Spinal Cord I

Question 1

Anterior

Answer 1

rostral

Question 2

posterior

Answer 2

caudal

Question 3

describe orientations for humans

Answer 3

forebrain is bent forwards relative to the spinal cord and brainstem

Dorsal = back, post
Ventral = ant stomach

For brain - dorsal = upper part, ventral = lower part, ant/rostral and post/caudal same

Question 4

what projects to the spinal cord

Answer 4

primary somatic sensory afferents

Question 5

describe length of spinal cord

Answer 5

Spinal cord = extension cns out of brain
42-45cm Long
<— 1 cm diameter

Question 6

How many segments of spinal cord

Answer 6

31 segments

Question 7

name and describe the segments of spinal cord

Answer 7

8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal

Question 8

what do the segments of spinal cord correspond to

Answer 8

Each segment = where sensory neurons enter

Corresponds to entry point of a pair of spinal nerves

Sensory in and motor out, bundles of fibers, peripheral nerves also have axons that go out to innervate muscles

Question 9

describe enlargements of spinal cord

Answer 9

correspond to segments that innervate limbs
More stuff in and out from arms and from legs so enlarged

Question 10

is the spinal cord the same length of the vertebral canal

Answer 10

Nooo shorter
Ends around 1st lumbar vertebra

Question 11

describe lumbar cistern

Answer 11

space through which spinal nerves project downwards
Space at lower, bottom, filled with csf

Question 12

what happens after spinal cord enters skull

Answer 12

Forms medulla (most caudal region of brainstem)

Question 13

what is cauda equina

Answer 13

Spinal nerves below 1st lumbar vertebra project downwards through lumbar cistern —> exit at vertebra forming cauda equina
= name fro collection of nerves for lower part of body

Question 14

where does spinal cord enter skull

Answer 14

through foramen magnum

Question 15

describe white matter

Answer 15

Bundles of myelinated axons

Question 16

where do spinal taps happen

Answer 16

Lumbar puncture in lumbar cisternae

Question 16

descrbe pathway through spinal cord and matter

Answer 16

sensory —> white matter —> brain
Brain —> white matter —> body

Question 17

what is spinal cord comprised of

Answer 17

Central gray matter surrounded by white matter

Question 17

describe gray matter

Answer 17

Regions of nervous system consisting of organized collections of neuronal cell bodies, dendrites and synapses
Central part, carries out computations

Question 17

what happens if sever axons in white matter

Answer 17

Paralysis

Question 18

describe staining of white matter

Answer 18

stained purple, bc stains myelin

Question 19

how big is spinal cord like irl?

Answer 19

Size of tip of pinky
Very small
Doesn’t extend all the way to tailbone

Question 20

describe dorsal horn of spinal cord Gray matter

Answer 20

Somatic sensory

Question 21

describe ventral horn of spinal cord Gray matter

Answer 21

motor

Question 22

describe peripheral nerves entering spinal cord

Answer 22

sensory and motor neurons If cut = no sensory or motor

Question 23

descrive intermediate region of spinal cord Gray matter - gen

Answer 23

Contains interneurosn and preganglionic autonomic neurons

Question 24

generally descrive what is in gray matter of spinal cords

Answer 24

Sensory info comes in dorsally And motor info exits ventrally- ventral part of gray matter= cell bodies of motor neurons (Meet to form peripheral nerve)

Question 25

descrive intermediate region of spinal cord Gray matter = interneurons

Answer 25

Many Connections between sensory and motor Like for reflexes = sensory info communicates with motor - spinal circuits, contained in spinal cord gray matter

Question 26

descrive intermediate region of spinal cord Gray matter = autonomic neurons

Answer 26

Cell bodies of preganglionic neurons of sympathetic branch of autonomic nervous system

Question 27

describe primary somatic sensory afferents entering spinal cord

Answer 27

Enter dorsal spinal cord through dorsal roots

Question 28

where do motor neurons project

Answer 28

To skeletal muscle fibers through ventral roots

Question 29

describe sns = activation/receptros

Answer 29

Symp preganglionic neurons release ach —> activated nicotinic ach receptors on postgang neurons Postgang neurons release norepinephrine = actiavted alpha and beta adrenergic receptors on target organs

Question 29

describe dorsal root ganglion

Answer 29

for all 31 nerves entering - 31 dorsal root ganglia on either side of spinal cord Ganglion = cluster, cell bodies of primary afferents neurons

Question 30

one neuron

Answer 30

cns —> pns

Question 30

describe outputs of sns

Answer 30

Leave cns but originate form thoracic and lumbar parts of spinal cord

Question 31

describe psns = activation/receptros

Answer 31

Axons of psns preganglionic neurons emerge from brain stem (cranial nerves) and sacral spinal cord Pregang exten almost to peripheral targets Psns postgang neurons extend the rest short distance

Question 31

describe what happens after dorsal root ganglion.

Answer 31

Can synapse in gray matter Or go into white matter to brain - column of fibers located dorsally = dorsal column pathway

Question 32

describe sns and psns - gen

Answer 32

Sensory neurons in body —> brainstem and spinal cord = inputs enable cns to make decisions —> outputs Sympathetic and parasympathetic systems tend to have opposed effects on target tissues

Question 33

describe balance between sns and psns

Answer 33

Always work together Symp = increase hr and strength of heat contraction = activating Para = decrease hr and contraction = vegetative Hr manage by balance of these 2 systems = to maintain stable internal body state

Question 34

describe what sns involves - neurons

Answer 34

2 neurons = central gray matter —> exit —> synapse close to spinal cord —> organ Cell bodies make chain = clusters = sympathetic ganglion

Question 34

descrive outputs of psns

Answer 34

Come mainly from brain stem (Also sacral spinal cord) Gives rise to cranial nerves = iii oculomotor, vii facial, ix glosso, x vagus

Question 35

what is a dermatome

Answer 35

Each pair of spinal nerves innervates a region of the body surface called a dermatome (sensory input)

Question 36

describe what psns involves - neurons

Answer 36

2 neurons Output always goes to target but sysnapses with another neuron first also have parasympathetic ganglia

Question 37

define nucleus

Answer 37

Plural = nuclei Organized cluster of neuronal cell bodies in central nervous system

Question 37

define ganglion

Answer 37

Plural = ganglia Organized cluster of neuronal cell bodies in peripheral nervous system (And/or synapses, some cases dendrites)

Question 38

descrive dorsal root ganglion = what

Answer 38

31 pairs of spinal nerves running down length of spinal cord

Question 39

describe fine touch primary afferents - gen

Answer 39

Enter dorsal columns and ascend to dorsal column nuclei in brainstem

Question 39

describe fine touch primary afferents - patwhay

Answer 39

Dorsal root —> spinal cord —> dorsal white matter —> brainstem Some branches into spinal cord gray matter = to motor neurons for reflexes

Question 40

describe temp/pain primary afferents - gen

Answer 40

synapse in dorsal horn of spinal cord gray matter

Question 41

describe temp/pain primary afferents - pathway

Answer 41

enter to spinal cord gray matter and synapse in dorsal horn —> 2nd order neuron - axon crosses over spinla cord and enters white matter —> brain More anterior and lateral