1. Each region has a homunculus
Fig a
S 2
Each region has a homunculus
10.10a.jpg

2. Initiates motor command
Decision to move
Fig
S 4
Initiates motor command
Coordinates secondary movements
Corticospinal and corticobulbar tracts
Balance and complex learned movements
Pathways?
Other inputs:
Vestibular &
Visual!
10.01.jpg
Reflex
Examples of motor disorders: Huntington’s Disease and Cerebellar Disorder

3. Jack Nicholson One Flew Over the Cuckoo’s Nest
Frontal lobotomy

4. Extra-Pyramidal tracts
Fig
S 16
Pyramidal tract
Descending Pathways
Corticospinal tract Corticobulbar tract
Fine motor control, esp. of extremeties
Extra-Pyramidal tracts
Reticulospinal tract Vestibulospinal tract
Originate in brainstem,
more involved with posture and equilibrium
10.12.jpg
Diagram is not accurate: This is not a monosynaptic pathway! Descending axons synapse onto interneurons which then synapse onto motoneurons.

5. Who Cares? S 17 Video of Huntington’s Chorea
Video of Cerebellar Dysfunction
Locked-in Syndrome

6. Local control Muscle spindle What is their role? The stretch reflex…
Spindle Afferent
gamma motoneurons
Muscle spindle
Stretch receptor
Intrafusal muscle fiber
What is their role?
The stretch reflex…
Follow the reflex arc
Be able to differentiate function of afferent fibers, alpha motor neurons, and gamma motor neurons
10.04.jpg
Motor units of alpha motoneurons

7. Fig ab
S 7
10.05ab.jpg
This doesn’t happen!

8. Fig c
S 8
10.05c.jpg
Co-activation of alpha and gamma motoneurons insures that the stretch of muscle can be detected regardless of the initial length or state of contraction of that muscle.

9. Synergistic & Antagonistic
Fig
S 9
Proprioception pathway via dorsal column-medial lemniscus pathway
One component of Stretch reflex is monosynaptic
Most common example: patellar reflex = “knee jerk reflex”
Synergistic & Antagonistic
Muscles
10.06.jpg

10. Stretch Reflex
S 10
Monosynpatic excitation of motoneurons of that muscle and synergistic muscles
and polysynaptic inhibition of motoneurons to antagonistic muscles.
Recall frog reflex lab and existence of spinal reflexes in single-pithed frogs.
Also, example Christopher Reeve and
patellar reflex.
10.06.jpg

11. Fig
S 11
10.07.jpg

12. Golgi tendon organs involved in a reflex to oppose excessive muscle tension. Not monosynaptic.
Not shown in text diagram: ascending axons in dorsal column-medial lemniscus tract.
S 12
10.08.jpg

13. Other proprioceptors S 13
Joint angle detectors and cutaneous mechanoreceptors also contribute to sense of body position (proproiception.)
Plus vision and vestibular inputs!

14. Something is incorrect on this figure from another textbook. Find it!