C: Spinal cord and Spinal Nerves Anatomy

Question 1

The vertebral column contains how many vertebrae?

Answer 1

30 (some say 33)
7 Cervical
12 Thoracic
5 Lumbar
5 Sacral
1(/4) coccygeal

Question 2

How many spinal cord segments are there?

Answer 2

31

Question 3

How many spinal nerves does each spinal cord segment give rise to?

Answer 3

1 pair of segmental spinal nerves

Question 4

How many spinal nerves are there, and of what type?

Answer 4

31
8 cervical
12 thoracic
5 lumbar
5 sacral

Question 5

Where does C1 spinal nerve pass out of the spinal cord?

Answer 5

Between the base of the skull and C1 vertebra

Question 6

Where do the spinal nerves pass out relative to their corresponding vertebra?

Answer 6

Cervical spinal nerves pass out the vertebral column superior to the pedicles of their corresponding vertebra
Thoracic, lumbar and sacral and coccygeal pass out inferior to the pedicles of their corresponding vertebra

Question 7

Where does spinal nerve C8 pass out of the vertebral column?

Answer 7

Between C7 and T1 vertebra

Question 8

Where is the transition in nomenclature of nerves?

Answer 8

Between C7 and T1

Question 9

How thick is the spinal cord?

Answer 9

About the thickness of a little finger

Question 10

What 2 enlargements can be seen in the spinal cord and why?

Answer 10

Cervical enlargement - gives rise to the brachial plexus

Lumbar enlargement - gives rise to nerves supplying lower limb

Question 11

What is the cauda equina?

Answer 11

Dorsal and ventral roots of lower lumbar and sacral and coccygeal segmental spinal nerves travelling to their corresponding vertebra

Question 12

What is the filum terminale?

Answer 12

Fine strand coming from the conus medullaris which travels and attaches to the coccyx, its an extension of pia mater and a remnant of the developing spinal cord

Question 13

How many layers of meninges surround the spinal cord?

Answer 13

3

Question 14

What 3 layers of meninges surround the spinal cord?

Answer 14

Dura mater (meningeal layer)
Arachnoid mater adhered tightly to the dura mater due to pressure of underlying CSF
Pia mater

Question 15

What separates the dura mater from bone?

Answer 15

Fat-filled epidural space

Question 16

What is the nature of the dura mater supplying the spinal cord?

Answer 16

Tough, fibrous

Question 17

What is the nature of the arachnoid mater surrounding the spinal cord?

Answer 17

Thin, delicate

Question 18

What is the nature of the pia mater surrounding the spinal cord?

Answer 18

Thin layer attached to the surface of the cord

Question 19

What lies between the arachnoid mater and pia mater?

Answer 19

Subarachnoid space containing CSF

Question 20

How does CSF enter the subarachnoid space surrounding the spinal cord?

Answer 20

By leaving the lateral and median apertures of the ventricular system

Question 21

What are denticulate ligaments?

Answer 21

Extensions of the pia mater, extending laterally from the spinal cord to attach to the walls of the spinal canal

Question 22

What is the function of the denticulate ligaments?

Answer 22

To stabilise the spinal cord and prevent rotatory movement

Question 23

The periosteal layer of dura mater surrounding the brain doesnt go on to surround the spinal cord, what is it instead continuous with?

Answer 23

When it reaches the base of the skull it is continuous with the periosteum of the skull

Question 24

Dorsal and ventral rootlets contain what kinds of info?

Answer 24

Dorsal rootlets - sensory

Ventral rootlets - motor

Question 25

Dorsal and ventral rootlets carry what kind of fibres?

Answer 25

Ventral carry efferent fibres | Dorsal carry afferent fibres

Question 26

What is a ganglion?

Answer 26

A collection of cell bodies in the PNS

Question 27

What does a dorsal root ganglion contain?

Answer 27

Cell bodies of primary sensory fibres which are single fibres carrying info from a particular area of skin and have their cell bodies in the dorsal root ganglion and then a short projection from the dorsal root ganglion to the spinal cord

Question 28

What is the difference between and epidural and a spinal anesthetic?

Answer 28

Epidural - goes into the epidural space and does not pass through the dura mater, can be specific to certain spinal nerves Spinal - pierces through the dura mater and enters the spinal canal, knocks out a larger portion of the body

Question 29

What is the lumbar cistern?

