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2. MOTOR EFFECTS ARE SEEN IN
 SOMATIC NS
SYMPATHETICFIBRE
S
 ANS
PARASYMPATHETIC
FIBRES

3.  Lowest level of motor neuron-LMN
 Primary motor area neuron in cerebral
cortex-UMN

4. MOTOR ACTIVITY OCCURS AT 3
LEVELS
 Spinal cord level -as a reflex action
 Brain stem level- as a cranial reflex
action
 Cortical level- as a voluntary action

5.  LMN receive input from UMN
 Most of the UMN synapse with
interneurons
 Some synapse with LMN
 UMN originate from cerebral
cortex,motor centres of brain stem,red
nucleus,vestibular nucleus,sop.colliculus
,reticular formation

6.  UMN from cerebral cortex reg.vol.
motor activity
 UMN from brain stem reg. muscle
tone,posture and equilibrium

7. Somatic motor pathway
 Direct motor/pyramidal
 Indirect motor/extrapyramidal
 Includes
Reticulospinal
Tectospinal
Vestibulospinal
Rubrospinal
olivospinal

8. Motor areas of brain
 Primary motor area located in precentral
gyrus.
 Brodman’s area.(area 4)
 Betz cells are the characteristic
feature of primary motor area.
 Topographical representaion (motor
homunculus) of entire body.

9. Contd..
• body representation in this area is
inverted & unilateral with the head
represented down & foot up.
• Bilateral representation is seen to LMN,
innervating the upper half of
face,muscles of
eyes,jaws,pharynx,larynx,neck,thorax &
abdomen.

10. Contd…
 Supplementary motor area-medial part of frontal
lobe to upper part of cingulate sulcus where the
entire body representation is seen.
 Area 6- premotor area or motor association area.
 Major descending tracts which arise from these
areas which control motor activity –
PYRAMIDAL TRACT

11. PYRAMIDAL TRACT
 Information from cerebral cortex for voluntary
motor activity.
 60 % fibres arise from primary motor cortex
(area 4.)
 40% fibres from supplementary or secondary
motor area and from sensory areas(area 3,1,2)
 80% motor area.
 20% sensory area.

12.  Motor nuclei of the cranial nerves in
which these axons terminate are that of
3,4,5,6,7,9,10,11,12 cranial nerves –
CORTICO NUCLEAR OR CORTICO
BULBAR fibres.
 Rest form CORTICO SPINAL fibres.

13. Contd…
 In medulla 80% of fibres cross to opp
side(controlateral)as pyramidal
deccusation.
 20% pass uncrossed(ipsilateral).
 Crossed fibres occupy lat funiculus of
spinal cord & go as lat corticospinal
tract.
 Uncrossed fibres in spinal cord forms
ant corticospinal tract.

16.  Right cerebral cortex controls muscles
of left side of the body and left
cerebral cortex controls the muscles of
right side of the body.

17. EXTRAPYRAMIDAL TRACTS
 All descending tracts other than pyramidal tract.
 Back ground tone, posture ,equilibrium etc. are
maintained.
 Arise from cerebral cortex & from sub cortical
structures like basal ganglia , brainstem, reticular
formation, red nucleus, tectal nucleus, vestibular
nucleus & olivary nucleus.

18. Cortically originating
 A) facilitatory fibres.- (+) muscle tone
and stretch reflex.(area6,supp.motor
area ,& area 7)
 B) inhibitory fibres- (-) motor activity
or reflexes.(suppressor strips of diff
areas of cortex like 4s 2s 8s 19s 24s
etc.)

19.  Cortically originating extra pyramidal
fibres descend intermingled with
pyramidal tract fibres. so any leison of
pyramidal tract in brain will be
associated with extra pyramidal
manifestations.

20.  Cortically occuring extra pyramidal
fibres do not go directly to the alpha
motor neuron instead relay in the
reticular formation directly or indirectly
through the basal ganglia.
 So reticular formation-relay &
integrating centre of extrpyramidal
influences.

21. 2.Reticulospinal
 Fibres arising from the reticular
formation
1) anterior
2) lateral
Consists of 2 parts
1.bulboreticular facilitatory area maintain
nl muscle tone.
2.caudal inhibitory area

22. 3.Vestibulo spinal
 Arise from lat vestibular nucleus
 Recieves connection from inner ear,
cerebellum, cortex, reticular formation.
 Facilitate activity of extensor group of
muscles-those that maintain posture.

23. 4.Rubrospinal
 Arise from red nucleus of mid brain.
 Connections to cortex, cerebellum, ret
formation.
 2 parts – magno cellular
parvo cellular
 Forrel’s deccusation.
 Maintain flexor group of muscles.

24. 5.Olivospinal
 Arise from inf. olivary nucleus in
medulla.
 Connected to cortex,cerebellum,
thalamus, red nucleus, reticular
formation.

25. 6.Tectospinal
 Arise from neurons in sup colliculus.
 Terminate in upper seg of spinal cord.
 Concerned with spino visual reflex.