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
Grey matter, or gray matter in American English, is a major component of the central nervous system, consisting of neuronal cell bodies, neuropil (dendrites and unmyelinated axons), glial cells (astrocytes and oligodendrocytes), synapses, and ...
within the
spinal cord
The spinal cord is a long, thin, tubular structure made up of nervous tissue that extends from the medulla oblongata in the lower brainstem to the lumbar region of the vertebral column (backbone) of vertebrate animals. The center of the spinal c ...
. They exit the spinal cord through the
ventral roots, carrying motor impulses to
skeletal muscle
Skeletal muscle (commonly referred to as muscle) is one of the three types of vertebrate muscle tissue, the others being cardiac muscle and smooth muscle. They are part of the somatic nervous system, voluntary muscular system and typically are a ...
through a
neuromuscular junction
A neuromuscular junction (or myoneural junction) is a chemical synapse between a motor neuron and a muscle fiber.
It allows the motor neuron to transmit a signal to the muscle fiber, causing muscle contraction.
Muscles require innervation to ...
.
Of the somatic efferent neurons, there exist subtypes.
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Alpha motor neurons (α) target
extrafusal muscle fiber
Extrafusal muscle fibers are the standard skeletal muscle fibers that are innervated by alpha motor neurons and generate tension by contracting, thereby allowing for skeletal movement. They make up the large mass of skeletal striated muscle tis ...
s.
*
Gamma motor neurons (γ) target
intrafusal muscle fibres
Cranial nerves also supply their own somatic efferent neurons to the
extraocular muscles
The extraocular muscles, or extrinsic ocular muscles, are the seven extrinsic muscles of the eye in human eye, humans and other animals. Six of the extraocular muscles, the four recti muscles, and the superior oblique muscle, superior and inferior ...
and some of the muscles of the
tongue
The tongue is a Muscle, muscular organ (anatomy), organ in the mouth of a typical tetrapod. It manipulates food for chewing and swallowing as part of the digestive system, digestive process, and is the primary organ of taste. The tongue's upper s ...
.
See also
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Nerve fiber
An axon (from Greek ἄξων ''áxōn'', axis) or nerve fiber (or nerve fibre: see spelling differences) is a long, slender projection of a nerve cell, or neuron, in vertebrates, that typically conducts electrical impulses known as action pot ...
*
Efferent nerve
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General visceral efferent fiber
General visceral efferent fibers (GVE), visceral efferents or autonomic efferents are the efferent nerve fibers of the autonomic nervous system (also known as the ''visceral efferent nervous system'') that provide motor innervation to smooth musc ...
(GVE)
*
Special visceral efferent fiber
Special visceral efferent fibers (SVE) are the efferent nerve fibers that provide motor innervation to the muscles of the pharyngeal arches in humans, and the branchial arches in fish.
Some sources prefer the term "branchiomotor" or "branchial eff ...
(SVE)
References
Peripheral nervous system
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