatini, and the tensor tympani muscles.

—The deep temporal nerves innervate the temporalis muscle.

—The nerve to lateral pterygoid innervates the two heads of the lateral pterygoid.

—The masseteric nerve innervates the two heads of the masseter muscle. A small branch of the masseteric nerve also conveys sensory innervation from the anterior temporomandibular joint.

—The buccal nerve, also known as the long buccal nerve, conveys general sensory information from the skin overlying the buccinator muscle and the oral mucosa from the surface deep to the buccinator down to the buccal gingiva of the mandibular teeth.

—The auriculotemporal nerve conveys general sense fibers from the skin of the posterior temple, anterior ear, and external acoustic meatus, and the posterior temporomandibular joint capsule. Parasympathetic fibers from the glossopharyngeal nerve travel with the auriculotemporal nerve on their way to the parotid gland.

—The lingual nerve conveys general sense fibers from the anterior two thirds of the tongue and much of the oral floor mucosa. It is also the nerve that parasympathetic and special sense taste fibers from the chorda tympani travel with to reach the oral cavity.

—The inferior alveolar nerve conveys general sense fibers from the skin of the chin and lower lip, and all the teeth of the mandible. It also briefly carries the motor fibers of the nerve to mylohyoid, which innervates the mylohyoid and anterior digastric muscles.

References

Norton, N. S. (2016) Netter's Head and Neck Anatomy for Dentistry E-BookElsevier Health Sciences.