Neuro phys 4

Question 1

Where do lower motor neurons originate from?

Answer 1

originate in the spinal cord grey matter

Question 2

Where is the cervicothoracic (brachial) intumescence located?

Answer 2

C6 to T2

Question 3

Where is the lumbosacral intumescence located

Answer 3

L4 to S3

Question 4

Where are the cell bodies of neurons innervating axial and proximal limb musculature located?

Answer 4

ventromedial

Question 5

Where are the cell bodies that innervate distal limb musculature located?

Answer 5

dorsolateral

Question 6

Where are the cell bodies located that innervate axial and proximal limb musculature?

Answer 6

ventromedial

Question 7

Where are motor neuron pools located?

Answer 7

grouped into pools that extend over one or more spinal segments

Question 8

What is meant by the term motor unit?

Answer 8

refers to the motor neuron and all the muscle fibres that it supplies

Question 9

What factors innervate force production of a whole muscle?

Answer 9

• number of active muscle fibres

- force production of individual muscle fibres- frequency of stimulation, fibre diameter, resting fibre length

Question 10

What are the different types of muscle fibres in motor units?

Answer 10

slow- contract very slowly, small forces, resisitant to fatigue
fast fatiguable- pale fibres, contract quickly and generate large forces
fast fatigue resistant- fast oxidative red fibres- represent more of an intermediate of these two

Question 11

What are the steps involved in the patellar motor reflex?

Answer 11

1. Tap patellar reflexes
2. Excites the femoral nerve but also inhibits the sciatic nerve
3. This facilitates extension of the limb

Question 12

What are the steps that are involved in the withdrawl and crossed extensor reflex

Answer 12

1. Response to activation of the nociceptor is that it stimulates the flexors and relaxes the extensors causing the limb to withdraw
2. Contrateral limb the opposite happens providing compensatory support
3. Basic reflex for maintenance of posture and locomotion

Question 13

What is the spinal reflex grading system

Answer 13

0 = areflexia 
1 = hyporeflexia 
2 = normal 
3 = hyperreflexia 
4 = clonus ( a repetitive response)

Question 14

What is the nerve and spinal segments involved in the biceps reflex?

Answer 14

musculocutanous nerve C6-C8

Question 15

What is the nerve and the spinal segments involved in the triceps reflex?

Answer 15

radial nerve C7-T2

Question 16

What are the spinal segments involved and the name of the nerve of patellar reflex?

Answer 16

femoral nerve L4-L6