Nervous System Flashcards
1
Q
The CNS is composed of (2):
A
- brain (forebrain/ midbrain/ hindbrain)
- spinal cord
2
Q
The PNS is composed of:
A
(everything else)
- cranial nerves
- spinal nerves
- peripheral ganglia
3
Q
2 types of cells within the nervous system:
A
- neurons (conduct signals)
- neuroglia (support cells for neurons - maintenance)
4
Q
How many neurons does the brain have?
A
Approx 100 billion neurons
5
Q
Neurons form connections to other cells via _______.
A
synapses
6
Q
T/F
Each neuron has about 100,000 connections with other neurons.
A
True
7
Q
A collection of nerve cell bodies within the CNS is called a _______.
A
nucleus
diff than that of a cell - nerve cell bodies like to stay clumped together
8
Q
A collection of nerve cell bodies in the PNS is called a ________.
A
ganglion
9
Q
Part of neuron that brings info INTO cell body; stimulated by environment.
A
dendrite
10
Q
Part of neuron that conducts nerve impulse towards a synaptic terminal.
A
axon
11
Q
Nissel bodies (in neuron)
A
- aids in production + dispersal of proteins and peptides
- resides in cytoplasm of neuron soma
12
Q
The initial segment of an axon, where it connects to the soma of the neuron. This is important for how the nerve fires/ depolarizes.
A
Axon Hillock
maximizes communication b/n nerves + cells
13
Q
Phospholipid layers covering an axon (shields contact w/ interstitial fluid). It improves the speed of an action potential.
A
Myelin sheath
14
Q
Individual myelinated cells that are wrapped around an axon to speed up conductive impulse.
A
Schwann cell (type of glial cell)
15
Q
Side branches of an axon.
A
axon collateral
16
Q
Synaptic bouton
A
The end of an axon terminal where one neuron synapses on another.
17
Q
What causes summation of the initial segment of the Axon Hillock?
A
[excitatory input] + [inhibitory input] = summation = threshold potential?
–> if threshold potential is reached, the neuron will fire.
THINK: threshold potential of Na+, K+ ion channels opening/closing
18
Q
This type of neuron has two poles separated by a cell body. It is found in special sense cells (i.e. sight).
A
Bipolar neuron
19
Q
This type of neuron has its cell body situated to one side. It is predominant in the sensory nervous system aka sensation (touch).
A
Unipolar neuron
20
Q
This type of neuron has multiple dendrites and a single axon. Most neurons are classified as this.
A
Multipolar neuron
21
Q
Give 5 examples of multipolar neuron cells.
A
- pyramidal cell (cortex)
- purkinje cell (cerebellum)
- stellate cell
- granule cell
- basket cell
22
Q
2 types of neuroglia found in PNS
A
- SATELLITE CELL (surround neuron cell bodies; maintains homeostatic environ. for efficiency in metabolic function)
- SCHWANN CELL (surround axons; assists in repair process)
23
Q
4 types of neuroglia found in CNS
A
- OLIGODENDROCYTE (myelinate axons - sometimes >1 axon/ cell)
- ASTROCYTE (maintains homeostatic balance around nerve cell body)
- MICROGLIA (remove pathogens+ waste via phagocytosis)
- EPENDYMAL (line inside lumen of nerve, brain; produces+ maintains cerebrospinal fluid)
24
Q
What is the function of spinal meninges? Name its 3 layers from superficial to deep.
A
- provides protection by covering the spinal cord and its neural tissue.
- dura mater > arachnoid mater > pia mater
(think: DAP - don’t approach penis?)
25
Spinal meninges:
| - thick, dense, strong fibrous tissue on outside covering of brain and spinal cord
dura mater
| think: fibrous = durable matter
26
Arachnoid mater
- intermediate meningeal layer
- simple squamous epithelium
- cerebrospinal fluid (shock absorber + diffusion medium for nutrients/waste)
27
Spinal meninges:
- deepest layer, in intimate contact w/ brain tissue; firmly bound to underlying neural tissue (outermost layer of brain tissue)
pia mater
28
T/F
| The CNS floats in cerebrospinal fluid.
True.
