Neuroanatomy - Ascending and Descending Pathways

Question 1

how many pairs of spinal nerves are there?

Answer 1

31

Question 2

what are the two enlargements of the spinal cord?

Answer 2

cervical

lumbar

Question 3

where does the spinal cord end in adults?

Answer 3

around the level of L1/L2

Question 4

what is the name of the end of the spinal cord?

Answer 4

conus medullaris

Question 5

what is the thin connective tissue continuation of the conus medullaris called?

Answer 5

the filum terminale

Question 6

where is the filum terminale anchored to?

Answer 6

the dorsum of the coccyx

Question 7

how are the spinal meninges continuous with the cranial meninges?

Answer 7

via the foramen magnum

Question 8

what suspends the spinal cord in the spinal canal?

Answer 8

denticulate ligaments on the lateral aspects

Question 9

what are the denticulate ligaments made of?

Answer 9

pia and arachnoid tissue

Question 10

what extends through the centre of the spinal cord?

Answer 10

central canal

Question 11

what happens to the central canal rostrally?

Answer 11

opens into the 4th ventricle

Question 12

what happens to the central canal caudally?

Answer 12

blind ending

Question 13

what is the white matter of the spinal cord divided into?

Answer 13

posterior, lateral and anterior columns

Question 14

describe the relationship between the columns of white matter in the spinal cord

Answer 14

lateral and anterior are continuous

posterior is isolated by the posterior horns

Question 15

what extra feature of grey matter is found at spinal segments T1-L2?

Answer 15

lateral horns

Question 16

what do the lateral horns of T1-L2 contain?

Answer 16

preganglionic sympathetic neurons

Question 17

what are the three major groups of vessels supplying the spinal cord?

Answer 17

longitudinal arteries
segmental arteries
radicular arteries

Question 18

how many longitudinal arteries are there?

Answer 18

three - one anterior and two posterior

Question 19

where do the longitudinal arteries originate?

Answer 19

vertebral arteries

Question 20

what arteries run the length of the spinal cord?

Answer 20

longitudinal

Question 21

what are the segmental arteries derived from?

Answer 21

vertebral, intercostal and lumbar arteries

Question 22

where do the radicular arteries travel?

Answer 22

along the dorsal and ventral roots

Question 23

what can embolic occlusion of any artery supplying the spinal cord result in?

Answer 23

areas of spinal cord infarction

Question 24

how are neurone organised in the primary somatosensory cortex and what does this mean?

Answer 24

somatotopic

the body is mapped onto the cortex

Question 25

where is the primary somatosensory cortex located?

Answer 25

post central gyrus of the parietal lobe

Question 26

how does information travel to the primary somatosensory cortex and what is the exception?

Answer 26

spinal cord information from the face and scalp

Question 27

what happens to the amount of white matter as you descend the spinal cord?

Answer 27

proportion reduces

Question 28

name two ascending tracts?

Answer 28

dorsal column | spinothalamic tract

Question 29

what is the dorsal column called in the brainstem?

Answer 29

medial lemniscus system

Question 30

what information is carried in the dorsal column?

Answer 30

fine touch | conscious proprioception

Question 31

where do the fibres of the dorsal column cross over?

Answer 31

the medulla

Question 32

what two nuclei receive the information from the dorsal column?

Answer 32

nucleus gracilis | nucleus cuneatus

Question 33

what information does the nucleus gracilis receive from the dorsal column?

Answer 33

info from the lower portion of the body

Question 34

what information does the nucleus cuneatus receive from the dorsal column?

Answer 34

information from the upper portion of the body

Question 35

what happens to the dorsal column in the cervical region of the spinal cord?

Answer 35

develops a sulcus - forms the fasciculus gracilis and cuneatus

Question 36

describe the role of the first, second and third order neurones in the dorsal column?

