Session 3- Abdominal Wall and Hernias

Question 1

Give the 4 functions of the abdominal wall

Answer 1

• Firm flexible wall keeps abdominal viscera in abdominal cavity
• Protects abdominal viscera
• Maintains position of abdominal viscera against gravity
• Involved in actions that increase intra-abdominal pressure e.g. coughing or vomiting.

Question 2

Name the flat muscles of the abdominal wall. State the direction in which they run.

Answer 2

1) External oblique – most superficial. Fibres run inferomedially (hands in pockets) and form an aponeurosis in the midline. In the mid line, the aponeuroses of all the flat muscles become entwined, forming the linea alba.
2) Internal oblique – Fibres run superiormedially (at a 90 degree angle to externalis). Contributes to linea alba
3) Transversus abdominis – Deepest layer of flat muscles. Transversely running fibres. Underneath this muscle is the transversalis fascia.

Question 3

What is the function of the flat muscles of the abdominal wall?

Answer 3

Laterally flex and rotate trunk

Question 4

State the vertical muscle of the abdominal wall. What is its function? What is its structure?

Answer 4

Split into two by linea alba.

Separated by tendinous intersections.

Assists flat muscles in compressing abdominal viscera, stabilises pelvis during walking, flexion of trunk, and depresses ribs.

Question 5

Label the following

Answer 5

Question 6

What is the rectus sheath? What forms its anterior and posterior walls?

Answer 6

• Formed by the aponeuroses of the three flat muscles and encloses the rectus abdominis
• Anterior wall formed by aponeuroses of the external and internal oblique
• Posterior wall formed by aponeuroses of the internal oblique and transversalis abdominis.

Question 7

Where is the arcuate line? What occurs below it?

Answer 7

• The area below the arcuate line (midway between umbilicus and pub symphysis) There is not posterior wall to the sheath and the rectus abdominis is in direct contact with the transversalis fascia.

Question 8

Label the following

Answer 8

Question 9

Label the following

Answer 9

Question 10

What is a grid iron incision?

Answer 10

cuts are made according to the way which the muscle fibres run to avoid cutting them.

Question 11

Where is mcburney’s point?

Answer 11

1/3 of the distance between the ASIS and the umbilicus

Question 12

Where is a transverse incision made? What does it give access to?

Answer 12

Made inferior and laterally to the umbilicus. Gives access to colon, duodenum and pancreas

Question 13

What is ectopia cordis and why does it occur?

Answer 13

Heart located out of thorax and is located in abdomen, cervical or thoracic area.

Occurs during lateral plate folding, sternum split and allows heart to leave thoracic cavity.

Question 14

What is patent urachus? Why is it clinically relevant?

Answer 14

Urachus which connects bladder to umbilicus remains open. Can lead to adenocarcinoma of the urachus

Question 15

What is patent vitellointestinal duct?

Answer 15

Duct connecting umbilicus and intestine remains open

Question 16

What is exampholos? Why does it occur

Answer 16

Peritoneum pouch protrudes through the umbilicus, Occurs due to defect in the abdominal muscles formed.

Question 17

Define referred pain.

Answer 17

Pain perceived at a site distant from the site causing the pain.

Question 18

What is somatic referred pain?

Answer 18

Pain caused by a stimulus in the proximal part of a somatic nerve is perceived in the distal dermatome of the nerve.

Question 19

Why does visceral referred pain occur? What makes visceral referred pain occur?

Answer 19

• Caused by ischaemia, inflammation or stretching
• Due to Low density of sensory innervation of viscera, pain is non specific. Convergence of the visceral nerves entering the spinal cord at the same level as somatic nerves results in the sensations being referred to surface areas of the body.

Question 20

Explain why early appendicitis and late appendicitis manifest differently in terms of pain localisation

Answer 20

Early appendicitis is general midgut.

Later is right midgut

In early appendicitis - visceral referred pain

In late appendicitis - Appendix becomes so inflamed that it starts to irritate the posterior abdominal wall, localising the pain to that area.

Question 21

Why does irritation of the diaphragm result in pain in the shoulder? Give 2 examples of what can irritate the diaphragm.

