What is the action of the gracilis muscle in the horse?

• A. Abduct the limb
• B. Flexes the stifle
• C. Adduct the limb
• D. Extends the hip

Answer: (C)

The main function of the gracilis in the horse is to adduct the limb—pull the hind leg toward the body's midline. This medial thigh muscle sits along the inner surface of the leg and acts to bring the limb inward, which is its defining action. It can also assist with flexion of the stifle (knee) as a secondary effect, but the action most representative of its role and most tested is adduction. Abduction would move the limb away from the midline, which isn’t a action of this muscle. Hip extension is performed mainly by other hip extensors, not by the gracilis.