Lower Motor Neurons

Question 1

Alpha Motor Neurons

Answer 1

Lower Motor Neurons

Neurons that innervate muscles

Heavily myelinated, fast-conducting.

Question 2

Where are the cell bodies of lower motor neurons located?

Answer 2

Brainstem and Spinal Cord

Question 3

Phrenic Nerve

Answer 3

C3-C5

Controls the diaphragm

Question 4

Onuf’s Nucleus

Answer 4

S3-S4

External anal and urethral sphincters

Question 5

Cranial Nerves with LMN Components

Answer 5

3,4,6.  Eye Movement
5. Jaw Opening
7. Facial expressions
9,10,11. Speaking, Swallowing, TRap. Sternocleidomastoid.
12. Tongue muscles

Question 6

Paralysis

Answer 6

Weakness so severe that muscle cannot contract

Question 7

Paresis

Answer 7

Weakness, or partial paralysis

Question 8

Plegia

Answer 8

Severe weakness or paralysis.
Diplegia- bilateral lower limb Plegia
Quadriplegia- all four limbs
Hemiplegia- one entire side of body weakness

Question 9

Palsy

Answer 9

Imprecise term for weakness OR no movement.

Question 10

Muscle Atrophy

Answer 10

Without innervate in, muscles cannot contract. If they do not contract then they will lose mass. They also lose tropic support from the motor neurons.

Question 11

Fibrillations in muscle.

Answer 11

Have to use EMG. Indicative of a denervated muscle.

Question 12

Fasciculations in muscles.

Answer 12

Larger potentials caused by spontaneous activity in motor unit(s).

Caused by LMN Lesions.

Large potential are suggestive of denervation and reinnervation.

Question 13

Spinal Muscle Atrophy (1-4)

Answer 13

A group of diseases caused by degeneration of the anterior horns.
Progressive, begin at infancy.
Due to abnormalities in Chromosome 5

Question 14

SMA 1 (Werdnig-Hoffman)

Answer 14

“Floppy baby”
Weakness and muscle wasting in:
Limbs, respiratory, bulbar muscles, sucking, swallowing, breathing.