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The somatic nervous system's principal goal is to facilitate the organs and striated muscles of the central nervous system so that we can carry out our daily responsibilities. The primary motor cortex, or precentral gyrus, is home to the higher motor neurons that make up the basic motor pathway. These neurons transmit signals to the lower motor ...
A neuromuscular junction (or myoneural junction) is a chemical synapse between a motor neuron and a muscle fiber. [1] It allows the motor neuron to transmit a signal to the muscle fiber, causing muscle contraction. [2] Muscles require innervation to function—and even just to maintain muscle tone, avoiding atrophy.
The muscle fibers belonging to one motor unit can be spread throughout part, or most of the entire muscle, depending on the number of fibers and size of the muscle. [2] [3] When a motor neuron is activated, all of the muscle fibers innervated by the motor neuron are stimulated and contract. The activation of one motor neuron will result in a ...
Somatic motor neurons originate in the central nervous system, project their axons to skeletal muscles [19] (such as the muscles of the limbs, abdominal, and intercostal muscles), which are involved in locomotion. The three types of these neurons are the alpha efferent neurons, beta efferent neurons, and gamma efferent neurons.
In biology, a motor unit is made up of a motor neuron and all of the skeletal muscle fibers innervated by the neuron's axon terminals, including the neuromuscular junctions between the neuron and the fibres. [1] Groups of motor units often work together as a motor pool to coordinate the contractions of a single muscle.
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 .
The main function of the facial nerve is motor control of all the muscles of facial expression. It also innervates the posterior belly of the digastric muscle, the stylohyoid muscle, and the stapedius muscle of the middle ear. These skeletal muscles are developed from the second pharyngeal arch.
Many voluntary movements rely on spinal lower motor neurons, which innervate skeletal muscle fibers and act as a link between upper motor neurons and muscles. [2] [3] Cranial nerve lower motor neurons also control some voluntary movements of the eyes, face and tongue, and contribute to chewing, swallowing and vocalization. [4]