Posterior muscles of the knee
Biceps
Short head from linea aspera, long head by a common tendon with semitendinosus from ischial tuberosity.
Two heads of the biceps femoris join laterally and insert on the head of the fibula.
Posterior to LCL on CS imaging
Semimembranosus
Origin at the ischial tuberosity to attach on horizontal groove on the posterior surface of the medial condyle of the tibia.
Semimembranosus
Origin at the ischial tuberosity to attach on horizontal groove on the posterior surface of the medial condyle of the tibia.
Deeper than semitendinosus
Semitendinosus
Originates by a common tendon with long head of biceps from ischial tuberosity and runs medially
Distally, the muscle gives way to very long and slender tendon, which attaches distally on tibial tuberosity.
Orthopods use part of the distal tendon to reconstruct torn ACL.
Superficial and medial to semimembranosus
Semitendinosus
Originates by a common tendon with long head of biceps from ischial tuberosity and runs medially
Distally, the muscle gives way to very long and slender tendon, which attaches distally on tibial tuberosity.
Orthopods use part of the distal tendon to reconstruct torn ACL.
Superficial and medial to semimembranosus
Gracilis
Runs from the ischial tuberosity to the tibial tuberosity (TT).
Sartorius
Runs from the ASIS to TT.
Pes anserinus
Distal tendons of the sartorius, gracilis and semitendinosus (SGS) pass medial to the medial collateral ligament on their way to TT and are collectively called pes anserinus.
Anserine bursa lies between three tendons and MCL and this should not be mistaken for a popliteal cyst. Popleteal cycts occurs more posteriorly, between the tendon of medial head of gastrocnemius and semimembranosus tendon.
Plantaris
Lies just under the lateral head of the gastrocnemius
Popliteus
Short muscle that helps to build part of the floor of the popliteal fossa.
Popliteus pulls LM posteriorly when knee is flexed, rotates the tibia with knee in extension
Deep to biceps and LCL
Gastrocnemius
Powerful flexor of the ankle and knee.
Two heads, arising above the medial and lateral femoral condyles, unite with a broad aponeurosis that extends distally to become the Achilles tendon.
The lateral head of the gastrocnemius may contain a small sesamoid bone called fabella (30%), ossified in 10 % and should not be mistaken for an intraarticular body.
