Abdominal wall

Superior - diaphragm
Inferior - pelvic inlet
Anterior - anterior abdominal wall
Posterior - lumbar vertebrae, upper part of bony pelvis. psoas and quadratus lumborum muscles

Cutaneous nerve supply from anterior rami lower six thoracic and first lumbar nerves
The dermatomes are supplied as follows:
- T7 - epigastrium
- T10 - umbilicus
- L1 - inguinal ligament
Cutaneous arteries are branches of:
- Superior and inferior epigastric arteries
- Intercostal and lumbar arteries
Venous drainage is into the axillary and femoral veins
A few small paraumbilical veins drain into the portal vein
Lymphatic drainage is into axillary and superficial inguinal nodes

Divided into two layers
- Superficial fatty layer - Camper's fascia
- Deep membranous layer - Scarpa's fascia
Fatty layer continuous with superficial fat of the rest of the body
Deep fascia continuous with deep fascia of the thigh
Deep layer also invests the perineum - Colle's fascia

Rectus sheath encloses rectus abdominis and pyramidalis muscle
Contains anterior rami of lower six thoracic nerves
Also contains superior and inferior epigastric vessels
Formed by aponeurosis of three lateral abdominal muscles
Between costal margin and anterior superior iliac spine
- Aponeurosis of internal oblique splits to enclose rectus muscle
- External oblique aponeurosis passes in front of muscle
- Transversus aponeurosis passes behind muscle
Between anterior superior iliac spine and pubis
- All three muscles form anterior wall
- Posterior wall is absent
Curved lower posterior border of rectus sheath is know at the arcuate line
At this level inferior epigastric vessels enter the rectus sheath
Rectus sheath is separated from fellow on opposite side by the linea alba

The abdominal wall