2C. Motor System - General Somatic Efferent (GSE) Lower Motor Division

Question 1

The process of ________________ is going to determine the net effect of all of the impulses that are synapsing on the LMN to determine if it’s going to generate that action potential or not

Answer 1

Summation

Question 2

Where is LMN located in the spinal cord?

Answer 2

Ventral Horn of the Spinal Cord

Question 3

GSE neurons to extrafusal fiber: Regular Skeletal muscle fiber

Answer 3

Alpha motor neurons

Question 4

GSE neurons to INTRAfusal fiber: Modified skeletal muscle fiber

Answer 4

Gamma motor neurons

Question 5

providing motor innervation to the extrafusal, we call this:

Answer 5

Alpha motor neuron

Question 6

If it innervates the muscle spindle or the intrafusal fiber, it would be a schematic example of a:

Answer 6

Gamma motor neuron

Question 7

Relatively rare, Myotatic reflex

Answer 7

Monosynaptic arc

Question 8

Lesion sites: Can occur anywhere along the extent of the LMN
1- Neuromuscular Junctions = Toxins
2- __________nerve = inflammation or trauma
3- Spinal nerve proper = trauma, fracture, neoplasia
4- _______________ = trauma, fracture, neoplasia
5- Cell body - pressure, ischemia

Answer 8

2- Peripheral
4- Ventral Root

Question 9

List the LMN signs

Answer 9

• Hyporeflexia
• Hypotonia
• Flaccid (soft) Paralysis
• Relatively QUICK muscular atrophy

Question 10

relating to the body, especially as distinct from the mind

Answer 10

Somatic

Question 11

Neurons that carry motor information away from the central nervous system to the muscles and glands of the body in order to initiate an action

Answer 11

Efferent

Question 12

Spinal GSE neurons are located in the ___________________ and then sent fiber out to reach a target, usually the skeletal muscle, either extrafusal or intrafusal fibers

Answer 12

Ventral gray matter

Question 13

Cranial LMN neurons
- Voluntary skeletal muscle

Answer 13

GSE: General Somatic Efferent

Question 14

Cranial LMN neurons
- Skeletal muscle of branchial arch origin

Answer 14

SVE: Special Visceral Efferent

Question 15

Cranial LMN neurons
- cardiac muscle, smooth muscle, glands

Answer 15

GVE: General Visceral Efferent

Question 16

The skeletal muscle that is developing in the area of the neck from the embryo

Answer 16

Branchial Arches

Question 17

If it is an “S” it is only in ______________ nerve

Answer 17

cranial

Question 18

Means that the cell body wants to be close to the target that it innervates

Answer 18

Neurobiotaxis

Question 19

Nuclear Column Concept and Cranial Nerve LMN Nuclei
- Neurobiotaxis and columnar fragmentation: produces ______________________ nuclei

Answer 19

cranial nerve

Question 20

GSE Nuclei and Cranial Nerves
- Nucleus Location - Rostral Colliculus
- Target - Extraocular muscles
(ex. might not be able to open eye)

Answer 20

Oculomotor nerve CN III

Question 21

GSE Nuclei and Cranial Nerves
- Nucleus Location - Caudal Colliculus
- Target - Extraocular muscles

Answer 21

Trochlear nerve CN IV

Question 22

GSE Nuclei and Cranial Nerves
- Nucleus Location - just caudal to caudal cerebellar peduncle
- Target - Extraocular Muscles

Answer 22

Abducens Nerve CN VI

Question 23

GSE Nuclei and Cranial Nerves
- Nucleus Location - Obex
- Target - Muscles of the Tongue

Answer 23

Hypoglossal nerve CN XII

Question 24

For which nerves is the target the extraocular muscles?
What do they do?

Answer 24

III, IV, VI
They cause CONTRACTION of them, if there is a lesion we lose the contractibility of the muscle

Question 25

is misalignment of the eyes, causing one eye to deviate inward (esotropia) toward the nose, or outward (exotropia), while the other eye remains focused

Answer 25

Strabismus

Question 26

If you see atrophy of the tongue, that would indicate a problem with nerve __________

Answer 26

XII

Question 27

The “final common pathway” of the nervous system refers to the:

Answer 27

LMNs in the Spinal Cord and Brainstem

Question 28

a reflex arc where the sensory neuron synapses directly on a motor neuron is classified as:

Answer 28

monosynaptic

Question 29

innervation of the extraocular muscles is provided by cranial nerves fibers that are functionally classified as:

Answer 29

GSE

Question 30

The motor component of spinal nerves is functionally classified as:

Answer 30

GSE