Motor Control Chapter 8

Question 1

Skeletal muscle is composed of two fiber types:

Answer 1

Extrafusal, Intrafusal

Question 2

This type of skeletal muscle is innervated by alpha-motor neurons from the spinal
cord: exert force

Answer 2

extrafusal

Question 3

This type of skeletal muscle is innervated by gamma-motor neurons

Answer 3

Intrafusal:

Question 4

This type of muscle fiber reports the length of intrafusal: when stretched, the fibers
stimulate the alpha-neuron that innervates the muscle fiber: maintains
muscle tone

Answer 4

• Afferent fibers:

Question 5

This type of muscle fiber deals with contraction adjusts sensitivity of afferent fibers.

Answer 5

• Efferent fibers:

Question 6

Each muscle fiber consists of a bundle of

Answer 6

myofibrils

Question 7

Each myofibril is made up of overlapping strands of ____

Answer 7

actin and myosin

Question 8

The ____ is the synapse formed
between an alpha motor neuron axon and a muscle fiber

Answer 8

The neuromuscular junction is the synapse formed
between an alpha motor neuron axon and a muscle fiber

Question 9

Each axon forms synapses with several muscle fibers

Answer 9

(forming a motor unit)

Question 10

____ is the neuromuscular junction neurotransmitter

Answer 10

ACh

Question 11

Smooth muscle is controlled by the

Answer 11

autonomic nervous system

Question 12

_____ smooth muscle is normally inactive
* Located in large arteries, around hair follicles (for piloerection) and in
the eye (lens adjustment, pupillary dilation)
* Responds to hormonal stimulation

Answer 12

Multiunit

Question 13

____ smooth muscle exhibits rhythmic contraction
* Single-unit muscle is found in gastrointestinal tract, uterus, small
blood vessels

Answer 13

Single-unit

Question 14

____ resemble striated muscle in appearance, but exhibit rhythmic contractions like that of single-unit smooth muscle

Answer 14

Cardiac muscle fibers

Question 15

Spinal cord is organized into ___ and ____ aspects

Answer 15

dorsal, ventral

Question 16

Dorsal horn receives incoming

Answer 16

sensory information

Question 17

Ventral horn issues efferent fibers (alpha-motoneurons) that ____

Answer 17

innervate extrafusal fibers

Question 18

______ involve a single synapse between a sensory fiber from a muscle and an alpha-motor neuron
– Sensory fiber activation quickly activates the alpha motor
neuron which contracts muscle fibers
* Patellar reflex

Answer 18

Monosynaptic reflexes

Question 19

____ involve multiple synapses between
sensory axons, interneurons, and motor neurons
– Axons from the afferent intracellular muscle fibers can synapse
onto:
* Alpha motoneuron connected to the agonist muscle
* An inhibitory interneuron connected to the antagonist muscle
– Signals from the intracellular muscle activate the agonist and inhibit the
antagonist muscle

Answer 19

Polysynaptic reflexes

Question 20

Primary motor cortex is located on the

Answer 20

precentral gyrus

Question 21

Motor cortex receives input from

Answer 21

• Premotor cortex
• Supplemental motor area
• Primary somatosensory cortex

Question 22

____ controls where to move, ____ controls what is moving, and _____ plans to move

Answer 22

parietal, temporal, frontal

Question 23

Planning of movements involves the _____
and the _____ which influence the primary motor cortex

Answer 23

premotor cortex, supplemental motor area

Question 24

“ideational apraxia” – verbal domain (a neurological disorder characterized by the inability to conceptualize, plan, and execute complex sequences of motor action)
– Sequencing complex behavior of talking is controlled by what part of the brain?

Answer 24

Left Frontal Lobe

Question 25

“Ideational apraxia” – spatial domain what part of the brain?

Answer 25

Right frontal Lobe

Question 26

Motor Pathways Lateral Group – controls _____ * More “lateralized” – Ventromedial group – controls _______ * More “medial”

Answer 26

controls independent limb movements gross or coordinated limb movements

Question 27

_____ * Corticospinal tract: hand/finger/foot movements * Corticobulbar tract: movements of face, neck, tongue, eye (independent) * Rubrospinal tract: fore- and hind-limb muscles

Answer 27

Lateral group:

Question 28

_____ * Vestibulospinal tract: control of posture * Tectospinal tract: coordinated eye and head/trunk movements * Reticulospinal tract: walking, sneezing, muscle tone (coordinated) * Ventral corticospinal tract: muscles of upper leg/trunk

Answer 28

Ventromedial group:

Question 29

rubrospinal track crosses over by ____!

Answer 29

pons

Question 30

corticospinal track (dark blue; upper legs and trunk) stays ____ and projects ____ ! (part of ventromedial pathways)

Answer 30

ipsilateral, bilaterally

Question 31

Basal ganglia consists of (3) – Input to the basal ganglia is from the

Answer 31

caudate nucleus, putamen and the globus pallidus, substantia nigra

Question 32

– Output of the basal ganglia goes to

Answer 32

* Primary motor cortex, supplemental motor area, premotor cortex * Brainstem motor nuclei (cerebellum to descending motor pathways)

Question 33

_____ involves muscle rigidity, resting tremor, slow movements, postural instability

Answer 33

Parkinson’s disease (PD)

Question 34

Parkinson’s results

Answer 34

from damage to dopamine neurons within the nigrostriatal bundle (projects to caudate and putamen)

Question 35

What area of the brain do you stimulate for deep brain stimulation for Parkinson?

Answer 35

Subthalamic Nucleus

Question 36

Huntington’s disease (HD) is:

Answer 36

involves uncontrollable, jerky movements of the limbs & terrible balance

Question 37

HD is caused by ____ – HD is a hereditary disorder caused by a * If one parent has the disorder, each child has a ___ chance of acquiring the disorder

Answer 37

degeneration of the caudate nucleus and putamen * Cell loss involves GABA-secreting axons that innervate the external division of the globus pallidus 50%

Question 38

_____ refers to an inability to properly execute a learned skilled movement following brain damage

Answer 38

Apraxia

Question 39

Sympathetic apraxia causes what?

Answer 39

damage to anterior left hemisphere causes paralysis of right arm and hand

Question 40

What is Callosal apraxia

Answer 40

person cannot perform movement of left hand to a verbal request (anterior callosum interruption prevents information from reaching right hemisphere)

Question 41

What is Left parietal apraxia

Answer 41

difficulty in initiating movements to verbal request

Question 42

What is Constructional apraxia

Answer 42

caused by right parietal lobe damage, Person has difficulty with drawing pictures or assembling objects

Question 43

What is flexion vs Extension

Answer 43

contraction of a flexor muscle draws in a limb (positive working out) contraction of extensor muscle “Anti-gravity (negative working out)