PHYSIOLOGY - somatic motor system Flashcards
where are upper motor neurons (UMN)
in the brain
what do UMN do
supply input to LMN
where are lower motor neurons (LMN)
in the brain stem/ventral horn of spinal cord
what do LMN do
command muscle contraction
which horn of the spinal cord do LMNs leave via
anterior/ventral horn
motor = want to be need the action = anterior
what happens after LMN leaves anterior/ventral horn
joins posterior/dorsal horn nerve (sensory) to form a mixed spinal nerve
what do the medial LMNs supply
axial/proximal muscles
eg shoulder
what do the lateral LMNs supply
distal muscles
what do the dorsal (posterior) LMNs supply
flexor muscles
think: elbow flexion moves the arm posteriorly
what do the ventral (anterior) LMNs supply
extensor muscles
think: elbow extension moves the arm anteriorly
what are synergistic muscles
muscles that work together
eg biceps brachii and brachialis
what do alpha motor neurons supply/innervate
are these intra/extrafusal muscle fibres
muscles that provide a force
intrafusal muscle fibres
what do gamma motor neurons supply/innervate
are these intra/extrafusal muscle fibres
sensory muscles eg organs
extrafusal muscle fibres
what is a motor unit
1 alpha motor neurone and all the skeletal fibres that it innervates
what is a motor pool
all the alpha motor neurons that supple one skeletal muscle (collection of motor units)
for type I and IIa muscle fibres where does ATP come from
oxidative phosphorylation
for type IIb muscle fibres where does ATP come from
what does this mean
glycolysis
when you are fatigued = wont make ATP
what type of muscles fibres are slow oxidative fibres
type I
what type of muscle fibres are fast
type II
why is it important to have a mix of type I, IIa and IIb fibres in each muscle
for different functions eg walking, running, jumping
what is the myotatic reflex
when a skeletal muscle is pulled it pulls back = reflex (eg knee jerk)
what do golgi tendon organs do
what sensation do they contribute to
reverse the myotatic reflex
proprioception
where are golggi tendon organs
the junction of muscles and tendons
where are joint receptors
what are they important for
the connective tissue of joints (eg ligaments, joint capsule)
proprioception
