Musculus corrugator supercilii
The corrugator supercilii is a small facial muscle that originates on the frontal bone above the medial orbital rim and inserts into the skin of the upper eyelid, blending with orbicularis oculi. Together with levator anguli oculi medialis, it contributes to pulling the skin above the inner corner of the eye dorsally and obliquely toward the medial frontal region. In horses this contributes to the “inner brow raiser” facial action unit that has been incorporated into equine pain-scoring systems (e.g., the Horse Grimace Scale). It is innervated by the auriculopalpebral branch of the facial nerve (CN VII). Isolated clinical disease is essentially nonexistent; its main relevance is in behavioral and pain assessment.
Origin: Frontal bone above the medial orbital rim
Insertion: Skin of the upper eyelid, blending with orbicularis oculi
Action: Works with levator anguli oculi medialis to raise the skin above the inner corner of the eye
Innervation: Auriculopalpebral branch of facial nerve (CN VII)
Not a primary clinical structure. Facial-nerve paralysis can reduce its function along with other mimetic muscles. Researchers and clinicians use the resulting facial expression as one component of pain evaluation.
## Overview Chronic pain indicators in horses include persistent behavioral changes such as reduced performance, altered posture, weight shifting, teeth grinding, reduced social interaction, or ongoi
A persistently “worried” or tightened expression around the eyes, especially when combined with other pain signs (ear position, nostril tension, etc.), may indicate discomfort; have the horse evaluated.
## Overview Chronic pain indicators in horses include persistent behavioral changes such as reduced performance, altered posture, weight shifting, teeth grinding, reduced social interaction, or ongoing muscle tension. These signs are non-specific and prompt investigation for musculoskeletal, dental, gastrointestinal, or other sources of long-standing discomfort. ## Causes Any unresolved painful condition (arthritis, dental disease, gastric ulcers, hoof pain, etc.). ## Diagnosis Systematic veterinary examination, including lameness evaluation, dental check, and additional diagnostics as indicated by the history. ## Treatment Directed at the identified source of pain. Multimodal analgesia and management changes support comfort while the primary problem is addressed. ## Recovery and Prognosis Depends on the underlying cause. Many chronic pain states improve once the driver is treated. ## Prevention Early recognition and treatment of painful conditions before they become chronic. Signs include: reduced performance; altered posture or weight shifting; teeth grinding; decreased social interaction; persistent muscle tension; changes in eating or lying behavior
Not a primary clinical structure. Facial-nerve paralysis can reduce its function along with other mimetic muscles. Researchers and clinicians use the resulting facial expression as one component of pain evaluation.
A persistently “worried” or tightened expression around the eyes, especially when combined with other pain signs (ear position, nostril tension, etc.), may indicate discomfort; have the horse evaluated.
See the Corrugator Supercilii on our interactive 3D horse model. Open 3D Model