Mandibular Nerve: Anatomy and Branches

• The mandibular nerve is a branch of the trigeminal ganglion.
• It lies in the dura mater of the middle cranial fossa, lateral to the cavernous sinus.
• It joins the motor root of the trigeminal nerve and enters the foramen ovale.
• After emerging from the foramen ovale, it lies deep to the upper head of the lateral pterygoid, on the tensor palati muscle.
• The otic ganglion is applied to the deep surface of the nerve at a point 4 cm deep to the articular tubercle through the mandibular notch.
• The mandibular nerve divides into a small anterior (mainly motor) and a large posterior (mainly sensory) branch.

Branches From The Main Trunk

• There is one sensory and one motor branch.
• The meningeal branch (nervus spinosus) re-enters the middle cranial fossa via the foramen spinosum or ovale.
• It supplies the meninges of the posterior half of the middle cranial fossa, the mastoid antrum, and air cells.
• It gives twigs to the cartilaginous part of the auditory tube before entering the skull.
• The nerve to the medial pterygoid runs forwards to the muscle and gives off the motor root to the otic ganglion.
• The motor root to the otic ganglion passes near or through the ganglion without synapsing.
• Its fibers supply the tensor palati and tensor tympani muscles.
• This motor root should not be confused with the secretomotor root of the ganglion, which is the lesser petrosal nerve.

Branches From The Anterior Division

• This division is mainly motor, except for the buccal nerve.
• Deep temporal branches to temporalis pass above the upper border of the lateral pterygoid muscle and are usually two in number (anterior and posterior).
• A third, middle branch may join them, emerging with the buccal nerve between the two heads of the lateral pterygoid.
• The masseteric nerve passes above the upper border of the lateral pterygoid and emerges through the mandibular notch to enter the deep surface of the masseter.
• It gives an articular branch to the temporomandibular joint.
• The nerve to the lateral pterygoid runs with the buccal nerve and supplies both heads of the muscle.
• The buccal nerve is wholly sensory and contains all the fibers of common sensation in the anterior division of the mandibular nerve.
• It emerges between the two heads of the lateral pterygoid and runs in a fascial tunnel on the deep surface of temporalis.
• It then runs on the buccinator, giving branches to the skin over the cheek and proprioceptive fibers to the buccinator.
• It supplies the mucous membrane of the cheek and the gum of the lower jaw opposite the lower molars and second premolar (up to the mental foramen).

Branches From The Posterior Division

• Except for motor fibers distributed via the mylohyoid nerve, this division is sensory.
• There are three branches.
• The auriculotemporal nerve is derived by two roots from the posterior division, embracing the middle meningeal artery.
• It passes backward between the neck of the mandible and the sphenomandibular ligament.
• The nerve lies above the maxillary vessels, deep to the parotid gland.
• It gives a branch to the temporomandibular joint and ascends over the posterior root of the zygomatic arch, behind the superficial temporal vessels.
• The auricular part innervates the skin of the tragus and upper part of the pinna, the external acoustic meatus, and the outer surface of the tympanic membrane.
• The temporal part is distributed to the skin of the temple.
• The auriculotemporal nerve also supplies the parotid gland and carries postganglionic secretomotor fibers from the otic ganglion.
• It does not supply the parotid fascia, which is supplied by the great auricular nerve.
• The inferior alveolar nerve emerges below the lower head of the lateral pterygoid and curves down on the medial pterygoid.
• It lies anterior to its vessels between the sphenomandibular ligament and the ramus of the mandible, and enters the mandibular foramen.
• Anesthetic solution is introduced into this region, just above the foramen, for inferior alveolar nerve block.
• The mylohyoid nerve leaves the inferior alveolar nerve at the foramen.
• It pierces the sphenomandibular ligament, lies on the mandible above the insertion of the medial pterygoid, and runs forward on the superficial surface of the mylohyoid.
• It supplies the mylohyoid and the anterior belly of the digastric.
• The inferior alveolar nerve runs with its vessels in the mandibular canal and supplies the three molar and two premolar teeth.
• It divides into the mental nerve and the incisive nerve.
• The incisive nerve supplies the pulps and periodontal membranes of the canine and both incisors, with some overlap into the opposite central incisor.
• The lingual nerve appears below the lateral pterygoid on the side wall of the pharynx and passes forwards and downwards between the medial pterygoid and the mandible.
• It comes into contact with the mandible, sometimes leaving a groove below and medial to the third molar.
• It enters the mouth on the surface of the mylohyoid, beneath the mucous membrane of the floor of the mouth.
• The chorda tympani (from the facial nerve) joins the lingual nerve 2 cm below the base of the skull and is distributed with it to the anterior two-thirds of the tongue.
• It carries all the parasympathetic secretomotor fibers to the submandibular ganglion and all the taste fibers from the anterior two-thirds of the tongue.

Otic Ganglion

• A small body that lies between the tensor palati and the mandibular nerve, just below the foramen ovale.
• It is about 2-3 mm in diameter.
• It is a relay station for parasympathetic secretomotor fibers to the parotid gland.
• The lesser petrosal branch of the glossopharyngeal nerve brings these fibers.
• A branch from the nerve to the medial pterygoid passes through the ganglion to the tensor muscles (tympani and palati).

Overview of the mandibular nerve, a branch of the trigeminal ganglion. Describes its location in the skull, its path through the foramen ovale, and its relationship to the otic ganglion. Details the sensory and motor branches, including the meningeal branch.