Musculus lateralis nasi
These related muscles pull the lateral alar cartilage or fold outward to enlarge the nostril. They originate from the nasal or incisive bones or lateral nasal cartilage and insert on the lateral alar cartilage or fold. They are innervated by the dorsal buccal branch of the facial nerve (CN VII). Because horses cannot breathe through their mouths, adequate nostril dilation is important for athletic performance, especially at high speeds when minute ventilation is high.
Origin: Nasal and incisive bones
Insertion: Lateral alar cartilage of the nostril
Action: Dilates the nostril laterally
Innervation: Dorsal buccal branch of facial nerve (CN VII)
Rarely a primary clinical problem. Dysfunction can occur with facial nerve injury. Relevant in evaluations of upper airway function.
## Overview Dynamic nasal collapse is inward collapse of the nasal structures (alar folds or related tissues) during high-speed inspiration. It produces a fluttering noise at the nostrils and can lim
Reduced nostril flare during exercise or after facial trauma should be evaluated, especially if the horse shows signs of respiratory effort.
## Overview Dynamic nasal collapse is inward collapse of the nasal structures (alar folds or related tissues) during high-speed inspiration. It produces a fluttering noise at the nostrils and can limit performance. External nasal dilator strips may provide temporary relief. Diagnosis requires exercising endoscopy. ## Causes Insufficient rigidity of the alar cartilages or fatigue of the dilator muscles under high negative pressure. ## Diagnosis Exercising endoscopy demonstrating collapse at the nostril level. Resting examination is often normal. ## Treatment Nasal strips (for example, FLAIR strips) can help some horses. Surgical options are limited. Management of concurrent airway inflammation is supportive. ## Recovery and Prognosis Variable. Some horses perform adequately with strips; others remain limited. ## Prevention None specific. Signs include: fluttering noise from the nostrils at gallop; exercise intolerance; nostril collapse on inhalation; improvement with nasal strips
Rarely a primary clinical problem. Dysfunction can occur with facial nerve injury. Relevant in evaluations of upper airway function.
Reduced nostril flare during exercise or after facial trauma should be evaluated, especially if the horse shows signs of respiratory effort.
See the Lateral Nasal Muscle on our interactive 3D horse model. Open 3D Model