Module 1: Organization of the Nervous System Flashcards
Develop understanding of the organization of the nervous system.
1
Q
What are the 3 divisions of the primitive (fish) brain?
A
Prosencephalon (front brain)
Mesencephalon (midbrain)
Rhombencephalon (hindbrain)
2
Q
In mammals, the prosencephalon develops to form which two structures?
A
Telencephalon
Diencephalon
3
Q
In mammals, the rhombencephalon develops into what two structures?
A
Metencephalon
Myelencephalon
4
Q
What are the 5 components of the telencephalon?
A
Neocortex Basal Ganglia Limbic System Olfactory Bulb Lateral Ventricles
5
Q
What are the 4 components of the diencephalon?
A
Thalamus
Epithalamus (pineal body)
Hypothalamus
Third ventricle
6
Q
What are the 3 components of the mesencephalon?
A
Tectum
Tegmentum
Cerebral Aqueduct
7
Q
What are the 3 components of the metencephalon?
A
Cerebellum
Pons
Fourth Ventricle
8
Q
What are the two components of the myelencephalon?
A
Medulla Oblongata
Fourth Ventricle
9
Q
Midsagittal
A
the plane vertically dividing the body through the midline into right and left halves
10
Q
Sagittal
A
any plane parallel to the midsagittal line dividing the body into right and left portions
11
Q
Transverse
A
(horizontal) any plane dividing the body into superior and inferior portions
12
Q
Coronal
A
(frontal) Any plane dividing the body into anterior and posterior portions; at a right angle to sagittal plane
13
Q
Ipsilateral
A
When two structures lie on the same side
14
Q
Contralateral
A
When two structures lie on opposite sides
15
Q
Bilateral
A
When two identical structures lie on each side of the body.
16
Q
Proximal
A
Structures that are close to one another; also closer to the midline of the body
17
Q
Distal
A
Structures that are far away from one another; also ones that are farther away from the midline.
18
Q
Afferent
A
An approaching pathway
19
Q
Efferent
A
Pathway that is traveling away from a given structure
20
Q
Dermatomes
A
Area of skin supplied with sensory (afferent) nerve fibers by a single spinal segment
21
Q
What formation do dermatomes take?
A
Dermatomes encircle the body in a ring formation; they are distorted in humans due to the upright posture.
22
Q
What is the CNS composed of?
A
brain + spinal cord
23
Q
What is the PNS composed of?
A
12 cranial nerves + 31 pairs of spinal nerves
24
Q
What comprises the 31 pairs of spinal nerves?
A
8 cervical (C) 12 thoracic (T) 5 lumbar (L) 5 sacral (S) 1 coccygeal
25
What do cord segments connect with?
Dermatomes of the same number
26
Dorsal Root
A collection of fibers entering the dorsal portion of the spinal cord that carry information from the sensory receptors
27
Ventral Root
Collection of fibers leaving the ventral (anterior) portion of spinal cord that carry information from spinal cord to muscles
28
What type of function does the dorsal root serve?
Sensory
29
What type of function does the ventral root serve?
Motor
30
Bell-Magendie Law
Cutting the dorsal root causes loss of sensation while cutting the ventral root causes loss of motor function
31
Dermatomes of internal organs
Organs (liver, kidney, heart, lungs) in the body are also arragned segmentally
32
True of False: Organs have no sensory representation in the brain.
True
33
Where is pain in organs felt?
Within the portion of the dermatome it resides in
34
Referred pain
Pain that is felt in a body part that is away from the site of disease or injury
35
Where is the spinal cord damage in an individual with paraplegia?
In the lower regions, i.e. lumbar or sacral
36
Where is the spinal cord damage in an individual with quadriplegia?
At the higher regions, i.e. cervical
37
Spinal Reflex Arc
The neural pathway that controls an action reflex through a synapse in the spinal cord; allows for quicker response to pernicious sensory information by initiating a motor response without awaiting input from the brain.
38
Withdrawal Reflex
A polysynaptic spinal reflex intended to protect the body from damaging stimuli via stimulation of sensory, association, and motor neurons
39
What is the withdrawal reflex proportional to?
The intensity of the stimulus.
40
Stimulation of what receptors cause flexor withdrawal reflex?
Pain and temperature
41
Stimulation of what receptors cause an extensor reflex?
Fine (discriminative) tactile/touch and pressure receptors
42
What does the hindbrain consist of?
Medulla Oblongata
Pons
Cerebellum
43
Sensory (afferent) fibers from the spinal cord pass through where on their way to the thalamus?
Brainstem
44
Motor (efferent) fibers from the cortex to the anterior horn of the spinal cord pass through which structure?
