The facial nerve exits the stylomastoid foramen and gives off its first branch before entering the parotid gland. Which structure does this first branch supply?

Explanation

## Facial Nerve Course and Branches **Key Point:** The facial nerve (CN VII) exits the stylomastoid foramen and immediately gives off the posterior auricular nerve as its first extracranial branch, before it enters the parotid gland. ### First Branch: Posterior Auricular Nerve The posterior auricular nerve arises from the main trunk of CN VII just distal to the stylomastoid foramen and supplies: - Posterior belly of the digastric muscle - Stylohyoid muscle - Occipitalis muscle (auricular region) ### Subsequent Branches Within Parotid Gland After entering the parotid gland, the facial nerve divides into its terminal branches: | Branch | Motor Supply | |--------|---------------| | Temporal | Frontalis, orbicularis oculi, corrugator supercilii | | Zygomatic | Orbicularis oculi, zygomaticus major/minor | | Buccal | Buccinator, orbicularis oris, risorius | | Marginal mandibular | Depressor anguli oris, depressor labii inferioris | | Cervical | Platysma | **High-Yield:** Remember that the posterior auricular nerve is the FIRST branch of CN VII after it exits the stylomastoid foramen — this is a classic anatomy board question. **Mnemonic:** **TZBC** — Temporal, Zygomatic, Buccal, Cervical (the five terminal branches within/after the parotid gland). **Clinical Pearl:** Damage to the facial nerve proximal to the stylomastoid foramen (e.g., in Bell's palsy or parotid surgery) affects all branches including the posterior auricular nerve, whereas distal damage spares the posterior belly of digastric. [cite:Clinically Oriented Anatomy 8e Ch 8]