Lecture nine: control of movement Flashcards
what are Extrafusal Muscle fiber?
<2muscles attached to the bones by tendons, for movement”
Activated by alpha motor neurons
Intrafusal muscle fibers
set makes muscle spindle
Wrapped by afferent fibers (sensory endings)
But also: activated by gamma motor neurons
For detection of muscle length
For detection of muscle length
Golgi tendon organ
for detection of change in muscle tension
Pacinian corpuscles and free nerve endings
for detection compression of muscle (during contraction) and waste products
What does Myofibrils consist of?
Myofibrils in extrafusal fibers consist of Actin and Myosin
mechanism of muscle contraction
- Myosin (yellow) binds actin (pink).
- Myosin heads fall over and slide forward along the actin.
- Myosin heads release
- Rest condition
What is the Monosynaptic stretch-reflex?
- weight falls on hand
2.detection
muscle extension - reflexive muscle contraction
What is the Polysynaptic inhibitory-reflex?
Inhibition α neuron by Golgi tendon organ
prevents excessive tension on muscle
Lift more by sedating Golgi tendon organs
Explain the function of monosynaptic stretch
reflexes
Monosynaptic stretch responses function to control limb
movements when weight is applied or removed quickly
and to maintain upright posture.
Contrast the structures and function of
polysynaptic reflexes with monosynaptic reflexes:
Monosynaptic reflexes include a single synapse involved
in simple reflexes like the patellar reflex. Polysynaptic
reflexes involve multiple synapses involved in more
complex reflexive behavior, such as inhibiting a
withdrawal reflex. Polysynaptic reflexes contain at least
one interneuron between the sensory neuron and the
motor neuron.
Corticospinal paths
Lateral group:
for independent limb movements:
(very importat sh$t)
Rubrospinal tract (via red nucleus)
lower arms, hands (not fingers)
lower legs, feet (not toes)
Corticobulbar tract
neck, face, eyes, tongue
Lateral corticospinal tract
arms, hands, fingers
legs, feet, toes
Rubrospinal tract
Rubrospinal tract (via red nucleus)
lower arms, hands (not fingers)
lower legs, feet (not toes)
Corticobulbar tract
neck, face, eyes, tongue
Lateral corticospinal tract
Lateral corticospinal tract
arms, hands, fingers
legs, feet, toes
What is the Ventromedial group for:
for balance (body posture) and walking and controlled via nuclei in brainstem