Musculus cricoarytenoideus lateralis
The cricoarytenoideus lateralis originates on the cranial lateral surface of the cricoid cartilage and inserts on the muscular process of the arytenoid cartilage (more ventrally than the CAD). Its action is to adduct (close) the arytenoid cartilage, narrowing the rima glottidis. This protects the airway during swallowing and contributes to vocalization. It works antagonistically to the cricoarytenoideus dorsalis. Like the other intrinsic laryngeal muscles (except cricothyroideus), it is innervated by the recurrent laryngeal nerve. In recurrent laryngeal neuropathy the adductor muscles are also affected, but the clinical problem is dominated by loss of abduction.
Origin: Cranial lateral surface of the cricoid cartilage
Insertion: Muscular process of the arytenoid cartilage (ventral aspect)
Action: Adducts the arytenoid cartilage; closes the rima glottidis; protects the airway during swallowing
Innervation: Caudal laryngeal nerve (recurrent laryngeal nerve, CN X)
Part of the adductor group. Ultrasound or endoscopic findings in roaring horses reflect denervation of multiple intrinsic muscles. Isolated problems are rare.
## Overview Arytenoid chondritis is a progressive inflammatory condition of one or both arytenoid cartilages of the larynx. Mucosal injury is thought to allow bacterial invasion, leading to cartilage
The same signs that suggest roaring (noise on inspiration, exercise intolerance) warrant endoscopic examination; the lateralis is evaluated as part of the overall laryngeal assessment.
## Overview Arytenoid chondritis is a progressive inflammatory condition of one or both arytenoid cartilages of the larynx. Mucosal injury is thought to allow bacterial invasion, leading to cartilage infection, deformation, and enlargement. The affected arytenoid loses the ability to abduct fully, narrowing the airway. The condition is seen most often in young racehorses and produces exercise intolerance and inspiratory noise similar to recurrent laryngeal neuropathy. ## Causes The precise cause is unknown. Mucosal trauma (possibly from inhaled particulate matter or forced glottic closure) followed by bacterial infection is the leading hypothesis. Respiratory tract infection may also play a role. ## Diagnosis Endoscopy reveals an enlarged, misshapen, poorly mobile arytenoid, often with granulation tissue or a contact lesion on the opposite cartilage. Laryngeal ultrasound helps define the lateral extent of cartilage involvement. Clinical signs include poor performance and inspiratory stridor; severe cases show dyspnea at rest. ## Treatment Mild mucosal lesions may respond to systemic and topical anti-inflammatories plus antibiotics and airway rest. Advanced cartilage deformity usually requires surgical debridement or partial arytenoidectomy. Temporary tracheostomy is sometimes needed for severe airway obstruction. ## Recovery and Prognosis Prognosis is good for mild cases managed medically. After unilateral arytenoidectomy, many horses return to racing, although performance level may be reduced. Bilateral disease carries a poorer prognosis. ## Prevention No specific prevention is established. Minimizing airway irritation in young racehorses may be beneficial. Signs include: exercise intolerance; inspiratory respiratory noise; poor performance; enlarged or immobile arytenoid on endoscopy; dyspnea at rest in severe cases
Part of the adductor group. Ultrasound or endoscopic findings in roaring horses reflect denervation of multiple intrinsic muscles. Isolated problems are rare.
The same signs that suggest roaring (noise on inspiration, exercise intolerance) warrant endoscopic examination; the lateralis is evaluated as part of the overall laryngeal assessment.
See the Cricoarytenoideus Lateralis on our interactive 3D horse model. Open 3D Model