structure & function of nervous system Flashcards
1
Q
what do sensory nerves do?
A
allow us to sense our environment (internal environment like heartbeat, pain of muscles etc and also external environment like someone has touched us, a smell etc)
2
Q
what are special senses?
A
things like taste, touch, sight, hearing etc
3
Q
what do motor functions do?
A
allows us to react & respond (can be voluntary or involuntary like glands or hormones)
4
Q
what are the 2 ways the nervous system can be divided?
A
- split down anatomically
- also can be split functionally
5
Q
what is the CNS?
A
central nervous system
= brain & spinal cord
brain & spinal cord = also called central controller
6
Q
what is the PNS?
A
peripheral nervous system
= all other tissues not within CNS
= spinal nerves (connect spinal cord)
= cranial nerves (connect with brain)
= autonomic nerves (organs, smooth muscle, glands, visceral afferents, sympathetic nerves, parasympathetic nerves)
= wiring
7
Q
what does afferent mean?
A
fancy word for sensory
8
Q
what does efferent mean?
A
fancy word for motor
9
Q
what is visceral afferent?
A
organ sensory
10
Q
what is the structure of a neuron?
A
has main cell body with nucleus and dendrites and other long processes extending out body
cell body = have connections to other cell bodies, they send & receive electrical impulses
11
Q
what are dendrites?
A
extensions that just receive signal and conduct them towards the body (increase surface area for reception)
12
Q
what are the long processes coming off cell body of neuron?
A
nerve fibres/axons = send signal away from cell body
axons - can be up to metre long but can be in sequence & synapse so cover entire length of body
13
Q
what is the purpose of myelin sheath?
A
makes conduction easier & faster (cover lots of nerves but not all)
14
Q
what is a collection of nerves called in the CNS?
A
nucleus
15
Q
what is a collection of nerves called in the PNS?
A
ganglion
16
Q
what are nerves made up of?
A
1 nerve is made up of bundles of axons or nerve fibres (axons & nerve fibres the same thing)
17
Q
how do travelling bundles of axons leave original nerve?
A
they leave as branches at like limbs for example
18
Q
what is modality?
A
type of nerve fibre/axon
19
Q
what are named nerves?
A
generally larger nerves supplying body wall, body cavities & organs
20
Q
what are the 6 different modalities?
A
- somatic sensory function = carries sensory information from soma
- somatic motor function = nerve fibre from brain or spinal cord and tells muscle to contract
- special sensory function = carry special sensations back to spinal cord & brain
- visceral afferent function = carry sensory information back from organs
- sympathetic function = motor going to smooth muscles & cardiac muscles etc
- parasympathetic function = motor going to smooth muscles & cardiac muscles etc
21
Q
what is soma?
A
body wall
22
Q
what is viscera?
A
organs
23
Q
what modality do nerves tend to have?
A
they tend to be mixed as nerves = bundles of axons (axons have different types) - some nerves have same function but unlikely
each axon carries 1 type
24
Q
what direction to motor (efferent) nerves run?
A
action potential towards body wall, body cavity or organs
- from CNS →PNS
25
what direction to sensory (afferent) nerves run?
action potential towards brain
- from PNS →CNS
26
what is gyri?
singular = gyrus
- it's the ridge (bumps) of the brain
27
what is sulci?
singular = sulcus
- it's the dips of the brain
28
how is the brain divided?
into same regions as bone above
- so occipital at back, temporal at sides, frontal at front and parietal on top towards back
29
what is a good trick for identifying anterior vs posterior of a brain?
look for temporal lobe as always points anteriorly (forward)
30
how many cranial nerves are there?
12 pairs
31
what is the trick for remembering modality of cranial nerves?
Some Say Marry Money But My Brother Says Big Brains Matter More
S= sensory
M = motor
B = both
32
what is name, number (in roman numeral) and modality of cranial nerve 1?
- cranial nerve I
- olfactory nerve (smell)
- sensory (special)
33
what is name, number (in roman numeral) and modality of cranial nerve 2?
- cranial nerve II
- optic nerve (sight)
- sensory (special)
34
what is name, number (in roman numeral) and modality of cranial nerve 3?
- cranial nerve III
- oculomotor nerve (motor)
- motor
35
what is name, number (in roman numeral) and modality of cranial nerve 4?
- cranial nerve IV
- trochlear nerve (moves 1 muscle of the eye)
- motor
36
what is name, number (in roman numeral) and modality of cranial nerve 5?
- cranial nerve V
- trigeminal nerve
- both
37
what is name, number (in roman numeral) and modality of cranial nerve 6?
- cranial nerve VI
- abducent nerve (abducts eye)
- motor
38
what is name, number (in roman numeral) and modality of cranial nerve 7?
