Biceps Femoris Muscle
Long Head of the Biceps Femoris
Origin: Posterior side of the ischial tuberosity, conjoined with semitendinosus
Insertion: The styloid process of the fibula and the lateral condyle of the tibia
Actions: Flexion of the leg at the knee, external rotation of the knee, extension of the thigh at the hip
Innervation: Tibial portion of the sciatic nerve (L5,S1)
Blood Supply: Branches from the internal iliac, popliteal and profunda femoris arteries
Primary Actions of the Biceps Femoris Long Head
1. Flexion of the leg at the knee
Agonists:
- Semimembranosus
- Semitendinosus
Antagonists:
- Vastus lateralis
- Vastus medialis
- Vastus intermedius
- Rectus Femoris
Gracilis, sartorius, popliteus, gastrocnemius, and plantaris assist with flexion of the knee
2. External rotation of the knee
Agonists:
- Biceps femoris (short head)
Antagonists:
- Popliteus
- Semitendinosus
- Semimembranosus
3. Extension of the thigh at the hip
Agonists:
- Gluteus maximus
- Semitendinosus
- Semimembranosus
- Adductor magnus (posterior fibers)
Antagonists:
- Psoas Major
- Iliacus
Short Head Of the Biceps Femoris
Origin:Middle third of the linea aspera
Insertion: The styloid process of the fibula and the lateral condyle of the tibia
Actions: Flexion of the leg at the knee, external rotation of the knee
Innervation: Common peroneal portion of the sciatic nerve (L5, S1)
Blood Supply: Branches from the internal iliac, popliteal and profunda femoris arteries
Primary Actions of the Biceps Femoris Short Head
Primary Actions of the Biceps Femoris Short Head:
1. Flexion of the leg at the knee
Agonists:
- Semitendinosus
- Semimembranosus
Antagonists:
- Vastus lateralis
- Vastus medialis
- Vastus intermedius
- Rectus femoris
Gracilis, sartorius, popliteus, gastrocnemius, and plantaris assist with flexion of the knee
2. External rotation of the knee
Agonists:
- Biceps Femoris (long head)
Antagonists:
- Popliteus
- Semitendinosus
- Semimembranosus
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Muscle Pain Information: The biceps femoris muscle contributes to pain in the back of the knee that extends to the outside of the thigh.
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For intermediary anatomy students learning skeletal and muscle structure.
For beginning and intermediary anatomy . Muscle overlays on the human body. Excellent visuals!