29
3 main parts of the brain
- cerebrum (think: umbrella - largest part)
- cerebellum
- brain stem
30
5 functions of cerebrum
1) higher COGNITIVE FUNCTIONS (thought, creativity, planning)
2) LANG. & SPEECH (formulation, comprehension)
3) somatic MOTOR FUNCTION (skeletal muscle activity, coordinates movement - basal ganglia)
4) somatic SENSORY function (interpret stimuli from environ.)
5) regulates EMOTIONAL aspects of behaviour
31
What is the basal ganglia (cerebrum) responsible for?
- regulates and coordinates movement [somatic motor function]
32
Cerebral cortex
- outside
- GREY matter
- made of: neuronal cell bodies
33
Cerebral medulla
- inside
- WHITE matter
- made of: axons
34
Name the 3 poles of the cerebrum.
- frontal
- occipital
- temporal
35
Name the 4 lobes of the cerebrum.
- Frontal
- Parietal
- Occipital
- Temporal
36
Which lobe controls vision?
occipital lobe
37
Which lobe controls perception of self in space and sensory?
```
parietal lobe
(think: Perception = Parietal)
```
38
Which lobe controls higher cognitive functions such as planning, strategy and motor skills?
frontal lobe
39
Which lobe controls memory, hearing, learning and social behaviour?
```
temporal lobe
(think: hearing @ ears = temporal)
```
40
Where does the motor homunculus exist along the cortex of the brain?
```
Precentral gyrus (primary motor cortex)
- most space dedicated to hands and face
```
41
Where does the sensory homunculus exist along the cortex of the brain?
```
Postcentral gyrus (primary sensory cortex)
- most area dedicated to upper extremity and face
```
42
Name the 3 types of fibre tracts in the brain and their locations.
- PROJECTION fibres (cortex to other)
- ASSOCIATION fibres (cortex to cortex)
- COMMISSURAL fibres (interhemispheric)
43
Which type of fibre tract connects portions of the cerebral cortex within the same hemisphere?
Association fibres (think: lateral// short and long)
44
Which type of fibre tract connects the cerebral cortex to other regions of the brain and spinal cord?
Projection fibres (think: more vertical)
45
What type of fibre tract has interhemispheric connections?
Commissural fibres
46
What are the 3 main functions of the cerebellum (bell-shaped)?
- compares and corrects intended vs evolving movement
- ensures smooth, coordinated, purposeful movements (skilled)
- regulates posture + balance
47
What is cerebellar ataxia?
- disease of cerebellum
- intention tremor -- > reduced ability to effect control of movements
- lack of balance/ coordination
48
What are the 3 components of the brainstem?
- midbrain (superior)
- pons
- medulla oblongata (inferior)
- -> THINK: mighty penis me
49
What is the function of the thalamus?
- relays sensory info to the brain
| - acts as a centre for pain perception
50
What is the function of the hypothalamus?
- homeostatic functions within the body
51
What are the 5 functions of the brainstem?
1) motor + sensory connections from cortex/thalamus to spinal cord
2) houses cranial nerve nuclei (origins of CNs)
3) Reticular Activating System (arousal of cortex, consciousness)
4) regulate HR, breathing
5) regulates swallowing, gag reflex
52
What is another word for the midbrain?
mesencephalon
53
Ventricles of the Brain:
| The anterior, posterior and inferior horns collectively constitute the _________ ventricle?
lateral ventricle
54
T/F
The central canal within the spinal cord enlarges to the fourth ventricle as it moves towards the brain, eventually growing into the third ventricle.
True.
55
T/F
| The fourth ventricle of the spinal cord in the brain lies between the midbrain and cerebellum.
False.
| The fourth ventricle lies between the PONS and the cerebellum
56
T/F
| The third ventricle lies between the thalamuses.
True.
57
Why is the midbrain responsible for Parkinson’s disease?
- substantia nigra regulates motor activity + neuronal degeneration (Park’s)
58
The substantia nigra and red nucleus (regulator of motor activity) are found in which part of the brainstem?
Midbrain
| also a relay centre for visual + auditory pathways; CN 3+4
59
Why does the Pons of the brainstem have such a big belly?
