Central Nervous System Flashcards
1
Q
What are the four regions of the adult brain?
A
1) Cerebral Hemispheres
2) Diencephalon
3) Brain Stem
4) Cerebellum
2
Q
What are the 5 lobes of the cerebrum?
A
1) Frontal lobe
2) Parietal lobe
3) Occipital lobe
4) Temporal lobe
5) Insula –> “bonus lobe” underneath temporal
3
Q
What is the difference between gyri, sulci and fissures?
A
Gyri = ridges that stick out Sulci = shallow grooves Fissures = deep grooves
4
Q
Which lobes does the Lateral sulcus split and what is another name for this?
A
Lateral sulcus splits apart the temporal lobe from the frontal and parietal lobe.
Also called the Sylvain fissure
5
Q
What lobes does the transverse cerebral fissure split?
A
Separates the cerebellum from cerebrum
6
Q
What does the Calcarine sulcus separate?
A
The Calcarine sulcus separates the primary visual cortex
7
Q
What layers protect the brain? (5)
A
- SCALP
- Bone/Skull
- Blood-brain barrier
- Membranes/meninges
- Watery cushon/CSF
8
Q
What does SCALP stand for?
A
S - skin C - connective tissue A - aponeurotic layer L - loose connective tissue P - Pericranium
9
Q
What is the function of the blood-brain barrier?
A
1) maintains stable environment for the brain
2) acts as a metabolic barrier –> endothelial cells quickly metabolize anything coming in
10
Q
Where is the blood-brain barrier not found?
A
Vomiting centre –> your body needs to know quickly if there is something it should get rid of
(area postrema)
Pituitary –> barrier would prevent release of hormones
11
Q
How are brain capillaries different?
A
- they won’t let things move through them as easily because of tight junctions
- -> specifically lipid soluble
- more continuous
- insulated by astrocytes
12
Q
What is the function of the meninges?
A
- cover and protect CNS
- forms the partitions in the skull
- protects blood vessels
- protects venous sinuses
- contains CSF
13
Q
What are the two layers of dura mater?
A
1) Periosteal
2) Meningeal
14
Q
What is the dura mater septa and what does it do?
What layers are there?
A
Dura mater septa are two layers of dura mater fused together that limit movement of the brain
You have:
- falx cerebri - separates cerebral hemispheres
- tentorium cerebelli - separates cerebrum from cerebellum like a “tent” over the cerebellum
- falx cerebelli - behind the cerebellum
15
Q
What separates the dura mater from the arachnoid mater?
A
Subdural space - this is a potential space
16
Q
What is the subarachnoid space?
A
- Contains CSF and blood vessels
- arachnoid villi stick into the superior sagittal sinus to reabsorb CSF
17
Q
What are the functions of CSF? (4)
A
- Buoyancy to brain (like egg in water)
- Protect against trauma
- Nourishing, carries chemical signals
- Clears out waste
18
Q
What does the chorioid plexus do and how?
A
Choroid plexus produces blood filtrate/CSF ~500mL per day
Choroid plexus is a meshwork of capillaries lined by endothelial cells –> lots of surface area to filter waste and pumps out things that we need (oxygen, glucose, water, and ions)
19
Q
What type of cells line the choroid plexus and the ventricles?
A
Ependymal cells
20
Q
How is CSF circulated through the ventricles?
A
choroid plexus makes the CSF within the ventricles so that they are filled with it, then it follows this sequence:
- lateral ventricles
- inter-ventricular foramen
- third ventricle
- cerebral aqueduct
- fourth ventricle
then exits through apertures and ends up in subarachnoid space
21
Q
What is contained in the dural venous sinuses?
A
venous blood
*this is different from CSF because it also contains blood
22
Q
What is the cerebral cortex?
A
Thin layer of superficial grey matter
23
Q
What type of connection does the cerebral hemisphere have with the body?
A
Contralateral –> means that the right hemisphere is in control of the left side
24
Q
What are the functional areas of the cerebral cortex?
A
- Motor areas
- Sensory areas
- Association area –> processes and integrates diverse information
25
What is the functional name of the pre-central gyrus and what does it do?
