Lecture 7: Spinal Cord, CSF, and Cranial Nerves

Question 1

what is the spinal cord?

Answer 1

-a major organ of the CNS

-a downward extension of the medulla oblongotta
-ranges from 16.5 to 17.7” in adults

-carries motor info from the brain to the periphery
-carries sensory info from the periphery to the brain

**in reference to the spinal cord:
dorsal and ventral are used interchangeable with posterior and anterior respectively

-dorsal=posterior
-ventral=anterior

Question 2

what are the segments of the spinal cord?

Answer 2

1. cervical
2. thoracic
3. lumbar
4. sacral
5. coccygeal

Question 3

how many pairs of nerves does each segment have?

Answer 3

1. cervical - 8
2. thoracic - 12
3. lumbar - 5
4. sacral - 5
5. coccygeal - 1

Question 4

how do you remember the nerve pairs for the segments

Answer 4

“breakfast at 7 (+1), lunch at 12, dinner at 5, a big drink and a small dessert”

Question 5

what are the external landmarks of the spinal cord?

Answer 5

-enlargements (more gray matter) present in the cervical and lumbar regions

Question 6

what is the cervical enlargement responsible for?

Answer 6

controls the skeletal muscles of the upper limbs

Question 7

what is the lumbar enlargement responsible for?

Answer 7

controls skeletal muscles of the lower limbs

Question 8

what is the Cauda equina?

Answer 8

-the “horses tail”
-distal lumbar and sacral nerves

Question 9

what are the other external landmarks of the spinal cord

**make sure you can label :)

Answer 9

1. conus medullaris:
   -the terminal end of the spinal cord
   -ends at about the 12th thoracic vertebrae/first lumbar
2. the lumbar cistern:
   -has clinical relevance for puncture testing (taking cerebrospinal fluid)
3. filum terminale:
   -“terminal thread”- connective tissue
   -anchors the spinal cord inferiorly

Question 10

what is cerebrospinal fluid (CSF)

Answer 10

-ultrafiltrate of blood plasma (clear and odorless)
-has more Na+ but less K+ than blood plasma, and less proteins

Question 11

what are the functions of CSF?

Answer 11

1. protection (shock absorber for the brain against the skull)
2. nourishment
3. waste removal
4. helps regulate cerebral blood flow

Question 12

where is CSF produced?

Answer 12

ependymal cells

Question 13

where is CSF located?

Answer 13

-subarachnoid space around the brain and spinal cord
-ventricles of the brain

Question 14

how much CSF is there?

Answer 14

150 ml at any given time

500ml produced per day

Question 15

What are the internal landmarks of the spinal cord?

**make sure you can label :)

Answer 15

1. posterior gray horn (sensory neurons)
2. anterior gray horn (motor neurons)
3. posterior median sulcus
   4.anterior median sulcus
4. dorsal funiculus
5. lateral funiculus
6. ventral funiculus

Question 16

make sure you know the directions of spinal tracts

Answer 16

:)

Question 17

what happens to white matter as you go from the cervical segment down to the coccygeal segment

Answer 17

white matter decreases as you get lower

Question 18

what happens to gray matter as you go from the cervical segment down to the coccygeal segment

Answer 18

I think it increases but I’m not really sure

Question 19

what are spinal tracts?

Answer 19

-part of the PNS
-nerves arising from the spinal cord (8,12, 5, 5, 1 (31))
-distributed to the skin, sweat glands, mucosa, blood vessels, joints, and skeletal muscles
-can be sensory, motor, or inter
-involved in sensation, movement and sweating

Question 20

sensory neurons travel in what direction and up what part of the spinal cord?

Answer 20

they are ascending and they travel up the dorsal root

Question 21

motor neurons travel in what direction and down what part of the spinal cord?

Answer 21

they are descending and they travel down the ventral root

Question 22

look at the spinal tract diagram :)

Answer 22

:)

Question 23

cranial nerves (overview)

Answer 23

-part of the CNS
-nerves arising from the brain (12 pairs)
-distributed mainly to head and neck structures
-sensory motor and mixed neuron

“On Occassion Our Trusty Truck Acts Funny, Very Good Vehicle Any How”

Question 24

what are the cranial nerves

Answer 24

I. olfactory nerve
II. optic nerve
III. oculomotor n.
IV. trochlear n.
V. trigeminal nerve
VI. abducens nerve
VII. facial nerve
VIII. vestibulocochlear nerve
IX. glossopharyngeal nerve
X. vagus nerve
XI. accessory nerve
XII. hypoglossal nerve

Question 25

the olfactory nerve

Answer 25

I

smell

sensory

Question 26

the optic nerve

Answer 26

II

vision

sensory

Question 27

the oculomotor nerve

Answer 27

III

eyelid and eyeball movement
pupil size

motor

Question 28

the trochlear nerve

Answer 28

IV

eye movement

motor

Question 29

the trigeminal nerve

Answer 29

V

sensory (pain, temp, pressure, chewing)

both

Question 30

the abducens nerve

Answer 30

Vi

abducts eye (lateral movement)

motor

Question 31

the facial nerve

Answer 31

VII

facial expressions, eye and lip movement, taste

both

Question 32

the vestibulocochlear nerve

Answer 32

VIII

hearing
balance

sensory

Question 33

the glossopharyngeal nerve

Answer 33

IX

taste perception
swallowing

both

Question 34

the vagus nerve

Answer 34

X

speech
digestion
respiration
cardiac activity

both

Question 35

the accessory nerve

Answer 35

XI

head
neck
shoulder mvmt

motor

Question 36

the hypoglossal nerve

Answer 36

XII

tongue movement
speech

motor