Exam 2 Study Guide

Question 1

Where are cell bodies of UMN?

Answer 1

• cerebral cortex

- brainstem

Question 2

Where do UMN axons travel?

Answer 2

in pyramidal tracts

Question 3

UMN axons synapse with

Answer 3

• interneurons
• LMN

in brainstem or SC

Question 4

LMN cell bodies are located here (big picture)

Answer 4

• spinal cord

- brainstem

Question 5

alpha LMNs innervate

Answer 5

extrafusal fibers

Question 6

gamma LMNs innervate

Answer 6

intrafusal fibers

Question 7

coactivation of alpha and gamma LMN

Answer 7

maintain stretch on intrafusal fibers while extrafusal fibers contract

Question 8

mechanisms of sensory contribution to motor systems

Answer 8

• feedback

- feedforward

Question 9

feedforward

Answer 9

anticipatory use of sensory info to prepare for movement

Question 10

feedback

Answer 10

use of sensory info during or after movement to make corrections to ongoing movement or future movements

Question 11

When does neural transmission to a muscle fiber stop?

Answer 11

when ACH is removed from the synaptic cleft

Question 12

How does ACH removal occur?

Answer 12

• diffusion away from the synapse

- broken down by acetylcholinesterase to acetic acid and choline

Question 13

sequence of events that converts APs in a muscle fiber to a contraction

Answer 13

excitation contraction coupling

Question 14

2 terminal cisternae + 1 t-tubule

Answer 14

triad

Question 15

motor pathway overall

Answer 15

• decision from frontal cortex
• motor planning areas
• control circuits
• UMN conducts signals to LMN and interneurons
• LMN » skeletal muscles

Question 16

amount of tension in a muscle at rest

OR

amount of resistance to passive stretch exerted by a resting muscle

Answer 16

tone

Question 17

How is tone acquired?

Answer 17

• weak actin-myosin bonds
• titin
• active contraction

Question 18

How do muscles adapt to changes in length?

Answer 18

They are plastic/adaptable. When contracted or extended for a period of time, they either lose or gain sarcomeres

Question 19

What happens to someone who has had their arm in a cast or sling for 6 weeks?

Answer 19

• contracture

- greater resistance to stretch

Question 20

What happens to someone who suffers from spasticity (as in CP)?

Answer 20

• muscle more difficult to stretch

- spastic co-contraction makes it hard to walk

Question 21

How does the spinal region contribute to movement?

Answer 21

• reflexes
• stepping pattern generators
• inhibitory interneuron circuits

Question 22

Activation of ceruleospinal and raphespinal tracts produces

Answer 22

produce a generalized increase in activity of

• spinal interneurons
• motor neurons

Question 23

contribution of ceruleospinal and raphespinal tracts overall

Answer 23

may contribute to poorer motor performance when anxiety is high

Question 24

ceruleopinal and raphespinal tracts (example)

Answer 24

Climbers on a high wall move more slowly, make more exploratory movements, and use each hold longer than those on a lower climbing wall

Question 25

What reduces the rate of postural adjustments?

Answer 25

fear

Question 26

paresis

Answer 26

partial loss of voluntary movements

Question 27

paralysis

Answer 27

total loss of voluntary movements

Question 28

muscle atrophy

Answer 28

loss of muscle bulk

Question 29

2 types of atrophy

Answer 29

• disuse

- neurogenic

Question 30

disuse atrophy

Answer 30

lack of muscle use

Question 31

neurogenic atrophy

Answer 31

damage to nervous system

Question 32

spasm

Answer 32

sudden, involuntary contraction of muscle fibers

Question 33

cramp

Answer 33

severe, painful muscle spasm

Question 34

fasciculations

Answer 34

• quick twitches of muscle fibers of single motor units

- visible on surface of skin

Question 35

hypotonia caused by

Answer 35

• LMN lesions

- acute UMN lesions

Question 36

hypertonia caused by

Answer 36

chronic UMN lesions

Question 37

hyperreflexia

Answer 37

UMN problem

• loss of inhibitory corticospinal input
• excessive interneuron and LMN activity

Question 38

hyporeflexia

Answer 38

LMN problem