Spinal Cord and PNS

Question 1

Spinal Cord Functions

Answer 1

Convey sensory information from periphery to brain
Convey motor information from brain to periphery
Reflexes
Modify ascending and descending information

Question 2

Where does the spinal cord end?

Answer 2

At L1-L2 intervertebral space

Question 3

Filum Terminale

Answer 3

Connective tissue that connects end of cord to coccyx

Question 4

Cauda Equina

Answer 4

L2-S5 nerve roots

Question 5

Why are there cervical and lumbar enlargements?

Answer 5

Because of plexuses - lots of alpha-motor neurons so the area swells up

Question 6

Where are cell bodies of sensory neurons located?

Answer 6

Dorsal root ganglion

Question 7

What leaves the ventral horn?

Answer 7

Motor neurons

Question 8

What leaves the dorsal horn?

Answer 8

Sensory neurons

Question 9

Dorsal Horn (Sensory)

Answer 9

Contains endings of sensory neurons, interneurons and cell bodies of tract cells

Question 10

Lateral Horn

Answer 10

ONLY AT T1-L2 SPINAL SEGMENTS

Contains cell bodies of preganglionic sympathetic neurons

Question 11

Ventral Horn (Motor)

Answer 11

Contains cell bodies of lower motor neurons, alpha-motor and gamma-motor neurons

Question 12

Alpha-motor Neurons

Answer 12

Primary

Travel to muscles

Question 13

Gamma-motor Neurons

Answer 13

Secondary

Travel to spindle fibers (protect quick stretch of muscles and maintain appropriate length)

Question 14

Dorsal Column

Answer 14

Contains sensory tracts and medial lemniscus pathway

Question 15

Lateral Column

Answer 15

Contains sensory and motor tracts

Question 16

Anterior Column

Answer 16

Contains motor tracts

Involved with muscle regulation

Question 17

Dorsal Column

Answer 17

Divided in fasciculus gracilis and cuneatus

Question 18

Fasciculus Gracilis

Answer 18

Receives information from LE

Question 19

Fasciculus Cuneatus

Answer 19

Receives information from UE

Question 20

How to tell if you are looking at a cervical cross-section?

Answer 20

Indentation between cuneatus and gracilis

Question 21

Posterior Intermediate Sulcus

Answer 21

Separates different sections of dorsal column

Question 22

Anterior White Commissure

Answer 22

Connecting left and right spinal cord

Question 23

Muscle fibers are characterized into what group?

Answer 23

Medial

Question 24

Pain and temperature fibers are characterized into what group?

Answer 24

Lateral, in dorsal horn

Question 25

Large Myelinated Axon Classification

Answer 25

Efferent - A-alpha | Afferent - Ia, Ib, II

Question 26

Medium Myelinated Axon Classification

Answer 26

Efferent - A-gamma

Question 27

Small Myelinated Axon Classification

Answer 27

Efferent - B (smaller diameter) | Afferent - A-beta (larger diameter)

Question 28

Unmyelinated Axon Classification

Answer 28

Efferent - C | Afferent - C (pain, temperature, visceral receptors)

Question 29

Lesion in Spinal Region

Answer 29

Results in myotomal and/or dermatomal distribution

Question 30

Lesion in Periphery

Answer 30

Results in peripheral nerve distribution

Question 31

Periphery Lesion Symptoms

Answer 31

``` Paresis/paralysis Sensory loss Abnormal sensations Muscle atrophy Reduced/absent DTR ```

Question 32

Upper Motor Neuron

Answer 32

Neurons with axons that descend from cerebral cortex or brain stem and end on LMN Neurons within CNS

Question 33

UMN Example - Corticospinal Pathway

Answer 33

Starts in motor cortex, crosses in medulla and innervates LMN at respective spinal level

Question 34

Lower Motor Neuron

Answer 34

Cell body in brain stem or ventral horn of spinal cord Axone leaves CNS and synapses in periphery on muscle Starts in CNS but ends in PNS

Question 35

UMN Clinical Signs

Answer 35

Paresis Spasticity Hypertonia Hyperreflexia

Question 36

UMN Diseases

Answer 36

``` Stroke SCI Parkinson's TBI MS ```

Question 37

LMN Clinical Signs

Answer 37

Loss of reflexes Atrophy Flaccid paralysis Fibrillation/fasciculations

Question 38

LMN Diseases

Answer 38

Polio Peripheral Nerve Injury Guillan Barre

Question 39

Rexed's Laminae

Answer 39

10 regions of spinal gray matter

Question 40

Reflex

Answer 40

Involuntary, stereotyped response to sensory input | Involves sensory input and motor output

Question 41

Reflex Examples

Answer 41

Stretch reflex via spindle | Autogenic inhibition via GTO

Question 42

Reflex Arc

Answer 42

Quick stretch stimulates Ia afferent in spindle Ia afferent synapses in spinal cord with alpha-motor neurons *No interneuron involvement*

Question 43

Reflex Arc Modulation

Answer 43

Afferent input synapses with interneuron Also under influence of UMN Lose descending control (leads to hyperreflexia)

Question 44

Dorsal Column Function

Answer 44

Conscious touch | Proprioception

Question 45

Spinothalamic Function

Answer 45

Conscious pain | Temperature

Question 46

Spinoreticular Function

Answer 46

Alerting | Arousal

Question 47

Spinocerebellar Function

Answer 47

Unconscious proprioception

Question 48

Dorsal Column Neuron Orders from Body

Answer 48

1st: DRG 2nd: Nucleus cuneatus/gracilis 3rd: VPL nucleus of thalamus

Question 49

Dorsal Column Neuron Orders from Face

Answer 49

1st: Trigeminal ganglion 2nd: Main sensory nucleus of trigeminal nerve 3rd: VPM nucleus of thalamus

Question 50

Dorsal Column Pathway

Answer 50

``` Enters spinal cord Ascends dorsal column Synapses in medulla Crosses over and ascends in medial lemniscus to contralateral thalamus Synapses in thalamus Ascend to cortex ```

Question 51

Spinothalamic Column Neuron Orders from Body

Answer 51

1st: DRG 2nd: Dorsal horn of spinal cord 3rd: VPL nucleus of thalamus

Question 52

Spinothalamic Column Neuron orders from Face

Answer 52

1st: Trigeminal ganglion 2nd: Spinal nucleus of trigeminal nerve 3rd: VPM nucleus of thalamus

Question 53

Spinothalamic Pathway

Answer 53

``` Enters spinal cord Synapses in dorsal horn Crosses to contralateral spinal cord Ascends in spinothalamic tract Synapses in thalamus Ascends to cortex ```

Question 54

Corticospinal Function

Answer 54

Voluntary movement | Fine motor control

Question 55

Rubrospinal Function

Answer 55

Gross motor movements

Question 56

Reticulospinal and Vestibulospinal Function

Answer 56

Trunk movements | Postural control

Question 57

Tectospinal Function

Answer 57

Reflexive movement of head

Question 58

Corticospinal Tract Pathway

Answer 58

Cell body in motor cortex Crosses in medullary pyramid Descends in lateral column Synapses with alpha-motor neuron

Question 59

Rubrospinal Tract

Answer 59

Cell body in red nucleus Crosses immediately Synapses with alpha-motor neuron