Posterior thigh and hip flexor muscles

Question 1

Biceps femoris
* origin
* insertion
* action
* innervation

Answer 1

• origin:
  Long head: tuberosity of the ischium
  short head: linea aspera of the femur
• insertion: head of fibula; lateral condyle of tibia
• action:
  Both heads: flexion of the leg; external rotation of flexed leg
  Long head: extension of the thigh
• innervation:
  Long head: tibial nerve
  Short head: common peroneal nerve

Question 2

Semitendinosus
* origin:
* insertion:
* action:
* innervation:

Answer 2

• origin: tuberosity of the ischium; sacrotuberous ligament
• insertion: pes anserinus (proximal tibia)
• action: flexion of the leg; internal rotation of the flexed leg; extension of the thigh
• innervation: tibial nerve

Question 3

Semimembranosus
* origin:
* insertion:
* action:
* innervation:

Answer 3

• origin: tuberosity of the ischium
• insertion: dorsal surface of the medial condyle of the tibia
• action: flexion of the leg; internal rotation of flexed leg; extension of the thigh
• innervation: tibial nerve

Question 4

Psoas major
* origin:
* insertion:
* action:
* innervation:

Answer 4

• origin: transverse processes, L1-L5
• insertion: lesser trochanter of the femur
• action: flexion of the thigh; flexion of trunk (from supine)
• innervation: branches of lumbar plexus (branches of L1-L4)

Question 5

Iliacus
* origin:
* insertion:
* action:
* innervation:

Answer 5

• origin: iliac fossa
• insertion: lesser trochanter of femur
• action: flexion of thigh; flexion of trunk (from supine)
• innervation: femoral nerve