Trigeminal Nerve

Trigeminal Nerve

Introduction to Trigeminal Nerve

  • Definition: The trigeminal nerve (CN V) is the fifth cranial nerve responsible for sensory innervation to the face and motor innervation to the muscles of mastication.

A. Ophthalmic Branch

  • Route: Emerges through the Superior Orbital Fissure.

Branches of the Ophthalmic Branch

  1. Frontal Nerve
    • Innervation: Scalp, forehead, upper eyelid, conjunctiva, cornea.
      • Additional Note: Innervates the nose (including the tip) and frontal sinuses.

B. Maxillary Branch

  • Route: Passes through the Foramen Rotundum.

Branches of the Maxillary Branch

  1. Infraorbital Nerve
    • Innervation: Cheek, upper lip, upper teeth, gums.
      • Additional Note: Innervates nasal mucosa, palate, roof of the pharynx, maxillary, ethmoid, and sphenoid sinuses.

C. Mandibular Branch

  • Route: Passes through the Foramen Ovale.

Function of the Mandibular Branch

  • Innervation: Lower lip, lower teeth, gums, chin, jaw (excluding angle of the jaw).

Branches of the Mandibular Branch

i) Lingual Nerve

  • Innervation: Anterior 2/3 of the tongue.

ii) Inferior Alveolar Nerve

  • Innervation: Lower teeth, gums.

iii) Auriculotemporal Nerve

  • Innervation: Vulnerable to injury during tempomandibular surgery, leading to loss of sensation around the auricle and skin surrounding the ear.

iv) Buccal Nerve

  • Innervation: Mucous membranes of the buccal cavity.

v) Mental Nerve

  • Innervation: Chin, lower lip (mucous membrane); a branch of the inferior alveolar nerve.

Clinical Considerations

  • Sensory Loss: Damage to the trigeminal nerve branches can result in sensory loss in the corresponding areas of the face.
  • Temporomandibular Surgery: Care must be taken to avoid injury to the auriculotemporal nerve during temporomandibular surgery to prevent sensory deficits around the ear.

Summary

  • The trigeminal nerve has three main branches: ophthalmic, maxillary, and mandibular, each with specific sensory innervation to different regions of the face.
  • Understanding the anatomy and function of the trigeminal nerve branches is important for diagnosing and managing conditions involving facial sensation and motor function.