Summary Complete Limb and Trunk Anatomy Notes

BI2333 – Practical Anatomy



Posterior thigh, popliteal fossa and posterior leg

Dr Helen McCarthy, Dr Kirsty Richards

Posterior thigh muscles

Extensors of the thigh at the hip joint and flexors of the knee joint. They pull your leg when you’re trying to kick a
ball.

 Biceps femoris
 Semimembranosus
 Semitendinosus



i. Biceps femoris
Largest and strongest of the 3 muscles and consists of 2 parts, the long head and the short head. Only
muscle out of the 3 that can perform a little bit of external rotation of the knee joint

Origin: L – ischial tuberosity and the caudal part of the sacrotuberous ligament, S – linea aspera (rough
line on dorsal side of femur) and lateral supracondylar line of the femur
Insertion: both unite at the popliteal fossa and insert at the head of the fibula
Function: L – extension and stabilisation of
the hip joint, L+S – flexion of the knee joint
Innervation: L- tibial nerve, S – common
(peroneal) fibular nerve, Sciatic nerve splits
to become the tibial and peroneal nerves.



ii. Semimembranosus
Origin: Ischial tuberosity
Insertion: Medial condyle of the tibia
Function: Extension of the thigh at the hip
joint and flexion of the knee joint, internal
rotation of the knee joint
Innervation: Tibial nerve

iii. Semitendinosus
Origin: Ischial tuberosity and sacrotuberous ligament
Insertion: medial aspect of the tibia on the superficial pes anserinus (found next to the tibial tuberosity)
Function: Extension of the thigh at the hip joint, internal rotation of the knee joint and flexion of the
knee joint
Innervation: Tibial nerve

Pes anserinus – (goose foot) anatomical name given to conjoined tendons at the medial aspect of the knee.
Insertion point of 3 muscles, semitendinosus, musculus gracilis and musculus sartorius.