Transcript Posterior Abdominal Wall

Overview of the Posterior Abdominal Wall

  • This presentation covers the anatomy and contents of the posterior abdominal wall, including:

    • Diaphragm and associated muscles

    • Fascia and neurovascular structures

Anatomy of the Posterior Abdominal Wall

  • The posterior abdominal wall connects with the anterolateral wall.

  • Contains structures associated with:

    • Abdominopelvic region

    • Lower extremities

  • Key elements include:

    • Lumbar vertebrae

    • Intervertebral discs

    • Paravertebral gutters containing:

      • Psoas major

      • Psoas minor

      • Quadratus lumborum

Diaphragm

  • Marks the superior boundary of the posterior abdominal wall.

  • Features:

    • Left and right crus attach at anterior bodies of L1 to L3 vertebrae.

    • Dome shape with three apertures for vascular and digestive structures:

      1. Caval opening at T8 for inferior vena cava

      2. Esophageal hiatus at T10 for esophagus

      3. Aortic hiatus at T12 for aorta

  • Thick fascia cover psoas major and quadratus muscles on medial and lateral aspects.

Muscles of the Posterior Abdominal Wall

  • Psoas Major

    • Proximal: Transverse processes of lumbar vertebrae, T12 to L5 bodies, and discs.

    • Distal: Joins iliacus at lesser trochanter of femur.

  • Psoas Minor (when present)

    • Proximal: T12-L1 sides and discs.

    • Distal: Pectineal line of pubis.

  • Iliacus

    • Originates from iliac fossa, joins psoas below inguinal ligament.

  • Quadratus Lumborum

    • Proximal: Inferior border of 12th rib and lumbar transverse processes.

    • Distal: Internal lip of iliac crest and iliolumbar ligament.

    • Action:

      • Bilaterally extends lumbar segments and stabilizes spine.

      • Unilaterally flexes vertebral column and elevates pelvis.

Thoracolumbar Fascia

  • Comprised of three layers:

    • Anterior Layer: Covers psoas major and quadratus lumborum; continuous with transversalis fascia.

    • Middle Layer: Attaches to transverse processes, covers posterior aspect of quadratus lumborum.

    • Posterior Layer: Houses deep back muscles.

  • Anatomy of the fascia allows for stability of the vertebral column influenced by abdominal wall muscles.

Neurovascular Structures

  • Abdominal Aorta and Inferior Vena Cava: Located retroperitoneally along the posterior abdominal wall; supply various arteries:

    • Inferior Phrenic Artery: Supplies diaphragm.

    • Subcostal and Lumbar Arteries: Further supply posterior wall.

  • Veins:

    • Inferior vena cava

    • Right and left renal veins

    • Testicular or ovarian veins

  • Nerves:

    • Components of the lumbar plexus, including:

      • Subcostal Nerve (T12)

      • Iliohypogastric & Ilioinguinal Nerves (L1)

      • Genitofemoral Nerve (L1-L2)

      • Lateral Cutaneous Nerve of the Thigh (L2-L3)

      • Femoral & Obturator Nerves (L2-L4)

      • Lumbosacral Trunk (L4-L5)

  • The arrangement of lumbar plexus nerves varies as they course around or through the psoas major.

  • Genitofemoral Nerve: Splits into genital and femoral branches.

  • Obturator Nerve: Smaller, located posterior medial to psoas major.