unit 2 review - motor Flashcards
agonists/synergists are?
muscles that contract together
axial muscles vs. proximal vs. distal
axial= center: trunk and posture
proximal=shoulder, pelvis, elbow, knee; locomotion
distal=digits, fine motor skills, specialized in humans
how to motor neuron axons get to the brain?
by going through the ventral horn
what areas of the spinal cord are enlarged and why?
cervical and lumbar
- fine motor control, enlarged because of more motor neurons
what is contained in the lateral ventral horn?
lateral muscles
- like hands
what is contained in the medial ventral horn?
medial muscles
- like torso
where are flexors vs. extensors on the ventral horn spectrum?
flexors are more dorsal to neurons innervating extensors
what is a muscle fiber innervated by?
how many, what is the NT?
innervated by 1 alpha motor neuron
- NT=ACh
where does the muscle fiber synapse?
motor end plate
what is a motor unit?
- 1 alpha motor neuron
- all the muscle fibers it innervates
how many muscle fibers can an alpha motor unit innervate?
a muscle fiber can only be innervated by 1 alpha motor unit, but
- 1 alpha motor unit can innervate many muscle fibers
what is a motor pool?
all the alpha motor units that innervate 1 muscle
what determines slow vs. fast twitch?
can a motor unit have more than 1 type?
alpha motor unit determined fast/slow twitch type
what are the two ways that more muscle force can be generated?
1) increasing the firing rate of active motor neurons
- fasciculation=twitches
- temoral summation of twitches
2) increase number of active motor neurons
- size princliple
where are alpha motor neurons located?
where do they send their axons?
spinal cord
- send axons down to muscles to cause contraction
what are the 3 components that modulate alpha motor neurons?
1) sensory input
2) input from same and nearby spinal segments
3) brain
- upper motor neurons
where do muscles get sensory input from?
Aa and Ab
- fastest conduction
what two organs give muscles proprioceptive input?
- golgi tendon organs
- muscle spindles
what are golgi tendon organs?
where are they located in comparison to the muscle?
force/tension receptors
- located in series, at the junction between the muscle and tendon