Muscles of Posterior Thigh

Question 1

Semitendinosus

Answer 1

O:
Ischial tuberosity

I:
Medial surface of superior part of tibia

A: 
Extend thigh
Flex leg 
Medially rotate leg 
When thigh and leg fixed, can extend trunk 

N:
Tibial division of sciatic nerve L5-S2

Question 2

Semimembranosus

Answer 2

O:
Ischial tuberosity

I:
Posterior part of medial condyle of tibia
Oblique popliteal ligament

A: 
Extend thigh
Flex leg
Medially rotate leg 
Can extend trunk when LE fixed 

N:
Tibial division of sciatic n L5-S2

Question 3

Biceps Femoris

Answer 3

O:
Long head–ischial tuberosity
Short head–lateral lip of linea aspera and lateral supracondylar line

I:
Lateral side of head of fibula
Tendon is split by the LCL

A:
Flexes leg
Laterally rotates leg
Extends thigh at start of walking

N:
Long–tibial division of sciatic n L5-S2
Short–common peroneal div of sciatic n L5-S2