Transcript Lecture slides from 2007

Motor 1
All Movement
Involves the
rotation of
Skeletal Joints
Joints can rotate along:
•One axis (knee)
•Two axes (wrist)
•Three axes (hip)
Muscles only
Generate force
When they
Contract
So muscles are always
Arranged in pairs for
Rotating joints in both
directions
Note tendons which
Attach muscles to the
skeleton
Muscles Contract in Response to
Acetyl Choline
Cholinergic Motor neurons make these
connections
Muscles themselves are
Made of fibers
Each fiber contracts
In response to
Ach induced
depolarization
Muscle Has Different Fiber Types
Cat Gastrocmenius
Cat Soleus
Contractile Properties of Whole Muscles Vary
Muscles Have Heterogenous Properties
Twitch Contractions
The Motor Unit
Motor Units are Homogenous by Fiber Type
Fiber Types are Adaptive
Conduction Velocities of Alpha-MN Axons
soleus
Gastroc.
The Size Principle
Feedback Signals From Muscle
Muscles also have sensory transducers
Imbedded in them
Stretch receptors (also
Called spindles) have
A firing rate that
Indicates muscle length
The Stretch Reflex Circuit
The Motor Neuronal Pool
The Motor-Neuronal Pool
A pool of motor neurons
In the spinal cord
Serves each muscle
These pools form a
Topographic map
(sort of)
The Law of Combination
-Elwood Henneman