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26 October 2011
Lecture: Ch. 10 Control of Body Movement
Abstracts due Monday
Check schedule on website for assistance
About spreadsheets & JMP
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26 October 2011
Chapter 10:
Control of somatic
motor systems
Riding a bike, playing piano,
swinging a bat or golf club….
Video of Trampoline Championship
Benjamin Zander: Classical Music and Shining Eyes
1QQ # 21 for 8:30 section
Answer one question.
1. Which are characteristics of cardiac myofibers?
a) Ca++ for excitation-contraction coupling originates from
intracellular and extracellular sources
b) Cardiac myofibers have a twitch duration longer than smooth myofibers.
c) Produce action potentials that allow the influx of Ca++ for more than 100 ms.
d) Conduct action potentials to neighboring cells via
gap junctions of intercalated disks
e) Produce tension in proportion to the amount of cytosolic Ca++.
2. What type of myofiber can enter a latch state and what are the advantages
of the latch state?
1QQ # 21 for 9:30 section
Answer one question.
1. Which are characteristics of multi-unit smooth myofibers?
a) Each myofiber is individually innervated by autonomic neurons
b) Can be excited or inhibited by somatic motoneurons
c) Often have pacemaker potentials that result in periodic contractions
d) Are found in the walls of small-diameter blood vessels
e) Belong to large motor units.
2. Which properties of smooth muscle cells make them much better suited for
their role in the walls of hollow organs than skeletal myofibers?
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Fig. 10.10a
Each region has
a homunculus
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Fig. 10.02
Formerly called “basal ganglia”,
consist of caudate, putamen, and
globus pallidus
Decision to move
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Fig. 10.01
Initiates motor command
Coordinates
secondary movements
Corticospinal and
corticobulbar
tracts
Balance and
complex
learned
movements
Pathways?
Other inputs:
Vestibular &
Visual!
Reflex
Examples of
motor
disorders:
Huntington’s
Disease and
Cerebellar
Disorder
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Jack Nicholson
One Flew Over the Cuckoo’s Nest
Frontal lobotomy
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Local control
• Muscle spindle
Spindle
Afferent
gamma motoneurons
– 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
Motor units of
alpha motoneurons
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Fig. 10.05ab
This doesn’t happen!
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Fig. 10.05c
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.
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Fig. 10.06
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
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Stretch Reflex
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.
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Fig. 10.07
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Golgi tendon organs
involved in a reflex to
oppose excessive
muscle tension.
Not monosynaptic.
Not shown:
ascending axons in dorsal
column-medial lemniscus tract.
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Joint angle detectors and cutaneous mechanoreceptors
contribute to sense of body position (proproiception.)
Plus vision and vestibular inputs!
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Crossed-extensor reflex: Common sense… check the book!
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Something is incorrect on this figure from a textbook.
Find it!
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Pyramidal tract
Fig. 10.12
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
Not monosynaptic!
Descending Pathways
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Who Cares?
Video of Huntington’s Chorea
Video of Cerebellar Dysfunction
Locked-in Syndrome