The facial nerve exits the stylomastoid foramen and immediately gives off a branch that supplies the muscles of the posterior belly of the digastric and stylohyoid. Which nerve is this?

Explanation

## Facial Nerve Branches — Extratemporal Course **Key Point:** The posterior auricular nerve is the first extratemporal branch of the facial nerve, arising immediately after it exits the stylomastoid foramen, before the nerve enters the parotid gland. ### Anatomical Course The facial nerve (CN VII) exits the skull via the stylomastoid foramen and gives off several branches in a predictable sequence: 1. **Posterior auricular nerve** (first branch) — supplies: - Posterior belly of digastric - Stylohyoid muscle - Occipitalis muscle 2. Branches to parotid plexus (within the gland): - Temporal - Zygomatic - Buccal - Marginal mandibular - Cervical **High-Yield:** The posterior auricular nerve is clinically important because it is the **first branch** and helps identify the main trunk of CN VII during parotid surgery. Surgeons use it as a landmark to avoid iatrogenic facial nerve injury. **Mnemonic:** **TZBC** (Temporal, Zygomatic, Buccal, Cervical) — the five main branches within the parotid plexus, but **posterior auricular comes first**, before the plexus. ### Clinical Pearl Damage to the posterior auricular nerve alone causes loss of ear elevation (occipitalis) and posterior belly of digastric function, but spares all other facial muscles — a rare but clinically recognizable pattern.