The adductor mechanism of pecten

Abstract

The slow part of the adductor muscle of P. magellamcus on electrical stimulation gives a twitch which is about 100 times as slow as that of frog''s skeletal muscle, owing to its high viscosity; large tensions may be developed. In P. maximus and P. operations, separation of the slow and quick muscles usually results in a "contracture" of the former, during which the viscosity is increased, although the tensions developed are relatively small. This is due to reflex excitation from the several nervous connections, and can be partly or completely abolished by direct faradisation of the muscle. In intact animals, it would appear that the muscle contracts tetanically for the most part. The quick muscle gives a rapid twitch on electrical stimulation; fusion of the twitches is not readily obtained, and fatigue is rapid.