Brainstem
45
Why do even small lesions on the brainstem have large effects?
Because the brainstem is packed with fibers can cranial nerve nuclei.
46
Where is the Reticular Activating System (RAS) located?
In the central core of the brainstem, i.e. the midbrain, pons, and superior medulla
47
What is the function of the RAS?
Maintenance of consciousness
| control of sleep/wakefulness and arousal levels
48
What are the two subdivisions of the mesencephalon (midbrain)?
Tectum (roof) - above cerebral aqueduct
| Tegmentum (floor) - below cerebral aqueduct
49
What does the tectum contain?
2 sets of bilaterally symmetrical nuclei: superior colliculi and inferior colliculi
50
Superior Colliculi
Receives input from the retina; mediates visual behaviors
51
Inferior colliculi
Receives input from the ears; mediates auditory-related behaviors
52
Tegmentum
Contains some cranial nerve nuclei (primarily motor), substantia nigra, and the VTA
53
Cranial Nerve I
Olfactory - smell
54
Cranial Nerve II
Optic - vision
55
Cranial Nerve III
Occulomotor - eye movement/pupil constriction
56
Cranial Nerve IV
Trochlear - eye movement
57
Cranial Nerve V
Trigeminal - face sensation/ jaw movement
58
Cranial Nerve VI
Abducens - eye movement
59
Cranial Nerve VII
Facial - facial movements
60
Cranial Nerve VIII
Cochleo-vestibular - hearing/equilibrium
61
Cranial Nerve IX
Glossopharyngeal - taste/pharynx
62
Cranial Nerve X
Vagus - heart, vessels, viscera - movement of larynx and pharynx
63
Cranial Nerve XI
Spinal Accessory - neck muscles
64
Cranial Nerve XII
Hypoglossal - tongue muscles
65
What are the 3 major streams of input into the cerebellum?
From cortex
From vestibular apparatus
From body via spinal cord
66
Vestibular Apparatus
the inner ear structures that are associated with balance and position sense; includes the vestibule and semicircular canals
67
Of the 3 major streams of input to the cerebellum, which on controls skilled movement?
The major portions that receive input from the cortex
68
Of the 3 major streams of input to the cerebellum, which one maintains the body's equilibrium?
The portions that receive input from the vestibular system.
69
Of the 3 major streams of input into the cerebellum, which on is responsible for postural reflexes and coordinating related muscle groups?
The parts that receive input from the body
70
What does input from the cortex to the cerebellum control?
skilled movement
71
What does input from the vestibular system to the cerebellum control?
Maintenance of the body's equilibrium
72
What does input from the body to the cerebellum control?
Postural reflexes and coordination of related muscle groups
73
Folia
The many narrow folds found on the surface of the cerebellum
74
What are the 3 major pathways that connect the cerebellum to the brainstem?
Inferior, middle, and superior cerebellar peduncles
75
What types of impairments are present when the cerebellum is damaged?
equilibrium
skilled motor activity
postural defects
76
What are the effects of cerebellar damage?
- Smooth movement broken into jerky, sequential components
- impaired rapid alternation movements
- Directed movements overshoot their mark
77
What are the 3 thalamic structures that comprise the diencephalon?
Thalamus
Epithalamus (pineal body)
Hypothalamus
78
T or F: The functions of the epithalamus are not well understood.
True
79
What is one of the structures found in the epithalamus?
Pineal body
80
What does the pineal body contain?
Melanin
81
What does the pineal body do?
It regulates the circadian rhythm
82
With the exception of olfaction, what structure do all sensory systems pass through?
Thalamus
83
Hypothalamus
Composed of ~22 small nuclei
84
What passes through the hypothalamus?
Ascending fiber systems
85
What structures does the hypothalamus project to?
pituitary gland
| brainstem nuclei
86
Where does the chief brain nucleus controlling the autonomic nervous system reside?
Hypothalamus
87
What does the hypothalamus regulate?
Feeding, sexual behavior, sleep, temperature, emotional behavior, endocrine function
88
What does the forebrain consist of?
Cortex
Limbic structures
Thalamus
Olfactory bulbs and tract
89
Fissure
Cleft that extends deep into brain
90
Sulcus
Cleft that is more shallow than the fissure
91
Gyrus
A ridge on the cerebral cortex
92
T or F: All human brains contain identical gyri and sulci.
F; there are hemispheric and individual variations in the location and size of gyri and sulci.
93
What are the cortical landmarks?
```
Lateral (Sylvian) fissure
Central sulcus (aka fissure of Rolando)
Medial Longitudinal Fissure (aka interhemispheric fissure)
```
94
What are the 4 lobes found in each hemisphere of the brain?
