Motor Pathways

Question 1

walking, chewing, and other pre-programmed movements may be initiated independent of higher brain input. This is mainly an interaction between local circuit neurons and motor neurons

Answer 1

ok

Question 2

Motor cortex mostly responsible for what?

Answer 2

planning, initiating, and directing voluntary movements

Question 3

Brainstem centers responsible for?

Answer 3

regulating tone, and orienting posture with respect to sensory info

Question 4

Cerebellum does what?

Answer 4

acts as a servomechanism, detects the difference between an intended movement and the movement actually performed

Question 5

The cerebellum uses this movement to mediate both real-time and long-term adjustments

Answer 5

ok

Question 6

Basal ganglia does what?

Answer 6

Suppresses unwanted movements an dprepares upper motor neuron circuits for the initiation of movements

Question 7

What the hell is an upper motor neuron

Answer 7

One contained entirely within the central nervous system. No part of this neuron leaves

Question 8

What is a lower motor neuron?

Answer 8

A neuron that has a cell body in the CNS but is projecting its axon into the peripheral nervous system to innervate something anc cause an action

Question 9

What layers of Rexed’s laminae are the local circuit, autonomic, and commisural neurons found in?

Answer 9

layers 7 and 8

Question 10

Lower motor neurons are located in what level?

Answer 10

layer 9

Question 11

Lateral corticospinal tract serves what?

Anterior corticospinal tract serves what

Answer 11

ipsilateral motor neurons serving the distal extremities

Anterior corticospinal tract serves axial musculature

Question 12

What corticospinal tract serves axial muscles?

Answer 12

Ventral

Question 13

Does one motor neuron innervate several muscle fibers?

Answer 13

Yes…the larger the cell body of a motor neuron, the greater th enumber of fibers it synapses with

Question 14

Know that fine motor control is achieved by having only a single motor neuron innervate only a few muscle fibers, thus achieving precise control

Answer 14

ok

Question 15

Three general muscle fiber types are

Answer 15

1) Slow Fatigue Resistant
2) Fast Fatigue Resistant
3) Fast Fatiguable

Question 16

The motor neurons of slow resistant fibers tend to be small in size, thus the ratio of muscle fibers per neuron are also small. They also tend to be rich in mitochondria, myoglobin, and capillary beds

Answer 16

ok….dark meat, because of their myoglobin content

Question 17

SLow fatigue resistant muscles function mostly via which type of metabolism

Answer 17

aerobic

Question 18

Fast fatiguable muscle is inervated by much larger motor neurons and thus the muscle fiber to neuron ratio is very high

Answer 18

ok

Question 19

What is a motor unit

Answer 19

a group of muscles innervated by a single lower motor neuron

Question 20

What is the name of neurons that innervate skeletal muscle fibers to form motor units?

Answer 20

alpha motor neurons

Question 21

Alpha motor neurons can receive feedback from sensory organs within the bed of the muscle (spindle organs). The afferent neurons from these sensory organs have cell bodies in the DRG.

Answer 21

ok

Question 22

What is a common excitatory neurotransmitter for alpha motor neurons

Answer 22

acidic amino acids

Question 23

Common inhibitory neurotransmitters

Answer 23

GABA and Glycine

Question 24

muscle spindles give rise to what tpes of afferent nerves

Answer 24

Types Ia and type II

Question 25

What are the two types of sensory organs within the muscle bed

Answer 25

Spindle organs and Golgi Tendon organs

Question 26

Golgi Tendon organs give rise to what type of afferent nerves

Answer 26

Type Ib

Question 27

What does a gamma motor neuron do?

Answer 27

fires in concert with alpha motor neurons to insure that the intrafusal muscle fibers don’t become relaxed and non-responsive.

Question 28

Type II afferent nerves from muscle spindles…encodes muscle length information in the frequency of action potentials. Greater length = increased frequency of action potential, decreased lenght means decreased frquency

Answer 28

ok

Question 29

What does type Ia afferent encode

Answer 29

length and velocity of muscle change….quick change in muscle length generates a drastic increase in frquency

Question 30

Know golgi tendon organ stuff

Answer 30

ok

Question 31

Atrophy, decreased reflexes, decreased muscle tone, and fasiculations are all features of what kind of nerve lesion

Answer 31

lower motor neuron.

Question 32

Origins of upper motor neuron cell body located in the motor cortex which is located where?

Answer 32

precentral gyrus

Question 33

What are large motor neurons called?

Answer 33

Betz cells

Question 34

Precentral gyrus also called what?

Answer 34

Brodmann area

Question 35

Premotor area associated with which Brodmann area?

Answer 35

Brodmann area 6

Question 36

Primary somatosensory cortex associated with which Brodmann area

Answer 36

3,1,2

Question 37

Parietal asssociation cortex associated with which Brodmann area?

Answer 37

5,7

Question 38

Corticolubular tract is responsible for what?

Answer 38

fibers from the motor cortex to the cranial nerve motor nuclei

Question 39

Vestibulospinal tract does what

Answer 39

Fibers originate from vestibular nuclei, terminate at the cervical and thoracic spinal cord levles to innervate neck and trunk muscles

Question 40

Reticulospinal tract does what?

Answer 40

Fibers originate from neurons in the reticular system located diffusely in the brainstem. This tract along with the vestibulospinal tract terminates largely at the cervical and thoracic spinal cord level to innervate neck and trunk muscles

Question 41

Rubrospinal tract

Answer 41

fibers originate in the red nucleus. Travels closely with the lateral corticospinal tract and participates in control of arm muscles.

Question 42

Colliculospinal / tecto-spinal tract

Answer 42

Fibers originate from the superior colliculous. Terminates largely at the cervical spine to to innervate neck muscles. Coordinates head movements with eye movements

Question 43

Normal plantar response to stroking the lateral side of the foot with a blunt object=

Answer 43

flexion of the big toe and sometimes other toes

Question 44

Abnormal response to stroking the lateral side of the foot with a blunt object

Answer 44

Babinski sign…extension of the big toe and fanning of the other toes. means you have an upper motor neuron lesion, dawg

Question 45

Lower motor neurons serving the extremities are located where in the ventral horn?

Answer 45

Laterally

Question 46

Lower motor neurons serving the axial musculature located where

Answer 46

medial

Question 47

motor unit=

Answer 47

a group of muscle fibers inervated by a single lower motor neuron (or alpha neuron). Motor units vary in size and their size is determined by the number of fibers that are innervated which is in direct correlation with size of the motor neuron.

Question 48

When excitatory connections are made to motor neurons from afferents projecting above or below the spinal cord segment in which the motor neuron resides, the connection is through….

Answer 48

an excitatory interneuron!!!

Question 49

Corticobulbar pathway

Answer 49

fibers from the motor cortex to the cranial nerve motor nuclei