Muscles and muscular activity

Abstract

By virtue of its contractile properties, the muscular system comprises the main effector system of the body. All movements are due to contractions of muscles, be they the rapid thrust of legs during escape running, the leisurely sway of an antenna, or the churning of food in the gut. Actions of the muscular system are therefore the basis for an animal’s behaviour. However, most muscles cannot contract without an excitatory signal from a motoneuron, so one cannot fully understand the functional properties of muscles without also understanding the way motoneurons control them. In this chapter, I will therefore discuss not only the structure and physiology of the muscular system of P. americana, but also its neural control. Organization of the nervous system itself, although clearly reflected ultimately in the use of muscles, is considered in Chapter 8.