1. MOTOR AREAS EXTRAPYRAMIDAL SYSTEM

2. Definition:
Tracts other than corticospinal tract are
Known as extrapyramidal tracts.
The word extrapyramidal is slowly being
replaced by Corticonuclear &
corticobulbar tracts.

3. Components of extrapyramidal system
Basal Ganglia
Midbrain giving rise to following bulbospinal tracts:
Rubrospinal tract.
Vestibulospinal Tract.
Reticulospinal Tract
Tectspinal Tract.
Olivospinal Tract.

4. Descending Spinal Pathways extrapyramidal system
- Coordination of head & eye movements,
- Coordinated function of trunk & extremity musculature to maintaining posture and balance
- Synapse in some intermediate nucleus rather than directly with lower motor neurons

6. Reticulospinal Tract The reticular formation makes up a central core
through much of the brainstem. It contains many
different nuclear groups.
Pontine and medullary nuclei projects to the anterior
horn of the spinal cord.
Functions: influence motor functions as for example
voluntary & reflex movement and is also responsible
for the muscle tone.

7. Olivospinal Tract It arises in the cells of inferior olive of the
medulla and is found only in the cervical region
of the spinal cord.
Function is unknown.

8. Role of the brain stem Support of the Body Against Gravity.
Roles of the Reticular and Vestibular nuclei.

10. 1- The vestibular nuclei:
Selectively control the excitatory signals to the different antigravity muscles (the muscles of vertebral column and the extensor muscles of the limbs).
to maintain equilibrium in response to signals from the vestibular apparatus.
2- The medullary reticular system:
Transmit inhibitory signals to the same antigravity anterior motor neurons (medullary reticulospinal tract).
So that under normal conditions, the body muscles are normally tense.

11. Functions of the Cerebellum
Anterior and posterior lobes govern subconscious aspects of skeletal muscle movements.
Flocculondular lobe on inferior surface contributes to equilibrium and balance.
Main functions:
Cerebellum evaluates movements
smoothes movements
corrects errors
coordinates sequence
regulates posture and balance
makes possible all skilled muscular activities

12. Table 13.2 part 3

14. BASAL GANGLIA AND CONTROL OF MOTOR FUNCTIONS

15. Other nuclei include the substantia nigra and subthalamic nucleus.
BASAL GANGLIA
THE BASAL GANGLIA ARE MASSES OF GREY MATTER MADE OF CELL BODIES LYING DEEP INSIDE THE WHITE MATTER OF THE CEREBRUM, AND MAKES UP PART OFTHE MIDBRAIN.
An upper mass is called the caudate nucleus, is separated from a lower mass, the lentiform nucleus. The lentiform nucleus consists of the putamen and the globus pallidus.
Other nuclei include the substantia
nigra and subthalamic nucleus.

16. Basal Nuclei Caudate Nucleus Corpus Striatum Putamen Lenticular
Globus Pallidus
Subthalamic Nucleus
Substantia Nigra

18. Connections for Motor Control

19. Functions of Basal Ganglia
Control of movements
Planning and programming of movements
Cognition

20. The Putamen Circuit Executes Learned Patterns of Motor Activity
Basal ganglia function in association with the corticospinal system to control complex patterns of motor activity.
Examples are:
writing of letters of the alphabet.
cutting paper with scissors,
hammering nails,
shooting a basketball through a hoop,
passing a football,
throwing a baseball,
the movements of shoveling,
most aspects of vocalization,
controlled movements of the eyes
virtually any other of our skilled movements, most of them performed subconsciously.

21. The Caudate Circuit Cognitive Control of Sequences of Motor Patterns:
Cognition means the thinking processes of the brain, using both sensory input to the brain plus information already stored in memory. Thoughts are generated in the mind by a process called cognitive control of motor activity.
Example:
A person seeing a lion approach and then responding instantaneously and automatically by:
(1) turning away from the lion,
(2) beginning to run, and
(3) even attempting to climb a tree.
Thus, cognitive control of motor activity determines subconsciously, and within seconds, which patterns of movement will be used together to achieve a complex goal.

22. The Caudate Circuit
Change the Timing and to Scale the Intensity of Movements.
Two important capabilities of the brain in controlling movement are:
(1) to determine how rapidly the movement is to be performed and
(2) to control how large the movement will be.
For instance, a person may write the letter "a" slowly or rapidly. Also, he or she may write a small "a" on a piece of paper or a large "a" on a chalkboard. Regardless of the choice, the proportional characteristics of the letter remain nearly the same.

23. Movement Disorders Hypokinetic Hyperkinetic Parkinson’s Disease
Hemiballismus
Huntington’s Disease
Athetosis
Hypokinetic
Parkinson’s Disease
Drug Induced (Neuroleptics, MPTP)

24. Loss of dopamine-generating cells
Parkinson’s Disease PD
Loss of dopamine-generating cells
normal

25. Parkinson’s Disease Substantia Nigra, Clinical Feature (1)
Loss of DOPAminergic Neurons
Clinical Feature (1)
Slowness of Movement
- Difficulty in Initiation and Cessation
of Movement

26. Parkinson’s Disease Clinical Feature (2) Resting Tremor
Parkinsonian Posture
Rigidity-Cogwheel Rigidity

27. Parkinson’s Disease Described by James Parkinson
Degeneration of dopamine-generating cells in the substantia nigra (60-80 %).
Five cardinal features
Tremor
Rigidity
Akinesia & Bradykinesia
Postural Changes
Speech Changes

28. Huntington’s Disease Hereditory , autosomal dominant
Rare onset at 30-40s as early as 20s
Disease of caudate & putamen.
Early, Jerky movement of hands toward end of reaching an object
Later, hyperkinetic choreiform movements appear and gradually increase until they incapacitate the patient
Slurred speech and incomprehensive
Progressive Dementia