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Direct and indirect motor pathways to the spinal cord. In the lateral view of the human brain; numbered areas are functional areas identified by Brodmann.
The transverse section of the spinal cord shows three functional areas. The dorsal horn contains the sensory neurons of the spinal cord; the intermediate
zone contains interneurons; and the motor nuclei zone contains the motor neurons that innervate the muscles.
A. The corticospinal tract, also called the pyramidal tract, originates in a vast region around the central sulcus that includes the parietal lobe and the
posterior part of the frontal lobe (areas 4 and 6). Area 4, the primary motor cortex, is the only area of motor cortex that directly connects with spinal motor
neurons. Area
6 comprises
various
subareas,
most
of which
send fibers
to interneurons
the intermediate
zone of the spinal cord. The parietal lobe sends
Source:
Cognitive
Functions
of the
Premotor
Systems,
Principles
of Neural in
Science,
Fifth Editon
fibers to the dorsal horns.
Citation: Kandel ER, Schwartz JH, Jessell TM, Siegelbaum SA, Hudspeth AJ, Mack S. Principles of Neural Science, Fifth Editon; 2012 Available
B. Indirect pathways
to spinal motor neurons
originate
in 10,
area2017
4 and area 6 and terminate in medial and lateral areas of the brain stem. The main
at: http://mhmedical.com/
Accessed:
May
components Copyright
of the medial
pathways
are
the
reticulospinal,
medial
and lateral vestibulospinal, and tectospinal tracts; they descend in the ventral column
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and terminate in the ventromedial area of the spinal gray matter. The main lateral pathway is the rubrospinal tract, which originates in the magnocellular