topic 6 - NERVOUS SYSTEM IV - Motor "Output" - Corticospinal (Direct) Pathway

Question 1

corticospinal (Direct) pathway

• cortex to what?
• what are the 2 parts?

Answer 1

• cortex to skeletal muscle
• parts:
  
  1. upper motor neurons
  2. lower motor neurons in spinal nerves

Question 2

corticospinal (direct) pathway:

part: upper motor neurons

• cell bodies in where?
• axons into where?

Answer 2

• cell bodies in primary motor cortex
• axons into spinal cord

Question 3

corticospinal (direct) pathway:

part: upper motor neurons

• what is located in primary motor cortex?
• _____ into spinal cord

Answer 3

• cell bodies in primary motor cortex
• axons into spinal cord

Question 4

corticospinal (direct) pathway:

part: upper motor neurons

no hints (2 points)

Answer 4

• cell bodies in primary motor cortex
• axons into spinal cord

Question 5

corticospinal (direct) pathway:

part: lower motor neurons in spinal nerves

cell bodies located where?

Answer 5

cell bodies in ventral horn of spinal cord

Question 6

corticospinal (direct) pathway:

part: lower motor neurons in spinal nerves

what is located in ventral horn of spinal cord?

Answer 6

cell bodies in ventral horn of spinal cord

Question 7

corticospinal (direct) pathway

lower motor neurons in spinal nerves

no hints (1 point)

Answer 7

cell bodies in ventral horn of spinal cord

Question 8

clinical applications

destruction of what neurons?

Answer 8

destruction of upper motor neurons and lower motor neurons

Question 9

clinical applications

destruction of upper motor neurons:

• _____ ___ still present
• get:
  
  • _____ _______ = ______ muscle tone (no muscle ______)
  • _______ reflexes (e.g. patellar, ______, babinski ______ plantar _____ - scratch _____ of ______.
    
    • normal = ______ flexion (curl _____)
    • babinski sign = extend _____ ___

Answer 9

• reflex arc still present
• get
  
  • spastic paralysis - increased muscle tone (no muscle atrophy)
  • exaggerated reflexes e.g. patellar, achilles; Babinski Sign Plantar reflex - scratch sole of foot
    
    • normal = plantar flexion (curl under)
    • Babinski sign = extend big toe

Question 10

clinical application: destruction of __________

• reflex arc _________
• get
  
  • spastic paralysis - increased _____ _____ (__ ______ atrophy)
  • exaggerated _____ e.g. _____, achilles; _____ Sign _____ reflex - _____ sole of foot
    
    • _____ = ______flexion (curl under)
    • ______ _____ = _____ big toe

Answer 10

destruction of upper motor neurons

• reflex arc still present
• get
  
  • spastic paralysis - increased muscle tone (no muscle atrophy)
  • exaggerated reflexes e.g. patellar, achilles; Babinski Sign Plantar reflex - scratch sole of foot
    
    • normal = plantar flexion (curl under)
    • Babinski sign = extend big toe

Question 11

clinical applications: destruction of upper motor neurons

no hints

Answer 11

• reflex arc still present
• get
  
  • spastic paralysis - increased muscle tone (no muscle atrophy)
  • exaggerated reflexes e.g. patellar, achilles; Babinski Sign Plantar reflex - scratch sole of foot
    
    • normal = plantar flexion (curl under)
    • Babinski sign = extend big toe

Question 12

clinical applications: destruction of upper motor neurons

exaggerated reflexes: babinski sign

what does the babinski sign indicate?

indicates ______ to ______ _____ ______ (except in ________ where it’s ______ - ________ tract not yet fully ________.

Answer 12

indicates damage to upper motor neurons (Except in babies where it’s normal - corticospinal tract not yet fully myelinated

Question 13

clinical applications: destruction of upper motor neurons

exaggerated reflexes: babinski sign

what does the babinski sign indicate?

______ damage to upper motor neurons (_____ __ babies _____ ___ normal - corticospinal tract ____ ______ ____ myelinated)

Answer 13

indicates damage to upper motor neurons (Except in babies where it’s normal - corticospinal tract not yet fully myelinated

Question 14

clinical applications: destruction of upper motor neurons

exaggerated reflexes: babinski sign

what does the babinski sign indicate?

Answer 14

indicates damage to upper motor neurons (Except in babies where it’s normal - corticospinal tract not yet fully myelinated

Question 15

clinical application: destruction of _____ ______ ______

• get:
  
  • loss of ____ ____ (no reflex)
  • ______ paralysis (______ tone, marked ______ atrophy.
• example: ______ = ______ destroys ______ _____ in _____ ____ of spinal cord

Answer 15

clinical application: destruction of lower motor neurons

• get:
  
  • loss of reflex arc (no reflex)
  • flassid paralysis (decreased tone, marked muscle atrophy)
• example: polio (poliomyelitis) = virus destroys cell bodies in ventral horn of spinal cord

Question 16

clinical application: destruction of lower motor neurons

• get:
  
  • _____ ___ reflex arc (___ ____)
  • flassid ______ (decreased ____ , ____ muscle ______)
• example: polio (poliomyelitis) = virus _____ cell bodies in ventral horn of _____ _____

Answer 16

clinical application: destruction of lower motor neurons

• get:
  
  • loss of reflex arc (no reflex)
  • flassid paralysis (decreased tone, marked muscle atrophy)
• example: polio (poliomyelitis) = virus destroys cell bodies in ventral horn of spinal cord

Question 17

clinical applications:

destruction of lower motor neurons

no hints

Answer 17

• get:
  
  • loss of reflex arc (no reflex)
  • flassid paralysis (decreased tone, marked muscle atrophy)
• example: polio (poliomyelitis) = virus destroys cell bodies in ventral horn of spinal cord