Musculus sternothyroideus
The sternothyroideus is a strap muscle that originates from the manubrium of the sternum (deep to the sternohyoideus) and inserts on the lateral surface of the thyroid cartilage of the larynx. Its actions are to depress the larynx and open the airway after swallowing. It is innervated by ventral branches of C1-C2 via the ansa cervicalis. It works with the sternohyoideus to stabilize the airway during exercise.
Origin: Manubrium of the sternum (deep to sternohyoideus)
Insertion: Lateral surface of the thyroid cartilage of the larynx
Action: Depresses the larynx; opens the airway after swallowing
Innervation: Ventral branches of C1-C2 via the ansa cervicalis
Relevant in evaluations of laryngeal position and airway function. Dysfunction can contribute to airway dynamics issues. Isolated injury is uncommon.
## Overview Laryngeal function refers to the ability of the larynx to open fully during exercise. The sternothyroideus and other extrinsic muscles help position the larynx. Dysfunction contributes to
## Overview Fourth branchial arch defect (also called laryngeal dysplasia or 4-BAD) is a congenital malformation of laryngeal structures derived from the fourth branchial arch. It most often affects
Abnormal respiratory noise or difficulty swallowing after trauma should be evaluated.
## Overview Laryngeal function refers to the ability of the larynx to open fully during exercise. The sternothyroideus and other extrinsic muscles help position the larynx. Dysfunction contributes to dynamic airway collapse, respiratory noise, and reduced exercise tolerance. It is assessed by resting and exercising endoscopy. ## Causes Neuromuscular dysfunction, inflammation, or anatomic abnormalities affecting laryngeal position and stability. ## Diagnosis Exercising endoscopy is the gold standard. Resting endoscopy may show reduced arytenoid movement. ## Treatment Depends on the specific abnormality (for example, tie-forward for dorsal displacement of the soft palate, or prosthetic laryngoplasty for recurrent laryngeal neuropathy). ## Recovery and Prognosis Variable by diagnosis and chosen treatment. ## Prevention Management of airway inflammation and appropriate conditioning. Signs include: respiratory noise during exercise; reduced exercise tolerance; abnormal laryngeal position on endoscopy
## Overview Fourth branchial arch defect (also called laryngeal dysplasia or 4-BAD) is a congenital malformation of laryngeal structures derived from the fourth branchial arch. It most often affects the right side and can cause respiratory noise, exercise intolerance, or dysphagia from birth. ## Causes Developmental failure of cartilage and muscle formation (thyroid and cricoid cartilages, associated muscles). ## Diagnosis Endoscopy showing reduced arytenoid abduction or rostral displacement of the palatopharyngeal arch, plus ultrasound, radiographs, or computed tomography confirming cartilage abnormalities. ## Treatment Surgical options are limited and case-dependent. Some horses are managed conservatively if signs are mild. Severe dysphagia or airway obstruction may require more aggressive intervention. ## Recovery and Prognosis Variable. Mild cases may perform adequately. Severe defects limit athletic use or cause ongoing dysphagia. ## Prevention None (congenital). Signs include: respiratory noise from birth; dysphagia or nasal return of milk in foals; exercise intolerance; arytenoid dysfunction on endoscopy
Relevant in evaluations of laryngeal position and airway function. Dysfunction can contribute to airway dynamics issues. Isolated injury is uncommon.
Abnormal respiratory noise or difficulty swallowing after trauma should be evaluated.
See the Sternothyroideus on our interactive 3D horse model. Open 3D Model