Left Laryngeal Hemiplegia
The muscle that holds the laryngeal arytenoid open during inspiration is innervated by the recurrent laryngeal nerve. The left nerve courses around the greater vessels of the heart and back up to the larynx. Occasionally, there is progressive loss of nerve fibers of this nerve, leading to loss of arytenoid function. This is known as left laryngeal hemiplegia or recurrent laryngeal neuropathy. As a horse with this condition inspires, especially during exercise, the arytenoid can then impinge across the opening of the larynx, obstructing airflow and ultimately decreasing athletic performance.