Lower lumbar branching of caudal medullary expiratory neurons of the cat.

Extracellular spike activities of medullary expiratory (E) neurons in the caudal ventral respiratory group were recorded in cats anesthetized with sodium pentobarbital. The majority of E neurons extended their axons in the lower lumbar or the sacral segments and distributed collaterals in L5-L7. These results suggest that E neurons are involved not only in respiratory activities but also in the respiratory modulated motor activities of the lower lumbar segments.