Musculus dilator naris lateralis
Dilates the nostril by pulling lateral alar cartilage outward. Since horses are obligate nasal breathers, critical for athletic performance. Minute ventilation can reach 1,800 L/min at gallop.
Origin: Lateral nasal cartilage
Insertion: Lateral alar fold of the nostril
Action: Dilates the nostril laterally
Innervation: Dorsal buccal branch of facial nerve (CN VII)
Collapse or inadequate dilation of the nasal passages during the high airflow demands of exercise. The alar cartilage may lack sufficient rigidity, or the dilator muscles may fatigue. This is a form o
Collapse or inadequate dilation of the nasal passages during the high airflow demands of exercise. The alar cartilage may lack sufficient rigidity, or the dilator muscles may fatigue. This is a form of dynamic upper airway obstruction. More recently recognized with the advent of exercising endoscopy (overground endoscope). May coexist with other dynamic airway obstructions. Signs include: Fluttering noise from nostrils at gallop; exercise intolerance; nostril collapse during inhalation; improved with nasal strips.; Inspiratory noise during intense exercise; noise originates at the nostril level; variable performance limitation; may be positional (worse with certain head/neck positions); more common in horses that work at high speeds; diagnosis requires exercising endoscopy showing dynamic collapse of nasal structures; external nasal dilator strips (FLAIR strips) may provide temporary relief
See the Lateral Nostril Dilator on our interactive 3D horse model. Open 3D Model