15. Transverse Abdominis
Origin: Lateral 1/3 of the inguinal ligament, anterior 2/3 of the iliac crest, thoracolumbar fascia, and inner surface of lower 6 costal cartilages and their ribs (7-12)
Insertion: Linea alba, aponeurosis of internal oblique, pubic crest and pectineal line of the pubis
Action:
- Increases intraabdominal pressure
- Assists in supporting the lumbar spine
- Unilaterally ipsilateral trunk rotation
Innervation: Lower 5 intercostal nerves, subcostal nerve (T12), ilioinguinal (L1), and iliohypogastric (L1) nerve

Needling
Typically, this muscle is not considered when needling as it is too deep.