Locomotion and muscles

Definition

The integrated neuromuscular systems that enable arthropod movement, encompassing the striated skeletal muscles that attach to the exoskeleton via apodemes (internal cuticular invaginations) and the neural coordination required for walking, running, jumping, swimming, and flight. Arthropod muscles are typically obliquely striated, with relatively few fiber types compared to vertebrates, and operate the jointed appendages through lever mechanics constrained by the rigid exoskeleton. The study of this system bridges biomechanics, neuroethology, and muscle physiology.

Etymology

Latin 'loco motio' (movement from a place) and Latin 'musculus' (little mouse, from the appearance of muscles under skin)

Example

In the jumping spider Salticidae, the enlarged femoral muscles of the fourth pair of legs generate hydraulic pressure and rapid contraction to produce leaps exceeding 50 body lengths; these muscles attach to the leg segments via apodemes rather than tendons, illustrating the distinctive arthropod arrangement where the exoskeleton serves as both origin and insertion point.

Related Terms

• apodeme
• Exoskeleton
• hydraulic skeleton
• striated muscle
• neuromuscular junction
• proprioception
• metamere
• appendicular musculature
• direct flight muscle
• indirect flight muscle

Usage Notes

Specialists distinguish between direct flight muscles (attached directly to wing bases, found in Odonata and some basal groups) and indirect flight muscles (attached to the thorax wall, deforming it to move wings, characteristic of most Neoptera including Diptera and Hymenoptera). The term excludes smooth visceral muscles and cardiac muscle, which are treated separately. 'Locomotion' alone typically emphasizes the behavioral and ecological output, while 'muscles' emphasizes the cellular and mechanical machinery; together they signal integrative study of the movement system.