Answer 29

Enlargement of the subarachnoid space between the conus medullaris of spinal cord and inferior end of subarachnoid space and dura mater.

Question 30

What 3 things does the lumbar cistern contain?

Answer 30

1) CSF 2) Filum terminale 3) Cauda equina

Question 31

Why is the lumbar cistern a good place to administer a lumbar puncture?

Answer 31

Spinal cord is not present here so not at risk of damage Nerve roots making up the cauda equina are mobile and move out of the way when a lumbar puncture is adminstered so are also not at risk of damage

Question 32

How does the length of the spinal cord change from foetus to adult and why?

Answer 32

Spinal cord extends the entire length of the spinal column in a foetus at 2-3 months - at this point all segmental spinal nerves are give off at their corresponding vertebral level As the vertebral column grows at a faster rate than the spinal cord, at birth the spinal cord terminates at around L3 and by adulthood the spinal cord terminates at L1/L2

Question 33

What is the main blood supply of the spinal cord?

Answer 33

Receives arterial blood mainly via the unpaired anterior and paired posterior spinal arteries which typically arise from the vertebral arteries The segmental medullary and radicular arteries support the spinal arteries along the length of the cord

Question 34

Which arteries do the spinal arteries come off in the neck, thoracic, abdominal and pelvic regions?

Answer 34

``` Neck = vertebral Thorax = Posterior intercostal Abdomen = Lumbar Pelvis = lateral sacral ```

Question 35

What is the difference between white and grey matter in the spinal cord?

Answer 35

White matter contains axons | Grey matter contains cell bodies

Question 36

We have a dorsal, a ventral and a lateral grey horn, each contains what kind of nuclei?

Answer 36

Dorsal grey horn = sensory Ventral grey horn = somatic motor Lateral grey horn = autonomic

Question 37

At what levels can a lateral grey horn be seen in a cross section of the spinal cord?

Answer 37

``` (T1-L2) = sympathetic (S2-S4) = parasympathetic ```

Question 38

What kind of fibres travel in the dorsal root?

Answer 38

Sensory

Question 39

What kind of fibres travel in the ventral root?

Answer 39

Somatic motor and visceral motor

Question 40

What happens to the amount of white matter as you ascend the spinal cord?

Answer 40

The amount of white matter increases as you ascend the spinal cord

Question 41

How does the size of the ventral grey horn change as you move along the cord?

Answer 41

Ventral grey horn is enlarged where motor fibres to the limbs arise At the cervical (Upper limb) and lumbosacral (lower limb) enlargements

Question 42

Above which spinal cord segment can 2 dorsal columns be seen on each side of the midline and what are they called?

Answer 42

Above T6 | Gracile fascicle medially and cuneate fascicle laterally

Question 43

What kind of sensory info is carried in the cuneate and gracile fascicle?

Answer 43

Sensory info from the lower limb is carried in the gracile fascicle and sensory info from the upper limb is carried in the cuneate fascicle, so the cuneate fascicle only arises at the level at which sensory info from the upper limb reaches the spinal cord

Question 44

What is meant by the statement that 'the spinal grey matter is regionally specilised'?

Answer 44

The grey matter is divided into regions called laminae These are the sights of sensory or motor nuclei They each extend a varying length of the cord Certain functions in the body relate to certain laminae

Question 45

Name 4 major ascending and descending fibre tracts?

Answer 45

1) Dorsal column 2) Lateral corticospinal tract 3) Ventral corticospinal tract 4) Spinothalamic tract

Question 46

What info is carried in the dorsal columns?

Answer 46

Joint position sense and vibration sense

Question 47

What info carried in the lateral and ventral corticospinal tracts?

Answer 47

Voluntary movement

Question 48

What info is carried in the spinothalamic tract?

Answer 48

Pain, light, touch and temperature sense

Question 49

Do the dorsal columns carry info from the contralateral or ipsilateral side?

Answer 49

Ipsilateral

Question 50

What is meant by ipsilateral?

Answer 50

Same side

Question 51

Do the lateral corticospinal tracts carry info to the contralateral or ipsilateral sides?

Answer 51

Ipsilateral

Question 52

Do the ventral corticospinal tracts carry info to the contralateral or ipsilateral sides?

Answer 52

Contralateral

Question 53

Do the spinothalamic tracts carry info from the contralateral or ipsilateral sides?

Answer 53

Contralateral