Anterior Abdominal Wall

Question 1

Which bones make up the pelvis?

Answer 1

• X2 pelvic bones
• X1 sacrum
• X1 coccyx

Question 2

What is another name for the pelvic bone?

Answer 2

• coxal bone

- hip bone

Question 3

What are the X3 parts of the pelvic bone?

Answer 3

1) ilium
2) ischium
3) pubis

Question 4

What is the socket joint which is formed by the fusion of the ilium, ischium and publis bones of the pelvic bone?

Answer 4

The acetabulum.

Question 5

What are the attachments of the inguinal ligament?

Answer 5

It runs from the ASIS (anterior superior iliac spine) to the ipsilateral pubic tubercle.

Question 6

What is the inguinal ligament formed from?

Answer 6

An infolding of the aponeurosis of the external oblique muscle.

Question 7

What are aponeuroses?

Answer 7

Flat, white layer of fibrous tissue (tendon like) that aids muscle attachment.

Question 8

Which joints join the sacrum to the coxal bones?

Answer 8

The sacroiliac joints.

Question 9

What is the name of the anterior join of the 2 pelvic bones?

Answer 9

The pubic symphysis.

Question 10

What is the name of the superior area of the ilium where it opens and flattens out?

What is the name of the depression in the bone found on the medial side of the ilium bone?

Answer 10

The wing of the ilium.

The Iliac fossa.

Question 11

What are the X2 imaginary vertical lines which help split the abdomen into its X9 subdivisions?

Answer 11

The mid-clavicular or mid-inguinal lines.

Question 12

What are the X2 imaginary horizontal lines which help split the abdomen into its X9 subdivisions?

Answer 12

The trans-pyloric plane
= the line which travels along the plane at which the pyloric sphincter of the stomach sits. This can be judged to be a hands width below the sternum.

The trans-tubercular plane
= the line which travels between the two ILIAC tubercles (not tubercles) - these are found above the ASIS and on the outside of the iliac wing.

Question 13

Name the X9 subdivisions of the stomach from top right to bottom left.

Answer 13

1) Right hyperchondriac
2) Epigastric
3) Left hyperchondriac

4) Right lumbar
5) Umbilicus
6) Left lumbar

7) Right iliac/inguinal
8) Hypogastric/suprapubic
9) Left iliac/inguinal

Question 14

What is the name of the pair of anterior abdominal wall muscles which run vertically?

Answer 14

Rectus abdominis

Question 15

What are the X3 layers of muscle which (along with rectus abdominis) make up the anterior abdominal wall?

Which is most superficial and which is deepest?

Answer 15

1) External oblique (most superficial)
2) Internal oblique
3) Transversus abdominis (deepest)

Question 16

Which X2 muscles make up the posterior abdominal wall?

Answer 16

1) Quadratus lumborum

2) Psoas major

Question 17

What are the layers of tissue superficial to the anterior abdominal wall muscles?

Answer 17

1) skin
2) campers fascia (fatty layer)
3) scarpers fascia (thin, membranous layer)

Question 18

What exists deep to the anterior abdominal wall muscles?

Answer 18

Deep fascia.

This sits deep to the anterior abdominal wall muscles but superficial to the parietal peritoneum. The fascia is named differently depending on its location (e.g. transversalis fascia = the deep fascia which sits behind transversus abdominis).

Question 19

What are the X2 types of peritoneum?

What is the difference?

Answer 19

Parietal peritoneum
= lines the abdominal-pelvic cavity and is adjacent to the abdominal wall muscles

Visceral peritoneum
= a continuation of the parietal peritoneum which leaves the POSTERIOR abdominal wall to line some of the abdominal organs.

Question 20

What is the name of the sections of peritoneum which connect the visceral and parietal peritoneum?

Answer 20

The mesentary,.

Question 21

What is the importance of the peritoneal organs and the mesentary?

Answer 21

They are mobile due to these structures. Retroperitoneal organs are immobile.

