Rectus Sheath

Question 1

Rectus sheath

Answer 1

1. Aponeurotic sheath enveloping rectus abdominis and pyramidalis muscles with their associated nerves and vessels
2. Formed by 3 aponeuroses of anterolateral abdominal wall muscles

Question 2

Formation

Answer 2

1. Above costal margin
2. Between costal margin and level midway between umbilicus and symphysis pubis
3. Below level midway between umbilicus and symphysis pubis (below arcuate line)

Question 3

Above costal margin: Anterior wall

Answer 3

External oblique aponeurosis

Question 4

Above costal margin: posterior wall

Answer 4

Deficient (muscle rests directly on 5th, 6th, and 7th costal cartilages

Question 5

Between costal margin… (Anterior wall)

Answer 5

1. External oblique aponeurosis
2. Anterior lamina of internal abdominal oblique aponeurosis

Question 6

Between costal margin… (posterior wall)

Answer 6

1. Posterior lamina of internal abdominal
2. Transversus abdominis aponeuroses

Question 7

Below level midway…(anterior wall)

Answer 7

By 3 muscles aponeuroses:
1. External abdominal oblique
2. Internal abdominal oblique
3. Transversus abdominis
2 and 3 unite to form conjoint tendon

Question 8

Below level midway…(posterior wall)

Answer 8

1. Deficient
2. Muscle is directly related to fascia transversalis

Question 9

Features: anterior wall

Answer 9

1. Forms complete covering for rectus abdominis which is thin above and increases in thickness downwards
2. Firmly attached to rectus abdominis tendinous intersections

Question 10

Features: posterior wall

Answer 10

1. Deficient above costal margin also deficient below level midway between umbilicus and symphysis pubis
2. Its lower border forms curved margin (arcuate line)

Question 11

Contents

Answer 11

2 muscles:
1. Rectus abdominis
2. Pyramidalis
2 vessels:
3. Superior epigastric
4. Inferior epigastric
5. Lower 5 intercostal and subcostal nerves and vessels
6. CT
7. Lymphatics: from breast to umbilicus
8. Sympathetic fibers
3 and 4 form anastomosis at umbilicus lying between rectus muscle and sheath posterior wall

Question 12

Applied anatomy: Paramedian abdominal incision

Answer 12

Rectus muscle is retracted lateral to avoid injury of its nerve supply

Question 13

Applied anatomy: breast cancer

Answer 13

Malignant cells may spread from cancer in the breast through lymphatics in rectus sheath leading to malignant nodules in umbilicus