Primary motor cortex --> conscious control of precise and voluntary movements
26
What does somatotopic arrangement mean?
This refers to the map in the precentral gyrus/primary motor cortex that shows specific areas on the brain that control specific movements
27
What is the functional name of the frontal lobe anterior to the pre-central gyrus and what does it do?
Premotor cortex --> sends information to the primary motor cortex so that muscle groups can coordinate and perform sequential movements
also controls learned, repetitious or patterned motor skills
also plans movements depending on sensory feedback
28
What is the functional name of the part of the frontal lobe that is anterior to the inferior region of premotor area?
Broca's area
29
What does Broca's area do? Is it on one side of the brain?
1. Controls motor speech and directs tongue muscles
2. active when someone prepares to speak
Left side is dominant for language
--> right side controls sarcasm vs sincere communications, not considered part of the Broca's area, this also does non-verbal communication
30
Where is the frontal eye field and what does it do?
Frontal eye field is superior to Broca's area and it controls voluntary eye movements
31
What is the functional name of the post-central gyrus and what does it do?
Primary Somatosensory cortex --> receives information from the skin, skeletal muscles and joints (can discriminate between the regions of the body being touched)
--> it can tell that something is touching you and where, but not what it is
32
What is the functional name of the area posterior to the primary somatosensory cortex and what does it do?
Somatosensory association cortex --> integrates sensory information from primary somatosensory cortex
This can tell what is touching you (size, texture and relationship of parts of objects being felt)
33
What is the functional name of the posterior tip of the occipital lobe and what does it do?
Primary visual (striate) cortex --> receives the visual information from the retinas
34
What is the functional name of the area surrounding the primary visual cortex and what does it do?
Visual association area --> uses past visual experiences in order to tell what you're seeing
35
In the visual association area, what streams are there?
Dorsal stream --> pathway that determines "where"
Ventral stream --> pathway that determines "what"
these pathways move towards the post-central gyrus, complex processing involves entire posterior half of the cerebral hemispheres
36
What is the functional name of the superior margin of the temporal lobe and what does it do?
Primary auditory cortex --> interprets information from inner ear as pitch, loudness and location
*does not necessarily know what it is
37
What is the functional name of the area posterior to the primary auditory cortex and what does it do?
Auditory association area --> stores memories of sounds and uses that to understand what the ears are hearing
*adding in meaning to what is being heard
38
What is the functional name of the medial aspect of the temporal lobes and what does it do? (Right beside hippocampus)
Olfactory cortex --> controls conscious awareness of smells
*right beside the hippocampus; reason why smells illicit memories so quickly
39
Where is the gustatory cortex and what does it do?
In the insular lobe ("bonus lobe") --> involved in perception of taste
40
What area is found posterior to the gustatory cortex and what does it do?
Visceral sensory area --> conscious perception of visceral sensations
*not a lot of the cortex is devoted to this area so this is why we're bad at knowing where pain is coming from in the visceral abdomen
41
What is a multimodal association cortex?
This is the part of the brain that sends information places using all of the integrated information from the association areas (that get information from the primary cortexes that get information from sensory areas)
42
What is the significance of the multimodal association cortex?
Allows us to attach meaning to information that is received, stores it as a memory, compares it to other experiences and decides on actions to take.
43
What are the three parts of the multimodal association cortex?
1. Anterior association area (prefrontal cortex)
2. Posterior association area
3. Limbic system (deep)
44
What is the other name for the anterior association area and what does it do?
Prefrontal cortex --> involved in intellect, cognition, recall and personality, contains working memory that you need for judgement, persistence, and conscience
*this is the most complicated area in cortical region and develops slowly in children
45
Where is Wernicke's area and what does it do?
Found in the posterior association area (a part of the multimodal association cortex) --> involved in understanding written and spoken language
46
What is prosopagnosia and what multimodal association cortex is it involved with?
Face blindness
Involved with the posterior association area which helps in recognizing patterns, faces and localizing ourselves in space
47
What does the limbic association area do?
Limbic association area is part of the multimodal association cortex --> lets us have emotional impact that helps establish memories
48
What is cerebral white matter and how are they characterized?
