Tracts of spinal cord

1. TRACTS OF SPINAL
CORD
By: RAJNISH KUMAR
CIMS BILASPUR

3. Transverse section of spinal cord

4.  Ascending sensory pathway are organised in
 Three neuronal chain
 First order neuron
 Second order neuron
 Third order neuron

5. LATERAL SPINOTHALAMIC TRACT
 Pain and thermal impulses.
 Transmitted to spinal cord in delta A and C fibres
 Central process enters the spinal cord through posterior
nerve root proceed to the tip of the dorsal gray matter.
 SECOND ORDER NEURON:
-In the dorsal horn cross to the opposite side (decussate)
-Ascend to the controlateral vertical column.
-End in VPL nucleur of thalamus.
 THIRD ORDERS NEURON:
-In the VPL nucleus of thalamus.
-Project to Cerebral cortex(area 3,1and 2)

7. ANTERIOR SPINOTHALAMIC TRACT
 Light touch and pressure inputs
 FIRST ORDER NEURON:
Dorsal root ganglion (all level)
 SECOND ORDER NEURON:
-In the dorsal horn cross to the opposite side (decussate)
-Ascend in the controlateral Ventral column.
-End in VPL nucleus of thalamus.
 THIRD ORDER NEURON:
-In the VPL nucleus of thalamus.
-Project to the cerebral cortex (area 3,1 and 2)

8. FASCICULUS GRACILLIS AND FASCICULUS
CUNEATUS
Occupy the posterior white column of cord.
Fasciculus gracillis bring medial to the faciculus
Cuneatus.
Fasciculus gracillis contains fibres received at
sacral lumbar and lower thoracic level.
Faciculus Cuneatus contains fibres received at
Upper thoracic and cervical levels.

9.  Contains impulses concerned with proprioception and
discriminative touch from ipsilateral side of the body.
 Contains axons of primary afferent neuron that have
entered chord through dorsal roots of spinal nerve.
 Fibres ascend without interruption where they terminal
into 2nd order neuron in nucleus gracillis and nucleus
cuneatus.
 The axons of 2nd order neuron decussate in the medulla
as internal arcuate fibres and ascend through the brain
stem as Medial lemniscus.
 The medial lemniscus terminates in the ventral posterior
nucleus of the thalamus upon third order neuron which
project to somatosensory Cortex (thalamocortical fibres)

10. POSTERIOR AND ANTERIOR SPINOCEREBELLAR
TRACT
 Transmit unconscious proprioceptive information to
cerebellum.
 Receive input from muscle spindles and pressure
receptors.
 Involves in coordination of posture and movement of
individual muscle of the lower limb.

11. DESCENDING TRACTS

12. CORTICOSPINAL TRACT
 Arises from the pyramid cells of cerebral cortex.
 Fibres travel through
-Corona radiata
-Posterior limb of internal capsule
-cerebral peduncle
-Pons
-Medulla oblongata
 Eventually the fibres crosses the midline and terminal on the lower
motor neuron of anterior gray column of respective spinal cord
segments.

13. RUBROSPINAL TRACT
 Nerve cells in red nucleus (Tegmentum of midbrain at the
level of superior colliculus)
 Nerves fibres/axons
-cross the midline
-Descend as RUBROSPINAL tract.(through pons and
medulla oblongata)
 Terminate at anterior gray column of spinal cord

14. TECTOSPINAL TRACT
 Nerve cells in superior colliculus of mid brain.
 Nerve fibers/axons
- cross the midline
- descend close to medial longitudinal fasciculus
 Terminate at anterior gray column of upper cervical
segment of spinal cord.

15. VESTIBULOSPINAL TRACT
 Nerve cells in vestibular nucleus(in pons and medulla
oblongata)
-receive afferents for inner ear and cerebellum.
 Axons descend uncrossed.
-Through the medulla and length of spinal cord.
 Synapse with neuron in the anterior gray column of
spinal cord.

16. RETICULOSPINAL TRACT
 Nerve cells in reticular formation
 Nerve passes through
-Midbrain, pons and medulla oblongata
 Ends at anterior gray column of spinal cord
-Control activity of motor neurons.

17. BROWN SEQUARD SYNDROME
(Hemisection of spinal cord)
 Ipsilateral loss of proprioception, fine touch, vibration-
Posterior column lesion.
 Contralateral loss of Pain, temperature, crude touch-
Anterior Column lesion.

18. THANK YOU
“True education means fostering the ability to be interested in something.”