The Abdominal Wall

Question 0

Describe the major landmarks of the abdominal wall

Answer 0

Linea alba down midline
Linea semilunaris
Tendinosus intersections (six pack)

Question 1

Describe the structure and layers of the abdominal wall

Answer 1

Layers - skin, subcutaneous fat, camper fascia, scarpa fascia, muscles, transversalis fascia, peritoneum

Question 2

Describe the abdominal wall musculature

Answer 2

External oblique - downwards (ribs --> aponeurosis) 
Internal oblique - upwards (pelvic brim --> aponeurosis) 
Transversalis abdominis (transverse processes --> aponeurosis) 
Rectus abdominus

Question 3

Describe commonly used surgical incisions in the abdominal wall

Answer 3

Below arcuate line (1/3 umbilicus –> pubic symphysis) - Pfannenstiel incision for C section
McBurney’s point (2/3 umbilicus –> ASIS) - appendicectomy (gridiron incision)

Question 4

Describe and give examples of referred pain relating to the abdominal cavity

Answer 4

Appendicitis:
Initially felt around belly button area (T10) due to irritation of visceral pleura
Later felt in right iliac fossa when inflammation has spread to parietal pleura

Question 5

Give some causes of referred diaphragmatic irritation causing shoulder tip pain

Answer 5

Peritonitis
Perforated ulcer
Ruptured spleen 
Ectopic pregnancy 
Due to C3,4,5

Question 6

Describe areas of potential weakness in the abdominal wall

Answer 6

Linea alba
Epigastric
Umbilicus
Inguinal ligament

Question 7

Distinguish direct and indirect inguinal hernias and describe them in relation to their relevant anatomy

Answer 7

Direct inguinal hernia - herniation through superficial ring of inguinal canal, weak area within Hesselbach’s triangle
Indirect inguinal hernia - herniation through deep inguinal ring, within the diverging arms of the transversalis fascial sling (appear in scrotum/labia majora)
Hesselbach’s triangle - weak area found medial to inferior epigastric and femoral vessels, lateral of rectus abdominus muscle

Question 8

Describe the location of the inguinal ligament

Answer 8

ASIS –> pubic tubercle

Question 9

Describe how to differentiate direct and indirect hernias in clinical practise

Answer 9

Reduce hernia
Occlude deep inguinal canal
Ask patient to cough
If hernia protrudes –> direct

Question 10

Explain the concept of somatic and visceral referred pain

Answer 10

Referred pain - pain perceived at a site distant from the site causing pain
Somatic - noxious stimulus to the proximal part of a somatic nerve perceived in the distal dermatome
Visceral - visceral afferent pain fibres follow sympathetic fibres back to same spinal cord segments that give rise to preganglion sympathetic fibres –> CNS perceives pain as coming from somatic portion of body supplied by relevant spinal cord segment

Question 11

Describe epigastric, umbilical and femoral hernias in relation to their relevant anatomy

Answer 11

Epigastric (hiatus hernia):
Sliding - gastrooesophageal junction slides through diaphragm into chest
Rolling - part of fundus of stomach passes into chest along with oesophagus
Umbilical:
Risk of strangulation
Occur in children (weakness of umbilical scar)
Protrude through linea alba
Femoral:
Any hernia occurring below the inguinal ligament
Common in females
More likely to strangulate