Houses axons travelling b/n cerebrum + cerebellum
| CN 5-8
60
What is the medulla oblongata responsible for?
Contains vital cardio-respiratory regulatory centres.
| CN 9-12
61
Which artery in the brain connects the anterior+posterior blood supply?
Posterior communicating artery
62
Which artery in the brain connects the R/L hemisphere blood supplies?
Anterior communicating artery
63
Differentiate the functions of the anterior/ middle/ posterior cerebral arteries.
- ANTERIOR: supplies blood to many diff (anterior) regions
- MIDDLE - supplies blood to anterior brain
- POSTERIOR - supplies blood to temporal + occipital lobes
64
Which artery in the brain supplies the anterior region of the brain?
Internal carotid artery
65
Which artery in the brain supplies the posterior region of the brain?
Vertebral artery
66
Name of the artery made by two vertebral arteries fusing together on the anterior surface of the pons.
basilar artery
67
Circle of blood vessels at the base of the brain. If blockage occurs here, can recover some functionality by shunting blood thru other vessels.
Circle of Willis
68
What is the size of your spinal cord compared to?
Diameter of your pinky finger.
69
What is are the ventricles' function in the brain?
- contain CSP, transporting nutrients, chemical messengers, waste products
70
An enlargement of the spinal cord at the cervical region = branches of spinal nerves innervating upper limbs.
brachial plexus
71
Lumbosacral plexus
Enlargement of spinal cord in lumbar region; formed by branches of spinal nerves innervating lower limbs
72
What is the lateral horn? Where is it found?
- in thoracic spinal cord
| - where cell bodies of sympathetic nervous system reside
73
What is the conus medullaris?
- part of spinal cord that begins to taper in diameter into "cone-like" structure (tip of spinal cord resides here - only nerve roots grow down)
- @ L1-2
74
What is the cauda equina?
- bunch of nerve fibres that hang (like a horsetail)
| - beneath conus medullaris
75
Where is the filum terminale found? What is its function?
- sacral region
| - anchors/ attaches spinal cord to coccyx so it doesn't move around
76
T/F
| Concerning the spine, bony growth happens faster and longer than the neural growth.
True
77
Posterior dorsal horns within the spinal cord have ________ function.
sensory
78
Anterior ventral horns in the spinal cord have _________ function.
motor
79
Dorsal and ventral roots join up to form a _______ ________.
spinal nerve
80
If sensory neurons = inward, motor neurons = _______.
outward
81
Another term for muscles (effected by motor neurons).
peripheral effecters
82
Ascending pathways between the periphery and higher centres communicate _______ information.
sensory
83
Descending pathways between the periphery and higher centres communicate ________ information.
motor
84
Each ascending (sensory)/ descending (motor) pathway consists of a chain of _______ and associated nuclei or ganglia.
neurons
85
Interneuronal connections are also called _________.
synapses
86
Name of the neural pathway from spinal cord to thalamus (area of the brain receiving sensory info)
spinothalamic pathway
87
Name of the neural pathway from cerebral cortex to spinal cord
corticospinal pathway
88
3 major somatic sensory pathways:
1) dorsal column (medial lemniscal) pathway
2) spinothalamic (anterolateral) pathway
3) spinocerebellar pathway
89
Somatic sensory pathway in charge of unconscious proprioception (amount of force applied to effect a movement - pertaining to muscle/ tendons)
spinocerebellar pathway
90
Somatic sensory pathway in charge of pain/temperature/ deep touch (non-discriminant).
spinothalamic (anterolateral) pathway
91
The function of the dorsal column (medial lemniscal) pathway.
- joint (limb) position/ motion sense (proprioception - body in 3D space)
- light touch (discriminant; stereognosis; graphesthesia)
92
Dorsal columns (2 types):
- fasciculus gracilis (upper extremities; lateral)
| - fasciculus cuneatus (lower extremities, medial)
93
T/F:
Dorsal column pathway has 2 order neurons.
(think: conscious proprioception//"discriminant touch")
FALSE.
