A manual of anatomy . e cord. 2. The direct pyramidal tract {fasciculus cerebrospinalis anterior)lies lateral to the preceding and consists of descending fibers from themotor cells of the cerebral cortex. It represents undecussatedfibers (10 to 15 per cent.) of the oblongata but they ultimately crossto the opposite ventral horn through the white commissure at vari- THE SPINAL CORD 367 ous levels. It does not extend below the midthoracic segments ofthe cord. 3. The vestibulospinal tract {fas. vestibidospinalis) consists ofdescending fibers from the vestibular nuclei of the brain stem, thatend i
A manual of anatomy . e cord. 2. The direct pyramidal tract {fasciculus cerebrospinalis anterior)lies lateral to the preceding and consists of descending fibers from themotor cells of the cerebral cortex. It represents undecussatedfibers (10 to 15 per cent.) of the oblongata but they ultimately crossto the opposite ventral horn through the white commissure at vari- THE SPINAL CORD 367 ous levels. It does not extend below the midthoracic segments ofthe cord. 3. The vestibulospinal tract {fas. vestibidospinalis) consists ofdescending fibers from the vestibular nuclei of the brain stem, thatend in the ventral horn of the cord as far as the sacral region. 4. The ventral ground bundle (fasc. anterior propritis) lies at themedial side of the ventral horn. It consists of intersegmental asso-ciation fibers of the ventral cells of the same and opposite sides{ascending and descending). 5. The ventral spinothalamic tract {fasc. spinothalamicus anterior)lies in the intermediate zone of the ventral columns, consists of. Fig. 262.—Diagram of the various tracts of the spinal cord and their origin or termination. ascending axones of the cells of the opposite dorsal horn that passthrough the white commissure and ascend to end in the fibers convey toiwh and pressure impressions from the oppositeside of the body. The lateral column is more extensive and contains more tracts. 1. The olivospinal tract {fasc. olivospinalis) lies at the side of, or inthe ventral root region and consists of descending axones fromthe cells of the olivary nucleus (in the oblongata); they end aroundthe ventral horn cells. This tract is found in the cervical segments. 2. The superficial ventrolateral spinocerebellar tract {of Gowers){fasc. spinocerebellaris anterior) is at the periphery of the cord andconsists of axones from the cells of the dorsal horn of the opposite 368 THE NERVE SYSTEM side that cross through the white commissure and ventral horn toform this tract. These fibers ascend to t
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