Anatomy of Facial Nerve – Branches

Anatomy of the Facial Nerve - Branches

The facial nerve (cranial nerve VII) is a mixed nerve that carries motor, sensory, and parasympathetic fibers.

Its branches can be categorized based on their origin along the nerve's course:

1. Branch from the Geniculate Ganglion

a. Greater Superficial Petrosal Nerve (GSPN)

• Origin: Arises from the geniculate ganglion.

• Function: Carries preganglionic parasympathetic fibers to the pterygopalatine ganglion.

• Course:

  • Passes through the facial hiatus → middle cranial fossa
  • Joins the deep petrosal nerve at the foramen lacerum
  • Forms the nerve of the pterygoid canal (vidian nerve) → pterygopalatine ganglion

2. Branches within the Facial Canal

a. Nerve to Stapedius

• Origin: Arises from the facial nerve within the facial canal.

• Function: Innervates the stapedius muscle, which stabilizes the stapes bone in the middle ear.

b. Chorda Tympani

• Origin: Branches ~5 mm proximal to the stylomastoid foramen.

• Function:

  • Taste sensation from anterior 2/3rd of the tongue
  • Parasympathetic fibers to submandibular and sublingual glands

• Course:

  • Enters tympanic cavity → crosses tympanic membrane
  • Exits via petrotympanic fissure → joins lingual nerve in infratemporal fossa

3. Branches after Exiting the Stylomastoid Foramen

a. Posterior Auricular Nerve

• Origin: Arises immediately after exiting the stylomastoid foramen.

• Function:

  • Motor supply to:
    • Occipital belly of occipitofrontalis
    • Auricular muscles
  • Communicates with the auricular branch of the vagus nerve

b. Muscular Branches

• Innervate:
  • Posterior belly of digastric muscle
  • Stylohyoid muscle

4. Terminal Branches within the Parotid Gland

After entering the parotid gland, the facial nerve divides into:

• Temporofacial Division
• Cervicofacial Division

These give rise to five terminal branches:

1. Temporal Branch

   • Frontalis
   • Orbicularis oculi
   • Corrugator supercilii

2. Zygomatic Branch

   • Orbicularis oculi
   • Zygomaticus major and minor

3. Buccal Branch

   • Buccinator
   • Orbicularis oris

4. Marginal Mandibular Branch

   • Depressor anguli oris
   • Mentalis

5. Cervical Branch

   • Platysma

5. Communicating Branches

a. Auricular Branch of the Vagus Nerve (Arnold's Nerve)

• Communication: Posterior auricular nerve ↔ Auricular branch of vagus nerve

• Function: Sensory innervation to:

  • External ear (concha)
  • External acoustic meatus