Anterior Abdominal Wall Anatomy

Overview

• Discussing anterior view of the abdominal wall, moving from skin to coelomic sac.
• Previous tutorial focused on cross-sectional view.

Innervation

• Dermatomes:
  • Skin innervated by intercostal nerves (T7 to L1).
  • T7 to T12: segmental nerves innervating the abdominal wall.
  • L1: Inguinal region innervation.
• Nerve Pathways:
  • Ventral ramus travels between internal oblique and transverse abdominis muscles.
  • Lateral cutaneous nerve branches laterally.
  • Anterior cutaneous branch innervates mid-sagittal line.

Layers of the Abdominal Wall

1. Skin
2. Hypodermis/Fascia:
   • Camper's Fascia:
     • Adipose tissue responsible for the pannus or beer belly.
   • Scarpa's Fascia:
     • Fibrotic, found between umbilicus and inguinal region.
3. External Muscle Fascia:
   • Underneath hypodermis, covers somatic muscle plane.

Muscle and Aponeurosis Layers

• Lateral Wall Muscles:
  • External Oblique:
    • Fibers run at an angle, external aponeurosis connects to linea alba.
  • Internal Oblique:
    • Fibers run at right angles to external oblique, aponeurosis fuses at linea alba.
  • Transverse Abdominis:
    • Deepest layer, aponeurosis courses behind rectus abdominis.
• Ventral Strap Muscle:
  • Rectus Abdominis:
    • Runs vertically, divided by linea alba.
    • Contains tendinous intersections (six-pack appearance).

Rectus Sheath

• Above Umbilicus:
  • Aponeuroses (external/internal oblique) course over and behind rectus abdominis.
• Below Arcuate Line:
  • All aponeuroses course in front of rectus abdominis.

Fascia Layers

• Transversalis Fascia:
  • Deeper muscle fascia.
• Preperitoneal Fascia:
  • Anchors parietal peritoneum to body wall.

Parietal Peritoneum

• Forms Lateral Umbilical Folds: houses inferior epigastric vessels.
• Medial Umbilical Folds: Obliterated umbilical arteries.
• Median Umbilical Fold: Contains obliterated urachus.

Additional Structures

• Falciform Ligament:
  • Contains round ligament of liver (remnant of umbilical vein).

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These notes outline the key anatomical features and structures of the anterior abdominal wall as discussed in the lecture.