posterior_compartment__and_popliteal_fp - 1-Muscles B i c e p s f e m o r i s S e m i t e n d i n o s u s S e m i m e m b r a n o s u s a small part of

posterior_compartment__and_popliteal_fp - 1-Muscles B i c e...

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1-Muscles: B i c e p s f e m o r i s S e m i t e n d i n o s u s S e m i m e m b r a n o s u s a small part of the adductor magnus (h a m s t r i n g p a r t o r i s c h i a l p a r t ) 2-Blood supply : Branches of the profunda femoris artery 3-Nerve supply: Sciatic nerve
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B i c e p s f e m o r i s Origin : two heads 1- Long head : ischial tuberosity 2-Short head : linea aspera, lateral supracondylar ridge of shaft of femur Insertion : Head of fibula Nerve supply: Long head: tibial portion of sciatic nerve Short head: common peroneal portion of sciatic nerve Actions: Flexes and laterally rotates leg at knee joint; long head also extends thigh at hip joint
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S e m i t e n d i n o s u s Origin : Ischial tuberosity Where? Insertion: Upper part of medial surface of shaft of tibia (SGS area) Nerve supply : Tibial portion of sciatic nerve Actions: Flexes and medially rotates leg at knee joint; extends thigh at hip joint
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Origin: Ischial tuberosity, where? Insertion: Medial condyle of tibia Nerve supply: Tibial portion of sciatic nerve S e m i m e m b r a n o s u s Actions : Flexes and medially rotates leg at knee joint; extends thigh at hip joint
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Origin: Ischial tuberosity Insertion: Adductor tubercle of femur Nerve supply: Tibial portion of sciatic nerve Actions: E x t e n d s t h i g h a t h i p j o i n t D o e s i t f l e x t h e k n e e ? A d d u ct o r ma g n u s ( h a mst rin g p o rt io n ) Or ischial part
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Pay attention to the fact that the muscles of the thigh are designed To act on the knee joint For example, quadriceps femoris occupies the anterior compartment of the thigh but its Main action is to extend the knee joint The same should be considered for the muscles of the posterior compartment of the thigh Although they occupy the posterior compartment of the thigh Their main function is to flex the knee joint Now think! Which muscles will rotate the knee joint medially and laterally? Keep in your mind that when the knee joint is extended medial and lateral rotation is not possible! The joint said to be locked Therefore, we need to unlock the extended (locked) knee joint A small muscle called popliteus unlocks the knee joint by rotating the femur on the tibia laterally before any flexion of the knee can take place Now the joint said to be unlocked Only now when the knee joint is semiflexed The biceps femoris can act as a lateral rotators of the leg The semimembranousus and semitendinosus can act as medial rotators of the leg
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A terminal branch of the sacral plexus (L4 and 5; S1, 2, and 3) Emerges from the pelvis through the lower part of the greater sciatic foramen below the piriformis muscle It is the largest nerve in the body and consists of the tibial and common peroneal nerves bound together with fascia.
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  • Fall '16
  • Tibial nerve, peroneal nerve

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