Anatomy study note · Abdomen

External oblique

The most superficial of the three flat muscles of the anterolateral abdominal wall. Most of its fibres end in a broad aponeurosis that forms the inguinal ligament and the superficial inguinal ring.

Key points

• Lower 8 ribs → linea alba, pubic tubercle, iliac crest.
• T7–T12 + iliohypogastric + ilioinguinal (L1).
• Aponeurosis forms the inguinal ligament (ASIS → pubic tubercle).
• Superficial inguinal ring = gap in its aponeurosis.
• External spermatic fascia comes from it.
• Trunk muscles: from myotomes of the somites.
• Dorsal part → dorsal-ramus muscles; ventral part → ventral-ramus muscles.
• Skeletal muscle: multinucleated, peripheral nuclei, striated.
• Epimysium → perimysium → endomysium.

The full note in the atlas also covers

Features · Origin · Insertion · Action · Nerve supply · Histology · Development · Clinical notes

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Written from

• Snell’s Clinical Anatomy by Regions, 10th ed., ch. 6, PDF pp. 700–706, 725–727, 735
• Inderbir Singh’s Human Embryology, ch. 7, PDF pp. 108–109
• BRS Cell Biology & Histology, 7th ed., ch. 8, PDF pp. 135–144

More from the abdomen

• Gallbladder
• Iliac arteries
• Iliacus
• Iliohypogastric and ilioinguinal nerves
• Inferior epigastric vessels
• Inferior mesenteric artery
• Inferior vena cava
• Inguinal ligament
• Internal oblique
• Jejunum and ileum
• Kidney
• Large intestine

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