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The target of these neurons varies, but in the somatic nervous system the target will be some sort of muscle fiber. There are three primary categories of lower motor neurons, which can be further divided in sub-categories. [17] According to their targets, motor neurons are classified into three broad categories: [18] Somatic motor neurons
Acetylcholine binds to nicotinic acetylcholine receptors of alpha-motor neurons. [3] The somatic nervous system controls all voluntary muscular systems within the body, and the process of voluntary reflex arcs. [10] The basic route of nerve signals within the efferent somatic nervous system involves a sequence that begins in the upper cell ...
The general (spinal) somatic efferent neurons (GSE, somatomotor, or somatic motor fibers) arise from motor neuron cell bodies in the ventral horns of the gray matter within the spinal cord. They exit the spinal cord through the ventral roots , carrying motor impulses to skeletal muscle through a neuromuscular junction .
A motor nerve, or efferent nerve, is a nerve that contains exclusively efferent nerve fibers and transmits motor signals from the central nervous system (CNS) to the muscles of the body. This is different from the motor neuron , which includes a cell body and branching of dendrites, while the nerve is made up of a bundle of axons.
They bear two types of sensory ending, known as annulospiral and flower-spray endings. Both ends of these fibers contract, but the central region only stretches and does not contract. Intrafusal muscle fibers are walled off from the rest of the muscle by an outer connective tissue sheath consisting of flattened fibroblasts and collagen . [ 5 ]
The parasympathetic nerve supply comes from the parasympathetic preganglionic neurons in the sacral spinal cord and also terminates in the longitudinal and circular smooth muscle layers. Finally the somatic nerve supply arises from the urethral sphincter motor neurons in the ventral horn of the sacral spinal cord; better known as Onuf's nucleus.
Renshaw cells, neurons with both ends linked to alpha motor neurons; Unipolar brush cells, interneurons with unique dendrite ending in a brush-like tuft; Granule cells, a type of Golgi II neuron; Anterior horn cells, motoneurons located in the spinal cord; Spindle cells, interneurons that connect widely separated areas of the brain
The PNS includes motor neurons, mediating voluntary movement; the autonomic nervous system, comprising the sympathetic nervous system and the parasympathetic nervous system and regulating involuntary functions; and the enteric nervous system, a semi-independent part of the nervous system whose function is to control the gastrointestinal system.