Question 22

In which tissue layer do superficial veins lie?

What pathways do these take to drain?

Answer 22

Campers fascia (although tiny and hard to see).

They arise from the paraumbilical region and can either drain superiorly to the axilla (lateral thoracic veins) or inferiorly to the inguinal region (femoral veins).

Question 23

What is the lymphatic drainage of the superficial anterior abdominal wall?

Answer 23

Above the plane of the umbilicus = into axillary nodes

Below the plane of the umbilicus = into inguinal nodes

Question 24

In which direction do the external oblique muscle fibres run?

Answer 24

Forwards and downwards (hands in pockets).

Question 25

In which direction do the internal oblique muscle fibres run?

Answer 25

Backwards and downwards (opposite of pockets).

Question 26

In which direction do the transversus abdominus muscle fibres run?

Answer 26

Transversely.

Question 27

What is the name of the structure created by the aponeurosis of the external oblique, internal oblique and transversus abdominis muscles which encloses the rectus abdominis muscles?

Answer 27

The rectus sheath.

Question 28

What is the name of the midline point at which the aponeurosis of the anterior abdominal wall muscles meet?

Answer 28

The linear alba (white line).

Question 29

What is the name of the line below which the rectus sheath components deep the the anterior abdominal wall muscles change?

Where is this line located?

Answer 29

The arcuate line.

This line is 2/3rds of the way down the rectus sheath.

Question 30

What is the path of the anterior abdominal wall muscle aponeuroses ABOVE the arcuate line?

Answer 30

Anterior rectus sheath layer
= external oblique aponeurosis
= 1/2 or internal oblique aponeurosis (it divides around rectus abdominis)

Posterior rectus sheath layer
= 1/2 or internal oblique aponeurosis (it divides around rectus abdominis)
= transversus abdominis aponeurosis
= transversalis fascia

Question 31

What is the path of the anterior abdominal wall muscle aponeuroses BELOW the arcuate line?

Why is there this change?

Answer 31

All aponeurosic sheets move superficial to the rectus abdominis muscles and the only posterior component of the rectus sheath is transversalis fascia.

This is so the inferior epigastric artery can pierce the thin fascia and gain access to the structures above.

Question 32

Which parts of the rectus sheath do the tendinitis intersects of rectus abdominis adhere to?

Answer 32

They adhere anteriorly but not posteriorly.

Question 33

What are the X3 bilateral folds of peritoneum deep to the rectus sheath?

What has caused them?

Answer 33

1) lateral umbilical folds
= contains the inferior epigastric artery

2) medial umbilical folds
= contains remnants of the umbilical artery

3) median umbilical folds
= contains the remnant of urachus (the allantois which connected the foetal bladder to the umbilicus)

Question 34

What is the cutaneous nerve supply of the abdomen?

What is the journey of the nerves?

Answer 34

The lower 6 intercostal nerves as they cross the costal margin and pierce the posterior wall of the rectus sheath to supply the abdominal wall.

The intercostal nerves themselves come from the anterior rami (NOT root, rami carry both sensory and motor) of T1-T11 spinal nerves.

The supply to the lowest part of the anterior abdominal wall comes from the iliohypogastric and ilioinguinal nerves which both arise from L1.

Question 35

What is the motor nerve supply of the abdomen?

What is the journey of the nerves?

Answer 35

They are the thoraco-abdominal nerves which arise from the anterior rami (NOT root) of the spinal nerves from T6-L1.

Question 36

What are the superior and inferior epigastric arteries (which help to supply the anterior abdominal wall) branches of?

Answer 36

Superior epigastric arteries are continuations of the internal thoracic artery which branches off and descends from the subclavian artery. Where the internal thoracic crosses the costal margin is where they start to be called the superior epigastric arteries. They are bilateral (X1 either side of the thoracic/abdominal cavity).

Inferior epigastric arteries are branches of the external iliac arteries, themselves being part of the bifurcation of the common iliac into internal and external.