Nerve
Superior laryngeal nerve
Two vagal branches with different laryngeal roles
High-yield
Internal branch: chiefly supraglottic sensory input. External branch: principal cricothyroid motor supply. Communicating branches make the actual nerve pattern less sharply divided than this teaching summary.
Overview
The superior laryngeal nerve leaves the vagus near its inferior ganglion and divides in the upper neck. Its larger internal branch reaches the laryngeal mucosa through the thyrohyoid membrane. The external branch descends toward cricothyroid beside the superior thyroid region.
Reference facts
- Origin
- Vagus nerve near the inferior, or nodose, ganglion below the skull base.
- Root value
- Cranial nerve X.
- Course
- Runs deep in the upper neck before dividing. The internal branch accompanies superior laryngeal vessels through the thyrohyoid membrane; the external branch descends on the inferior constrictor.
- Motor
- External branch supplies cricothyroid and may send fibers to the inferior constrictor, with variable laryngeal communications.
- Sensory
- Internal branch supplies much of the supraglottic lining, epiglottic region and adjacent piriform mucosa; territories overlap at their margins.
Clinical correlation
External branch injury can reduce pitch range and vocal endurance. Its variable relation to superior thyroid vessels matters in thyroid surgery. Bilateral loss of internal branch sensation can impair airway protection during swallowing; voluntary closure and coughing need not disappear.
Frequently asked questions
What type of nerve is the superior laryngeal nerve?
The superior laryngeal nerve is cranial nerve X.
What muscles does the superior laryngeal nerve supply?
External branch supplies cricothyroid and may send fibers to the inferior constrictor, with variable laryngeal communications.
What is the sensory distribution of the superior laryngeal nerve?
Internal branch supplies much of the supraglottic lining, epiglottic region and adjacent piriform mucosa; territories overlap at their margins.
What is the course of the superior laryngeal nerve?
Runs deep in the upper neck before dividing. The internal branch accompanies superior laryngeal vessels through the thyrohyoid membrane; the external branch descends on the inferior constrictor.