Extremities Divided

Extremities such as legs or antennae each may have a membrane like a diaphragm down their centers. These membranes often separate flexor muscle groups from groups of extensor muscles on the opposite side. When muscles on one side of a leg, the flexors let's say, contract, to raise a leg, the contracting muscles squeeze hemolymph from this flexor compartment back into the hemocoel of the thorax. When the insect steps down, muscles in the opposite compartment, the extensor compartment, contract and squeeze hemolymph on their side of the membrane back into the thoracic hemocoel. The relaxing compartment alternates in each phase of stepping and filling with fresh hemolymph from the hemocoel each time. There are several types of pumping mechanics for the accessory pumps in different groups (Chapman, 1998).

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