Musculus levator nasolabialis
The levator nasolabialis is a broad, flat muscle that elevates both the upper lip and the nostril. It originates from the frontal and nasal bones between the orbits and inserts on the upper lip and lateral wing of the nostril. Related fibers or the levator of the upper lip elevate the upper lip. Both are innervated by the dorsal buccal branch of the facial nerve (CN VII). They are used during the flehmen response and for lip movement while eating.
Origin: Frontal and nasal bones, between the orbits
Insertion: Upper lip and lateral wing of the nostril
Action: Elevates the upper lip and dilates the nostril
Innervation: Dorsal buccal branch of facial nerve (CN VII)
Dysfunction can occur with facial nerve injury. Rarely a primary problem otherwise.
## Overview Facial nerve paralysis is loss of function of the facial nerve (cranial nerve VII), which controls the muscles of facial expression. It produces lip droop, ear droop, inability to blink,
## Overview Headshaking syndrome (trigeminal-mediated headshaking) is characterized by sudden, violent, involuntary head jerks, nose flicking, and snorting without an obvious external stimulus. It is
Inability to elevate the upper lip or perform flehmen after facial trauma should be checked.
## Overview Facial nerve paralysis is loss of function of the facial nerve (cranial nerve VII), which controls the muscles of facial expression. It produces lip droop, ear droop, inability to blink, and muzzle deviation toward the normal side. Trauma and post-anesthetic neuropathy are common causes. ## Causes Trauma to the nerve as it crosses the face, prolonged halter pressure, or central lesions. Inflammation or infection can also be involved. ## Diagnosis Clinical observation of asymmetric facial movement. Neurologic examination localizes the lesion. Further diagnostics if a central cause is suspected. ## Treatment Anti-inflammatories if acute, eye protection to prevent corneal ulcers, and time for nerve recovery. Physical therapy or acupuncture is sometimes used. ## Recovery and Prognosis Variable. Many traumatic cases improve over weeks to months. Complete recovery is not guaranteed. ## Prevention Careful halter fit and avoidance of facial trauma. Signs include: lip droop; ear droop; inability to blink; muzzle pulled to the normal side; food falling from the mouth; drooling
## Overview Headshaking syndrome (trigeminal-mediated headshaking) is characterized by sudden, violent, involuntary head jerks, nose flicking, and snorting without an obvious external stimulus. It is linked to hyperexcitability of the trigeminal nerve and often worsens in sunlight or wind. It affects roughly 1 percent of horses. ## Causes Trigeminal nerve sensitization. Triggers include bright light, wind, and exercise. The exact initiating factor is unknown. ## Diagnosis Clinical history and observation. Other causes of headshaking (dental, ear, ocular, tack) must be excluded. Response to certain diagnostic tests supports the diagnosis. ## Treatment Nose nets, cyproheptadine or other medications, magnesium supplementation, and in refractory cases surgical or neuromodulatory procedures. Management is often multimodal and incomplete. ## Recovery and Prognosis Variable. Some horses are managed successfully; others remain severely affected and may be retired. ## Prevention None specific. Avoid known triggers when possible. Signs include: sudden violent head jerks; nose rubbing on legs; snorting; nose flicking; worse in sunlight or wind; seasonal pattern
Dysfunction can occur with facial nerve injury. Rarely a primary problem otherwise.
Inability to elevate the upper lip or perform flehmen after facial trauma should be checked.
See the Levator Nasolabialis on our interactive 3D horse model. Open 3D Model