- cranial nerve VII
- facial nerve (supplies muscle of facial expression)
- both
39
what is name, number (in roman numeral) and modality of cranial nerve 8?
- cranial nerve VIII
- vestibulocochlear nerve (hearing & balance)
- sensory (special)
40
what is name, number (in roman numeral) and modality of cranial nerve 9?
- cranial nerve IX
- glossopharyngeal nerve (tongue & pharynx)
- both
41
what is name, number (in roman numeral) and modality of cranial nerve 10?
- cranial nerve X
- vagus nerve (what is name, number (in roman numeral) and modality of cranial nerve)
- both
42
what is name, number (in roman numeral) and modality of cranial nerve 11?
- cranial nerve XI
- spinal accessory nerve (comes by spine)
- motor
43
what is name, number (in roman numeral) and modality of cranial nerve 12?
- cranial nerve XI
- hypoglossal nerve (underneath the tongue)
- motor
44
when looking at underneath of brain - what is a way you can know which nerve is which?
go from 1 -12
- when you go anterior to posterior and medial to lateral
45
what is the brain stem made up of?
- mid brain (bump bit)
- pons
- medulla oblongata
46
what cranial nerves are in anterior cranial fossa?
only cranial nerve I
47
what cranial nerves are found in middle cranial fossa?
CN II, III, IV, V (all 3 types of 5), VI
48
what cranial nerves are found in posterior cranial fossa?
CN VII, VIII, IX, X, XI, XII
49
is sensory or motor nerve going into/out of cranial cavity?
sensory = into cranial cavity (cause needs to tell brain message)
motor = out cranial cavity (cause needs to action to muscle etc)
50
what cranial nerve goes through cribriform plate of ethmoid bone?
cranial nerve I in anterior cranial fossa
51
what cranial nerve comes through optic canal?
cranial nerve II (middle cranial fossa)
52
what cranial nerves comes through superior orbital fissure?
CN III, IV, V1 (one of 3 cranial nerve 5) & VI
- middle cranial fossa
(3, 4, 5, 6)
53
what cranial nerve comes through foramen rotundum?
cranial nerve V2 ( 2 out of 3 of cranial nerve 5)
- middle cranial fossa
54
what cranial nerve comes through foramen ovale?
Cranial nerve V3 (3rd of the 3 cranial nerve 5)
- middle cranial fossa
55
what cranial nerve comes through internal acoustic meatus?
cranial nerve VII & VIII
- posterior cranial fossa
56
what cranial nerve comes through jugular foramen?
cranial nerve IX, X & XI
- posterior cranial fossa
57
what cranial nerve comes through hypoglossal canal?
cranial nerve XII
58
what comes through foramen magnum?
spinal cord
59
what is spinal cord protected by?
vertebral canal
60
what are 2 enlargements of spinal cord?
- cervical
- lumbasacral
= enlarged as a lot of nerve tissue since control upper & lower limbs
61
how many pairs of spinal nerves?
31 pairs
= spinal connects bilaterally with spinal nerves
62
how many cervical spinal nerves are there?
8
63
how many thoracic spinal nerves are there?
12
64
how many lumbar spinal nerves are there?
5
65
how many sacral spinal nerves are there?
5
66
how many coccygeal spinal nerves are there?
1
67
when does spinal cord end?
at L1/L2 inter vertebral disc level
= called conus medullaris (looks like cone shape)
68
how are spinal nerves named?
named according to vertebrae ABOVE it
EXCEPTION!! = in cervical region they're named according to vertebrae BELOW it
69
is adult vertebral column or adult spinal cord longer?
adult vertebral column is longer than the spinal cord (bony bits are longer than the spinal cord)
70
what is cauda equina?
since bones are getting bigger and longer at end of vertebral column, nerves have to come down longer to get out at correct place →this means collection of nerves at end (also called horse tail)
71
what is the only bit of nerve that is actually spinal nerve?
located only within the intervertebral foramina (in the little gap between inter vertebral foramen)
72
what do spinal nerves supply?
the soma (body wall)
73
what are rami?
what spinal nerves turn to to connect with structures of the soma
(away from spinal cord)
74
what are roots & rootlets?
nerves that the spinal cord turns into when going into spinal cord
(towards spinal cord)
- roots come together to make spinal cord
75
out of posterior/anterior rami/roots which are biggest and why?
anterior rami = much bigger as do everything else, come all the way round and supply body wall
76
what does each pair of spinal nerves supply?
just 1 strip stroma
77
what does posterior rami supply?
supply small posterior strip
78
what does anterior rami supply?
supply the remainder of the posterior part, the lateral and the anterior parts of the strips = supply all of the limbs
79
what do dermatomes show?
shows strip that spinal nerves is supplying = area of skin supplied by both the anterior & posterior rami of spinal nerve
80
what are the dermatomes i should know?
