Trigeminal Nerve Mandibular branch

Trigeminal Nerve - Mandibular Branch (V3)

• The trigeminal nerve is the largest of the five cranial nerves.
• It has three divisions: ophthalmic (V1), maxillary (V2), and mandibular (V3).
• The mandibular branch (V3) is the largest division.
• It exits the skull via the foramen ovale.
• It contains both sensory and motor fibers.

Learning Outcomes

• Describe the function of the mandibular branch of the trigeminal nerve (CN V3).
• Outline the anatomical regions supplied by the mandibular branch.
• Explain the relevance of the mandibular branch to dentistry.

Anatomical Regions Supplied

• 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 Supply (Muscles of Mastication)

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

Anatomical Course

• Shortly after exiting the skull, the mandibular branch divides into a smaller anterior trunk and a larger posterior trunk.
• Branches from the nerve before it divides include:
  • Meningeal branch
  • Nerve to the medial pterygoid muscle

Branches of V3

• Anterior Trunk Branches:
  • Masseteric nerve
  • Deep temporal nerves
  • Nerve to the lateral pterygoid muscle
  • Long buccal nerve
• Posterior Trunk Branches:
  • Auriculotemporal nerve
  • Lingual nerve
  • Inferior alveolar nerve

Muscles of Mastication

• Medial Pterygoid: Enters the deep surface of the muscle, and also supplies the tensor tympani and tensor veli palatini. Its action is to elevate the jaw.
• Masseter: Elevates the mandible.
• Temporalis: Elevates the mandible.
• Lateral Pterygoid: Elevates and protracts the mandible. Includes a nerve that runs part way with the long buccal nerve.

Long Buccal Nerve

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

Auriculotemporal Nerve

• First branch of the posterior trunk.
• Sensory.
• Autonomic to the parotid gland.
• Runs backwards under the lateral pterygoid muscle and lies between the condyle and the sphenomandibular ligament..
• Emerges between the TMJ and the external auditory meatus.
• Finally ascends on the side of the head.

Lingual Nerve

• Second branch of the posterior trunk.
• Sensory.
• Unites with the chorda tympani, a branch of the facial nerve, and receives parasympathetic fibres for the submandibular and sublingual glands.
• Passes under the lateral pterygoid muscle between the mandibular ramus and medial pterygoid muscle, through the pterygomandibular space.
• Lies anterior to the inferior alveolar nerve.
• Passes toward the floor of the mouth.
• Twists around the submandibular duct.
• Enters the tongue behind the sublingual salivary gland.
• Supplies the mucosa covering the anterior two-thirds of the tongue's dorsum, the floor of the mouth, and the lingual gingiva of the mandibular teeth.

Inferior Alveolar Nerve

• Sensory and motor.
• Descends deep to the lateral pterygoid muscle, behind the lingual nerve.
• Enters the mandibular foramen.
• Travels in the inferior dental or mandibular canal.
• Divides near the premolars into the mental nerve and incisive nerve.
• Mental nerve emerges at the mental foramen.
• Incisive nerve runs anteriorly in the incisive canal.
• Supplies the mandibular molars, premolars, and their supporting structures.
• Mylohyoid nerve (a branch) is given off just before the mandibular foramen and runs in the mylohyoid groove to supply the mylohyoid muscle and the anterior belly of the digastric muscle. It depresses the mandible (on a fixed hyoid) or elevates the hyoid in swallowing.
• Branches include mentalnerve and incisive nerve which provide motor and sensory innervation to the mental foramen and the anterior teeth

Nerve Blocks

• ID (Inferior Alveolar) nerve block
• Mental nerve block

Trigeminal and Facial Nerve Examination

• This covers the examination procedure involving the trigeminal and facial nerves.

Summary

• The trigeminal nerve is the largest and fifth cranial nerve. It has three divisions: ophthalmic, maxillary, and mandibular.
• The mandibular branch leaves the skull via the foramen ovale, supplying the mandibular teeth and supporting structures, the mucosa of the anterior two-thirds of the tongue and floor of the mouth, and the muscles of mastication.