1st: skin receptor > dorsal horn > MEDULLA (ipsilateral side) via FASCICULUS CUNEATUS/ GRACILIS
2nd: crosses midline onto contralateral side -- travels up MEDIAL LEMNISCUS (brainstem) > MIDBRAIN > THALAMUS
3rd: synapses in thalamus > projects onto 1º sensory cortex (THALAMORTICAL PROJECTIONS)
94
T/F:
Anterior spinothalamic tract has 3 order neurons.
(think: deep/ crude touch - indiscriminant)
True.
1st: skin receptor > dorsal root
2nd: dorsal horn > crosses midline to ascend contralateral ANT. SPINOTHALAMIC TRACT > MIDBRAIN > THALAMUS
3rd: thalamus > 1º sensory cortex
95
T/F:
The lateral spinothalamic tract has 3 order neurons.
(think: pain, temperature)
True.
1st: skin receptor > dorsal root
2nd: dorsal horn > crosses midline to ascend contralateral LATERAL SPINOTHALAMIC TRACT > MIDBRAIN > THALAMUS
3rd: thalamus > 1º sensory cortex
96
T/F:
The spinocerebellar pathway (unconscious proprioception) has a 2-order neuron process involving 3 neurons which end on the CONTRALATERAL side of the cerebellum.
False.
1st: joint/muscle/tendon receptor > dorsal horn
2nd: synapse onto a) POSTERIOR spinocerebellar tract on original side> medulla > pons > cerebellum; b) ANTERIOR sp. tract, which crosses to contralateral side > medulla > pons > crosses BACK to ipsilateral side > cerebellum
97
To effect contraction of skeletal muscle, commands are distributed to the body from the ________ to the _______.
CNS to PNS
98
Somatic motor pathways involve at least 2 motor neurons:
- upper motor neuron (cell body in CNS
| - lower motor neuron
99
Upper motor neuron
- somatic motor neuron
| - cell body in CNS processing centres
100
Lower motor neuron
- somatic motor neuron
| - cell body in ventral horn of spinal cord// motor cranial nerve nucleus in brainstem
101
The upper motor neuron can effect a ________ or _________ synapse onto the lower motor neuron.
excitatory or inhibitory
102
An upper motor neuron lesion in a somatic pathway would cause a[n] __________ synapse, leading to ________ paralysis at the periphery.
- inhibitory synapse
- spastic paralysis (rigidity)
(LMN has no one to stop/ regulate the flow - muscle contracts until cannot contract anymore)
103
A lesion in the lower motor neuron partaking in an excitatory OR inhibitory synapse effects ______ response in the periphery, causing _______ paralysis.
- no response
- flaccid paralysis
(LMN tries to send signal down but it can't get to the muscle - have no signal getting to/from muscle; remains flaccid)
104
T/F:
| The lower motor neuron is known as the Common Final Pathway for muscle contraction.
True.
| - only axon that extends to skeletal muscle
105
T/F:
Conscious motor commands controlling skeletal muscle travel over several descending motor pathways involving the upper motor neuron.
True.
106
Which motor pathway regulates the distal musculature in the limbs + trunk?
(imp for precise, skilled, learned movements [fingers])
Corticospinal (pyramidal) pathway
| - UMN: cortex to spinal cord
107
Which motor pathway regulates the muscles of the head + neck?
Corticonuclear/bulbar pathway
| - UMN: cortex to motor cranial nerve nuclei in brainstem
108
The name given for subsidary descending pathways that are used as imp backup systems for other pathways.
Extrapyramidal pathways
109
Why is continuous sensory feedback vital for motor systems?
It is important to know whether mistakes are being made/ need to be corrected.
110
What is the role of basal nuclei (ganglia) and the cerebellum in the corticospinal tract?
Modulate + modify activity to ensure smooth, coordinated, purposeful movement.
111
Which part of your brain is responsible for the PLANNING and EXECUTION of movement?
(think: central motor program)
1) Identification of target (posterior parietal cortex)
2) Planning action (premotor cortex + supplementary motor cortex)
3) Execution of action (primary motor cortex) --> motor commands thru UMN > LMN > muscle contraction
112
Which 3 areas of the cortex do fibre bundle pathways originate from in the corticospinal pathway?
