Layers of the Abdominal Wall Anatomy

Abdominal Wall Layers

• The abdominal wall consists of 9-12 layers, depending on the location with respect to the arcuate line.
• The layers of the abdominal wall are:
  • Skin
  • Camper's fascia (fatty layer)
  • Scarpa's fascia (membranous layer)
  • External oblique muscle
  • Internal oblique muscle
  • Transversus abdominis muscle
  • Transversalis fascia
  • Extraperitoneal fat
  • Parietal peritoneum

Rectus Sheath

• The rectus sheath is a protective covering over the rectus abdominis muscle.
• It is composed of the aponeurosis of the three flat muscles (external oblique, internal oblique, and transversus abdominis) as they converge in the midline to form the median linea alba.
• The composition and arrangement of muscle layers differ depending on the location with respect to the arcuate line.
• Inferior to the arcuate line, the aponeuroses of all 3 lateral abdominal muscles pass anterior to the rectus abdominis muscle.
• At this level, the internal aspect of the rectus abdominis muscle is in direct contact with the transversalis fascia.

Camper's Fascia and Scarpa's Fascia

• Camper's fascia is a thick superficial layer of adipose and areolar connective tissue that sits just deep to the skin of the abdomen.
• It is more prominent in the lower aspect of the abdomen (inferior to the umbilicus).
• Scarpa's fascia is a deep membranous layer that sits between Camper's fascia and the rectus sheath.
• It is anchored laterally to the aponeurosis of the external oblique and medially to the linea alba of the rectus sheath.

Abdominal Muscles

Anterior Abdominal Wall Muscles

• Obliquus externus abdominis (External abdominal oblique muscle):
  • Origin: External surfaces of lower 8 ribs
  • Insertion: Linea alba, pubic tubercle, anterior half of iliac crest
  • Function: Nerve supply from intercostal nerves (T7 to T12)
• Obliquus internus abdominis (Internal abdominal oblique muscle):
  • Origin: Lateral 1/3 of inguinal ligament, anterior 2/3 of iliac crest, thoracolumbar fascia
  • Insertion: Linea alba, lower 3 ribs
  • Function: Nerve supply from intercostal nerves (T6 to T12) & L1
• Transversus abdominis muscle:
  • Origin: Not specified
  • Insertion: Not specified
  • Function: Not specified

Test your knowledge on the layers of the abdominal wall including Skin Camper’s Fascia, Scarpa’s Fascia, and Rectus Sheath. Understand the arrangement of anterior and posterior laminae, as well as structures like Transversalis fascia, extraperitoneal fat, and parietal peritoneum.