Workbook - Spinal cord and spinal nerves

Question 1

What are the 3 layers of meninges surrounding the spinal cord?

Answer 1

• Dura mater
• Arachnoid mater
• Pia mater

Question 2

How many layers does the dura mater consist of in the spinal cord?

Answer 2

One.

Question 3

What are the denticulate ligaments?

Answer 3

Expansions of pia mater in cervical and thoracic regions.

-provide stability for the spinal cord against movement

Question 4

What is the functional difference between the dorsal and ventral nerve roots?

Answer 4

Dorsal roots - sensory.

Ventral roots - motor.

Question 5

Where do the dorsal and ventral nerve roots unite to form the spinal nerves?

Answer 5

Within the intervertebral foramen.

Question 6

What do dorsal rami of the spinal nerves supply?

Answer 6

Intrinsic back muscles (epaxial) and a small strip of skin.

Question 7

What do the ventral rami of the spinal nerves supply?

Answer 7

Most other skeletal muscles (hypaxial), limbs, trunk and skin.

Question 8

Where is the epidural space located?

Answer 8

Between the dura mater and bone of the vertebral canal.

Question 9

What is the filum terminale?

Answer 9

A delicate strand of fibrous tissue extending from the conus medullaris to the coccyx.
-pia mater modification

Question 10

What is the conus medullaris?

Answer 10

Cone-shaped end of the spinal cord.

-around L1-2

Question 11

Which spinal nerves does the cauda equina consist of?

Answer 11

• L2-5
• S1-5
• Co

Question 12

What does the cauda equina descend through?

Answer 12

Lumbar cistern.

Question 13

What is the lumbar cistern?

Answer 13

Enlargement of the subarachnoid space between the conus medullaris (~L2) and the inferior end of subarachnoid space and dura mater (~S2).

Question 14

What does the lumbar cistern contain?

Answer 14

• Cauda equina
• Filum terminale
• CSF

Question 15

What is the lumbar cistern used for clinically?

Answer 15

• Lumbar puncture

- Spinal anaesthesia

Question 16

Where does the spinal cord terminate in the foetus?

Answer 16

Coccyx.

Question 17

Where does the spinal cord terminate in newborns (neonates)?

Answer 17

~L3.

Question 18

Where does the spinal cord terminate in adults?

Answer 18

~L1-2.

Question 19

Where does the subarachnoid space terminate inferiorly?

Answer 19

Lower S2.

Question 20

Where does the subarachnoid space terminate superiorly?

Answer 20

Cranial cavity.

Question 21

What does the subarachnoid space contain?

Answer 21

CSF.

Question 22

What are the diagnostic purposes of obtaining CSF samples?

Answer 22

• Meningitis
• Subarachnoid haemorrhages
• Guillain-Barre syndrome

Question 23

Where is a needle normally inserted for lumbar puncture?

Answer 23

In the midline, between vertebrae L3/L4.

Question 24

What surface landmarks are used to identify the site of lumbar puncture (between L3/L4)?

Answer 24

Horizontal line between the superior border of the posterior iliac crests&raquo_space; L4 spinous process.

Question 25

What are the layers pierced by a lumbar puncture needle?

Answer 25

- Skin - Fascia/subcutaneous fat - Ligaments - Epidural space - Dura mater - Arachnoid mater

Question 26

What are the signs and symptoms of L5/S1 nerve root compression?

Answer 26

- Leg pain (sciatica) - Numb/weak legs - Lower back pain - Cauda equina syndrome

Question 27

What are the nerve roots of the sciatic nerve?

Answer 27

L4-S3.

Question 28

What is cauda equina syndrome?

Answer 28

Compression/damage to the cauda equina. | >> lower back pain, leg pain/weakness, urinary incontinence

Question 29

Which section of the spinal cord has the most white matter?

Answer 29

Cervical. | -all the fibres to the body travel here

Question 30

What is the white matter of the spinal cord?

Answer 30

Paler tissue around the outside. | -consists of mainly nerve fibres and there myelin sheaths

Question 31

What is the grey matter of the spinal cord?

Answer 31

Darker, butterfly-shaped centre. | -consists of mainly cell bodies and branching dendrites

Question 32

What is confusing about the grey/white matter of the spinal cord?

Answer 32

When stained, the white matter appears dark and the grey matter appears light.

Question 33

What are the main factors that help to determine the level of a spinal cord segment? (3)

Answer 33

- ratio of grey to white matter - size of the ventral horns - presence/absence of lateral horns

Question 34

How does the ratio of grey to white matter differ throughout the cord?

Answer 34

General a larger proportion of white matter near the top of the cord. -very little in the sacral region

Question 35

At which spinal cord levels are the ventral grey horns enlarged, and why?

Answer 35

Cervical and lumbosacral enlargements. | -motor innervation to arms and legs

Question 36

At which spinal cord levels is a lateral grey horn/column present, and what is it involved with?

Answer 36

T2-L1. | -contain cell bodies of the sympathetic division of the autonomic system

Question 37

Where in the spinal cord is the dorsal white matter divided into 2 columns on each side?

Answer 37

Above T6. - Gracile fascicle (med) - Cuneate fascicle (lat)

Question 38

What are the main 2 ascending sensory pathways from the body?

Answer 38

- Spinothalamic tract | - Dorsal column pathway

Question 39

What type of information does the spinothalamic tract contain?

Answer 39

Pain and temperature. | -some touch

Question 40

Does the spinothalamic pathway runs ipsilaterally or contralaterally in the cord?

Answer 40

Contralaterally. | -synapses at level of entry

Question 41

In which region of the cerebral cortex does the spinothalamic pathway terminate?

Answer 41

Brainstem. | -venteromedial medulla

Question 42

What does the spinothalamic pathway become at the medulla?

Answer 42

Spinal lemniscus.

Question 43

Where does the 2* sensory area for somaesthetic information lie?

Answer 43

In the parietal lobe. | -posterior to the PCG

Question 44

What type of information is carried in the dorsal column pathway?

Answer 44

- Discriminative tough (2-point) | - Proprioception

Question 45

Where do the fibres of the dorsal column pathway run at the level of the spinal cord?

Answer 45

Ipsilaterally. | -in gracile/cuneate fascicles

Question 46

Where do the fibres of the dorsal column pathway run at the level of the closed medulla?

Answer 46

Ipsilaterally (/contralateral). | -gracile/cuneate nuclei

Question 47

Where do the fibres of the dorsal column pathway run at the level of the open medulla?

Answer 47

Contralaterally. | -medial lemniscus

Question 48

Where do the fibres of the dorsal column pathway synapse and cross over?

Answer 48

At the level of the closed medulla.

Question 49

What does the dorsal column pathway become at the medulla?

Answer 49

Medial lemniscus.

Question 50

Where does the gracile fascicle carry information from?

Answer 50

Below T6 & lower limb.

Question 51

Where does the cuneate fascicle carry information from?

Answer 51

Above T6 & upper limb.

Question 52

If there is a lesion below T6 involving one side of the spinal cord, why might light touch and pressure sensitivity still be present over the whole body?

Answer 52

Both pathways do a bit of touch and pressure. | -compensation

Question 53

CASE STUDY - proprioception and vibration sense lost in left leg - analgesia and thermoanaesthesia in right leg Where is the lesion?

Answer 53

Left side of spinal cord below T6. - dorsal column runs ipsilaterally - spinothalamic tract runs contralaterally

Question 54

What effect would a left sided hemisection below T6 have on leg movements?

Answer 54

Upper motor neuron deficit >> loss of proprioception on LHS. -Can move legs, but don't know how