This muscle lies just below the internal oblique, originating from the lumbar fascia, iliac crest, and inguinal ligament.

It spans the area from the pelvis to the abdomen and inserts in the xiphoid cartilage and linea alba.

The transversus abdominis is innervated by the lower thoracic nerves and supplied by the lumbar arteries and this muscle assists in breathing.

Brief clarifications of the above terms as shown in bold words

• transverse fibers: the thin threadlike pieces found in body tissues that form the nerves and muscles extending or lying across bodily parts.
• internal oblique: a slanting, small, thin, deep muscle of the abdomen.
• lumbar fascia: back layer of loose tissue just beneath the skin.
• iliac crest: hip bone.
• inguinal: part of the groin where the abdomen and thighs meet.
• ligament: inelastic white materials which surround the joints, and connect bones, or strengthen the attachments of various organs, or keep them together.
• xiphoid cartilage: bottom part of the breastbone which is firm with very elastic tough tissue.
• linea alba: "white line", a fibrous band running vertically the entire length of the center of the anterior abdominal wall, receiving the attachments of the oblique and transverse abdominal muscles.