The Spinal Cord, Spinal Nerves, & Injuries

Question 1

list the 3 structures that protect the spinal cord

Answer 1

• bone
• meninges
• CSF

Question 2

where does the spinal cord end

Answer 2

at the conus medullaris (L1 or L2 in adults)

Question 3

describe the caudal equina

Answer 3

collection of nerve roots

Question 4

describe the function of the filum terminale

Answer 4

anchors the cord to the coccyx

Question 5

describe the function of the meninges and the 3 layers from out to inner

Answer 5

Layers of connective tissue covering the spinal cord 
Layers: 
1. Dura Mater 
2. Arachnoid mater 
3. Pia Mater

Question 6

describe the characteristics of the dura mater

Answer 6

• tough outer covering
• not attached to the vertebral column
• ends at S2

Question 7

describe the characteristics of the arachnoid mater

Answer 7

• loose middle covering layer
• separated from dura mater by subdural space (which contains blood vessels & CSF)
• ends at S2

Question 8

describe the characteristics of the Pia mater

Answer 8

• connective tissue which clings to brain & spinal cord
• rich with tiny blood vessels
• projections that attach cord to the dura mater

Question 9

how many pairs of spinal nerves

Answer 9

31

Question 10

what axons do the dorsal roots contain

Answer 10

contains the axons of the sensory neutrons

Question 11

where are the cell bodies of sensory neutrons found within

Answer 11

dorsal root ganglion

Question 12

what is the function of the dorsal root

Answer 12

relays sensory input from receptors of the posterior body trunk to the spinal cord

Question 13

what axons do the ventral roots contain

Answer 13

the ventral roots contain the axons of motor neurons

Question 14

what is the function of the ventral roots

Answer 14

relay motor commands to effector glands & muscles of the rest of the trunk & limbs

Question 15

list the 2 grooves of the spinal cord cross section

Answer 15

1. ventral median fissure

2. dorsal median fissure

Question 16

is the grey matter of the spinal cord on the inside or outside

Answer 16

on the inside which is connected by the grey commissure

Question 17

what does the dorsal side of the spinal cord convey

Answer 17

incoming info = afferent = sensory

Question 18

what does the ventral side of the spinal cord convey

Answer 18

outgoing info = efferent = motor

Question 19

what forms the dorsal root

Answer 19

afferent (incoming) fibres carry impulses from peripheral sensory receptors forms the dorsal root

Question 20

what forms the ventral horns

Answer 20

cell bodies of somatic motor neurones

Question 21

what forms the lateral horns

Answer 21

cell bodies of automatic motor neurones that innervates internal organs

Question 22

list how the spinal grey matter is organised into 4 different nucleis

Answer 22

1. interneurons receiving somatic sensory neurones
2. interneurons receiving visceral sensory neurones
3. visceral motor (autonomic) neurones
4. somatic motor neurones

Question 23

list the 3 columns of the spinal cord white matter

Answer 23

1. dorsal
2. lateral
3. ventral

Question 24

describe the role of 2nd order neurones

Answer 24

transmit impulses to the thalamus or cerebellum where they synapse

Question 25

describe the role of 3rd order neurones

Answer 25

relay impulses to somatosensory cortex of the cerebrum

Question 26

list the ascending pathways

Answer 26

- dorsal column medial lemniscal pathway - spinothalamic pathway - spinocerebellar pathway

Question 27

what impulses does the dorsal -medial lemniscal pathway transmit

Answer 27

- touch - vibration - proprioception

Question 28

what is the dorsal column-medial lemiscal pathway made up of

Answer 28

- dorsal white column | - medial lemniscus

Question 29

list the neurones involved in the dorsal column-medial lemniscal pathway

Answer 29

1st order neurones travel into dorsal white column via FC & FG tracts that synapses in the lower part of the medulla 2nd order neurones travel from medulla and synapses in the thalamus 3rd order neurones travel to specific areas of the cortex

Question 30

what impulses does the spinothalamic pathway transmit

Answer 30

- pain - temperature - coarse touch - pressure

Question 31

what tracts is the spinothalamic pathway formed from

Answer 31

- lateral spinothalamic tracts | - ventral spinothalamic tracts

Question 32

what information is transmitted via the spinocerebellar pathways

Answer 32

- muscle or tendon stretch to the cerebellum

Question 33

what tracts is the spinocerebellar pathways formed from

Answer 33

- ventral spinocerebellar | - dorsal spinocerebellar

Question 34

what sensory information is conveyed by the fasciculus cuneatus & fasciculus gracilis tracts and their location

Answer 34

- fine touch - vibration - pressure - proprioception located in dorsal column

Question 35

what sensory information is relayed by anterior and posterior spinocerebellar tracts and its location

Answer 35

- unconscious proprioception located in lateral column

Question 36

what sensory information is relayed by anterior (ventral) spinothalamic tract and its location

Answer 36

- crude touch - pressure located in ventral column

Question 37

what are the 2 groups of descending pathways

Answer 37

1. direct pathways | 2. indirect pathways

Question 38

where do direct pathways originate and where it synapses

Answer 38

primary motor cortex and synapses with lower motor neurones in the ventral horn

Question 39

list what indirect pathways regulate

Answer 39

- axial muscles to maintain posture - muscles controlling coarse limb movements - head, neck and eye movements

Question 40

list the 4 indirect pathways

Answer 40

1. reticulospinal tract 2. vestibulospinal tract 3. rubrospinal tract 4. tectospinal tract

Question 41

function of reticulospinal tract

Answer 41

controls muscle tone & visceral motor functions - tract located in ventral and lateral white column

Question 42

function of vestibulospinal tract + location of tract

Answer 42

maintains balance by varying tone of postural muscles - tract located in ventral white column

Question 43

function of rubrospinal tract + location of tract

Answer 43

muscle tone of distal limb movements - tract located in lateral white column

Question 44

function of tectospinal tract + location of tract

Answer 44

mediates head movements in response to visual stimuli

Question 45

list the motor commands relayed by lateral corticospinal tracts and its white column location

Answer 45

- voluntary motor commands that control skeletal muscles located in lateral white column

Question 46

list the motor commands relayed by ventral corticospinal tracts and its white column location

Answer 46

- voluntary motor commands that control the skeletal muscles of the axial skeleton, pectoral and pelvic girdle located in the ventral white column

Question 47

define paralysis

Answer 47

loss of motor function

Question 48

define paraesthesias

Answer 48

abnormal sensations and sensory loss

Question 49

what occurs with damage to lower motor neurones in the ventral horns

Answer 49

flaccid paralysis in affected muscles

Question 50

list the outcomes of damage to primary motor cortex or upper motor neurone tracts

Answer 50

- spastic paralysis - spinal reflexes stimulate muscles irregularly - no voluntary control