Motor 2 Flashcards
alpha motor neurons
ventral root
make skeletal muscles contract
gamma motor neurons
ventral root
make muscle spindles more sensitive to stretch
α Motoneurons
innervate extrafusal skeletal muscle fibers
γ Motoneurons
innervate specialized intrafusal muscle fibers
Muscle Spindle
monitor changes in the length of skeletal muscle
Nuclear bag fibers
larger, and their nuclei are accumulated in a central (“bag”) region
Nuclear chain fibers
smaller, and their nuclei are arranged in rows (“chains”)
group 1a afferent nerve
innervates nuclear bag fibers and the nuclear chain fibers
group 2 afferent nerves
innervates nuclear chain fibers
Dynamic γ motoneurons
synapse on nuclear bag fibers in “plate endings”
Static γ motoneurons
synapse on nuclear chain fibers in “trail endings”
α-γ motor coactivation
γ-motor discharge ↑es along with ↑ed discharge of α-MN
Group Ib fibers
primary afferents
Golgi Tendon Organ Reflex
group Ib afferent fibers
inhibitory neurons
changes in FORCE
inhibit the α motoneurons
muscle spindle reflex
contraction
Golgi tendon reflex
muscle relaxation and load drop
spinal reflex
Stretch reflex
cranial reflex
pupillary light reflex
monosynaptic reflex
single synapse between the afferent and efferent neurons
polysynaptic reflex
two or more synapses
through an interneuron
tonic stretch reflex
maintains posture
S1-2 reflex
ankle jerk
1, 2 buckle my shoe
L3-4 reflex
ankle jerk
3, 4 kick the door
C5-6 reflex
biceps and supinator jerks
5, 6 pick up sticks