White matter are the myelinated fibers and their tracts. They are characterized by where they connect.
49
What fibers connect the gray matter of the cerebral hemispheres?
Commissural fibers --> found in corpus callosum
50
What fibers connect different parts of the same hemisphere?
Association fibers
51
What fibers connect hemispheres with lower brain or spinal cord?
Projection fibers --> corona radiata and the internal capsule
52
What is meant by lateralization of cortical function?
Dividing the work between the hemispheres
53
What is meant by cerebral dominance?
Designates the hemisphere that is dominant for language
*about 90% of the population is left dominant
54
What functions are centralized in each the right and left hemispheres?
Left --> language, math and logic
Right --> insight, visual-spatial skills, intuition, and artistic skills
55
What is subcortical nuclei and what "structures" does it consist of?
Grey matter that is part of the cerebrum but not the cortex
Consists of corpus striatum:
- lentiform nucleus
- caudate nucleus
56
What are the two parts of the lentiform nucleus?
Putamen and globus pallidus
57
What are thought to be the functions of basal nuclei?
- influence muscular control
- regulate attention and cognition
- intensity of slow/stereotyped movements
- stop antagonistic and unecessary movements
58
What are the three main parts of the diencephalon?
1. hypothalamus
2. thalamus
3. epithalamus
59
What is the thalamus and what is its function?
Thalamus is a collection of grey matter
--> information is sent here to be sorted, edited and relayed; almost all information goes through this center of the brain
60
What is the hypothalamus and what does it do?
Hypothalamus is a collection of nuclei and is the AUTONOMIC control centre for many visceral functions.
- regulates sleep/sleep cycle
- produces posterior pituitary hormones
- controls the release of hormones by the anterior pituitary
- center for emotional response (4 Fs)
61
What are the emotional responses? (four Fs)
1. fornication
2. feeding
3. fighting
4. fearing
62
What does the paraventricular nucleus do?
also called PVN --> sends information to the pituitary gland
63
What does the supraoptic nuclei do?
produces posterior pituitary hormones
64
What does the supra-chiasmatic nucleus do?
regulates sleep/wake cycle
65
What do the mammillary bodies do?
Important in learning, memory, smell and emotion --> relay center
66
What does the pinneal gland do?
secretes melatonin
67
What are calcareous concretions and where does this happen in the brain?
~age 17 you see the appearance of calcareous concretions (corpora arenacea) --> this is the calcification of the pinneal gland and is also called brain sand
68
What are the structures contained in the brain stem?
1. Midbrain
2. Pons
3. Medulla oblongata
69
Where are the cerebral peduncles found and what do they do?
Located in the midbrain --> contain pyramidal motor tracts
70
What is the Corpora quadrigemina?
Structures on the anterior side of the midbrain broken into superior and inferior aspects:
- superior colliculi: visual reflex centres
- inferior colliculi: auditory relay centers
71
What are the three midbrain nuclei and what are their functions?
1. Substantia nigra: linked to striatum (dopamine)
2. Red nucleus: relay for some descending motor pathways & part of the reticular formation
3. Periaqueductal gray: suppresses pain
72
What does the Pons do and where is it located?
The pons forms the anterior wall of the fourth ventricle
- contains some nuclei of reticular formation
- nuclei that maintain normal rythm of breathing
73
Where is the pyramidal tract and what does it do?
Pyramidal tract is found in the pons and connects higher brain centres with the spinal cord
74
How can you tell the difference between the medulla oblongata and the spinal cord?
The medulla oblongata meets the spinal cord at the foramen magnum
75
What are the structures of the medulla oblongata and what do they do?
Pyramids: 2 ventral longitudinal ridges formed by pyramidal tracts --> this is where the crossover of corticospinal tracts are
Olives: lateral ridges that relay sensory information from the muscles and joints to the CEREBELLUM
--> nucleus cuneatus and nucleus gracilis
76
What is the function of the medulla oblongata?
contains multiple centers:
- autonomic reflexes
- cardiovascular centre --> controls heart rate, vasoconstriction and dilation
- respiratory centre --> controls rythm/rate & depth of breathing
- others include vomiting, hiccupping, swallowing, coughing and sneezing
77
What does the cerebellum do?
