They are not expected to contract constantly over long periods of time. In contrast, the muscles of the lower extremity resist fatigue by having larger numbers of slow-twitch fibers that allow them to perform for extended periods under a workload. Muscle functions . Muscles whose origins and insertion lie within a single plane will more likely have very simple movement patterns, such as only flexion and extension or abduction and adduction. However, if a muscle belly and its tendon run in an oblique direction or warp around a shaft or joint, there may be several different motions available through the joint.
Rotational movements are possible and result from muscles with indirect paths.
Neuromuscular Regulation of Movement Muscle spindles in skeletal muscles constantly relate information to the central nervous system about current muscle length, contraction speed, and stretch. Golgi tendon organs are specialized receptors in tendons near where they attach to the muscles. They are afferent neurons and collagen fiber groups. In some areas, terminal branches of sensory axons are wrapped around groups of collagen fibers. Not all collagen tissue has afferent innervation.