GLOSSARY

The transversus abdominis (TrA) is the deepest muscle of the abdominal wall, with almost horizontal fibres wrapping around the abdomen like a natural corset.

Attachments and Innervation

• Origin: the inner surfaces of the seventh to twelfth costal cartilages, the thoracolumbar fascia, the iliac crest, and the inguinal ligament.
• Insertion: the linea alba and pubis via the conjoint tendon.
• Nerve: the intercostal nerves T7–T12, iliohypogastric, and ilioinguinal nerves.

Actions

• Compressing the abdomen and raising intra-abdominal pressure.
• Tensioning the thoracolumbar fascia, increasing lumbar stiffness.
• Active expiration, assisting coughing and childbirth.
• No significant trunk movement, because of its horizontal fibres.