T4 = nipple
T10 = umbilicus
81
what are plexuses?
= intertwining of nerves (only anterior rami are involved, posterior rami don't participate in cervical plexuses)
82
what are types of plexus and what do they supply?
- cervical plexus, C1-4
(posterior scalp, neck wall...and diaphragm)
- brachial plexus, C5-T1
(upper limb)
- lumbar plexus, L1-4
(lower limb)
- sacral plexus, L5-S4
(lower limb, gluteal region & perineum)
= intertwining of nerves
83
what are senses sensed by mechanoreceptors?
- coarse touch
- fine touch
- vibration
- proprioception
84
what are senses sensed by thermoreceptors?
- temperature
85
what are senses sensed by nociceptors?
pain
86
what is somatic nervous system made up of?
- soma (head & neck walls, chest wall, back, diaphragm, abdominal wall, pelvic wall, limbs)
- structures (skin, fascia, skeletal muscle, skeleton, internal lining of body cavities)
87
what type of pain would a patient describe for somatic pain?
sharp or stabbing - localised (would be able to say where)
88
what is the general route of somatic sensation if sensory stimulation on thigh?
- somatic sensory mechanoreceptors in L2 dermatome are stimulated
- action potentials conducted along axons within the L2 anterior ramus
- the same L2 axons weave their way through the lumbar plexus to the L2 spinal nerve
- APs conducted via the same axons which pass through the dorsal (posterior) root ganglion, the dorsal (posterior) roots and dorsal (posterior) rootlets
- APs arrive at the posterior horn of the L2 spinal cord segment
- AP’s cross over the midline and then ascend towards the brain
89
what is the general route of somatic sensation after sensory stimulation? (from brain -> action)
- somatic motor axons cross over in brainstem then descend to the anterior horn
- APs conducted along axons within anterior rootlets, then anterior roots, then into spinal nerves
- APs conducted along axons in named nerves of lumbar plexus
- Synapse onto skeletal muscle of lower limb
- skeletal muscles contract and move the lower limb
90
what happens in spinal reflexes?
- reflex is extremely rapid
- miss out pathway to brain
- involuntary response
sensation travels through posterior root/rootlets but need to quick so we miss out connection to brain and there’s quick connection that goes to motor nerve for response
91
what is included in autonomic nervous system?
- viscera e.g. heart, lungs, kidney
- glands e.g. muscous, sweat, salivatory
- smooth & cardiac muscle
- external lining of organs
92
where is autonomic nervous system found?
- internal organs in body cavities = chest cavity, pelvic cavity, abdominal cavity
- body wall organs = sweat glands, arrector smooth muscle, arterioles
93
what sensations can be detected by autonomic nervous system?
- touch, temperature, pain
- ischaemic
- colicky (comes & goes)
94
what type of pain would patient describe if autonomic pain?
dull, achy, nauseating - poorly localised
95
what dual motor control is involved in ANS?
many organs have both sympathetic & parasympathetic nerve supply
= both motor controls
= like accelerator or brake
96
what are effects of sympathetic division? (7)
fight or flight response - supplies all internal organs, body wall organs, arterioles
pupils - dilate (so you can see clearly)
heart rate - increase (try to pump blood around body)
lungs - bronchioles dilate (more oxygen)
GI tract - motility reduced (don’t want to waste time digesting)
liver - released glucose (for energy)
adrenal gland - adrenalin
arterioles - dilate(muscles) or constrict (skin) →so skin feels cold and looks pale because want blood to go to muscles not skin
97
what is sympathetic outflow?
thoratholumbar outflow (between T1&L2)
= control central in brain starts to provide sympathetic innervation →passes down spinal cord → only exits between T1-L2 →travels to sympathetic chain and can leave there and then get higher or lower →gets a ride with arteries (runs along surface to get to where it needs to go)
98
sympathetic axon direction of travel?
leaves spinal cord in anterior rootlets or roots as sympathetic type of motor
99
what are effects of parasympathetic division?
=rest & digest - often supplies same organs as sympathetic, doesn't supply body wall organs or arterioles
Pupils - constrict
Heart - rate decreases
Lungs - bronchioles constrict
GI tract- motility is increased
Liver - glucose synthesis
Bladder – sphincter relaxes
100
what is parasympathetic outflow?
= craniosacro
cranial nerves (3,7,9, 10 have parasympathetic innervation)
S2, S3, S4 - carry parasympathetic innervation
- lots of ganglia in head
- vagus nerve important for carrying parasympathetic innervation
101
what does vagus nerve supply?
organs of the neck, chest and abdomen as far as the mid-gut
102
what does parasympathetic ganglia in head supply?
to lacrimal gland and salivary glands
103
what does sacral spinal nerves do in parasympathetic outflow?
‘carry’ parasympathetic axons to the hindgut, pelvis and perineum
