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A motor neuron (or motoneuron or efferent neuron [1]) is a neuron whose cell body is located in the motor cortex, brainstem or the spinal cord, and whose axon (fiber) projects to the spinal cord or outside of the spinal cord to directly or indirectly control effector organs, mainly muscles and glands. [2]
In that view, a neuron in the motor cortex sends an axon or projection to the spinal cord and forms a synapse on a motor neuron. The motor neuron sends an electrical impulse to a muscle. When the neuron in the cortex becomes active, it causes a muscle contraction. The greater the activity in the motor cortex, the stronger the muscle force.
Betz cells (also known as pyramidal cells of Betz) are giant pyramidal cells located within the fifth layer of the grey matter in the primary motor cortex.These neurons are the largest in the central nervous system, sometimes reaching 100 μm in diameter.
With their flask-shaped cell bodies, many branching dendrites, and a single long axon, these cells are essential for controlling motor activity. Purkinje cells mainly release GABA (gamma-aminobutyric acid) neurotransmitter, which inhibits some neurons to reduce nerve impulse transmission. Purkinje cells efficiently control and coordinate the ...
Central pattern generators are groups of neurons in the spinal cord that are responsible for generating stereotyped movement. It has been shown that in cats, rhythmic activation patterns are still observed following removal of sensory afferents and removal of the brain., [1] indicating that there is neural pattern generation in the spinal cord independent of descending signals from the brain ...
A neuroeffector junction is a site where a motor neuron releases a neurotransmitter to affect a target—non-neuronal—cell. This junction functions like a synapse.However, unlike most neurons, somatic efferent motor neurons innervate skeletal muscle, and are always excitatory.
A motor pool consists of all individual motor neurons that innervate a single muscle. Each individual muscle fiber is innervated by only one motor neuron, but one motor neuron may innervate several muscle fibers. This distinction is physiologically significant because the size of a given motor pool determines the activity of the muscle it ...
A single motor neuron and the muscle fibers it innervates are called a motor unit. For example, the rectus femoris contains approximately 1 million muscle fibers, which are controlled by around 1000 motor neurons. Activity in the motor neuron causes contraction in all of the innervated muscle fibers so that they function as a unit.