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The superior laryngeal nerve is a branch of the vagus nerve. It arises from the middle of the inferior ganglion of vagus nerve and in its course receives a branch from the superior cervical ganglion of the sympathetic nervous system.
The superior laryngeal nerve consists of two branches: the internal laryngeal nerve , which supplies sensory fibers to the laryngeal mucosa, and the external laryngeal nerve , which innervates the cricothyroid muscle.
The superior laryngeal nerve innervates the two cricothyroid muscles.
The recurrent laryngeal nerve gets its name from the fact that it loops below the aorta on its way to the intrinsic muscles of the larynx. The left recurrent laryngeal nerve passes under and around the aorta on its way to the larynx, whereas the right recurrent laryngeal nerve passes under and around the subclavian artery. Because the aorta is inferior to the subclavian artery, the left recurrent laryngeal nerve is a bit longer than the right recurrent laryngeal nerve. However, there is no discernible effect on the timing of neural impulses to the muscles these two nerves serve. By comparison with the recurrent laryngeal nerves, the superior laryngeal nerve takes a more direct route on the way to the cricothyroid muscles.