Gracilis Muscle
Origin: Lower half of the body of the pubis, the inferior pubic ramus, and the adjoining part of the ischial ramus.
Insertion: Upper part of the medial flare of the tibia, just below the medial condyle, proximal and slightly anterior to the attachment of semitendinosus, and posterior and somewhat inferior to the attachment of sartorius.
Actions: Assists with flexion and adduction of the thigh
Innervation: Anterior division of the femoral nerve (L2. L3)
Blood Supply: Obturator artery from the internal iliac artery
Primary Actions of the Gracilis
1. Because of its lack of mechanical advantage, the gracilis is not capable of isolated movements. It does not have a primary action.
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Secondary Actions of the Gracilis
1. Assists with flexion of the knee
Agonists:
- Biceps femoris
- Semitendinosus
- Semimembranosus
Antagonists:
- Vastus lateralis
- Vastus medialis
- Vastus intermedius
- Rectus femoris
Sartorius, popliteus, gastrocnemius, and plantaris also assist with flexion of the knee.
2. Assists with internal rotation of the knee when the knee is flexed
Agonists:
- Popliteus
- Semitendinosus
- Semimembranosus
Antagonists:
- Biceps femoris
The Sartorius also assists with internal rotation of the knee when the knee is flexed.
3. Assists with adduction of the thigh at the hip
Agonists:
- Adductor longus
- Adductor brevis
- Adductor magnus (anterior part)
Antagonists:
- Gluteus maximus (upper fibers)
- Gluteus medius
- Gluteus minimus
Pectineus also assists with adduction of the thigh at the hip.
Muscle Pain Information: The gracilis muscle contributes to groin and pelvic pain.
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