Part 4: Posterior Compartment of Thigh

Question 1

What is the majority of cutaneous supply of the posterior compartment?

Answer 1

Posterior femoral cutaneous nerve

Question 2

What is the origin, insertion, action and innervation of semimebranosis?

Answer 2

O: Upper outer quadrant of post ischial tuberosity
I: Medial condyle tibia, below articular margin
A: Flexes and medially rotates knee, extends hip
N: Tibial portion of sciatic nerve

Question 3

What is the origin, insertion, action and innervation of semitendinosis?

Answer 3

O: Upper inner quadrant of post ischial tuberosity
I: Upper medial shaft of tibia, behind gracilis
A: Flexes and medially rotates knee. Extends hip
N: Tibial portion of sciatic nerve

Question 4

What is the origin, insertion, action and innervation of Biceps Femoris long head

Answer 4

O: Upper inner quadrant of post ischial tuberosity
I: Styloid process of head of fibula, lateral collateral ligament + lateral tibial condyle
A: Flexes and laterally rotates knee, extends hip
N: Tibial portion of sciatic nerve

Question 5

What is the origin, insertion, action and innervation of Biceps Femoris short head

Answer 5

O: Middle 1/3 linea aspera, lateral supracondylar ridge of femur
I: Styloid process head of fibula, lat collateral ligs and lat tibial condyle
A: Flexes and laterally rotates knee - short head has no action on hip
N: Common peroneal portion of sciatic nerve

Question 6

Describe the path of sciatic nerve

Answer 6

Emerges below piriformis, runs vertically down deep to long head of biceps; At apex of popliteal fossa it divides to peroneal and tibial portions.
Has it own artery (branch of inferior gluteal) which runs along with it.