Motor 1

All Movement
Involves the rotation of
Skeletal Joints
Joints can rotate along:
•One axis (knee)
•Two axes (wrist)
•Three axes (hip)

Note tendons which
Attach muscles to the skeleton
Muscles only
Generate force
When they
Contract
So muscles are always
Arranged in pairs for
Rotating joints in both directions

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