RESPIRATORY DIAPHRAGM THORACIC CAVITY RESPIRATORY DIAPHRAGM

Diaphragm A diaphragm is a muscular sheet with an inferior and a superior fascia: Superior fascia = parietal thoracic fascia. Inferior fascia = transversalis fascia. Separates thorax and abdomen. In moderate expiration: Reaches level of 5th rib on right side and 5th IC space on left.

Diaphragm Origins Sternal part: Costal part: Lumbar part: Xiphoid process. Costal part: Lower 6 ribs and cartilages. Lumbar part: Lumbar vertebrae and crura: Right: L1-L3 Left: L1-L2

Central Tendon “Y-shaped” Attaches to lumbar vertebrae via crura. Pierced by three openings (described later).

Central Tendon Three parts to central tendon: Fig. 2.71 Right: Middle: Largest part. Middle: Left: Smallest part. Fig. 2.71

Crura Muscular pillars Originate from lumbar vertebrae: Right from L3. Left from L2. Right swings left and forms a weak sphincter around the esophagus.

Arcuate Ligaments Median: Medial: Lateral: Around aortic opening. Bridges proximal ends of crura. Medial: From deep fascia of psoas major muscle. From transverse process to body of L1. Lateral: From deep fascia of quadratus lumborum muscle. From transverse process of L1 to rib 12.

Diaphragm Openings Caval opening: Esophageal opening: Aortic opening: Level T8 Inferior vena cava; right phrenic nerve Esophageal opening: Level T10 Esophagus; vagus nerves Aortic opening: Level T12 Aorta; thoracic duct; azygos vein

Diaphragm Innervation Phrenic Nerve C3-5

Diaphragm Arterial Supply Superior aspect: Pericardiacophrenic artery from IT. Musculophrenic artery from IT. Superior phrenic artery from aorta. Inferior aspect: Inferior phrenic artery from aorta.