What is the circulation of blood, lymphatic drainage, and innervation of the abdominal wall?

Circulation of Blood and Lymph and Innervation of the Abdominal Wall

The abdominal wall has a rich vascular supply primarily from the deep inferior epigastric arteries, which provide the main blood supply to the lower abdominal wall, along with the superior epigastric arteries, while innervation comes from thoracoabdominal nerves (T7-T12) and branches of the lumbar plexus.

Arterial Supply

Deep System

• Deep Inferior Epigastric Artery (DIEA)

  • Main blood supply to the lower abdominal wall 1
  • Arises from the external iliac artery just above the inguinal ligament
  • Usually associated with two veins (90% of cases) 1
  • Divides into lateral and medial branches:
    • Lateral division is dominant in 80% of cases 1
    • Lateral perforators are greater in number and more consistent than medial perforators 1

• Superior Epigastric Artery (SEA)

  • Continuation of the internal thoracic (mammary) artery
  • Enters the rectus sheath at the costal margin
  • Forms important perforators within 4 cm of the costal margin 2
  • These perforators are more consistent in morphology and orientation compared to DIEA perforators 2

• Anastomosis Patterns

  • Three main patterns between DSEA and DIEA 3:
    • Type I (29%): Single DSEA and DIEA
    • Type II (57%): Double-branched system of each vessel
    • Type III (14%): Three or more major branches
  • Anastomosis occurs via choke vessels in the segment above the umbilicus 3

Superficial System

• Superficial Inferior Epigastric Artery (SIEA)

  • Arises from the femoral artery
  • Supplies the lower abdominal skin and subcutaneous tissue
  • Forms multiple communications with other abdominal wall vessels 4

• Superficial Circumflex Iliac Artery

  • Supplies the lateral aspects of the lower abdominal wall
  • Anastomoses with the superficial inferior epigastric artery 5

Perforator Vessels

• Musculocutaneous Perforators

  • Most important vessels supplying the anterior abdominal wall 1
  • Average of 5.4 large perforators (>0.5 mm) per person 1
  • Concentrated laterally and below the umbilicus, approximately 4 cm from the umbilicus 1
  • Can have direct or indirect course:
    • Larger perforators (>0.5 mm) have direct course to skin 1
    • Smaller perforators terminate in deep fat layer 1

• Paraumbilical Perforators

  • Highest concentration of major perforators is in the paraumbilical area 5
  • These are terminal branches of the DIEA
  • Feed into a subcutaneous vascular network that radiates from the umbilicus 5

Venous Drainage

• Deep System

  • Deep inferior epigastric veins (usually paired) accompany the arteries 1
  • Superior epigastric veins drain into the internal thoracic veins

• Superficial System

  • Superficial inferior epigastric veins drain into the femoral vein
  • Forms extensive subcutaneous venous plexus

Lymphatic Drainage

• Upper Abdominal Wall

  • Above umbilicus: drains primarily to axillary lymph nodes
  • Follows the course of superior epigastric vessels

• Lower Abdominal Wall

  • Below umbilicus: drains to superficial inguinal lymph nodes
  • Follows the course of superficial inferior epigastric vessels

• Deep Lymphatics

  • Follow the deep blood vessels
  • Drain into external iliac and common iliac lymph nodes

Innervation

• Anterior Abdominal Wall

  • Thoracoabdominal nerves (T7-T12)
  • These are the anterior rami of the lower six thoracic spinal nerves
  • Travel between the internal oblique and transversus abdominis muscles
  • Provide both motor and sensory innervation

• Lower Abdominal Wall

  • Iliohypogastric nerve (L1)
  • Ilioinguinal nerve (L1)
  • Both arise from the lumbar plexus

• Cutaneous Innervation

  • Segmental distribution:
    • T7-T9: Supply skin above the umbilicus
    • T10: Supplies skin at the level of the umbilicus
    • T11-T12: Supply skin below the umbilicus
    • L1: Supplies skin of the inguinal region and upper thigh

Clinical Significance

• Abdominal Wall Perfusion

  • Preservation of SEA perforators adjacent to the costal margin during abdominoplasty can improve abdominal wall perfusion 2
  • The unpredictable course of DIEA perforators may account for ischemia-related morbidity in DIEA-based perforator flaps 2

• Abdominal Compartment Syndrome

  • Increased intra-abdominal pressure can reduce visceral perfusion 6
  • Even mild intra-abdominal hypertension (IAP of 15 mmHg) can decrease intestinal microcirculatory blood flow 6
  • Can lead to bowel wall permeability changes and bacterial translocation 6

• Vascular Complications

  • Mesenteric ischemia can occur due to arterial embolism, arterial thrombosis, non-occlusive mesenteric ischemia, or mesenteric venous thrombosis 7
  • CT angiography is the preferred imaging modality for suspected mesenteric ischemia 6

Understanding the vascular anatomy of the abdominal wall is crucial for surgical planning, especially in procedures involving abdominal wall flaps, and for recognizing potential complications related to abdominal wall perfusion.