Abdominal wall and inguinal region

Abdominal wall and inguinal region

Abdominal wall and inguinal region

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Abdominal Wall Layers - Stack 'em Up

Abdominal Wall Transverse Section

  • Superficial to Deep:
    • Skin
    • Camper's Fascia (fatty superficial)
    • Scarpa's Fascia (membranous deep)
    • External Oblique M. (fibers ↓ medially, "hands in pockets")
    • Internal Oblique M. (fibers ↑ medially)
    • Transversus Abdominis M. (fibers transversely)
    • Transversalis Fascia
    • Extraperitoneal Fat
    • Parietal Peritoneum

⭐ Below the arcuate line, the posterior rectus sheath disappears. Here, the rectus abdominis is only covered posteriorly by the thin transversalis fascia and peritoneum, creating a potential site for Spigelian hernias.

Rectus Sheath - The Six-Pack Sheath

  • Contents: Rectus abdominis & pyramidalis muscles, superior & inferior epigastric vessels, and terminal parts of lower 5 intercostal & subcostal nerves.
  • Formation: A strong, fibrous compartment formed by the aponeuroses of the three flat abdominal muscles.
  • Key Landmark: The arcuate line dictates the sheath's composition. It is located midway between the umbilicus and pubic crest.

Rectus sheath above and below arcuate line

⭐ Below the arcuate line, the posterior wall is absent. The inferior epigastric vessels perforate the transversalis fascia to enter the rectus sheath, creating a potential site of weakness.

Inguinal Region - Canal & Hernias

Inguinal Canal: Normal vs. Indirect & Direct Hernias

  • Inguinal Canal: Oblique 4 cm passage in the lower anterior abdominal wall.

    • Contents: Spermatic cord (♂) or Round ligament (♀); Ilioinguinal nerve.
    • Walls (Mnemonic 📌 MALT - from superior, clockwise):
      • Muscle (Internal oblique & Transversus abdominis) - Roof
      • Aponeurosis (External oblique) - Anterior
      • Ligament (Inguinal) - Floor
      • Transversalis fascia - Posterior
  • Hernia Types:

    • Indirect: Lateral to inferior epigastric vessels, through deep inguinal ring. Congenital (patent processus vaginalis).
    • Direct: Medial to inferior epigastric vessels, through Hesselbach's triangle. Acquired weakness.
    • Femoral: Below inguinal ligament. High risk of strangulation.

High-Yield: Indirect inguinal hernias are the most common hernia in both sexes, following the path of testicular descent through the inguinal canal.

Neurovasculature - Wall's Power & Data

Abdominal wall: thoracolumbar fascia & neurovascular plane

  • Arterial Supply:
    • Superior Epigastric A. (from Internal Thoracic) & Inferior Epigastric A. (from External Iliac) anastomose in the rectus sheath.
    • Superficial supply from superficial epigastric & circumflex iliac arteries.
  • Venous Drainage:
    • Veins accompany arteries.
    • 💡 Thoracoepigastric vein connects superficial epigastric v. to lateral thoracic v., forming a key SVC-IVC collateral pathway.
  • Innervation (Segmental):
    • Thoracoabdominal Nerves (T7-T11), Subcostal N. (T12), Iliohypogastric & Ilioinguinal Nn. (L1).
    • 📌 Dermatome landmarks: T10 at umbilicus, L1 at inguinal ligament.
  • Lymphatic Drainage:
    • Above umbilicus → Axillary nodes.
    • Below umbilicus → Superficial inguinal nodes.

⭐ The inferior epigastric artery is the landmark for classifying inguinal hernias. Direct hernias are medial to the artery; indirect hernias are lateral.

High‑Yield Points - ⚡ Biggest Takeaways

  • Direct inguinal hernias are medial to the inferior epigastric vessels, through Hesselbach's triangle, due to acquired weakness.
  • Indirect inguinal hernias are lateral to the inferior epigastric vessels, through the deep inguinal ring, from a patent processus vaginalis.
  • Below the arcuate line, the posterior rectus sheath is absent, leaving only transversalis fascia covering the rectus abdominis posteriorly.
  • The ilioinguinal nerve is at risk during hernia repair.
  • Femoral hernias are inferior to the inguinal ligament and have a high risk of strangulation.

Practice Questions: Abdominal wall and inguinal region

Test your understanding with these related questions

During an examination of the cranial nerves, a patient shows inability to move their eye laterally past the midline. Which of the following structures in the cavernous sinus is most likely affected?

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Flashcards: Abdominal wall and inguinal region

1/10

The fundus and upper portion of the greater curvature of the stomach are supplied by the _____ arteries

TAP TO REVEAL ANSWER

The fundus and upper portion of the greater curvature of the stomach are supplied by the _____ arteries

short gastric

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