Motor Pathaways

Question 1

The start of motor pathways

Answer 1

CEREBRAL CORTEX

Question 2

Motor pathways travel down the spinal cord

Answer 2

SPINAL CORD

Question 3

Motor pathways then innervate skeletal muscles

Answer 3

SKELETAL MUSCLES

Question 4

Originate in ventral horns of spinal cord; axons leave via ventral roots

Answer 4

LOWER MOTOR NEURONS

Question 5

Organization of lower motor neurons that correspond to their anatomical relationship with skeletal muscles

Answer 5

Somatotopically

Question 6

Innervate extrafusal muscle fibers

Answer 6

ɑ-Motor neurons

Question 7

Innervate intrafusal muscle fibers

Answer 7

ɣ-Motor neurons

Question 8

One ɑ-motor neuron and all of the skeletal muscle fibers it innervates.
Can be large (one ɑ-motor neuron innervating many skeletal muscle fibers) or small (one ɑ-motor neuron innervating a few skeletal muscle fibers)

Answer 8

MOTOR UNIT

Question 9

Allows for communication of neural impulses between neurons

Allows neural impulses to be relayed to several areas within the nervous system at once

Provide synchronization to coordinate complex motor pathways

Answer 9

Interneurons

Question 10

Where ɑ-motor Neurons Originate in the Cerebral Cortex

Contains motor areas tasked with controlling voluntary skeletal muscle movement

Answer 10

Motor cortex

Question 11

True or False:

Most neurons decussate before synapsing with lower motor neurons, but some don’t

Answer 11

True

Question 12

Organized somatotopically

Population vectors determine direction of contraction

Composed of 6 layers

Answer 12

Primary Motor Cortex

Question 13

Layer V contains large pyramidal

Answer 13

“Betz” cells

Question 14

Works together with primary motor cortex but also sends signals directly down spinal cord

Controls muscle responses to visual or sound cues

Stores motor memory (along with primary motor cortex)

Controls muscle movement in context

Answer 14

PREMOTOR CORTEX

Question 15

Controls complex or sequential muscle movements

Implicated in bilateral muscle movements

Determines amount of strength, distance and direction required for muscle movements

Answer 15

SUPPLEMENTARY MOTOR AREA

Question 16

Located in the prefrontal cortex and the posterior part of the parietal cortex

Helps to modify muscle movements initiated in the motor cortex

Answer 16

The Association Cortex

Question 17

Ensures muscle movement behavior is appropriate

Answer 17

Prefrontal Association Cortex

Question 18

Allows for precise muscle movements

Answer 18

Parietal Association Cortex

Question 19

Source of indirect (extrapyramidal) motor tracts

Answer 19

Brain Stem

Question 20

Main areas pertaining to motor pathways in brain stem (2)

Answer 20

1. Vestibular nuclei

2. Reticular formation

Question 21

Modulate and modify impulses from the upper motor neurons

Regulate thalamus through two neurotransmitters: GABA and glutamate

Answer 21

Basal Nuclei

Question 22

Continually sends excitatory impulses to motor cortex

Answer 22

Thalamus

Question 23

Exicitatory

Answer 23

Glutamate

Question 24

Inhibitory

Answer 24

GABA

Question 25

Adjusts motor impulses to ensure muscle movements are precise and accurate Mossy fibers and Purkinje cells Impulses travel to deep cerebellar nuclei, and then out to other areas of the brain

Answer 25

Cerebellum

Question 26

mainly responsible for carrying information into the cerebellum

Answer 26

Mossy fibers

Question 27

mainly responsible for sending impulses out of the cerebellum

Answer 27

Purkinje cells

Question 28

Types of Motor Pathways

Answer 28

Direct (Pyramidal) and Indirect (Extrapyramidal)

Question 29

Control skeletal muscle | Direct connection from cerebral cortex to spinal cord or brain stem

Answer 29

Direct (Pyramidal)

Question 30

Upper motor neurons originate in the brain stem Travel down spinal cord and synapse in the ventral horns of the specific spinal cord innervation Vesibulospinal Tracts, Reticulospinal Tracts, Rubrospinal Tracts and Tectospinal Tracts

Answer 30

Indirect (Extrapyramidal)

Question 31

Control skeletal muscles associated with chewing, facial expression, tongue movement and swallowing

Answer 31

CORTICOBULBAR TRACTS

Question 32

Some axons decussate at the pyramids of the medulla oblongata Some axons decussate and others don't

