L3.3 Abdomen walls

Question 1

Layers of ANT ab wall

Answer 1

1. Skin
2. Fatty layers (superficial fascia)
   
   • Outer (camper’s fascia)
   • Inner membranous layer (scarpa’s fascia)
3. Muscles
4. Transversalis fascia
5. Extraperitoneal fascia
6. Parietal peritoneum
   
   • Single layer of serous membrane lining cavity

Question 2

Common features of the 3 layers of abdominal muscles

Answer 2

• All meet at the linea alba in midline (fibres interdigitate)
• Attaches POS to thoraco-lumbar fascia
• Fleshy LAT, aponeurotic MED

Question 3

External Oblique

Answer 3

• Direction = anteroinferiorally
• Overlap costal margin
• Attaches to ASIS & Pubic bone inferiorly
  
  • Creates the free INF edge → thickens to become the inguinal ligament

Question 4

Lacunar ligament

Answer 4

• crescent shaped extension from MED IL towards pectineal line

Question 5

Pectineal ligament

Answer 5

• Along pectineal line

Question 6

Internal oblique muscle

Answer 6

• Direction = posteroinferiorally
• Attaches to costal margin
• INF fibres arise from 2/3 of LAT IL → arches into pubic crest via conjoint tendon

Question 7

Transverse abdominus

Answer 7

• Direction = horizontal
• Underlapping costal margin
• Continuous with diaphragm
• INF fibres arise from 1/3 of LAT IL → arches into pubic crest via conjoint tendon

Question 8

Rectus abdominus

Answer 8

• Ascends & diverges (wider as ascending)
• Overlap costal margin → attaches to costal cartilage 5-7
• Tendinous intersection at level of umbilicus, xiphisternum, halfway point
  
  • Makes shorter muscles ∴ stronger
• Enclosed within rectus sheath

Question 9

Rectus sheath

Answer 9

• SUP: Aponeurosis of other muscles pass ANT or POS to RA
• INF: Apo of other muscles pass ONLY ANT.

Question 10

Contents of the rectus sheath

Answer 10

• Vessels to Ab wall
• Neurovascular plexus b/w mid & deep layer

Question 11

N to ab wall

Answer 11

• T10 = umbilicus
• L1 = groin

Question 12

Arteriole supply to ANT ab wall

Answer 12

• Epigastric vessels in rectus sheath, deep to RA
  
  • SUP = branch of internal thoracic
  • INF = branch of external iliac
    
    • Both anastomose
• Superficial epigastric A = branch of femoral A
  
  • In superficial fascia

Question 13

Venous drainage of the ANT ab wall

Answer 13

• S/I epigastric V & superficial epigastic V
• Paraumbilical V into hepatic system

Question 14

Gonads

Answer 14

• Dev in extraperitoneal fat
• Descent of testes: through inguinal canal into scrotum
  
  • Timeframe:
    
    • 12wks - pelvis
    • 28wks - through inguinal canal
    • 32wks - scrotum

Question 15

Deep inguinal ring

Answer 15

• At transversalis fascia
• 1/2 way b/w ASIS & pubic tubercle

Question 16

Superficial inguinal ring

Answer 16

• At external oblique (triangle space formed by EOM)

Question 17

Layers of the spermatic cord

Answer 17

• Connects ab cavity & system vascular supplyy

1. Internal spermatic fascia (through fascia transversalis)
2. Cremasteric fascia (beneath arching fibres of TA & IO)
   
   • Responsible for testicular contraction in the cold
3. External spermatic fascia (leaving EO)

Question 18

Inguinal hernias (general)

Answer 18

• protrusion through deep ring into inguinal inguinal canal

Question 19

Indirect inguinal hernia

Answer 19

• Following canal into scrotum (most common)
• Arise from incomplete closure of processus vaginalis (pouch dragged from parietal peritoneum)
  
  • Herniated contents extended into scrotum

Question 20

Direct inguinal hernia

Answer 20

• Contents not traversing inguinal canal
• Protrusion fwd into canal through area if weakness in POS wall
• Inguinal hesselbach triangle → weakest area