Nervous System II: Spinal Cord

Question 1

spinal cord nervous system general location

Answer 1

-in vertebral column enclosed by vertebrae in vertebral canal

Question 2

spinal cord nervous system location extent

Answer 2

-foramen magnum of the medulla to intervertebral disc between L1 and L2

Question 3

spinal cord nervous system components

Answer 3

• conus medullaris
• cauda equina
• filum terminale
• cervical and lumbar enlargements
• spinal nerves

Question 4

conus medullaris

Answer 4

• aka “horse tail”
• composed of nerve roots
• extends from the distal end of the spinal cord

Question 5

filum terminale

Answer 5

• a long filament of CT
• extends inferiorly from the conus medullaris (extension of pia mater)
• functions to anchor the spinal cord to coccyx (so it doesn’t shift

Question 6

cervical and lumbar enlargements

Answer 6

• thickened regions

- contains neurons that control the skeletal muscle of the upper and lower limbs

Question 7

spinal nerves

Answer 7

-arranged in plexi originate from these enlargements
31 pairs of spinal nerves
-exit the spinal cord thrugh the intervertebral foramina in the cervical, thoracic, lumbar, and sacral regions

Question 8

meninges composition

Answer 8

-three layers of CT which cover and protect the Brain and spinal cord

Question 9

meninges components

Answer 9

• dura mater
• arachnoid
• pia mater

Question 10

dura mater

Answer 10

• outermost layer

- tough as parchment

Question 11

arachnoid mater

Answer 11

• very thin middle layer

- like cellophane

Question 12

pia mater

Answer 12

• CT covering

- touches spinal cord and brain

Question 13

spaces within the meninges

Answer 13

• subarachnoid space
• epidural space
• subdural space

Question 14

subarachnoid space location

Answer 14

• deep to arachnoid
• between arachnoid and pia mater
• brain and spinal cord

Question 15

subarachnoid space composition

Answer 15

-cerebrospinal fluid (CSF)

Question 16

cerebrospinal fluid

Answer 16

-ultra filtrate of plasma produced in ventricles of the brain

Question 17

characteristics of cerebrospinal fluid

Answer 17

• clear/colorless/odorless

- serves to cushion and nourish the brain and spinal cord

Question 18

cerebrospinal fluid production location

Answer 18

• choroid plexus in the ventricles of the brain

- circulates in the subarachnoid space

Question 19

choroid plexus in the brain

Answer 19

-specialized capillaries that produces CSF

Question 20

epidural space

Answer 20

• located in external to dura mater

- contains fat and blood vessels which supply the spinal cord

Question 21

subdural space

Answer 21

• deep to the dura mater
• normally nothing is found in this space
• arachnoid is pressed against dura)

Question 22

when would something be in the subdural space?

Answer 22

-during injury, it may fill will blood (aka subdural hemorrhage)

Question 23

what happens during meningitis?

Answer 23

-inflammation of the meninges

Question 24

what could inflammation also mean?

Answer 24

-infection

Question 25

how can you diagnose meningitis?

Answer 25

- spinal tap | - lumbar puincture

Question 26

at what vertebral level can you put a needle to test for meningitis safely without damaging the spinal cord? and why?

Answer 26

- between L4 and L5 | - it's safe because the spinal cord ends at L1-L2

Question 27

what anatomical landmark could you use to help locate the vertebral level when testing for meningitis?

Answer 27

- palpate the iliac crests | - a line drawn from one crest to the other passes through the junction of vertebrae L4 and L5

Question 28

list in order the structures the needle to test for meningitis would have to pierce to reach the subarachnoid space

Answer 28

- skin - subcutaneous tissue - interspinous ligaments (CT) - epidural space - dura mater - arachnoid space - subarachnoid space

Question 29

when inserting the needle to test for meningitis, what areas do you not want to pierce?

Answer 29

- pia mater | - spinal cord

Question 30

how many segments is the spinal cord divided into?

Answer 30

-31 segments

Question 31

what are the names of the spinal segment regions?

Answer 31

- cervical - thoracic - lumbar - sacral - coccygeal

Question 32

how many segments are within each spinal segment region?

Answer 32

- C: 8 - T: 12 - L: 5 - S: 5 - C: 1

Question 33

white matter

Answer 33

- fiber bundles(tracts) of myelinated axons | - often arranged in columns of fasciculi

Question 34

what causes the white color in myelin?

Answer 34

-due to myelin (made of lipid)

Question 35

gray matter

Answer 35

-contains cell bodies of neurons located in horns

Question 36

where are gray matter horns?

Answer 36

- regions that are H-shaped | - central portion of the spinal cord

Question 37

ventral grey horn

Answer 37

-contain cell bodies of motor neurons

Question 38

dorsal root

Answer 38

- extends laterally from spinal cord - contains sensory nerve fibers - collection of cell bodies outside of nervous system

Question 39

dorsal root ganglion

Answer 39

- attached to dorsal root | - contains cell bodies of sensory neurons

Question 40

ventral root

Answer 40

- extends laterally from spinal cord | - contains motor nerve fibers

Question 41

what is located at each spinal cord segment?

Answer 41

-a pair of spinal nerves

Question 42

what are the components of a spinal nerve?

Answer 42

-motor and sensory fibers

Question 43

what do spinal nerves pass through?

Answer 43

-intervertebral foramen

Question 44

what are spinal reflexes?

Answer 44

- rapid, unconscious automatic response to a stimulus | - protect areas of the body from injury (i.e. overstretching s muscle/tendon)

Question 45

what part of the body does a spinal reflex not involve?

Answer 45

-the brain

Question 46

reflex arc

Answer 46

- a conduction pathway | - includes multiple components

Question 47

components and location of a stretch reflex

Answer 47

- receptor in muscle spindle (aka tendon) - sensory neuron in dorsal root ganglion - motor neuron in ventral gray horn of spinal cord - effector in the skeletal muscle

Question 48

spinal reflex receptor function

Answer 48

- responds to stimulus | - initiates impulse

Question 49

spinal reflex sensory neuron function

Answer 49

-transmits impulse to CNS (spinal cord)

Question 50

spinal reflex motor neuron function

Answer 50

-transmits impulse from CNS to PNS (spinal nerve)

Question 51

spinal reflex effector function

Answer 51

-muscle that impulses responds to motor neuron impulse

Question 52

how many synapses are necessary in a stretch reflex arc?

Answer 52

-one

Question 53

how does a withdrawal reflex differ from a stretch reflex?

Answer 53

-withdrawal reflex includes a interneuron

Question 54

where is the receptor for a withdrawal reflex located?

Answer 54

-in the skin

Question 55

where does an interneuron transmit information to?

Answer 55

-the sensory neuron to the motor neuron

Question 56

what is an interneuron also called?

Answer 56

-associative

Question 57

how many synapses are necessary in a withdrawal reflex arc?

Answer 57

-two