Answer 36

``` 1 = spinal cord - ML system 2 = ML system - thalamus 3 = thalamus - primary somatosensory cortex ```

Question 37

what information does the spinothalamic tract carry?

Answer 37

sensory fibres for pain, temperature and deep pressure

Question 38

where do the fibres of the spinothalamic tract cross?

Answer 38

segmentally throughout the spinal cord

Question 39

where do the first order neurones for the spinothalamic tract synapse?

Answer 39

immediately as they enter the spinal cord

Question 40

describe the role of the first, second and third order neurones in the spinothalamic tract

Answer 40

``` 1 = sensory receptor - spinal cord 2 = spinal cord - thalamus 3 = thalamus - PSC ```

Question 41

where do the fibres in the spinothalamic tract cross over?

Answer 41

in the segment where it synapsed | then joins the tract

Question 42

what are other possible names for the spinothalamic tract?

Answer 42

anterolateral tract | anterolateral system

Question 43

where is the primary motor cortex located?

Answer 43

the precentral gyrus of the frontal lobe

Question 44

what is another name for the corticospinal tract?

Answer 44

the pyramidal tract

Question 45

what type of movement is the corticospinal tract involved in?

Answer 45

fine, precise movements

Question 46

why is the corticospinal tract called the pyramidal tract?

Answer 46

forms visible ridges known as the pyramids on the anterior surface of the medulla

Question 47

where do the majority of the fibres of the corticospinal tract cross?

Answer 47

in the caudal medulla at the decussation of the pyramids around 85% of fibres

Question 48

what do the crossed fibres of the corticospinal tract form and where do they go?

Answer 48

the lateral corticospinal tract descend in the lateral column of the cord to their effector tissue

Question 49

what do the uncrossed fibres of the corticospinal tract form and where do they go?

Answer 49

the ventral corticospinal tract cross segmentally when they reach the appropriate spinal level and then move out of the column

Question 50

where does the corticospinal tract begin?

Answer 50

the primary motor cortex

Question 51

how does the corticospinal tract exit the brain?

Answer 51

passes through the internal capsule and then descends out through the brainstem

Question 52

what does a CVA of the internal capsule result in?

Answer 52

lack of descending control of the corticospinal tract - resulting in a spastic paralysis with hyperflexion of the upper limbs sometimes known as decorticate posturing

Question 53

name three tracts that are part of the extrapyramidal system

Answer 53

tectospinal tract reticulospinal tract vestibulospinal tract

Question 54

where does the input to the tectospinal tract come from?

Answer 54

cervical segments

Question 55

what does the tectospinal tract mediate?

Answer 55

reflex head and neck movement due to visual stimuli

Question 56

where does the tectospinal tract begin?

Answer 56

the midbrain

Question 57

where do the fibres of the tectospinal tract cross the midline?

Answer 57

the midbrain

Question 58

where does the tectospinal tract pass out of the spinal cord?

Answer 58

in the cervical region only extends as far down as the cervical region

Question 59

what forms the central core of the brainstem?

Answer 59

reticular formation

Question 60

what is one function of the reticulospinal tract?

Answer 60

influences voluntary movements

Question 61

where do the fibres of the reticulospinal tract originate?

Answer 61

in areas of the reticular formation in the pons and medulla

Question 62

what movements are facilitated by reticulospinal tract fibres originating in the pons?

Answer 62

extensor movements inhibits flexor movements

Question 63

what movements are facilitated by reticulospinal tract fibres originating in the medulla?

Answer 63

flexor movements inhibit extensor movements

Question 64

what does the vestibulospinal tract provide?

Answer 64

excitatory input to anti-gravity extensor muscles

Question 65

where do the fibres of the vestibulospinal tract originate?

Answer 65

vestibular nuclei of the pons and medulla

Question 66

where do the fibres of the vestibulospinal tract receive input from?

Answer 66

the vestibular labyrinth

Question 67

where do the fibres of the vestibulospinal tract cross the midline?

Answer 67

nowhere