T2 - Anterior Compartment OF Thigh PDF

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COMPARTMENT S OF THIGH...

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SHORT NOTES FOR THE LOWER LIMB (THIGH): UNIT 2

WALTER SISULU UNIVERSITY FACULTY OF HEALTH SCIENCES DEPARTMENT OF HUMAN BIOLOGY

SUPPORT MATERIAL FOR THE MUSCULOSKELETAL BLOCK (MBChB II) THE THIGH (5 UNITS: 2 of 5)

COMPILED BY: Sylvia Kamanzi-wa

UNIT 2: THE ANTERIOR COMPARTMENT OF THE THIGH Figure references are provided on page 7

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Orientation

Figure 1 Notice that in the left 3 pictures, a page has been fixed to a board and pages have been attached to a binder. Observe the effect of point/ area of fixation on the movement possible by the object. When fixed by the drawing pin, the page can only swivel in the plane of the board. When fixed on the top, the pages of the binder can flip either forward or backwards. When fixed at the side, the pages of the binder can be turned either left or right. Common sense reasoning like this helps us to understand rotation about an axis at joints. The 3 pictures on the right, summarize the point and areas of fixation as axes (anteroposterior, mediolateral, and vertical). Note that planes and axes are imaginary lines that help us to develop a three dimensional visualization of the body.

Figure 2 When the body is ‘fixed’ as if by the drawing pin (ventral to dorsal), movement occurs in the frontal plane and is termed abduction and adduction. If the body is fixed by pins attached in a medial to lateral direction, movement occurs in the sagittal plane (flexion and extension. If the fixing pins are vertically placed (cranial to caudal), the body is able to pivot medially or laterally (medial/ internal rotation and lateral or external rotation respectively).

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Figure 3

Figure 3

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Movement therefore occurs as couples: flexion vs extension; abduction vs adduction; medial rotation vs lateral rotation. Using the logic developed on page 2 helps us to predict where to find the different muscle groups that make these movements possible. We note the following with respect to the hip joint: Flexors are anterior to the center of the joint and extensors are posterior to it in order to effect movement in the sagittal plane around the medial-lateral axis. Because of limb rotation during development, knee flexors are posterior and knee extensors are anterior. Abductors are lateral to the center of the joint and adductors are medial to it in order to effect movement in the coronal (frontal) plane. Medial and lateral rotators are more complex to explain. We can summarize as follows: both lateral and medial muscles can be medial and lateral rotators. If, the line of pull of the muscle turns the center of the hip joint towards the anterior midline then medial/ internal rotation has occurred. If the line of pull of the muscle turns the center of the joint towards the posterior midline then lateral/ external rotation has occurred. This movement couple occurs around the vertical axis.

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The anterior compartment of the thigh includes 8 large muscles and 1 very small one. Seven of the 8 muscles are shown in Figure 1 (key in adjacent table). The eighth muscle (vastus intermedius) cannot be seen in Figure 1 because it is at a deeper level (deep to muscle 5). The smallest muscle is associated with the knee joint (we need not dwell on it).

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Muscles 1 and 2 are together known as the iliopsoas; muscles 5, 6, 7, 8 are collectively known as the quadriceps femoris.

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The muscles of this compartment are supplied by the femoral nerve with two exceptions: psoas major is supplied by the ventral rami of L1-L3 and is therefore said to occupy the anterior compartment rather than be an actual muscle of it; the pectineus muscle receives a dual neve supply (obturator and femoral) and thus belongs to both the anterior and the medial (adductor) compartment.

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Although the muscles indicated by the red and white asterisks appear anterior facing, they are not supplied by the femoral nerve.

1

2

*

1 2 3

3 4 5

* *

Muscle Iliopsoas Pectineus

4 5 6 7 8

Sartorius Quadriceps femoris

* **

Gluteal muscle Muscles of medial compartment

6 7

Iliacus Psoas major

Rectus femoris Vastus lateralis Vastus medialis Vastus intermedius is not shown

Nerve Femoral L1-L3 Femoral, obturator

Femoral

Superior gluteal Obturator

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The muscles of the anterior compartment can act across two joints (hip and knee). The muscles that cross anterior to the hip (iliopsoas, pectineus, and straight head of rectus femoris) cause flexion there. The vasti originate from the femur only and thus do not acts across the hip. The quadriceps tendon crosses anterior to the knee joint and inserts on the tibial tuberosity as the patellar tendon. It is therefore an extensor of the knee joint.

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Notice that although sartorius muscle originates anterior to the hip joint it inserts posteromedially at the knee. It therefore flexes both joints.

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Since psoas attaches to the lesser trochanter, its line of pull also allows for lateral rotation at the hip. The line of pull of the sartorius is also favorable for lateral rotation.

Figure 5

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Ignore the obturator nerve (in Figure 5). The root values of the femoral nerve are L2, 3, 4. You are not required to know the individual nerve supply of muscles. The picture serves to reinforce the concept of nerve of the compartment.

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The artery of the anterior compartment is the femoral artery (Figure 6). At this stage, we shall only focus on its surface markings. It begins as a continuation of the external iliac artery midway between the anterior superior iliac spine and the pubic symphysis. This is known as the femoral point and is where the femoral pulse can be felt. It travels almost vertically down the thigh towards the adductor tubercle (green arrow) and enters the popliteal fossa by passing through the adductor hiatus.

Figure 6

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Reference Figure 1

https://www.cleanpng.com/png-paper-clip-post-it-note-drawing-pin-clip-art-pinne4033026/ https://clip.cookdiary.net/wallpaper-7886169

2

https://www.cleanpng.com/png-paper-clip-post-it-note-drawing-pin-clip-art-pinne4033026/ https://clip.cookdiary.net/wallpaper-7886169 https://thesebonesofmine.com/2011/02/28/the-biological-basis-of-bone-anatomicaldirectional-terms/

3

https://thesebonesofmine.com/2011/02/28/t he-biological-basis-of-bone-anatomicaldirectional-terms/ https://ouhsc.edu/bserdac/dthompso/web/namics/hipintro.htm

4

https://ouhsc.edu/bserdac/dthompso/web/namics/hipintro.htm https://teachmeanatomy.info/lower-limb/muscles/thigh/anterior-compartment/

5

https://www.orthobullets.com/anatomy/10058/vastus -lateralis

6

https://www.slideshare.net/AtifRaza11/anterior-cmpartment-of-thigh

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