A manual of anatomy . F,G. 302. Diagram of the neurons in the direct and indirect motor pathways and the con-nections of the cerebellum with the brain stem and the spinal cord. Direct.—Neuron I. .4toB; neuron 2, B to C. Indirect.—Neuron I, .-1 fcerebral cortex) to D; 2, D to E; 3, £ to F; g; 5, s to B; 6, B to C. hand, and in the case of the cerebral nerves comprises the cells ofthe various nuclei of origin and their processes that form the motorportion of the cerebral nerves. These axones pass out of the graysubstance, become myehnated and ultimately end directly in a vol-untary striate
A manual of anatomy . F,G. 302. Diagram of the neurons in the direct and indirect motor pathways and the con-nections of the cerebellum with the brain stem and the spinal cord. Direct.—Neuron I. .4toB; neuron 2, B to C. Indirect.—Neuron I, .-1 fcerebral cortex) to D; 2, D to E; 3, £ to F; g; 5, s to B; 6, B to C. hand, and in the case of the cerebral nerves comprises the cells ofthe various nuclei of origin and their processes that form the motorportion of the cerebral nerves. These axones pass out of the graysubstance, become myehnated and ultimately end directly in a vol-untary striated muscle fiber. This is the end of the second new on, a pj^ramidal cell in the motor cortex of the cerebrum 4i8 THE NERVE SYSTEM and its axone that forms a part of the pyramidal tract and thatends in a cerebral nerve nucleus, or the ventral gray of the spinalcord. Second neuron, the cell in the nucleus of origin or in the ventral. Fig. 303. -The origins, decussations and courses of the fibers forming the medial and laterallemnisci. Direct sensor pathway. gray of the spinal cord, and its axone that ends in a voluntarystriated muscle fiber. The Indirect Motor Pathway.—This is more complex and com-prises six neurons. First, from the motor area of the cerebrum (sayright side) through the pyramidal tract, as above, to the nucleipontis of the same side (right); second, from the nuclei pontis through THE SENSOR PATHWAY 419 the brachium pontis to the cerebellar cortex of the opposite (left) side;third, from the cerebellar cortex to the dentate nucleus of the cere-bellum of the same (left) side; fourth, from the dentate nucleusthrough the brachium conjunctivum to the red nucleus of the opposite(right) side; fifth, from the red nucleus of that side through therubrospinal tract to the cerebral nerve nucleus, or ventral horn ofthe spinal cord of the opposite (left) side. (The fibers of the rubro-spinal tract cross to the
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