Anatomy

Origin

Sternal part—inner part of xiphoid processCostal part—inner surfaces of lower six ribs and their cartilages Lumbar part—upper two or three lumbar vertebrae and lateral and medial lumbocostal arches.  These tendinous structures, also known as the medial and lateral arcuate ligaments, allow the diaphragm to bridge the upper parts of the Psoas Major and Quadratus Lumborum muscles.

Insertion

Fibers converge and meet on a central tendon

Nerve

Phrenic nerve (C3–C5)

Actions

Draws central tendon inferiorly, for inspiration