This lies deep to the muscles mentioned previously. Fibres run from the lower 6 ribs and the thoracolumbar fascia to the linea alba. The inferior fibres run to insert at the pubis with the internal oblique muscle.

Transversus abdominis muscle (TA); the transversus abdominis plane (arrowhead); internal oblique (IO); and external oblique (EO).The transversus abdominis plane is important in the anaethetisation of the abdominal wall post operatively since this is the plane through which the the intercostal and subcostal nerves pass. The associated arteries and veins follow the same course as the nerves. Inferiorly, the iliohypogastric and ilioinguinal nerves travel in this plane, but pass through internal oblique and the external oblique aponeurosis anteriorly.