Frontal
Parietal
Temporal
Occipital
95
What are the 3 gyri found in the lateral prefrontal lobe?
Superior frontal gyrus
Middle frontal gyrus
Inferior frontal gyrus
96
What gyrus is found in the lateral frontal lobe?
Precentral gyrus
97
What are the medial frontal lobe gyri?
```
Superior frontal gyrus
Gyrus rectus
Subcallosal gyrus
Cingulate gyrus
Paracentral gyrus
```
98
What are the 3 lateral parietal lobe gyri?
Superior parietal lobule
Supermarginal gyrus
Angular gyrus
99
What is the medial parietal gyrus?
Percuneous
100
What are the three lateral temporal lobe gyri?
Superior temporal gyrus
Middle temporal gyrus
Inferior temporal gyrus
101
What is the medial temporal lobe gyrus named?
The uncus
102
What are the two inferior surface temporal lobe gyri?
```
Parahippocampal gyrus
Occipitotemporal gyrus (aka fusiform gyrus)
```
103
What is the one lateral occipital gyrus called?
Lateral occipital lobe gyrus
104
What are the two medical occipital lobe gyri?
Cuneus
| Lingual gyrus
105
Insula
Cortex that lies underneath posterior-inferior frontal lobe and the anterior-superior temporal lobe
106
What is the posterior-inferior frontal lobe region also known as?
Frontal Opercular Region
107
What is the anterior-superior temporal lobe also known?
Temporal Opercular Region
108
Projection maps
Tracing axons from sensory systems to cortex & from cortex to motor systems
109
Cytoarchitectonic maps
Study of different types of cells across the neocortex
110
Functional maps
Lesions, electrical stimulation of cortex, recording cortex in response to sensory sensory stimulation, functional neuroimaging.
111
What brain region does the visual sensory information project to?
Occipital lobe
112
What brain region does the audio sensory information project to?
Temoral lobe
113
What region does somatosensory information project to?
Parietal lobe
114
What region of the brain does major motor outflow project to?
Frontal lobe
115
Primary projection zones
Regions of the brain to which certain sensory information is projected (e.g. sensorimotor info to the parietal lobe, visual info to the occipital lobe, etc. )
116
Secondary projection zones
Primary projection area neurons send projections to adjacent areas; serve to elaborate on elementary sensory input (e.g. vision = color, stereopsis, texture)
117
Cortical neurons are arranged in how many layers?
6
118
What is the first layer of cortical neurons?
Molecular layer I - most superficial
119
What is the second layer of cortical neurons?
External granular layer II - sensory
120
What is the third layer of cortical neurons?
External pyramidal layer III - motor
121
What is the fourth layer of cortical neurons?
Internal granular layer IV - sensory
122
What is the fifth layer of cortical neurons?
Internal pyramidal layer V - motor
123
What is the sixth layer of cortical neurons?
Polymorphic cell layer VI - innermost
124
What is an example of of one of the most common cytoarchitectural maps?
Brodmann's map; the number on this map has no special meaning, just represent the order in which he examined the areas
125
What are the major Brodmann's areas related to vision?
Areas 17, 18, 19
126
What are the major Brodmann's areas related to audition?
Areas 41, 42
127
What are the major Brodmann's areas related to touch?
Areas 3, 1, 2
128
What is the major Brodmann's area related to motor function?
Area 4
129
What did Dr. Wilder Penfield's experiment consist of?
He directly stimulated the brains of conscious patients during brain surgery
130
What were some of the major findings discovered from Dr. Penfield's experiment?
- Point-to-point relations between parts of body and parts of cortex
- Areas with finder discriminative touch have larger areas of representation on cortex
- Body represented upside down on postcentral and precentral gyrus - largest areas were designated for the lips and thumbs
131
What is the purpose of functional maps?
To determine the parts of the cortex that are responsible for somatosensory, motor, and language; done during neurosurgery to avoid resecting vital areas of functioning for the patient
132
What are two types of functional mapping?
Sensorimotor mapping
| Speech mapping
133
What are the 4 main types of functional imaging used by neuroscientists?
fMRI
PET
SPECT
MEG
134
MEG
magnetoencephalography
135
SPECT
single-positron emission computed tomography
136
What are the 3 types of axon projections in the cortex?
```
Short connections (between two gyri)
Longer connections (between lobes)
Interhemispheric connections (between two hemispheres)
```
137
Short connections are also known as:
U fibers or arcuate fibers
138
Longer connections are also known as:
Fasciculi or tracts
139
What are interhemispheric connections also known as:
Commissures
140
T or F: Isolated damage to a pathway results in less severe damage than damage to the cortex.
F; isolated damage to a pathway may result in as severe a deficit as damage to the cortex proper.
