North American Veterinary Licensing Examination (NAVLE) Practice Test

The left recurrent laryngeal nerve plays a crucial role in the function of the larynx by innervating the majority of the intrinsic muscles that operate the vocal cords. Damage to this nerve can lead to a condition known as laryngeal hemiplegia, which is quite common in horses. This condition results in the paralysis of one side of the larynx, specifically affecting the ability of the vocal cords to abduct (open) during inspiration, leading to airflow obstruction and respiratory distress.

In horses, the left recurrent laryngeal nerve is particularly susceptible to trauma or stretching due to its anatomical path. As it runs around the aorta, it is longer than its right counterpart and can be affected by various factors, including anatomic variations or pressure changes within the thoracic cavity. Therefore, when horses exhibit labored breathing or noisy inspiration (stridor), and if laryngeal function is suspected to be impaired, injury to the left recurrent laryngeal nerve is a prime concern.

While the right recurrent laryngeal nerve does also innervate laryngeal muscles, it is less frequently associated with significant respiratory distress in horses than the left nerve. The cricothyroid muscle and vocal