recurrens

Recurrens is a Latin term meaning "recurrent" or "running back." In anatomy, the name most often appears in reference to the nervus recurrens, known in English as the recurrent laryngeal nerve, a branch of the vagus nerve (cranial nerve X).

On the right side, the recurrent laryngeal nerve loops upward around the subclavian artery; on the left, it loops under the aortic arch. It then ascends in the tracheoesophageal groove to reach the larynx, where it supplies motor innervation to most intrinsic muscles of the larynx (except the cricothyroid, which is served by the external branch of the superior laryngeal nerve) and provides sensory innervation to the mucosa below the vocal folds, with some fibers carrying proprioceptive information.

Functionally, the nerve facilitates voice production by moving the vocal cords and contributes to protective airway reflexes through its sensory input from the larynx.

Clinical significance is tied to its susceptibility during thyroid, mediastinal, and carotid procedures. Injury can cause hoarseness or vocal weakness; bilateral damage may compromise airway protection. Anatomical variations include a nonrecurrent laryngeal nerve, more commonly on the right with an aberrant subclavian artery, in which the nerve takes a direct course to the larynx rather than looping around a vessel.

Etymology and usage: nervus recurrens is the Latin nomenclature found in older texts; the English term is recurrent laryngeal nerve. The concept of recurrence also appears in other anatomical contexts but the nerve is the primary association.