141
What is the limbic lobe?
The middle brain layer sandwiched between the new brain (neocortex) and old brain (diencephalon) that is responsible for memory and emotion
142
What are the 4 major structures of the limbic lobe?
Amygdala
Hippocampus
Septa nuclei
Cingulate gyrus (and cingulum bundle)
143
What is the main function of the cingulate gyrus?
Motivation, drive; lesions here result in akinetic mutism, reduced drive
144
What is the main function of the septal area?
"Pleasure center"; mediator of self-stimulation, self-reward
145
Basal Ganglia
Group of nuclei lying deep beneath the anterior regions of the cortex
146
What are the 5 components of the BG?
```
Caudate nucleus (tailed nucleus)
Putamen (shell)
Globus pallidus (pale globe)
Amygdala (almond)
Substantia nigra in the midbrain
```
147
Where does the caudate receive input from?
All areas of the cortex
148
Where does the caudate project to?
Putamen and globus pallidus --> Thalamus
| Thalamus --> motor areas of cortex
149
The caudate and the putamen comprise what structure?
The neostriatum
150
What does the substantia nigra deliver to the BG?
Dopamine (DA)
151
What does damage to the BG result in?
- Changes in posture, muscle tone, and abnormal movements (e.g. twitches, jerks, tremors)
- Deficits in sequencing movements into smooth progression
152
The BG is also though to support what type of learning?
habit/procedural learning
153
Thalamus
Group of relay nuclei deep within the center of the brain
154
Lateral geniculate body (LGB)
Receives input from retina, projects to visual cortex (Brodmann's area 17) in occipital lobe
155
Medial geniculate body (MGB)
Receives auditory projections, projects to primary auditory cortex (transverse gyri of Heschl, Brodman's area 41, 42).
156
Posterior areas of the cortex send projections to and receive input back from _________.
pulvinar
157
Ventral posterior lateral (VPL) nucleus
Receives touch, pressure, pain, and temperature input from body - projects to somatosensory cortex (Brodmann's areas 3, 1, 2).
158
Limbic system project to the frontal lobe through what structure?
Dorsomedial (DM) nucleus
159
Other limbic projections pass through mammillary bodies to __________ to cingulate gyrus.
Anterior nucleus
160
BG projects to the motor cortex through what?
Ventral anterior nucleus (VA)
161
Cerebellum projects to the motor cortex through what?
Ventral lateral nucleus (VL)
162
Crossed Brain
Each cerebral hemisphere responds to sensory stimulation from the contralateral side of the body; also controls musculature on contralateral side of body
163
Decussation
Occurs when sensory and motor nerve fibers cross obliquely from one side of the brain to another
164
What produces CSF?
Chorioid plexus (specialized cluster of glial cells lying inside the ventricular cavity)
165
How many ventricles are there in the mammallian brain?
4
166
What are the 4 ventricles of the human brain?
```
Lateral ventricles (I & II)
Third ventricle (III) - ventricle in the diencephalon
Fourth ventricle (IV) - lies between brainstem and cerebellum
```
167
What are the main functions of the cerebral ventricles?
- hydraulic buffer to protect tissue by absorbing blows to the head
- dissemination of chemical to intercellular space
- drains off metabolic waste
168
CSF flows from ventricles to where?
Subarachnoid space
169
What results from blocking CSF outflow?
hydrocephalus
170
How is hydrocephalus treated?
Placement of a ventriculo-perotineal shunt in the lateral ventricles to drain excess CSF to the abdominal cavity
171
What are the two major pairs of arteries that supply blood to the brain?
```
Internal carotid arteries
Vertebral arteries (merge into basilar artery)
```
172
Internal carotid arteries
Supply the anterior 2/3rds of the brain with blood (80%); predominantly cerebral distribution
173
Vertebral arteries
Merge into basilar artery on the ventral brainstem (pons); supplies posterior 1/3rd of brain; predominantly cerebellar and brainstem distribution
174
The internal carotid artery (ICA) enters skull at base of brain and branches into:
Anterior cerebral artery (ACA) and medial cerebral artery (MCA) which irrigates anterior-lateral and mesial cortex.
175
The basilar artery gives rise to:
Posterior cerebral artery (PCA) which irrigates occipital lobe and medial temporal cortex
176
Name the 4 ways in which the brain and spinal cord are protected from injury & infection.
1) Thick skull protects brain, vertebrae of spine protect spinal cord
2) 3 Outer membranes surround the brain & cord
3) Ventricles and CSF cushion brain from shock and sudden changes in CSF pressure
4) Blood-Brain-Barrier (BBB) protects against infection
177
What are the three membranes protecting the brain?
Dura mater, arachnoid space, Pia mater