- conductor of coordinated movement that is ipsilateral to the body
- plays a role in nonmotor functions; word associations and puzzle solving
78
What connects the two hemispheres of the cerebellum?
vermis
79
Where are Purkinje cells found and what do they do?
Found in the folia of the cerebellum, they are multipolar neurons --> have a lot of dendrites for receiving information
80
There are 3 paired tracts that connect the cerebellum to the brain stem. What are they and what do they connect?
1. Superior cerebellar peduncle: connect cerebellum to midbrain
2. Middle cerebellar peduncle: connect pons to cerebellum
3. Inferior cerebellar peduncles: connect the medulla and cerebellum
81
What is the circle of Willis and what is its significance?
Circle of Willis: cerebral arterial circle --> circulates blood to the brain, the actual circle is around the diencephalon
Circle is significant because if there is a blockage somewhere, blood can still get to the brain
82
Where does the middle cerebral artery supply blood?
- Broca's area
- pre-central and post-central gyri (primary motor and somatosensory cortexes)
- Wernicke's area
- auditory area
83
If a person had a stroke in the left side of the middle cerebral artery, what problems would this cause?
problems with language
84
Where does the posterior cerebral artery supply blood?
- supplementary motor area
| - motor area for foot, leg and bladder
85
Where does the posterior cerebral artery supply?
- visual cortex with striate area and calcarine sulcus
86
What are the general functions of the limbic system?
1. establish emotional states
2. linking conscious and intellectual functions of cerebral cortex with unconscious & autonomic functions of brain stem
3. memory storage and retrieval
87
What is the hippocampus and what does it do?
Hippocampus is a structure in the limbic system, connected to the mammilary bodies
plays a role in learning, memory and emotion
88
What is the amygdala and what does it do?
Amygdala is an almond shaped structure in the limbic system
- -> anterior to tail of caudate
- -> critical in responding to perceived threats
- -> attaches meaning to memories
89
What is the cingulate gyrus and what does it do?
Structure of the limbic system
- -> next to corpus callosum
- -> role in responding to perceived threats, expressing emotion using gestures, resolves mental conflict
90
What is the reticular formation?
3 broad columns along brain stem with far reaching axonal connections --> reaches thalamus, cerebral cortex, cerebellum and spinal cord
91
What does the reticular formation do?
MOTOR function:
- regulate visceral motor functions
- helps control coarse limb movements
92
What is RAS (reticular activating system)?
- sends impulses to cerebral cortex to keep it conscious
- filters out repetitive and weak stimuli
- mediates dreaming
93
What inhibits RAS (reticular activating system)?
Sleep centres of hypothalamus
also depressed by alcohol, sleep inducing drugs and tranquilizers
94
What nuclei in the hypothalamus mediate sleep and how?
suprachiasmatic and preoptic nuclei --> release peptide orexins that activate reticular formation
95
What are the 2 major types of sleep?
NREM - non-rapid eye movement (restorative stage)
| REM - rapid eye movement (boosts immune system)
96
What happens to people deprived of REM sleep?
moody, depressed and various personality disorders may be seen
97
What are the two stages of memory storage?
1. Short-term memory/working memory --> temporary holding of information, limited to 7 or 8 pieces
2. Long-term memory --> limitless capacity
98
What are the factors that affect the transfer memory from STM to LTM?
1. Emotional state --> best if alert, motivated, surprised & aroused
2. Rehearsal --> repetition and practice
3. Association --> tying new information with old memories
4. Automatic memory --> subconscious information stored in LTM
99
What is happening at a molecular level during learning?
- altered mRNA is made and moved to the axons and dendrites
- dendritic spines change shape
- extracellular proteins are put in synapses involved in LTM
- number and size of presynaptic terminals may increase
- neurotransmitters released by presynaptic neurons
100
What are the two categories of memory? What are the subcategories?