Answer 21

The phrenic nerve innervates the diaphragm, and therefore irritating the diaphragm can result in referred pain to the shoulder which is served by the spinal nerves C3-C5.

Ectopic pregnancy, and ruptured spleens.

Question 22

Name the 3 parts of the small intestine and state them in proximal to distal order. Are they retro or intraperitoneal?

Answer 22

Duodenum, jejunum, ileum Proximal duodenum is retro.

Everything else in intra.

Question 23

Label the following

Answer 23

Question 24

Where is the pancreas located? Where is the duodenum in relation to the pancreas? Is it intra or retroperitoneal?

Answer 24

Posterior and inferior to the stomach.

Head of the duodenum curves around pancreas.

Aside from tail it is retroperitoneal

Question 25

Where is the gall bladder located? is it intra or retroperitoneal?

Answer 25

Intraperitoneal.

Inferior to liver.

Question 26

Where is the spleen located? intra or retro?

Answer 26

Intraperitoneal.

Posterior to the stomach

Question 27

What spinal levels are the kidneys found at?

Answer 27

T11-L2 (left kidney) and T12-L3 (right kidney)

Question 28

What is the peritoneal cavity and why is it considered a potential space?

Answer 28

Peritoneal cavity is a potential space between the parietal and visceral peritoneum. referred to as a potential space because excess fluid can accumulate in the peritoneal cavity resulting in ascites.

Question 29

What can the greater sac be divided into? What does each division contain?

Answer 29

• Divided in two by the transverse colon into the supracolic and infracolic compartments.
• Supracolic lies above the transverse colon and contains the stomach, liver and spleen
• Infracolic lies below the transverse colon and contains the small intestine, ascending and descending colon

Question 30

What is the difference between males and females in the peritoneum? Why is there a difference? Why is it clinically relevant?

Answer 30

Males:

• The rectovesical pouch is a double folding of peritoneum between the rectum and the bladder.
• Peritoneal cavity is completely closed in males.

Females:

• Rectouterine pouch between rectum and uterus. Vesicouterine pouch between bladder and uterus.
• The peritoneal cavity is not closed in females, and therefore infections of vagina and uterus may result in infection of peritoneum.

Question 31

Define mesentery. What is contained within mesentery?

Answer 31

o Double layer of visceral peritoneum that connects an intraperitoneal organ to the posterior abdominal wall.

o Provides a pathway for nerves, blood vessels, and lymphatics from the body wall to the viscera

Question 32

What is the function of the greater omentum?

Answer 32

Can migrate to infected viscera, has role in immunity

Question 33

What is the mesocolon

Answer 33

mesentery of the colon

Question 34

Where are the subphrenic spaces located?

Answer 34

Between the diaphragm and upper side of the liver. Located on each side of the falciform ligament which splits the liver in two.

Question 35

What are the left and right paracolic gutters? Why are they clinically relevant?

Answer 35

Paracolic gutters are the spaces between the colon and the abdominal wall

Fluids can run up these gutters and infect or irritate areas remote from organ of origin.

Question 36

Define a hernia

Answer 36

Where an internal part of the body pushes through a weakness in the muscle or surrounding tissue wall.

Question 37

Give 4 areas a hernia can occur

Answer 37

Umbilical, inguinal, femoral, and epigastric

Question 38

What are the two types of inguinal hernia? Define both of them. Why is it more common in males?

Answer 38

Direct and indirect

Direct - Goes through hesselbach’s triangle, a weak area in the abdominal wall

Indirect - Abdominal contents protrude through the deep inguinal ring More common in males as they have a larger opening in the inguinal ring formed by the route of the descending testes.

Question 39

Where does a femoral hernia occur? What does this area contain?

Answer 39

Femoral canal - lymph vessels

Question 40

What is the roof of the inguinal canal made of?

Answer 40

Transversus abdominis

Question 41

What is the anterior wall of the inguinal canal made up of?

Answer 41

Internal oblique

Question 42

What is the floor of the inguinal canal made up of?

Answer 42

Inguinal ligament

Question 43

What is the posterior wall made up of?

Answer 43

Transversalis fascia