ORGANUM
A key distinction of the tracts is as follows:
Pyramidal tracts may directly innervate motor neurons of the spinal cord or brain stem via action of the anterior ventral horn cells or certain cranial nerve nucelis.
Extrapyramidal system centers of the modulation and regulation (indirect control) of the anterior ventral horn cells. Controls automatic activities and influences voluntary motility.
THESE TRACTS ARE ONLY CONCERNED WITH MOVEMENT. SENSORY TRACTS ARE COMPLETELY DIFFERENT. I REPEAT, THESE TRACTS ARE ONLY CONCERNED WITH MOVEMENT.
Extrapyramidal tracts, as their name suggests, is a system that reach their targets by travelling through the pyramids of the medulla
It is part of the motor system network that causes involuntary movement actions
They are chiefly found in the reticular formation of the pons and medulla
EXTRA-PYRAMIDAL TRACTS TARGET LOWER MOTOR NEURONS IN THE SPINAL CORD THAT ARE INVOLVED IN REFLEXES, LOCOMOTION, COMPLEX MOVEMENTS AND POSTURAL CONTROL. THE INDIRECT CONTROL COMES FROM THE FACT THAT DIFFERENT AREAS OF THE BRAIN ARE ABLE TO MODULE LOWER MOTOR NEURONS WITHOUT DIRECT CONNECTIONS. THESE AREAS OF THE BRAIN ARE NOT DIRECTLY INNERVATING THE LMN, BUT INSTEAD, INTERACTING WITH EXTRA-PYRAMIDAL TRACTS TO CAUSE MODULATION.
A GREAT EXAMPLE OF THIS IS THE NIGROSTRIATAL PATHWAY IN TARDIVE DYSKINESIA. TARDIVE DYSKINESIA WILL AFFECT DOPAMINE IN NIGROSTRIATAL PATHWAY,
EACH TRACT OF THE EXTRA-PYRAMIDAL MODULATES SOME FORM OF SIGNAL, AND READING EACH TRACT WILL HELP UNDERSTAND THE ROLE OF THE EXTRAPYRAMIDAL TRACTS:
Rubrospinal tract
Conflicts between the motor command sent by the cerebrum and body position information provided by the proprioceptors cause the cerebellum to stimulate the red nucleus of the midbrain. The red nucleus then sends corrective commands to the spinal cord along the rubrospinal tract.
Reticulospinal tract
Connects the reticular system, a diffuse region of gray matter in the brain stem, to the spinal cord. It contributes to muscle tone and influences autonomic functions
Lateral vestibulospinal tract
Connects the brainstem nuceli of the vestibular system with the spinal cord. This allows posture, movement, and balance to be modulated on the basis of equilibrium information provided by the vestibular system.
Tectospinal tract
Projects from the midbrain to the spinal cord and is important for postural movements that are driven by the superior colliculus.
ALL THESE TRACTS ARE MODULATED BY THE NIGROSTRIATAL PATHWAY, THE BASAL GANGLIA, THE CEREBELLUM, VESTIBULAR NUCLEI AND SENSORY CEREBRAL CORTEX. ALL THESE REGULATORY STRUCTURES ARE CONSIDERED PART OF THE EXTRAPYRAMIDAL SYSTEM - THEY MODULATE MOTOR ACTIVITY WITHOUT DIRECTLY INNERVATING MOTOR NEURONS.