Answer 32

CORTICOSPINAL TRACTS

Question 33

Axons that decussate; mainly innervate appendicular skeletal muscles

Answer 33

Lateral corticospinal tracts

Question 34

Axons that don't decussate; mainly innervate axial skeletal muscles

Answer 34

Ventral corticospinal tracts

Question 35

An Example of a Direct (Pyramidal) Tract

Answer 35

Wrist extension

Question 36

Control balance and posture

Answer 36

Vesibulospinal Tracts

Question 37

Upper motor neurons originate in lateral vestibular nuclei of medulla and pons Synapse with lower motor neurons in region of spinal cord associated with postural muscles

Answer 37

Lateral Vesibulospinal Tracts

Question 38

Upper motor neurons originate in medial vestibular nuclei of medulla and pons Synapse with lower motor neurons in ventral horn of cervical spinal cord

Answer 38

Medial Vesibulospinal Tracts

Question 39

Control axial and proximal muscles associated with posture, locomotion and stimulus-driven muscle movement Exert control over skeletal muscles and autonomic nervous system

Answer 39

Reticulospinal Tracts

Question 40

Affects extensor muscles

Answer 40

Medial Reticulospinal Tracts

Question 41

Inhibit extensor muscles

Answer 41

Lateral Reticulospinal Tracts

Question 42

Play a role in voluntary motor function, mostly in vertebrates other than humans In humans, primarily innervates muscles associated with flexion Originates in red nucleus of midbrain Tract decussates and travels down lateral column, parallel with lateral corticospinal tract Synapses with lower motor neuron at ventral horn

Answer 42

Rubrospinal Tracts

Question 43

Control muscle movement of head in response to visual stimuli Receive sensory input from optic nerves Originates in superior colliculus of midbrain Some fibers decussate, some do not Descend down anterior column of spinal cord Synapse with lower motor neurons in ventral horn of upper cervical spinal cord (C1-C4)

Answer 43

Tectospinal Tracts

Question 44

An Example of an Indirect (Extrapyramidal) Tract

Answer 44

Knee Extension

Question 45

System of neurons involved with rhythmic and locomotive movement patterns Involves complex coordination

Answer 45

CGP (central pattern generator )

Question 46

CGP can be _____ or _____

Answer 46

Autogenic (self-generating); subject to voluntary control

Question 47

Help Monitor Muscle Tone and Posture Stimulated by change in muscle tone (contraction of intrafusal muscle fibers) Sensation is sent to spinal cord, where reflexive action can prevent overstretching or stretching too fast Sensation can also be sent to cerebellum, which assesses changes in muscle tone

Answer 47

Muscle Spindles

Question 48

Also Monitors Muscle Tone Stimulated by tension (not stretch) upon muscle contraction Located within the tendon or where the muscle and tendon meet Composed of enclosed collagenous capsule of extrafusal muscle fibers Sends sensory information to both spinal cord and cerebellum

Answer 48

The Golgi Tendon Organ (GTO)

Question 49

Disorder or disease resulting from damage or lesions to an upper motor neuron (most commonly in cerebral cortex)

Answer 49

Upper Motor Neuron Disorders

Question 50

Damage to ɑ-motor neurons from trauma, viruses or autoimmune system diseases

Answer 50

Lower Motor Neuron Disorders

Question 51

Damage or malfunction of the basal nuclei

Answer 51

Basal Nuclei Disorders

Question 52

Damage to the cerebellum by autoimmune disease, inflammation, tumors, toxins or injury

Answer 52

Cerebellum Disorders

Question 53

Partial or total loss of movement of all 4 limbs; functioning could also be lost in areas of the torso

Answer 53

Quadriplegia

Question 54

Partial or total loss of movement on one side of the body

Answer 54

Hemiplegia

Question 55

Partial or total loss of movement in one or both lower limbs

Answer 55

Paraplegia

Question 56

Depending on the type, various motor functions are affected such as movement of facial and tongue muscles but also legs and arm movements can be affceted

Answer 56

Aprexia

Question 57

Thinning of the cerebral cortex Deterioration of pyramidal neurons in primary motor cortex Decreased dopamine receptors in neurons of the striatum of the basal nuclei Changes in motor units: decreased axonal transference, less mitochondria, fewer muscle filaments

Answer 57

Aging in Motor Pathways

Question 58

This structure mainly acts as a proprioceptor.

Answer 58

Intrafusal muscle fibers

Question 59

Which is not a function of the premotor cortex?

Answer 59

Implicated in bilateral muscle movements

Question 60

Mossy cells

Answer 60

Carry information into the cerebellum

Question 61

Which is not a feature of rubrospinal tracts?

Answer 61

Controls movement of head in response to visual stimuli

Question 62

Paralysis is thought of as which type of motor neuron disorder?

Answer 62

Upper motor neuron disorder