Spinal cord

Question 1

What is found at the cervicomedullary junction?

Answer 1

nucleus gacil and cuneate tuberlces (nuceli forming dorsal columns)

Question 2

where do nerve exit in the cervical region?

Answer 2

above nerve root (ie. between C7 and T1 is nerve root 8)

Question 3

where do nerve roots exit in lumbar and thoracic regions?

Answer 3

below level of vertebrae ie. between T6 and T7 is nerve T6

Question 4

Number of vertebrae and nerves in cervical region?

Answer 4

7 vertebrae
8 nerves

Question 5

Number of vertebrae and nerves in thoracic region?

Answer 5

12 vertebrae
12 nerves

Question 6

Number of vertebrae and nerves in lumbar region?

Answer 6

5 vertebrae
5 nerves

Question 7

Number of vertebrae and nerves in sacral region?

Answer 7

Sacrum vertebrae
5 nerves

Question 8

Number of vertebrae and nerves in coccygeal region?

Answer 8

Coccyx vertebrae
1 nerve

Question 9

how many nerves are in the spinal cord?

Answer 9

31

Question 10

What is the relative ascent of the spinal cord?

Answer 10

-vertebral column elongates more rapidly than spinal cord during fetal life
- spinal segmental levels lie superior to their corresponding vertebral levels (nerves run superiorally and obliquely

Question 11

what are the longest nerve roots?

Answer 11

lumbrosacral roots (constitute cauda equina)

Question 12

what is the conus medullaris?

Answer 12

slight swelling, more aoxns (where spinal cord ends)

Question 13

what is filum terminale and whats its role?

Answer 13

-where conus medullaris tapers into a filament
- lies in middle of cauda equina
- stops cord rebounding

Question 14

where are the two regions of expansion in the spinal cord and what do they correspond?

Answer 14

• cervical expansion (C4-T1) corresponds to nerve supply to the arms
• lumbrosacral expansion (L2-S3) corresponds to the nerve supply to the distal limbs

Question 15

what is the obex?

Answer 15

point in which 4th ventricle narrows to become central canal of spinal cord

Question 16

what is the ventriculus terminalis?

Answer 16

small focal dilation of the central canal in conus medullaris
- rarely seen in adults (seen in about 3% children under 5)

Question 17

how is the spinal cord suspended in dural sheath?

Answer 17

denticulate ligament on each side
- attached to lateral surface of the cord midway between the dorsal and ventral roots

Question 18

where does dura mater extend from and to?

Answer 18

from formen magnum to S2 level

Question 19

what is the spinal cord protected by?

Answer 19

vertebrae, ligaments, meninges and CSF

Question 20

what makes up the grey matter of the spinal cord?

Answer 20

dorsal horn (axons form ascending white matter fasciculi)
intermediate zone (interneurons involved in local circuitry)
ventral horn (motor cells innervate skeletal muscle)
lateral horn (preganglionic sympathetic efferetn neurons)
intermediolateral

Question 21

what makes up the white matter of the spinal cord?

Answer 21

• dorsal funiculus (medial gracile and lateral cuneate fasciculus)
• lateral funiculus (dorsolateral and ventrolateral)
• ventral funiculus

Question 22

Pattern of white matter down spinal cord?

Answer 22

white matter increases as you descend the cord due to increase in number of nerve fibres

Question 23

why are cervical and lumbar regions enlarged?

Answer 23

• more grey matter in ventral horns due to increased motor neurons due to increased limb movements

Question 24

what is laminae of Rexed?

Answer 24

laminae numbered 1-10 dorsal to ventral
- each laminae composed of a different cell type

Question 25

what does an absent tendon jerk mean?

Answer 25

afferent and efferent neurons of the stretch reflex are damaged

Question 26

what does an exaggerated tendon jerk indicate?

Answer 26

loss of inhibition of motor neurons by descending tracts

Question 27

what will a patient with abnormal signal in dorsal columns complain of?

Answer 27

• loss of light touch vibration and proprioception in feet and hands
• Rombergs sign positive
• legs may be weak and leg reflexes lost

Question 28

what can cause abnormal signals in dorsal column?

Answer 28

• vit. B12 deficiency
• syphilis
• MS
• HIV

Question 29

what does the spinothalamic tract carry?

Answer 29

• pain and temperature

Question 30

when does spinothalamic tract decussate?

Answer 30

• immediately

Question 31

what does dorsal column medial lemniscus pathway carry?

Answer 31

• joint position sense and vibration

Question 32

where does dorsal column medial lemniscus pathway decussate?

Answer 32

in lower medial into medial lemniscus

Question 33

What is brown sycard syndrome?

Answer 33

• hemisection of the cord can take out pain and temperature on one side of the body and joint and position sense in the other side