The recurrent laryngeal nerve innervates all intrinsic muscles of the larynx except which one?

Explanation

## Laryngeal Nerve Innervation: Intrinsic Muscles **Key Point:** The cricothyroid muscle is the ONLY intrinsic laryngeal muscle innervated by the superior laryngeal nerve (external branch), not the recurrent laryngeal nerve. All other intrinsic muscles are innervated by the recurrent laryngeal nerve. ### Innervation Pattern | Muscle | Nerve Supply | Action | | --- | --- | --- | | **Cricothyroid** | Superior laryngeal nerve (external branch) | Lengthens vocal cords; increases tension | | Posterior cricoarytenoid | Recurrent laryngeal nerve | Abducts vocal cords (only abductor) | | Lateral cricoarytenoid | Recurrent laryngeal nerve | Adducts vocal cords | | Interarytenoid (transverse & oblique) | Recurrent laryngeal nerve | Adducts vocal cords | | Thyroarytenoid | Recurrent laryngeal nerve | Shortens & relaxes vocal cords | | Vocalis | Recurrent laryngeal nerve | Fine-tunes vocal cord tension | **Mnemonic:** **SALT** = **S**uperior laryngeal nerve → **A**ll muscles except **L**arynx intrinsic (actually, Superior innervates **C**ricothyroid only). Better: **"CT is SLN"** — **C**ricothyroid is innervated by **S**uperior **L**aryngeal **N**erve. **High-Yield:** This is a classic NEET PG question. The cricothyroid is the exception — it is embryologically derived from the 4th pharyngeal arch (like the superior laryngeal nerve), while other intrinsic muscles are from the 6th arch (recurrent laryngeal nerve). **Clinical Pearl:** Bilateral recurrent laryngeal nerve injury causes vocal cord paralysis in the paramedian position (stridor), while bilateral superior laryngeal nerve injury causes voice fatigue and loss of pitch control.