The Muscular System

Abstract

Insect muscles are mostly translucent, colourless or grey, though the flight-muscles often show a yellowish or brown tinge. Both skeletal and visceral muscle fibres are cross-striated and some older reports of unstriated visceral muscles need reinvestigation. Insect muscles differ fundamentally from those of Annelids, both in histological structure and in not being incorporated into the body-wall to form a dermo-muscular tube. In most skeletal muscles, especially those of the appendages, one end of the muscle (its origin) is attached to a fixed skeletal region while the other end (its insertion) is attached to a movable part. Cuticular invaginations or apodemes, in the form of cords, bands or plate-like structures, may provide the true sites of attachment and therefore intervene between the muscle and the main structure on which it acts. For a general review of insect muscle see Usherwood (1975).