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The neuron then propagates an electrical signal down a specialized axon extension from the basal pole to the synapse, where neurotransmitters are released to propagate the signal to another neuron or effector cell (e.g., muscle or gland). The polarity of the neuron thus facilitates the directional flow of information, which is required for ...
Glutamate released from the upper motor neurons triggers depolarization in the lower motor neurons in the anterior grey column, which in turn causes an action potential to propagate the length of the axon to the neuromuscular junction where acetylcholine is released to carry the signal across the synaptic cleft to the postsynaptic receptors of the muscle cell membrane, signaling the muscle to ...
Generally, motor nuclei found higher in the brainstem (i.e., more rostral) innervate muscles that are higher on the face. For example, the oculomotor nucleus contains α-MNs that innervate muscles of the eye, and is found in the midbrain, the most rostral brainstem component.
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 posterior thoracic nucleus is a major relay center for unconscious proprioception.Sensory information from muscle spindles and tendon organs is carried by axons of larger neurons in dorsal root ganglia, which synapse onto neurons in the spinal cord including the posterior thoracic nucleus.
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. In the neuromuscular system, nerves from the central nervous system and the peripheral nervous system are linked and work together with muscles. [3]
A skeletal muscle cell is long and threadlike with many nuclei and is called a muscle fiber. [3] Muscle cells develop from embryonic precursor cells called myoblasts. [1] Skeletal muscle cells form by fusion of myoblasts to produce multinucleated cells in a process known as myogenesis.
Function corticospinal tract: from the motor cortex to lower motor neurons in the ventral horn of the spinal cord: The major function of this pathway is fine voluntary motor control of the limbs. The pathway also controls voluntary body posture adjustments. corticobulbar tract: from the motor cortex to several nuclei in the pons and medulla ...