Branches of the Facial Nerve and Their Distribution

The facial nerve (cranial nerve VII) is a mixed nerve responsible for motor, sensory, and parasympathetic functions. It plays a crucial role in facial expressions, taste sensation from the anterior two-thirds of the tongue, and secretory functions of various glands.

Anatomy of the Facial Nerve

The facial nerve originates from the brainstem, specifically the pons, and traverses through the internal acoustic meatus before emerging from the stylomastoid foramen.

Branches of the Facial Nerve

Intracranial Branches

• Greater petrosal nerve: Provides parasympathetic innervation to the lacrimal gland.
• Nerve to the stapedius: Controls the stapedius muscle in the ear.
• Chorda tympani: Carries taste sensation from the anterior two-thirds of the tongue and parasympathetic innervation to the salivary glands.

Extracranial Branches

Once the facial nerve exits the stylomastoid foramen, it gives rise to several motor branches.

• Temporal branch: Innervates the frontalis, orbicularis oculi, and corrugator supercilii muscles.
• Zygomatic branch: Controls the muscles around the eyes, such as the orbicularis oculi.
• Buccal branch: Responsible for motor control of the buccinator, orbicularis oris, and zygomaticus muscles.
• Marginal mandibular branch: Innervates muscles around the lower lip and chin.
• Cervical branch: Provides motor innervation to the platysma muscle.

Clinical Relevance

Damage to the facial nerve can result in Bell’s palsy, characterized by unilateral facial paralysis. Other conditions, such as Ramsay Hunt syndrome or surgical trauma, can also affect facial nerve function.