Posterior compartment of the thigh (dave's notes)

Question 1

What is the cutaneous supply to the posterior compartment of the thigh?

Answer 1

The posterior femoral cutaneous nerve

Question 2

Where is the posterior femoral cutaneous nerve found?

Answer 2

This nerve runs beneath the fascia lata, sending off a series of perforating vessels

Question 3

Describe the fascia lata

Answer 3

Relatively thin in the upper part but much thicker in the lower part

Question 4

What is the origin and insertion of semimembranosus?

Answer 4

Origin: Upper outer quadrant of the posterior surface of the ischial tuberosity
Insertion: medial condyle to the tibia below the articular margin, fascia over popliteaus and oblique popliteal line

Question 5

List the muscles of the posterior compartment of the thigh

Answer 5

Semimembranosus
Semitendinosus
Biceps femoris long head
Biceps femoris short head

Question 6

What is the origin and insertion of semitendinosus?

Answer 6

Origin: Upper inner quadrant of the posterior surface of the ischial tuberosity
Insertion: Upper medial shaft of the tibia behind gracilis

Question 7

What is the origin and insertion of biceps femoris (long head)?

Answer 7

Origin: Upper inner quadrant of the posterior surface of the ischial tuberosity
Insertion: Styloid process of the head of the fibular, lateral collateral ligament and lateral tibial condyle

Question 8

What is the origin and insertion of biceps femoris (short head)?

Answer 8

Origin: Middle 1/3 of line aspera, lateral supracondylar ridge of the femur
Insertion: Styloid process of the head of the fibula, lateral collateral ligament and lateral tibial condyle

Question 9

What is the action and innervation of semimembranosus? Where does it lie relative to tendinosis?

Answer 9

Action: Flexes and medially rotates the knee - extends the hip
Innervation: Tibial portion of the sciatic
Lies more lateral

Question 10

What is the action and innervation of semitendinosus? Where does it lie relative to membranous?

Answer 10

Action: Flexes and medially rotates the knee and extends the hip
Innervation: Tibial portion of the sciatic nerve

Question 11

What is the action and innervation of biceps femoris - long head?

Answer 11

Action: Flexes and laterally rotates the knee. Long head extends the hip.
Innervation: Tibial portion of the sciatic nerve

Question 12

What is the action and innervation of biceps femoris - short head?

Answer 12

Action: Flexes and laterally rotates the knee. Short head does not extend the hip.
Innervation: Common peroneal portion of the sciatic nerve

Question 13

Where does the sciatic nerve emerge and run thereafter?

Answer 13

Emerges below piriformis, and runs vertically down through the hamstring compartment

Question 14

What does the sciatic nerve lie deep to?

Answer 14

Long head of biceps

Question 15

Where does the sciatic nerve divide? Into what?

Answer 15

At the apex of the popliteal fossa it diodes into tibial and common peroneal (fibular)

Question 16

Describe an anatomical variant of the sciatic nerve

Answer 16

It may emerge as two separate nerves, in which case the peroneal (fibular) part pierces the lower margin of piriformis

Question 17

What does the sciatic nerve supply?

Answer 17

Tibial portion: Semimebranosus, semitendinosus, part of adductor magnus, long head of biceps.
Common peroneal portion: Short head of biceps

Question 18

What is the blood supply to the sciatic nerve?

Answer 18

The inferior gluteal artery - the artery of the sciatic nerve