Organization of the antero-lateral abdominal wall

Boundaries

Superiorly:

• Xiphoid process.
• Costal cartilages of the 7th and 10th ribs.

Inferiorly:

• Iliac crest.
• Anterior superior iliac spine.
• Inguinal ligament.
• Pubic tubercle, pubic crest and pubic symphysis.

Divided into 4 quadrants i.e

1. Right and left upper quadrants
2. Right and left lower quadrants

Can be Divided into 9 regions.

• Two vertical planes- midclavicular
• Two horizontal planes:
  • Subcostal plane – joining the most inferior points of the costal margins, and passing at L3.
    
    
  • Transtubercular plane, joining the tubercles of the iliac crest.

• Right and left hypochondrial regions (1and 3)
• Middle epigastric region (2)
• Right and left lumbar regions (6 and 4)
• A middle umbilical region (5)
• Right and left iliac (inguinal) region (7and 9)
• A middle hypogastric or suprapubic region (8)

Layers of anterior abdominal wall

• Skin
• Superficial fascia: Fatty and membranous
• Deep fascia
• Muscles:
• Extra peritoneal tissue
• Peritoneum.

Skin

• Shows ‘creases' which represent the lines of orientation of collagen fibres in the dermis- Langer's lines.
  
  
• These lines are surgically important – incisions along them heal better leaving a thin scar; while those across them leave big scars.
  
  
• In pregnant women, obese people and those with abdominal distention from whatever cause, there are dark elongate lines called striae gravidara.
  
  
• The skin is very sensitive to touch, and quickly when touched, the muscles contract.

Consists of two layers;

• Fatty layer (Camper's fascia) containing variable amounts of fat, more in females and in the lower abdomen.
  
  
• Membranous layer (Scarpa's fascia).
  
  (+) Contains fibrous tissue and very little fat.
  (+) Fuses with fascia lata below inguinal ligament)
  (+) Continuous with the superficial perineal fascia (Colle's fascia) and with that investing the scrotum and penis.
  
  

Unremarkable

There are 4 main muscles to note:

• External oblique
  
  
• Internal oblique
  
  
• Transversus abdominis
  
  
• Rectus abdominis

Note the attachment and innervation of these muscles.

• Support and protection for abdominal viscera
  
  
• Movement of the trunk – flexion, extension, twisting and lateral bending.
  
  
• Maintenance of     posture
  
  
• Increase intra abdominal pressure in functions such as defecation, micturition and parturition etc.