Medical Anatomy Commons^™

Validating Osteological Correlates For The Hepatic Piston In The American Alligator (Alligator Mississippiensis), Clinton A. Grand Pre, William Thielicke, Raul E. Diaz, Brandon P. Hedrick, Ruth M. Elsey, Emma R. Schachner

School of Graduate Studies Faculty Publications

Unlike the majority of sauropsids, which breathe primarily through costal and abdominal muscle contractions, extant crocodilians have evolved the hepatic piston pump, a unique additional ventilatory mechanism powered by the diaphragmaticus muscle. This muscle originates from the bony pelvis, wrapping around the abdominal viscera, extending cranially to the liver. The liver then attaches to the caudal margin of the lungs, resulting in a sub-fusiform morphology for the entire ‘‘pulmo-hepatic-diaphragmatic’’ structure. When the diaphragmaticus muscle contracts during inspiration, the liver is pulled caudally, lowering pressure in the thoracolumbar cavity, and inflating the lungs. It has been established that the hepatic piston …