Lab 9 - Descending Pathways to the Spinal Cord

Reticulospinal Pathways - Medulla

Figure 1 is a transverse section through the rostral medulla. The pontine reticulospinal tract fibers (uncrossed) form the major descending component of the medial longitudinal fasciculus.

The medullary reticular formation continues to give rise to medullary reticulospinal tract fibers, which projects bilaterally. The crossed and uncrossed fibers sweep laterally and join the spinothalamic and rubrospinal tracts posterior to the inferior olivary complex. The pontine and medullary reticular formation receive axons from the cerebral cortex (predominantly from motor and premotor areas), from somatosensory and vestibular structures and from the cerebellum (fastigial nucleus).

Figure 2 is a transverse section through the caudal medulla. The medial longitudinal fasciculus (pontine reticulospinal and medial vestibulospinal tracts) and the tectospinal tract have been shifted anteriorly and laterally by the fibers of the pyramidal decussation.