B • ANATOMY, NEUROPATHOLOGY AND REGENERATION
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fissure and is much smaller than the lateral cortico-spinal tract, moreover, its size
diminishes as it descends to the middle of the thoracic region.
(2) Vestibulo-spinal tract.
This tract has its origin in the lateral vestibular nucleus and
descends uncrossed alongside the periphery of the anterior funiculus. Its fibres are
connected with the cells of the anterior grey column serving postural control.
(3) Tecto-spinal tract.
This tract arises in the superior colliculus side and after crossing
in the oblongata runs on the opposite side in the spinal cord adjacent to the anterior
median fissure forming synapses with cells of the anterior grey column, particularly in
the cervical region. It is an efferent pathway for spino-visual reflexes, the afferent pathway
of which is the spino-tectal tract.
(4) Reticulo-spinal tracts.
These are fibres scattered mainly through the medial part of
the anterior fasciculus arising from the brain stem and ending on motor cells of the
anterior grey.
LATERAL FUNICULUS
(a)
Ascending tracts
(1) Posterior spino-cerebellar tract
(Flechsig). This tract commences at the level of the
upper lumbar nerves and ascends in the periphery of the posterior part of the lateral
funiculus to the cerebellum through the inferior cerebellar peduncle. It conveys pro-
prioceptive impulses for the co-ordinated control of locomotion and is mainly concerned
with conveying impulses from the lower limbs and trunk.
(2)
Anterior spino-cerebellar tract
(Gowers). This tract begins in the upper lumbar
region and ascends in the lateral funiculus in front of the posterior spino-cerebellar
tract to the upper part of the pons, from there it descends into the superior cerebellar
peduncle to terminate in the cerebellum. Like the posterior spino-cerebellar tract it
also serves conducting proprioceptive impulses for the co-ordinated control of locomotion.
(j)
Lateral spino-thalamic tract.
This tract conveys pain and other nociceptive and
emotional sensations (see section on Sensibility) as well as temperature sensibility from
the side of the body opposite to the side of the spinal ganglia. The first neurones of this
pathway are in the spinal ganglia, from there their axons enter the spinal cord via posterior
roots. They enter the substantia gelatinosa after having ascended a short distance in the
posterior-lateral tract. The great majority of fibres synapse with cells of the posterior
grey column. From there the axons progress forwards, traverse the white commissure
to the lateral funiculus of the opposite side of the cord and ascend to the brain, terminat–
ing eventually in the ventral nucleus of the thalamus. There is clinical evidence that some
of the fibres originate in the posterior grey of the same side.
(4) Spino-tectal tract.
This tract is topographically closely related to anterior spino-
cerebellar and lateral spino-thalamic tracts. Its fibres arise in the posterior grey column
