What Is the Extrapyramidal System?

In the broadest sense, the extrapyramidal system refers to the conduction pathways of all body movements except the cone system , including the striatum system and vestibular cerebellum system. It is relatively old in germline occurrence, and its main functions are to regulate muscle tension, coordinate muscle movements, maintain posture, maintain semi-automatic stereotypes and reflexive movements. Both the cone system and the extrapyramid system are inseparable and their functions are consistent. The extrapyramidal structure is complex and involves many structures in the brain, including the cerebral cortex, striatum, dorsal thalamus, hypothalamus, apical gyrus, red nucleus, substantia nigra, pontine nuclei, vestibular nucleus, cerebellum, and brain stem Like the structure, the body movement is adjusted through a complex loop to ensure the fine random movement of the cone system. The main function of the extrapyramidal system is to regulate muscle tension and coordinate muscle activity. The cone system can perform fine random movements while maintaining muscle coordination and appropriate muscle tension.

Extrapyramidal

Extra-pyramidal system

Extrapyramidal system

Extrapyramidal striatum

Fibers from the frontal, parietal, occipital, and temporal cortical cells of the brain terminate directly or indirectly through the dorsal thalamus at the caudate nucleus and the lenticular nucleus. The cone system also branches sideways to these two nuclei. Caudate and bean-shaped core-shell core-shell fibers terminate in pale globules. The fibers from the pale spheres terminate in the reticular structure of the red nucleus, substantia nigra, hypothalamus, and brain stem. Fibers from the red nucleus cross each other to form a red nucleus spinal cord bundle; some of the fibers from the reticular structure cross to the opposite side, and the rest go on the same side to form a reticular spinal tract. The red nucleus spinal cord tract and reticular spinal tract terminate directly or indirectly at the motor cells of the anterior horn of the spinal cord, and the issued nerve impulses finally pass through the spinal nerve to the skeletal muscle.

Striatum-Pale Globules

Extrapyramidal pontine-cerebellum

The fibers from the frontal lobe of the cerebral cortex form the frontal bridge bundle; the fibers from the parietal, occipital, and temporal lobe form the occipital-temporal bridge bundle; these fibers descend through the inner capsule, the sides of the foot of the brain, enter the pontine and terminate at the same Lateral pontine nuclei. Fibers from the pontine nucleus cross the midline, enter the cerebellum through the midfoot of the contralateral cerebellum, and terminate mainly in the neo-cerebellar cortex. The cerebellar cortex emits fibers and finally the dentate nucleus. The fibers from the dentate nucleus cross the upper foot of the cerebellum and are covered by the cap, and finally the contralateral red nucleus and the dorsal thalamic mid ventral and anterior ventral nucleus. The fibers emitted by the red nucleus cross the anterior cover to form the red nucleus spinal cord bundle. The descending ganglion finally has motor cells in the anterior horn of the spinal cord. The fibers from the thalamic ventral nucleus and anterior ventral nucleus to the cerebral cortex motor areas (regions 4 and 6) form a cortical-pontine-cerebellar-cortical loop.

Pontine-cerebellum