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________________________ Slide C-5 _____ rostral (corticospinal)

_________________________________ _____ rostral (rubrospinal))

___________________________________ _____ rostral (medial pathway)

This slide tries to show that most corticspinal fibers terminate in the grey matter of the cord (laminae IV - IX). Via interneurons, they influence lower motor neurons in the more lateral part of the anterior horn. A few axons (the solid arrows you can barely see) terminate directly on lower motor neurons.

The rubrospinal tract is labeled the "lateral pathway" here, following the Lawrence and Kuypers model (Figure 5-1). It terminates (mostly via internuncials) in the lateral part of the anterior horn, and is mainly involved in motor control of the distal parts of the extremities. In contrast, the medial pathways terminate in the medial part of the anterior horn; they activate lower motor neurons innervating trunk and proximal extremity muscles.

Click on one of the "rostrals" to look at the next rostral slide. Click on the red ball to return to the text, by way of the call-up view)