Trigeminal Nerve - Mandibular Branch medium

Trigeminal Nerve - Mandibular Branch (V3)

• The mandibular branch (V3) is the largest of the three divisions of the trigeminal nerve.
• It exits the skull through the foramen ovale.
• It contains both sensory and motor fibers.
• It supplies sensation to the mandibular teeth and their supporting structures.
• It provides sensory input to the mucosa of the anterior two-thirds of the tongue and the floor of the mouth.
• It also supplies sensation to parts of the lower face, temporal region, and outer ear.
• The mandibular branch innervates the muscles of mastication (chewing).

Divisions

• The trigeminal nerve has three divisions: ophthalmic (V1), maxillary (V2), and mandibular (V3).

Learning Outcomes

• Describe the function of the mandibular branch of the trigeminal nerve (CN V3).
• Outline the anatomical regions it supplies.
• Explain the importance of the mandibular branch of the trigeminal nerve to dentistry.

Why Know This?

• The three terminal branches of the trigeminal nerve innervate skin, mucous membranes, and sinuses of the face.
• The nerve provides sensation to mandibular teeth.
• Knowledge of this nerve is vital for local anesthetic procedures.

Anatomical Course

• Shortly after leaving the skull, the nerve divides into a smaller anterior trunk and a larger posterior trunk.
• Branches emerge from the nerve before division, including the meningeal branch and the nerve to the medial pterygoid muscle.

Branches of V3

Anterior Trunk Branches

• Masseteric nerve (motor)
• Deep temporal nerves (motor)
• Nerve to lateral pterygoid muscle (motor)
• Long buccal nerve (sensory)

Posterior Trunk Branches

• Auriculotemporal nerve (sensory)
• Lingual nerve (sensory) (also receives parasympathetic fibers from the chorda tympani)
• Inferior alveolar nerve(sensory and motor) (divides into mental and incisive nerves)
• Mylohyoid nerve (motor)

Muscles of Mastication

• Medial pterygoid nerve (motor)
  • Enters the deep surface of the muscle.
  • Also supplies the tensor tympani and tensor veli palatini.
  • Action: elevates the jaw.
• Masseteric nerve (motor): elevates the mandible.
• Temporalis nerve (motor): elevates the mandible.
• Lateral pterygoid nerve (motor): depresses the mandible.

Long Buccal Nerve

• The only sensory branch of the anterior trunk.
• Emerges between the lateral pterygoid heads.
• Runs on the lateral surface of the buccinator muscle.
• Gives branches to the skin of the cheek.
• Pierces the buccinator to supply buccal sulcus and buccal gingivae of mandibular molars and premolars.

Auriculotemporal Nerve

• First branch of the posterior trunk (sensory).
• Contains autonomic fibers to the parotid gland via otic ganglion.
• Two roots unite and lie between the condyle and sphenomandibular ligament.
• Emerges between the TMJ and external auditory meatus.

Lingual Nerve

• Second branch of the posterior trunk.
• Sensory: supplies anterior 2/3 of the tongue and the floor of the mouth.
• Unites with the chorda tympani branch of the facial nerve.
• Receives parasympathetic fibers for submandibular and sublingual glands.
• Emerges from under the lateral pterygoid muscle.
• Curves downwards and forward between the ramus of the mandible and the medial pterygoid muscle.
• Lies anterior but deeper than the inferior alveolar nerve.
• Passes towards the floor of the mouth.
• Twists around the submandibular duct and enters behind the sublingual salivary gland.
• Supplies anterior two-thirds of the tongue's dorsal surface, the floor of the mouth, and the lingual gingivae of the mandibular teeth.

Inferior Alveolar (Dental) Nerve

• A mixed (sensory and motor) nerve.
• 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 and incisive nerves.
• Mental nerve emerges at the mental foramen.
• Incisive nerve runs anteriorly in the incisive canal.

Branches of Inferior Alveolar Nerve

• Inferior Alveolar Nerve: supplies mandibular molars, premolars, and their supporting structures (e.g., gingivae)
• Mental Nerve: supplies skin of chin and lower lip, and labial gingivae of anterior mandibular teeth
• Incisive Nerve: innervates mandibular incisors and canines.

Mylohyoid Nerve

• Given off just before the mandibular foramen.
• Runs in the mylohyoid groove to supply the mylohyoid muscle and the anterior belly of the digastric.
• Motor function.

Nerve Blocks

• ID (inferior alveolar nerve block)
• Mental nerve block

Examinations

• Trigeminal and facial nerve examination