spinal cord

Question 1

what is gray matter?

Answer 1

• part of CNS that are abundant in cell bodies of neurons> axons
• unmyelinated

Question 2

what is white matter?

Answer 2

• axons that carry info up and down
• myelinated

Question 3

what is the structure of spinal cord?

Answer 3

cervical (7), thoracic (12), lumbar (5), sacral (5) , coccyx (4)

Question 4

describe cross section of spinal cord

Answer 4

• white matter surrounds gray matter

Question 5

what does ventral horn contain ? what does this allow?

Answer 5

• motor neurons so stimulation causes movement

Question 6

how does info travel in ventral horn?

Answer 6

• info travels down ventral roots

Question 7

what happens in dorsal horn?

Answer 7

• sensory information is localised

Question 8

where does info travel in dorsal horn?

Answer 8

• travels down dorsal roots

Question 9

what is the intermediate zone? what does it contain?

Answer 9

• contains interneurons which intergrate info

Question 10

what is the relationship between body regions known as?

Answer 10

• somatotopy

Question 11

what does the lateral descending system contain?

Answer 11

• corticospinal and rubrospinal tracts

Question 12

what is the purpose of corticospinal fibres?

Answer 12

• influence movement of every body part
• useful for individual finger use

Question 13

what do rubrospinal fibres compensate for?

Answer 13

• loss of descending corticospinal input
• can’t compensate its ability to use fingers individually

Question 14

where are lateral descending system fibres found and what movement does it influence?

Answer 14

• fibres found in dorsolateral part
• influences lateral muscular movement

Question 15

what does medial descending system consist of?

Answer 15

• vestibulospinal and reticulospinal tracts

Question 16

what is vestibulospinal tract involved in?

Answer 16

• retains balance when body is moved
• external disturbance

Question 17

what is reticulospinal tract involved in?

Answer 17

• retains posture and balance during own volitional movements
• internal disturbance

Question 18

where are the fibres in medial descending system found and what does it influence?

Answer 18

• fibres found in ventro- medial white matter
• influences medial muscles

Question 19

why is the vestibulospinal tract important?

Answer 19

• maintenance of balance

Question 20

what is reticulospinal tract important for?

Answer 20

posture

Question 21

what is the medial lemniscus ascending pathway? what info?

Answer 21

• carries sensory info from joint and skin
• info about fine touch, vibration, 2 point discrimination, proprioception

Question 22

what is the spinothalamic ascending pathway?

Answer 22

• conveys sensory info about crude touch, pain and temperature

Question 23

what does the position of spine determine?

Answer 23

• what part of body each nerve serves

Question 24

how many pairs of spinal nerves are there and how is size determined?

Answer 24

• 31 pairs
• determined by how many muscles served

Question 25

what is the two point discrimination?

Answer 25

- ability to recognise that two objects are touching you

Question 26

what is a motor unit?

Answer 26

- neurone and the fibres they contract

Question 27

how are muscles controlled?

Answer 27

motor pools of neurons

Question 28

how many fibres can a single neuron innervate?

Answer 28

many fibres

Question 29

how many neurons used for fine movements?

Answer 29

many neurons used

Question 30

why are hands and feet special?

Answer 30

- highly innervated - areas have enlarged spinal nerves

Question 31

how is info coded in sensory system?

Answer 31

- firing frequency codes for intensity

Question 32

what does intensity of stimulus determine?

Answer 32

- size of receptor potential and frequency of action potential

Question 33

what code is used by motor neurons?

Answer 33

rate code = signals amount of force exerted by a muscle

Question 34

what is the dorsal root ganglion?

Answer 34

- cell bodies of incoming sensory neurons lie outside the spine in a series of ganglion - unlike motor neurons as cell bodies in ventral horn

Question 35

what is a dermatome?

Answer 35

- area of a skin supplied by nerves from single spinal root

Question 36

compare single action potentials to multiple action potentials

Answer 36

- single APs produce single twitches - multiple APs occur in quick succession; force in muscle builds up

Question 37

what is maximal contraction?

Answer 37

- tetanic contraction where rate of muscle will be unable to contract further - muscles cannot relax between

Question 38

what are reflexes?

Answer 38

- rapid automatic control of movement - little or no voluntary control

Question 39

what are the two types of reflexes with examples

Answer 39

- simple e.g. spinal stretch reflex - complex e.g. swallowing

Question 40

what is reticular formation?

Answer 40

- set of interconnected nuclei that are located through brainstem

Question 41

what are vestibular nuclei?

Answer 41

- nuclei for vestibular system - located in brainstem

Question 42

what are Gnana cells?

Answer 42

- tiny cells that contain neurons, involved in filtering information

Question 43

what are the three pathways of the cerebellum?

Answer 43

- superior cerebellar peduncle, middle cerebellar peduncle and inferior cerebellar peduncle

Question 44

describe superior cerebellar peduncle path

Answer 44

- efferent pathway to red nucleus and cortex via thalamus and sup colliculus

Question 45

describe middle cerebellar peduncle path

Answer 45

- most fibres originate in pons, input from sensory, visual, vestibular and motor systems

Question 46

describe inferior cerebellar peduncle path

Answer 46

- carries info to and from spinal cord and vestibular nuclei

Question 47

why does red nucleus appear pink?

Answer 47

- due to blood vessels

Question 48

what does red nucleus receive?

Answer 48

- large input from cerebellum and primary motor cortex

Question 49

what are the two basal ganglia pathways? what do they do?

Answer 49

- direct pro- movement - indirect anti- movement - work in opposition

Question 50

what is the direct pathway in basal ganglia?

Answer 50

- runs directly through; short loop has excitatory effect on cortex - net movement is pro- movement

Question 51

what is the indirect pathway of basal ganglia?

Answer 51

- takes a longer loop that has inhibitory effect so anti- movement

Question 52

what does basal ganglia damage cause? give an example

Answer 52

- states where there is too much/ too little movement Parkinson's disease can't trigger movement