1. Declarative/explicit memory --> semantic (names, faces, dates, words), episodic (events), and spatial (locations)
2. Nondeclarative memory --> emotional, motor and procedural
101
What structures function to access memory and what neurotransmitter is necessary for memory formation and retreival?
hippocampus and surrounding temporal lobes
--> ACh from basal forebrain is necessary for memory formation and retreival
102
Nondeclaritive memory is split into 3 subtypes, what are they and what is the anatomical region associated with each type?
1. Emotional memory --> amygdala
2. Motor memory --> cerebellum
3. Procedural memory --> basal nuclei send motor & sensory to the premotor cortex and thalamus
103
how is nondeclarative memory aquired?
experience and repetition - this is hard to unlearn
104
Where does the spinal cord end and what level of vertebrae does that correspond to?
Ends at conus medullaris --> L1
105
What are the functions of the spinal cord?
1. Two-way communication to and from brain
| 2. contains spinal reflex centers
106
How many pairs of spinal nerves are there? Where do they exit?
31 pairs --> C1-C7 exit above vertebrae of same number, all others exit below vertebrae of same number
```
8 - cervical
12 - thoracic
5 - lumbar
5 - sacral
1 - coccygeal
```
107
Where does the dural and arachnoid mater of the spinal cord extend?
S2
108
What connects the masses of gray matter in the spinal cord and encloses the central canal?
Cray commissure
109
What type of motor neurons exit the ventral horns?
Somatic motor neurons
110
What types of neurons exit the lateral horns?
Sympathetic neurons
| *only in thoracic and lumbar regions
111
What types of neurons exit the dorsal horns and what is the dorsal root ganglia?
Interneurons receiving somatic and visceral sensory input
| --> dorsal root ganglia are the cell bodies of sensory neurons
112
What is funiculi?
Bilateral tracks in 3 white columns
113
What does it mean for a pathway to decussate?
crossover
114
In an ascending pathway, where do the axons of the first, second and third order neurons project?
First --> branches as it enters the spinal cord or medulla
Second --> axons extend to thalamus or cerebrum
Third --> axon extends to somatosensory cortex
115
What are the two pathways that transmit somatosensory information to the sensory cortex?
1. Dorsal column-medial lemniscal pathway (DCML)
| 2. Spinothalamic pathways (anterolateral pathway)
116
Where do the spinocerebellar tracts terminate?
Cerebellum
117
What do the DCML pathways transmit?
discriminative touch and vibrations
118
What does the lateral spinothalamic tract transmit?
pain and temperature impulses
119
What does the ventral spinothalamic tract transmit?
crude touch and pressure impulses
120
What does the spinocerebellar tract convey and what is the nature of its connections?
Subconscious proprioceptive information from trunk & lower limb to cerebellum
Only 2 neurons and is connected ipsilaterally
121
What are the descending pathways?
1. direct pathways --> corticospinal/pyramidal tract
| 2. indirect pathways --> all others
122
How many neurons are involved in descending pathways and where are they?
involves 2 neurons:
1. Upper motor neurons: cortex to spinal cord
2. Lower motor neurons: spinal cord to skeletal muscle (ventral horn motor neurons)
123
What are the steps in the direct descending pathway?
1. Signals from pyramidal neurons in pre-central gyri passes through pyramidal tracts (upper motor neurons)
2. Axons synapse with interneurons or ventral horn motor neurons
* regulates fast and fine/skilled movements
124
What are the three indirect/extrapyramidal system pathways?
1. Tectospinal tract --> mediate head movements to respond to visual stimuli (contralateral)
2. Vestibulospinal tract --> maintain balance during standing and moving (ipsilateral)
3. Corticobulbar tract --> motor to skeletal muscle of cranial nerves (both ipsilateral and contralateral)
125
What is the highest level of motor control? What is it made of and what does it do?
Precommand level --> cerebellum and basal nuclei
- programs and instructions according to feedback
126
What is the middle level of motor control, what is it made of and what does it do?
Projection level -->motor cortex and brain stem nuclei
* conveys instructions to the spinal cord motor neurons, then relays a copy of the instructions to the higher levels
* motor output
127
What is the lowest level of motor control, what does it consist of and what does it do?
Segmental level --> spinal cord
* contains central pattern generators
* reflex activity generates motor output
