Trigeminal Nerve - Mandibular Branch (V3)

Trigeminal Nerve - Mandibular Branch (V3)

• The trigeminal nerve is the largest of the 5th cranial nerves.
• Knowledge of this nerve is vital for dental professionals.
• It has 3 divisions: ophthalmic (V1), maxillary (V2), and mandibular (V3).
• The mandibular branch (V3) is the largest of the 3 divisions.
• The mandibular branch exits the skull via the foramen ovale.
• It carries both sensory and motor fibres.

Learning Outcomes

• Describe the function of the trigeminal nerve's mandibular branch (CN V3).
• Identify the anatomical regions this branch supplies.
• Understand the mandibular branch's relevance to dentistry.

What is Supplied?

• Sensory:

  • Mandibular teeth and supporting structures
  • Mucosa of the anterior two-thirds of the tongue and floor of the mouth
  • Skin of the lower face
  • Parts of the temporal region and outer ear

• Motor:

  • Muscles of mastication
  • Mylohyoid
  • Anterior belly of digastric
  • Tensor veli palatini
  • Tensor tympani

Anatomical Course

• Shortly after leaving the skull, the nerve divides into a small anterior trunk and a larger posterior trunk.
• Before division, it produces a meningeal branch and a nerve to the medial pterygoid muscle.

Branches of V3

• Anterior Trunk Branches:

  • Masseteric nerve
  • Deep temporal nerves
  • Nerve to lateral pterygoid muscle
  • Long buccal nerve

• Posterior Trunk Branches:

  • Auriculotemporal nerve
  • Lingual nerve
  • Inferior alveolar nerve

Muscles of Mastication

• Medial Pterygoid Nerve (Motor):

  • Enters the deep surface of the muscle.
  • Also supplies tensor tympani and tensor veli palatini.
  • Action: Elevates the jaw.

• Masseter:

  • First branch of the anterior trunk.
  • Crosses the masseter between the coronoid process and the condyle of the mandible.
  • Gives an articular branch to the TMJ.
  • Elevates the mandible (mouth closing).

• Temporalis:

  • Anterior and deep temporal nerves.
  • Elevates the mandible (mouth closing).

• Lateral pterygoid:

  • Nerve to lateral pterygoid may run part way with long buccal nerve.
  • Depresses mandible (mouth opening).

Long Buccal Nerve

• The only sensory branch of the anterior trunk.
• Emerges between the heads of lateral pterygoid and runs along the lateral surface of buccinator muscle in cheek, near the retromolar fossa.
• Gives branches to the skin of the cheek.
• Pierces the buccinator to supply buccal sulcus & buccal gingivae of mandibular molars & premolars.

Auriculotemporal Nerve (A)

• First branch of the posterior trunk.
• Sensory.
• Autonomic to parotid gland due to fibres from otic ganglion.
• 2 roots unite and run under lateral pterygoid muscle to lie between condyle and sphenomandibular ligament.
• Emerges between TMJ and external auditory meatus.
• Finally ascends on the side of the head.

Lingual Nerve

• Second branch of the posterior trunk.
• Sensory.
• Unites with chorda tympani branch of facial nerve & receives parasympathetic fibres for submandibular & sublingual glands.
• Emerges from under lateral pterygoid muscle & curves downwards and forwards between ramus of mandible & medial pterygoid muscle (pterygomandibular space).
• Lies anterior to but deeper than inferior alveolar nerve.
• Then passes towards the floor of the mouth.
• Twists around the submandibular duct and enters the tongue behind sublingual salivary gland.
• Supplies: mucosa covering anterior 2/3 dorsum of tongue, under surface of tongue, floor of mouth, & lingual gingivae of mandibular teeth.

Inferior Alveolar (Dental) Nerve

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

Branches of Inferior Alveolar Nerve

• Mylohyoid nerve (B): Given off just before mandibular foramen. Runs in mylohyoid groove to supply mylohyoid muscle and anterior belly of digastric (motor). It depresses the mandible 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.

Nerve Blocks

• Information about specific nerve blocks (e.g., ID nerve block, mental nerve block)
• Locations and techniques are discussed during more advanced studies.

Trigeminal and Facial Nerve Examination

• This topic is often covered in clinical settings and not in the fundamental study of trigeminal nerve, in this context examination methods are not described in this summary.

Summary

• The trigeminal nerve is the largest and 5th cranial nerve.
• It has 3 divisions (ophthalmic, maxillary, mandibular).
• The mandibular nerve exits via the foramen ovale.
• The mandibular branch supplies mandibular teeth, supporting structures, the anterior 2/3 of the tongue, the floor of the mouth and muscles of mastication