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Transverse abdominal muscle
Last reviewed: 07.07.2025
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The transverse abdominal muscle (m. transversus abdominis) forms the deepest, third layer in the lateral sections of the abdominal wall. The bundles of the transverse abdominal muscle are located horizontally, passing from behind to the front and medially. They originate on the inner surface of the six lower ribs (occupy the spaces between the teeth of the costal part of the diaphragm), on the deep plate of the lumbosacral fascia, the anterior half of the inner lip of the iliac crest and the lateral third of the inguinal ligament. Near the lateral edge of the rectus abdominis muscle, the muscle bundles pass into a wide aponeurosis along a line concave in the medial direction - the semilunar (Spiegelian) line (hinea semilunaris).
Function of the transverse abdominis muscle: reduces the size of the abdominal cavity, being an important component of the abdominal press; pulls the ribs forward to the midline.
Innervation of the transverse abdominis muscle: intercostal (ThV-ThXII), iliohypogastric (ThXII-LI) and ilioinguinal (LI) nerves.
Blood supply of the transverse abdominis muscle: posterior intercostal arteries, superior and inferior epigastric arteries, muscular-diaphragmatic artery.
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