- primary sensory cortex (sensory input)
- premotor + supplementary motor cortex (planning)
- primary motor cortex (execution)
113
What is the internal capsule within the corticospinal pathway?
Small spot where motor fibres are condensed (mm in diameter) -- imagine if this spot broke
114
What is the difference between spinal nerves and cranial nerves?
Spinal nerves - emerge from/ attached to spinal cord
| Cranial nerves - emerge from brain stem
115
What is the difference between sensory sensation (sp. pain) perceived by the somatic vs autonomic nervous system?
Somatic - pain sharp, direct, well-localized// temperature, touch, proprioception
Autonomic - pain vague, ache-like, indirect or referred pain// stretch or ischemia (lack of O2) at organs
116
How many spinal nerves exist in the body? How many per vertebral region?
```
TOTAL: 31
Cervical - 8
Thoracic - 12
Lumbar - 5
Sacral - 5
Coccygeal - 1
```
117
What is the classification of spinal nerves?
1) general SOMATIC AFFERENT (pain, proprioception, etc)
2) general SOMATIC EFFERENT (ventral horn to skeletal muscles)
3) general VISCERAL AFFERENT (pain, distension)
4) general VISCERAL EFFERENT (auto. fibres innervating smooth/ cardiac muscles, glands)
(afferent: in// efferent: out)
118
What is the dorsal horn responsible for?
sensory neurons entering spinal cord
119
What is the ventral horn responsible for?
motor neurons leaving spinal cord
120
The dorsal and ventral roots come together to form the SPINAL NERVE (1-1.5cm long). It then bifurcates into the _____________ and _____________.
- dorsal primary ramus (back functions)
| - ventral primary ramus (body wall/ limb functions)
121
What does the primary ventral ramus branch out into?
- lateral cutaneous branch (wraps around body wall)
- anterior cutaneous branch
(these nerves also run in subcutaneous space)
122
What does the primary dorsal ramus branch out into?
posterior cutaneous branch
| innervates muscles around vertebral column, on somatic wall
123
Where do nerves exit the spinal cord in the vertebral canal towards the somatic wall?
Nerves exit vertebral canal thru the INTERVERTEBRAL FORAMEN.
124
T/F:
Different fascicles within one individual spinal nerve carry motor or sensory info (not specific to one job or localized point in the body)
True.
A spinal nerve carries both motor and sensory info. It can travel to a big toe or the right ankle -- not specific to a point either.
125
What is the layer surrounding the spinal nerve (think: anatomy of nerve).
Epineurium
126
What is the outermost layer of a fascicle within a spinal nerve called?
Perineurium
127
What is the outermost layer of an axon in the spinal nerve called?
Endoneurium
128
Which step does the reflex arc bypass?
| only if stimulus is intense
Sending info to the primary sensory cortex from the spinal cord. Instead, activation of stimulus = activation of SENSORY NEURON leads straight to activation of MOTOR NEURON = response by EFFECTOR. //
UMN is bypassed - have direct connection to LMN.
129
Is it possible to overcome the reflex arc?
Yes, consciously. You can get past it if you decide to do so.
130
What does a reflex arc consist of?
- receptor
- sensory neuron
- motor neuron
- effector
131
What is the name for a specific region of the body surface monitored by the segmental division of dorsal and ventral rami along the spinal cord?
Dermatome
| supplies a map to the body wall to refer pain
132
T/F:
Nerves will grow to accommodate body growths (i.e. nerves on stomach growing in response to changes in body wall - pregnancy; boobs; scrotum)
True. Nerves just grow longer as the skin grows farther from thoracic/ abdominal/ pelvic wall.
133
What are some of the most obvious dermatomes (nipples, sternum, umbilicus, pubic arch)?
- Nipples (T4 nerves)
- Dip above sternum (T1)
- Umbilicus (T10)
- Pubic arch (L1)
134
Name the 3 main nerve plexuses.
- brachial plexus
- lumbar plexus
- [lumbo]sacral plexus
135
Which nerve plexus is responsible for the upper extremity?
Brachial plexus (C5 - T1)
136
Which nerve plexus is responsible for the gluteal region, lower extremity and perineal region/ genitals?
