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Flashcards in Spinal cord Deck (53):
1

At L1 spinal cord tapers into...

Conus medullaris

2

Where are the enlargements in the spinal cord and what do they represent

Cervical C7-8 and lumbrosacral L4-L5 --> enlargements where cervical/lumbosacral plexues arise --> supply limbs (reflects greater motor and sensory activity)

3

What is end of spinal cord at birth

L3

4

What is end of spinal cord in adult hood

L1-L2

5

Lumbar/sacral roots below end of spinal cord continue as...

Cauda equina

6

What does termination of spinal cord allow

Access of CSF via lumbar puncture at L4/L5

7

What happens to length of spinal roots progressively down spinal cord

Increase due to disparity between length of cord and vertebral column

8

Describe layers of meninges from out to in

Dura mater
Arachnoid mater
Pia mater

9

What is dura mater, where does it start/finish

Outer tough fibrous layer extending from head to S2

10

What does extradural space contain

Fat and internal vertebral venous plexus draining red bone marrow of vertebral bodies via basivertebral veins and links up with cerebral/pelvic veins
No valves

11

Where is subarachnoid space and where does it finish

Between arachnoid mater and pia mater, ending at S2

12

What does arachnoid space contain

CSF

13

What does arachnoid mater line

dura mater

14

What does pia mater extend inferiorly as

Filum terminale which pierces dural sac to attach to coccyx

15

What does pia mater do

Thickened on each side between nerve roots to form denticulate ligament which passes laterally to adhere to dura

16

What arteries supply blood to spinal cord

Anterior and posterolateral spinal arteries

17

Where does blood supply to spinal cord arise from

Intracranial part of vertebral artery

18

What layer is spinal blood supply found

Subarachnoid space

19

What reinforces spinal cord blood supply

Artery of Adamkiewicz --> lumbrosacral part of cord
Segmental spinal branches along roots.

20

What is central canal filled with

CSF

21

In what region do preganglionic sympathetic neurones arise from spinal cord and from where

Lateral horn
T1-L2

22

Describe where parasympathetic preganglionic fibres arise from

S2-S4 (cell bodies in lateral horn)

23

Where do spinal nerves arise from relative to corresponding vertebrae

C1-C7 arise above their vertebra
C8 emerges below C7 and subsequent nerves emerge below corresponding vertebrae

24

Describe the size of descending and ascending tracts going from caudal to rostral in spinal cord

Ascending tract increase in size
Descending tract decreases in size

25

How can you distinguish thoracic spinal cord

Prominent lateral horn

26

Describe how the proportion of grey: white matter changes along length of spinal cord

proportion of gray matter decreases as you go up spinal cord

27

In what regions is grey matter largest in spinal cord

Cervical and lumbar enlargements

28

Describe the organisation of the ventral horn

Compromises motor pools, in which all motor neurones innervate same muscle.
Motor columns formed from motor pools innervating muscles of similar embryonic origin

29

Describe the medial and lateral motor columns of ventral horn

Medial motor colimn: motor neurones innervating axial muscles of back and body wall --> posture and balance
Lateral motor column --> (found in lumbar and cervical spinal cord) motor neurones innervating limb muscles

30

Describe how ventral horn is arranged distally-proximally and ventrally/dorsally

Proximal --> distal = trunks --> hand
Ventral --> dorsal --> extensor --> flexor

31

What happens to large diameter axons A alpha and A beta as they enter dorsal horn

Enter medially and possess ascending collaterals

32

What happens to fine diameter axons as they enter dorsal horn e.g. A delta and C

Enter laterally and project across several segments in Lissauer's tract

33

What does laminar organisation of gray matter represent

Different functions of neurones

34

What lamina do A alpha and A beta innervate/influence

A alpha --> 6,7
A beta --> 3-6

35

What is lamina 1, give an example of what terminates here

Posteromarginal zone, including larger projection neurones that project via contralateral side to thalamus (nociceptive specific info)
E.g. A delta terminate here --> localisation of pain

36

What is lamina 2, given an example of what terminates here

Substantia gelatinosa - interneurone e.g. C fibres synapse onto interneurons, which synapse onto neurones in nucleus proprius (more synapses=more modulation)

37

What is lamina 4/5, give an example

Lamina proprius --> main sensory nucleus --> different inputs e.g nociceptive/somatosensory converge onto projection neurones that project contralaterally --> poor localisation and mixed modality --> wide dynamic range neurone

38

Describe the relevance of lateral horn in proprioceptive afferents

From leg the ascend to thoracic level and form axon collateral synapsing onto neurones in Clarke's column in lateral horn

39

What is Clarke's column

Thoracic nucleus in lateral horn --> relay to ipsilateral cerebellum via spinocerebellar tract

40

What does lateral horn contain

Preganglionic autonomic neurones Symp T1-L2 and para S2-S4

41

Name 5 descending tracts

Corticospinal
Vestibulospinal
Reticulospinal
Rubrospinal
Tectospinal

42

Name 3 ascending tracts

Dorsal/ventral spinocerebellar tract
Anterolateral columns
Dorsal columns

43

What is CST for

Major descending control pathway from cortex for voluntary movement

44

Describe course of most fibres in CST (90%)

Originate from primary motor cortex (and supplementary motor area, premotor cortex, sensory areas) decussate in medulla and descend on contralateral side of spinal cord in crossed lateral CST

45

What happens to 10% of CST fibres

DO not decussate and descend on ipsilateral side of spinal cord as uncrossed ventral CST (i.e. anterior and lateral uncrossed CST) and fibres synapse with ventral horn neurones on opposite side at each segment

46

What happens at each spinal segment to CST

Fibres enter intermediate zone to innervate interneurons and ventral horn to innervate motor neurones

47

Describe where vestibulospinal tract arises from, what does it do

Lateral and medial vestibular nucleus --> upright posture, balance, facilitates extensor and inhibit axial motor neurones, conscious realisation of spatial orientation

48

What does reticulospinal tract arise from and do

Brainstem reticular formation --> maintaining tone, balance and posture esp during body movements

49

WHat dose rubrospinal tract arise form and do

Red nucleus --> voluntary movement esp flexion of distal arm muscles

50

What does tectospinal tract arise from and do

tectum (superior colliculus) --> reflex postural movements in response to visual /auditory stimulu

51

What does dorsal/ventral spinocerebellar tracts do

Relay Clarke's columns neurones (proprioception from lower limb) to ipsilateral cerebellum through inferior and superior cerebellar peduncels respectively

52

What does dorsal column compromise

Medial fasciculus gracilis( legs) and lateral fasciculus cuneatus (arms) --> transmit ascending branches conveying touch/vibration/proprioception on ipsilateral side of cord to dorsal column nuclei in medulla

53

Where does fasciculus cuneatus arise from

T6