Motor Unit Flashcards
Movement is controlled by?
spinal cord & brainstem, lower motor neurons, descending systems, upper motor neurons, cerebellum, basal ganglia
Sensory inputs for LMN involve?
muscle, tendon, joints
Lower motor neurons are also called?
alpha motorneuron, spinal motorneuron
Lower motor neurons are characterized by?
large cell body, extensive dendritic tree, large axon,myelinated with Schwann cell
MNs to proximal muscles are located?
medial ventral horn
MNs to distal muscles are located?
lateral ventral horn
Whats is a motor pool?
motor pool is the total of all lower motor neurons innervating a given muscle
Motor unit is made up of?
cell body, its axon and all the muscle fibers that axon innervates
List some characterictics of a motor unit
axon innervates only one muscle
collection of muscle fibers innervated by that one axon known the muscle unit
properties of muscle fibers within a muscle unit are identical
all muscle fibers of the muscle unit normally contract together
size of muscle unit varies tremendously
LMN synapse where?
NMJ
Force generation in muscle occur?
Muscle (extrafusal) fiber
Force generation involves?
involves calcium binding, rotation of mysin cross-bridge, ATP which is needed for cross-brdge release
Name the different types of Motor units
S- slow to fatigue
FR- fatigue resistant
FF- fast, fatiguable
What is the difference between Twitch and Tetanus?
Twitch is one single stimulus to the motor unit axon
Tetanus is repeated stimuli to the axon, before the mechanical increase in force recovers to zero
Size principle states?
stronger inputs lead to recruitment of more powerful MUs
