Superior phrenic artery: an anatomic study.

The majority of anatomical textbooks offer very little information concerning the anatomy and distribution of the superior phrenic artery (SPA). However, in the last decade, a number of reports have appeared with reference to the transcatheter arterial chemoembolization of the collateral arterial supply of hepatic carcinoma (HC). Considering the potential role of the SPA as a source of collateral blood supply to HC, the aim of this study was to identify the origin and distribution of the SPA. One hundred formalin-fixed adult cadavers with no evidence of significant gross diaphragmatic pathology were examined. The right SPA originated from the aorta (R1) in 42%, as a branch of the proximal segment of the 10th intercostal artery (R2) in 33%, and as a branch of the distal segment of the 10th intercostal artery (R3) in 25%, of the specimens. The left SPA originated from the aorta (L1) in 51%, from proximal segment of the left 10th intercostal artery (L2) in 40%, and from the distal segment of the left 10th intercostal artery (L3) in 9%, of the specimens. In types R1, R2, L1 and L2 the SPA terminated, after a short course, within the medial and posterosuperior surfaces of the thoracic diaphragm and diaphragmatic crura. Conversely, in types R3 and L3 the lateral origin of the SPAs confined the ultimate distribution of the vessels to the posterior surface of the diaphragm. These findings could provide a better understanding of the anatomy and distribution of the arterial supply of the diaphragm and the potential involvement of the right SPA as an extrahepatic collateral artery developed in HC.