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The firing of gamma motor neurons in sync with alpha motor neurons pulls muscle spindles from polar ends of the fibers as this is where gamma motor neurons innervate the muscle. The spindle is innervated by type Ia sensory fiber that go on to synapse with alpha motor neurons, completing the gamma-loop. The parallel pulling keeps muscle spindles ...
Alpha motor neurons are distinct from gamma motor neurons, which innervate intrafusal muscle fibers of muscle spindles. While their cell bodies are found in the central nervous system (CNS), α motor neurons are also considered part of the somatic nervous system —a branch of the peripheral nervous system (PNS)—because their axons extend ...
Axons from upper motor neurons synapse onto interneurons in the spinal cord and occasionally directly onto lower motor neurons. [3] The axons from the lower motor neurons are efferent nerve fibers that carry signals from the spinal cord to the effectors. [4] Types of lower motor neurons are alpha motor neurons, beta motor neurons, and gamma ...
There are four subdivisions of group A nerve fibers: alpha (α) Aα; beta (β) Aβ; , gamma (γ) Aγ, and delta (δ) Aδ. These subdivisions have different amounts of myelination and axon thickness and therefore transmit signals at different speeds. Larger diameter axons and more myelin insulation lead to faster signal propagation.
1) Alpha-gamma coactivation. Here it is posited that gamma motor neurons are activated in parallel with alpha motor neurons to maintain the firing of spindle afferents when the extrafusal muscles shorten. [6] 2) Fusimotor set: Gamma motor neurons are activated according to the novelty or difficulty of a task. Whereas static gamma motor neurons ...
Alpha motor neurons and gamma motor neurons do not merely differ in their postsynaptic targets. The physiological differences between these two classes are significant. The axonal diameter of gamma-motor neurons is half of that of alpha-motor neurons, resulting in a higher cytoplasmic resistance and therefore a slower signal propagation velocity.
Gamma motor neurons, unlike alpha motor neurons, are not directly involved in muscle contraction. The nerves associated with these neurons do not send signals that directly adjust the shortening or lengthening of muscle fibers. However, these nerves are important in keeping muscle spindles taut. [8]
They constitute the muscle spindle, [2] and are innervated by both sensory (afferent) and motor (efferent) fibers. [3] Intrafusal muscle fibers are not to be confused with extrafusal muscle fibers, which contract, generating skeletal movement and are innervated by alpha motor neurons. [4]