2. By Definition these are
 Bundle or groups of nerve fibers
used for spinal cord connections
 Sub classed as..
 1- Short tracts.
 2-Long Tracts.

4. Short Tracts are just within the
spinal cord for its connections
with itself.
Subclassed as :
1- associative (Connects
adjecent parts of same side
spinal cord)

5. 2- Commissural connects
opposite halves of spinal cord.

6. LONG TRACTS connects spinal
cord to other parts of CNS .
Subdivided as
1- Ascending tracts (Ascend
fronm spinal cord to brain)
2-Decending tracts(Decends
from brain to spinal cord)

7. THE DESCENDING TRACTS
OF SPINAL CORD
 These tracts descends from brain to spinal
cord and carry motor information.
 These are further divided as
 1- Pyramidal tracts.
 2- Extrapyramidal tracts.

8. PYRAMIDAL TRACTS
 Pyramidal tracts or corticospinal tracts originate from
motor area of cerebral cortex and extend to the
thoracic region of spinal cord. Just a little of them
goes to sacral region.
 Further divided as
 1- Anterior
 2- Lateral

9.  Diameter of each nerve fiber is 4-22 microns
 They are presnt since birth but later in old age they
may dissapear causing automatic shivering
movements.
 ORIGIN : ; these originate from motor area of cerebral
cortex from following cells
 Betz Cells – Area 4 (30%)
 Premotor area 6 (30%)
 Somatosensory area of parietal lobe (39%)
 Other parts of frontal lobe. (1%)


10.  Course :
 Crona radiata (Fan like apparatus)
 Internal Capsul (passage bw thalamus andcaudate
nucleus)
 Pons
 M.O
 Spinal cord

17.  Termination :
 Motor neurons of gray horn. Upto mid thoracic level and
least to sacral region.
 Function :
 voluntary movements
 Fine and skilled movements of body.
 Effect of Lesions :
 Voluntary movements
 Muscle tone
 Reflexes
 Weakened muscles
 One body side paralysis
 Four limbs paralysis

18.  EXTRAPYRAMIDAL TRACTS :
 Other than pyramidal tracts.
 Medial longitudinal Fasciculus :
 Descends through posterior part of anterior white column.
 Origin : Takes origin from 4 different sites.
1. Vestibular nuclei (Present in medulla – cranial nuceli for
vestibular nerve)
2. Reticular Formation ( Region of pons involved in sleep wake
cycle)
3. Superior Colliculus (Area below thalamus – surrounds pineal
gland )
4. Internal cells of Cajal (pace maker cells of GIT that produce
Basal electrical rythem)

19.  Course : Directly enters the spinal cord from brain
stem and are well defined at cervical region only .
 Termination : they terminates on anterior motor
neurons either directly or indirectly via internuncial
neurons.
 Function : helps in reflex ocular movements and
movement of neck.
 Effect of lesion : Reflex ocular and neck movements
are effected.

20.  Anterior Vestibulospinal Tracts
 Situated in anterior white column along its periphery.
 Origin: Arise from medial vestibular nuclei of M.O .
and extend upto thoracic region.
 Termination : anterior motor neurons directly or
indirectly.
 Function : Concerned with adjustment of position of
head and body during angular and linear motion.

21. Lateral vestibulospinal tracts
 Situated in anterior part of lateral white matter.
 Origin : Lateral vestibular nuclei of Medulla – Dieter’s
nucleus.
 Extent : present throughout the spinal cord.
 Course : Descends from Dieter’s nucleus directly in the
spinal cord to its lateral white column with few being
crossed before reaching spinal cord.
 Termination : Anterior Motor neurons directly or
indirectly.
 Function : tht of previous one.
 Effect of lesion : adjustment of head and body remains no
more coordinated during acceleration.

22.  4-Reticulospinal Tracts :

 Situated in anterior white column , posterior to anterior
vestibulospinal tracts .
 Origin : Reticular formation of pons and medulla.
 Course : . pontine are uncrossed and descends in medial part of
anterior column.

 From medulla are crossed and uncrossed (mixed) and descends
to anterior parts of anterior and lateral column.

 Extention : upto thoracic segments.
 Termination : Gamma motor neurons of anterior gray horn.
 Function : Controls diameter of blood vessels , breathing ,
movementn maintenance .
 Effect of lesions : disturbed movement, breathing and b.p.

23.  Tectospinal tract :
 Situated in anterior white column of spinal tract .
 Origin : superior colliculous of mid brain.
 Extention : lower cervical segments.
 Course : after taking origin, it cross the mid line and
at decussation level and then descends directly in to
spinal cord.
 Termination : Anterior motor neurons , directly or
indirectly.
 Function : movement of head in response to audio and
video stimuli.
 Effect of Lesion : function is disturbed.

24.  Rubrospinal tract :
 Present in lateral white column of spinal cord.
 Origin : Red nucleus of mid brain (Larg cell area –
controls crawling of babies)
 Extent : upto thoracic level of spinal cord .
 Course : after taking origin, it cross the mid line and at
decussation level and then descends directly in to
spinal cord through reticular formation of midbrain .
 Termination : terminates at anterior motor neurons
only indirectly.
 Function: Facilitates the function of flexor joints.

25.  Olivospinal tract :
 Situated in lateral white column of spinal cord .
 Origin : Medulla oblongata – inferior olivary nucleus.
 Course : Descends directly to spinal cord from M.O .
 Termination : Anterior motor neurons.
 Function : Reflex movements of joints.
 Effect of lesion : Reflex movement of joints is lost .
