Anatomy
Origin:
Thoracolumbar fascia, iliac crest, inguinal ligament, costal cartilages and 7th to 12th ribs.
Insertion:
Xiphoid process, aponeruosis ending in linea alba, pubic crest and pectineal line.
Key relations:
-Deep to the internal obliques.
-Muscle fibres run transversely as the name suggests.
-Superior three-quarters lies posterior to the rectus abdominis.
-Inferior quarter lies anterior to the rectus abdominis.
Functions
Compresses abdominal cavity.
Supply
Nerve Supply:
-Anterior rami of thoracic spinal nerves (T7 to T12)
-Iliohypogastric nerve
-Ilioinguinal nerve
Blood Supply:
-Inferior epigastric artery
-Superior epigastric artery
-Lower six intercostal arteries.
Clinical
Fibres from the aponeurosis contribute to the transversalis fascia which forms the posterior wall of the inguinal canal and in which the deep inguinal ring is located. The deep inguinal ring is the site which indirect inguinal hernias originate.
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