Lumbosacral Plexus (L4 - S3)
137
Which regions are the lumbar plexus responsible for?
- lower anterior abdominal wall
- medial/ anterior thigh
- inguinal (groin) region
(T12 - L4)
138
What are the 5 main nerves of the brachial plexus (C5 - T1)?
think: upper extremity
1) axillary
2) median
3) musculocutaneous
4) radial
5) ulnar
139
What are the 6 main nerves of the lumbar plexus (L1 - L4)?
1) iliohypogastric
2) ilioinguinal
3) genitofemoral
4) lateral femoral cutaneous
5) femoral
6) obturator
140
What are the 6 main nerves of the lumbrosacral plexus (L4 - S3)?
1) tibial
2) common peroneal
3) superior gluteal
4) inferior gluteal
5) pudendal
6) posterior femoral cutaneous
141
Where along the vertebrae are the origin of sympathetic motor nerves found?
T1 - L2 (thoracolumbar)
142
Where along the vertebrae are the parasympathetic motor nerves found?
S2 - S4
CN 3, 7, 9, 10
(craniosacral)
143
What is the difference between somatic and autonomic motor systems?
SOMATIC: CNS > effector site (1 axon) = "common final pathway"
AUTONOMIC: pre/post-ganglionic fibre
144
Does the sympathetic or parasympathetic nervous system have a longer preganglionic fibre?
Parasympathetic has longer pre-g fibre because it is a slower acting system. Post-g fibres are shorter, in turn. "rest + digest" system //
Sympathetic NS is a faster acting system.
145
Does the para or sympathetic nervous system use the neurotransmitters norepinephrine and epinephrine?
Sympathetic NS --> increase HR + catabolism
146
Which neurotransmitters does the parasympathetic NS use?
Acetylcholine (diffuses smooth muscle, vasodilation)
147
Where are preganglionic cells found within the spinal cord (sympathetic nervous system)
T1 - L2
148
How are the following areas affected in sympathetic actions:
Eye; Trachea/Bronchioles; Heart; Gastrointestinal; Blood vessels; Genitalia
- pupil dilation
- dilation of trachea/bronchioles
- increase HR + contractility
- decrease motility, contract sphincter (GI, bladder)
- bl. vessels in skeletal mm dilate// viscera constrict
- F relaxes uterus/ M stimulates ejaculation
149
Where do preganglionic cells in the parasympathetic system originate from?
Brain stem (CN 3, 7, 9, 10) or bottom of spinal cord
150
Which CN are part of the parasympathetic NS, originating in the brain stem?
CN 3, 7, 9, 10
151
Which organ is controlled by the sympathetic nervous system but has no relation to the parasympathetic nervous system?
Skin
| do not need fine control: if sympathetic stops firing signals, hairs will slowly fall on its own
152
Which cranial nerve controls everything from the the neck down to the GI system in the parasympathetic NS?
CN X (heart/ lungs to large intestine)
153
Does the detrusor (bladder) muscle contract or relax under parasympathetic action?
Detrusor contracts while trigone and sphincter relaxes -- > facilitates waste elimination to external environ.
154
How are the following areas affected in parasympathetic actions:
Eye; Lacrimal glands; Salivary glands; Trachea/Bronchioles; Genitalia
- pupil constriction/ accommodation reflex
- stimulate tears
- copious H2O secretion
- trach/bronch. constrict, increase secretion
- stimulates erection
155
Both the para+sympathetic NS stimulate the male phallus. How do these differ in each system?
P - point
| S - shoot
156
What are the 2 diff patterns of sympathetic innervation within the body?
1) subcutaneous (skin)
2) organs above (supra) diaphragm
3) organs below (sub) diaphragm
157
Which part of the brain controls the autonomic motor command structure?
Hypothalamus - regulates + maintains homeostatic functions
158
After pain is relayed from the somatic to the CNS, it is directed to the sensory __________ in the brain to decipher where the pain is coming from.
sensory homunculus
159
Why does referred pain occur?
Pain sensations from visceral organs are innervated by same spinal nerves that innervate more superficial regions as well.
