Trigeminal Nerve: Mandibular Branch (V3)

• The trigeminal nerve is the largest cranial nerve, and knowledge of it is important for dental professionals.
• The trigeminal nerve has three divisions: ophthalmic (V1), maxillary (V2), and mandibular (V3).

Mandibular Branch (V3)

• The mandibular branch (V3) is the largest of the trigeminal nerve's three divisions.
• It exits the skull through the foramen ovale.
• It contains both sensory and motor fibers.

What V3 Supplies

• Sensory innervation includes mandibular teeth and supporting structures.
• Sensory includes the mucosa of the anterior 2/3 of the tongue and floor of the mouth.
• Sensory includes the skin of the lower face.
• Sensory includes parts of the temporal region and outer ear.
• Motor includes the muscles of mastication, mylohyoid, and the anterior belly of the digastric.
• Motor includes tensor veli palatini and tensor tympani.

Anatomical Course

• Shortly after leaving the skull, the mandibular nerve divides into a small anterior trunk and a larger posterior trunk.
• Branches that emerge from the nerve before it divides include the meningeal branch and the nerve to the medial pterygoid muscle.

Branches of V3

• Anterior trunk branches include the masseteric nerve, deep temporal nerves, nerve to the lateral pterygoid muscle and the long buccal nerve.
• Posterior trunk branches include the auriculotemporal nerve, lingual nerve and the inferior alveolar nerve.

Muscles of Mastication

• The medial pterygoid nerve enters the deep surface of the muscle.
• The medial pterygoid nerve also supplies the tensor tympani and tensor veli palatini.
• Action: Elevates the jaw.

Masseter

• The masseteric nerve is the first branch of the anterior trunk.
• It crosses the masseter between the coronoid process and condyle of the mandible.
• It gives an articular branch to the temporomandibular joint (TMJ).
• Action: Elevates the mandible (mouth closing).

Temporalis

• Innervated by anterior and deep temporal nerves.
• Action: Elevates the mandible (mouth closing).

Lateral Pterygoid

• Innervated by a nerve to the lateral pterygoid, which may run partly with the long buccal nerve.
• Action: Depresses mandible (mouth opening).

Long Buccal Nerve

• It is the only sensory branch of the anterior trunk.
• It emerges between the heads of the lateral pterygoid.
• It runs on the lateral surface of the buccinator muscle in the cheek, close to the retromolar fossa of the mandible.
• Branches supply skin of cheek.
• It pierces the buccinator and supplies the buccal sulcus and buccal gingivae of the mandibular molars and premolars.

Auriculotemporal Nerve (A)

• This is the first branch of posterior trunk
• Primarily sensory
• Parasympathetic fibers to the parotid pass via the otic ganglion
• Two roots unite and run backwards under the lateral pterygoid muscle.
• It then lies between the condyle & sphenomandibular ligament
• It emerges between TMJ & external auditory meatus
• Finally ascends on side of head

Lingual Nerve

• This is the 2nd branch of posterior trunk
• Is sensory
• It unites with the chorda tympani branch of the facial nerve and receives parasympathetic fibers for submandibular & sublingual glands.
• Emerges under the lateral pterygoid muscle.
• It curves downward and forwards between the ramus of the mandible & medial pterygoid muscle, in the pterygomandibular space
• Lies anterior to but deeper than the inferior alveolar nerve.
• Passes towards the floor of the mouth.
• Travels around the submandibular duct.
• Action: Enters tongue behind sublingual salivary gland.
• Supplies the mucosa covering the anterior 2/3 dorsum of tongue, under surface of the tongue, floor of mouth, and lingual gingivae of mandibular teeth.

Inferior Alveolar (dental) Nerve

• Sensory and motor
• It descends deep to the lateral pterygoid muscle behind the lingual nerve.
• Enters the mandibular foramen
• Travels in the inferior dental or mandibular canal in the mandible
• Divides near the premolars into the mental nerve & incisive nerve.
• The mental nerve emerges at the mental foramen.
• The incisive nerve runs anteriorly in incisive canal.

Mylohyoid nerve (B)

• This is a branch of the Inferior Alveolar Nerve.
• It is given off just before the mandibular foramen.
• Runs in the mylohyoid groove to supply the mylohyoid muscle & anterior belly of the digastric (motor).
• Action: Depresses the mandible (on a fixed hyoid) or elevates the hyoid in swallowing.

Inferior Alveolar Nerve

• Supplies mandibular molars & premolars & supporting structures (e.g. gingivae).

Mental nerve

• Supplies skin of chin & lower lip & labial gingivae of anterior mandibular teeth.

Incisive nerve

• Innervates mandibular incisors & canines.

The mandibular branch (V3) is the largest division of the trigeminal nerve. It exits the skull through the foramen ovale and contains both sensory and motor fibers. V3 provides sensory innervation to the mandibular teeth, mucosa of the anterior tongue, and skin of the lower face.