Anatomy and innervation of the diaphragm

(A) The diaphragm is dome-shaped and attaches to the chest and abdominal walls circumferentially. The diaphragm is composed of two muscle groups, costal and crural. The costal muscle group forms the diaphragmatic leaflets. The right and left crus of the diaphragm are thick but contribute minimally to the displacement of the diaphragm. The median arcuate ligament anterior to the aortic hiatus is formed by the continuation of the medial tendinous margins of the crura. The costal and crural fibers insert into the central tendon. The anterior portion of the central tendon attaches to the posterior aspect of the xiphisternal junction. The posterior portion of the central tendon attaches to L1 to L3.
(B) The phrenic nerve originates in the neck and traverses the mediastinum before inserting into the diaphragm centrally. The outer rim of the diaphragmatic muscle is innervated laterally from the T7 through T12. The crural group of muscles receive innervation from the vagus nerve.