T4 - Posterior Compartment OF Thigh PDF

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SHORT NOTES FOR THE LOWER LIMB (THIGH): UNIT 4

WALTER SISULU UNIVERSITY FACULTY OF HEALTH SCIENCES DEPARTMENT OF HUMAN BIOLOGY

SUPPORT MATERIAL FOR THE MUSCULOSKELETAL BLOCK (MBChB II) THE THIGH (5 UNITS: 4 of 5)

COMPILED BY: Sylvia Kamanzi-wa

UNIT 4: POSTERIOR COMPARTMENT OF THE THIGH Figure references are provided on page 6

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The posterior compartment of the thigh contains muscles that are collectively known as the hamstrings (muscles 1 -4 in Figure 1 and adjacent table). Note that the adductor component of adductor magnus is excluded. These muscles have a common origin from the ischial tuberosity (Figure 2). Notice how they diverge at the knee to create the upper borders of the popliteal fossa.

1 2 3 4

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Muscle Biceps femoris Semitendinosis Semimembranosis Adductor magnus (hamstring part) Gracilis Iliotibial tract

1 2

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3 3

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SHORT NOTES FOR THE LOWER LIMB (THIGH): UNIT 4

Figure 2

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The lateral hamstring is the biceps femoris. Notice that its short head is located lower in the thigh. The adjacent cross section therefore comes from the lower half to third of the thigh before semitendinosis becomes a tendon. Semitendinosis rests on the muscular semimembranosis in most of the thigh. Semimembranosis in turn rests on adductor magnus. The hamstrings cross both the hip and knee joints. They are extensors of the hip and flexors of the knee. Since biceps inserts onto the head of the fibula its additional action is in the leg. It rotates the lower leg laterally. Since semimembranosis and semitendinosis insert proximally on the medial tibia, they similarly, cause the lower leg to rotate medially. The root values of the sciatic nerve are L4, 5, S1, 2, 3. It passes into the thigh midway between the ischial tuberosity and the greater trochanter, and descends almost vertically. It most often divides in the upper popliteal fossa into tibial and common fibular branches (Figure 3). Ignore the branches of the sciatic nerve in the leg and foot. You are not required to know the branches to individual muscles. The objective is to reinforce the concept of nerve of the compartment.

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The nerve of this compartment is the tibial division of the sciatic nerve. The short head of the biceps femoris muscle is supplied by the common fibular branch of the sciatic nerve. The arteries of this compartment are perforating branches (3) of the profunda femoris branch of the femoral artery (Figure 4). Some consider the termination of the profunda to be the 4th perforator. The vessels enter the posterior compartment from the medial compartment via tendinous arches in adductor magnus.

Figure 3

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SHORT NOTES FOR THE LOWER LIMB (THIGH): UNIT 4

Figure 4

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Reference Figure 1

http://droualb.faculty.mjc.edu/Lecture%20Notes/Unit%203/muscles%20with%20figures.ht m

2

https://teachmeanatomy.info/lower-limb/muscles/thigh/hamstrings/

3

https://cz.pinterest.com/pin/185703184618611372/ https://teachmeanatomy.info/lower-limb/nerves/sciatic-nerve/

4

https://en.wikipedia.org/wiki/Perforating_arteries#/media/File:Gray548.png

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