The somatic nervous system is that part of the peripheral nervous system associated with the voluntary control of body movements through the action of skeletal muscles, and also reception of external stimuli. The somatic nervous system consists of afferent fibers that receive information from external sources, and efferent fibers that are responsible for muscle contraction. The peripheral nervous system or PNS, is part of the nervous system,and I have no clue what it does. ... Structure of a skeletal muscle Skeletal muscle is a type of striated muscle, attached to the skeleton. ... In nervous systems, afferent signals or nerve fibers carry information toward the brain. ... Efferent nerve fibers carry information away from the brain. ...

The basic route of the efferent somatic nervous system includes a two neuron sequence. The first is the upper motor neuron, whose cell body is located in the precentral gyrus (Brodman Area 4) of the brain. It receives stimuli from this area to control skeletal (voluntary) muscle. The upper motor neuron carries this stimulus down the cortico spinal tract and synapses in the ventral horn of the spinal cord with the lower motor neuron. The upper motor neuron releases acetylcholine from its axon terminal knobs and these are received by nicotinic receptors on the lower motor neuron. The lower motor neurons cell body sends the stimulus down its axon via the ventral root of the spinal cord and proceeds to its neuromuscular junction of its skeletal muscle. There, it releases acetylcholine from its axon terminal knobs to the muscles nicotinic receptors, resulting in stimulus to contract the muscle. Upper motor neurons, or Betz cells, are motoneurons located in the primary motor cortex. ... Illustration of the major elements in a prototypical synapse. ... The anterior horn is the anterior division of the lateral ventricle of the brain. ... Cross-section through cervical spinal cord. ... Lower motor neurons are the motoneurons connecting the spinal cord to the muscle fibers, bringing the nerve signals from the upper motor neurons out the spine to the muscles. ... An axon, or nerve fibre, is a long slender projection of a nerve cell, or neuron, which conducts electrical impulses away from the neurons cell body or soma. ... Receptor may refer to: In telecommunication, a receiver. ... The term stimulus (plural: stimuli) has several related meanings: In physiology, a stimulus is something external that elicits or influences a physiological or psychological activity or response. ... In anatomy and neurology, the ventral root is the efferent motor root of a spinal nerve. ... A top-down view of skeletal muscle Skeletal muscle is a type of striated muscle, attached to the skeleton. ... Nicotinic Receptors form ion channels present in the plasma membrane of cells. ...