Skeletal musculature structure

The smallest structural unit of skeletal musculature is the striated muscle fiber. 

The smallest structural unit of skeletal musculature is the striated muscle fiber. It contracts in response to an impulse of its motor nerve. In executing motor programs, the brain sends impulses to the spinal cord. These converge on a-motoneurons in the anterior hom of the spinal medulla. Bundled in motor nerves, efferent axons course to skeletal muscles. Simple reflex contractions to sensory stimuli, conveyed via the dorsal roots to the motoneurons, occur without participation of the brain. Neural circuits that propagate afferent impulses into the spinal cord contain inhibitory intemeurons. These serve to prevent a possible overexcitation of motoneurons (or excessive muscle contractions) due to the constant barrage of sensory stimuli. 

The Motor Output subsystem consists of those structures which we physically affect the external world and our own bodies. In terms of conscious awareness, these structures are primarily the skeletal, voluntary musculature. If I take a minute out from writing to pet my cat, I am using my Motor Output subsystem with full awareness. The Motor Output subsystem elements that primarily affect our own bodies are glandular secretions and other internal, biological processes. These latter, involuntary effectors are controllable not directly, but through intermediates. I cannot directly increase the amount of adrenaline in my bloodstream, for example, but if I make myself angry and wave my fists and shout and holler, I will almost certainly increase the amount of adrenaline secreted. 

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