Intro: UMN vs LMN

Question 1

LMN & UMN are

Answer 1

a set of tracts or nerves & nuclei that form a clinically recognizable functional unit

Question 2

LMN consist of parts of the NS that when injured

Answer 2

Decrease the strength of the Muscle Stretch Reflex (MSR)

Question 3

UMN consist of parts of the NS that when injured

Answer 3

Increase the strength of the Muscle Stretch Reflex (MSR)

Question 4

Reflex sign of a LMN lesion

Answer 4

Hypo-reflexia

Question 5

Reflex sign of a UMN lesion

Answer 5

Hyper-reflexia

Question 6

Tone sign of a LMN lesion

Answer 6

Hypotonia

Question 7

Will a patient have fasciculation and fibrillation w/ LMN lesion?

Answer 7

Yes

Question 8

Will a patient demonstrate weakness from a LMN lesion?

Answer 8

Yes, from decreased innervation

Question 9

Will a patient demonstrate atrophy of the muscles from a LMN lesion?

Answer 9

Yes

Question 10

Tone sign of a UMN lesion

Answer 10

Hypertonia

Question 11

Will a patient have fasciculation and fibrillation w/ UMN lesion?

Answer 11

No

Question 12

Will a patient demonstrate weakness from a UMN lesion?

Answer 12

Yes - from disuse

Question 13

Will a patient demonstrate atrophy of the muscles from a UMN lesion?

Answer 13

No

Question 14

A good indication of whether a patient has a UMN or LMN injury

Answer 14

LMN: Individual muscles may be affected

UMN: Muscles always affected in groups, never individual muscles

Question 15

2 Abnormal UMN Reflexes

Answer 15

Babinski’s

Clonus

Question 16

Clonus

Answer 16

An involuntary, repetitive, rhythmic contraction of a muscle when held in a stretched state. Initiated in the spinal cord.
Is usually a sign of damage to the nerve tracts above the place where the stretch reflex is initiated

Question 17

What is muscle tone?

Answer 17

Tone is the resistance of muscles to passive stretch or elongation

Question 18

What is the purpose of normal tone?

Answer 18

Normal tone resists the effects of gravity in posture and movement, yet is low enough to allow free movement.

Question 19

Spasticity

Answer 19

A velocity dependent increase in resistance to passive movement. The faster the passive movement the stronger the resistance. It’s an involuntary muscle contraction. Measured on the Modified Ashworth Scale

Question 20

Rigidity

Answer 20

A non velocity dependent increase in resistance to passive movement

Question 21

Fasciculations

Answer 21

A LMN sign
Visible, coordinated twitches among the muscle fibers. The earliest objective sign of muscle denervation.
Caused by spontaneous APs generated after injury to the axon.

Question 22

Fibrillations

Answer 22

LMN sign
Small, non-visible uncoordinated contractions among the muscle fibers.
Cause: As axon degenerates further, motor units are no longer joined by a functioning axon so muscle fibers do not contract as a unit