Fasciculus Gracilis (FG) and Nucleus Gracilis (NG)
Fasciculus Cuneatus (FC) and Nucleus Cuneatus (NC)
Spinal Trigeminal Nucleus and Tract (SpTN, SpTTr)
Dorsal and Ventral Spinocerebellar Tracts (DSCT, VSCT)
Spinothalamic Tract (STT)
Rubrospinal Tract (RST)
Medial Longitudinal Fasciculus (MLF)
Tectospinal Tract (TST)
Reticulo- and Vestibulospinal Tracts (Rt+VST)
Hypothalamo-Autonomic Tract (HAT)
Solitary Nucleus (SN)
Note:
The Pyramidal tract fibers arise in cerebral cortex, descend to the lower medulla, and cross here to the contralateral spinal cord where they form the Corticospinal Tract. Although the internal features at this level are similar to those in the spinal cord, some changes, particularly in the arrangement of the gray matter, have taken place.
As mentioned previously, the Dorsal Horn is now related primarily to the trigeminal nerve and is called the Spinal Trigeminal Nucleus. This nucleus is a rostral continuation of the substantia gelatinosa of the spinal cord; the actual transition occurs at the lower levels of C2-3, below which the substantia gelatinosa becomes much smaller.
The medulla retains an oval outline, but notice that the groove of the Posterior Intermediate Sulcus between the Cuneate and Gracile Fasciculi is now deeper and that the Nucleus Gracilis and Nucleus Cuneatus are now present. These nuclei are synaptic stations for the long dorsal root fibers which have passed up the Dorsal Columns. What are the sensory modalities transversing these pathways?
