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Descending tracts are pathways by which motor signals are sent from upper motor neurons in the brain to lower motor neurons which then directly innervate muscle to produce movement. The anterior corticospinal tract is usually small, varying inversely in size with the lateral corticospinal tract , which is the main part of the corticospinal tract .
The lateral corticospinal tract is a descending motor pathway that begins in the cerebral cortex, decussates in the pyramids of the lower medulla [1] (also known as the medulla oblongata or the cervicomedullary junction, which is the most posterior division of the brain [2]) and proceeds down the contralateral side of the spinal cord.
The pyramidal tracts include both the corticobulbar tract and the corticospinal tract.These are aggregations of efferent nerve fibers from the upper motor neurons that travel from the cerebral cortex and terminate either in the brainstem (corticobulbar) or spinal cord (corticospinal) and are involved in the control of motor functions of the body.
Neural top–down control of physiology concerns the direct regulation by the brain of physiological functions (in addition to smooth muscle and glandular ones). Cellular functions include the immune system’s production of T-lymphocytes and antibodies, and nonimmune related homeostatic functions such as liver gluconeogenesis, sodium reabsorption, osmoregulation, and brown adipose tissue ...
4.1 Motor systems / Descending fibers. 4.2 Somatosensory system. ... Subfornical organ; Periventricular nucleus; ... Cortex Primary auditory cortex ...
The cerebral crus are the main tracts descending from the thalamus to caudal parts of the central nervous system; the central and medial ventral portions contain the corticobulbar and corticospinal tracts, while the remainder of each crus primarily contains tracts connecting the cortex to the pons.
In humans, the tectospinal tract (or colliculospinal tract) is a decussating extrapyramidal tract that coordinates head/neck and eye movements. [1]It arises from the superior colliculus of the mesencephalic (midbrain) tectum, and projects to the cervical and upper thoracic spinal cord levels. [2]
Red nucleus: This is a motor nucleus that sends a descending tract to the lower motor neurons. Substantia nigra pars compacta : This is a concentration of neurons in the ventral portion of the midbrain that uses dopamine as its neurotransmitter and is involved in both motor function and emotion.