Flashcards in CNS Deck (156):
What are the two parts of the CNS?
brain and spinal cord
evolution of a CNS with an elaboration of the anterior end of the CNS along with an increase in the number of neurons in the head
a thickening of the surface ectoderm along the dorsal midline of the embryo that eventually becomes the CNS
the invagination of the neural plate
the superior edges of the neural folds come together to turn the neural groove into this
What does the neural tube do shortly after it forms?
detaches from the ectoderm and sinks to a deeper position
small groups of neural fold cells migrate between the surface ectoderm and the neural tube to form this
What will the cells of the neural crest eventually become?
Give the simple and the complex name for the three primary brain vesicles
1. prosencephalon - forebrain
2. mesencephalon - midbrain
3. rhombencephalon - hindbrain
meaning of encephalo
swellings of the anterior end of the neural tube
primary brain vesicles
what the primary brain vesicles divide to become
secondary brain vesicles
What does the forebrain divide into?
telencephalon - endbrain
diencephalon - interbrain
What does the hindbrain divide into?
metencephalon - afterbrain
mesencephalon - spinal brain
What does the telencephalon become
What 4 things does the diencephalon form?
What does the metencephalon divide to form?
What does the myelencephalon form?
What three structures are considered the brain stem?
3. medulla oblongata
What does the mesencephalon become?
What does the cavity of the neural tube enlarge to form?
Why does the brain need to flex and fold?
not enough room in the skull
What are the two major flexures?
What are the foldings of the cerebral surface called? What is their purpose?
convolutions - increase SA for more neurons
What is the outer layer of gray matter on both the cerebrum and cerebellum?
What happens to the gray and white matter as you proceed down the spinal cord?
switch places - spinal cord has gray interior and white exterior
What fills the brain ventricles?
CSF - cerebrospinal fluid
What lines the brain ventricles and circulates the CSF?
ependymal cells (neuroglia)
What are the paired C shaped cavities that fill the cerebral hemispheres?
What thin membrane separates the anterior horns of the lateral ventricles?
What connects the lateral ventricles to the third ventricle?
Where is the third ventricle?
What connects the third and fourth ventricles?
Where is the cerebral aqueduct?
Where is the fourth ventricle?
dorsal to the pons and superior medulla
What cavity runs through the spinal cord and connects to the fourth ventricle?
What are the openings in the fourth ventricle that connect to the subarachnoid space around the brain?
2 lateral apertures and a median aperture
What portion of the brain accounts for 83% of the total brain mass?
What are the ridges on the cerebral surface?
What are the shallow grooves on the cerebral surface?
What are the deep grooves on the brain surface?
What fissure separates the cerebral hemispheres?
What fissure separates the cerebral hemispheres from the cerebellum?
transverse cerebral fissure
What are the 5 major lobes of the brain?
What sulcus separates the frontal and parietal lobes?
What gyrus is in front of the central sulcus? What is its function?
precentral gyrus - primary motor cortex
What gyrus is behind the central sulcus? What is its function?
postcentral gyrus - primary somatosensory cortex
What sulcus separates the parietal and occipital lobes?
What sulcus separates the parietal and frontal lobes?
What lobe is an "island" of cortex hidden beneath the temporal, parietal, and frontal lobes?
What are the pieces of gray matter buried inside the white matter of the brain? (2 terms)
basal nuclei (or historically basal ganglia)
the depressions in the skull where the brain fits - name the three, and say what part of the brain is in each.
1. anterior - frontal lobes
2. middle - temporal
3. posterior - brain stem and cerebellum
What is gray matter? How thick is it? What do the convolutions do for it?
neuron cell bodies dendrites, glia, and blood vessels - 2-4mm - surface area is tripled by convolutions
What is white matter? What is its function?
myelinated axons bundled into tracts - that communicate between different parts of the brain
What type of imaging technique allows us to see maximal metabolic activity of the brain?
What type of imaging technique shows blood flow in the brain?
In general, which hemisphere controls the sensory and motor functions of which side of the body?
opposite - contralateral
What is the term for the understanding that the two hemispheres are specialized for certain functions?
Do the functional areas of the brain work independently of one another? Explain.
NO! Most conscious behavior involves the entire cortex
What are the large neurons in the primary motor cortex? What are their descending tracts called? (2 terms)
pyramidal cells - form pyramidal tracts also called corticospinal tracts
the representation of the entire body as a "little man" on the primary motor cortex
- the same thing on the primary somatosensory cortex
mapping of the body in CNS structures
Where is the premotor cortex, and what is it responsible for?
anterior to the primary motor cortex - learned, repetitious motor skills and planning movements
the motor speech area is called what? Where is it located? What does it do?
Broca's area - anterior to the premotor cortex - controls speech planning and production
What is unusual about Broca's area?
usually only on one side of brain
Where is the frontal eye field, and what does it do?
above Broca's area - controls voluntary eye movements
What is the term for the ability of a person to discriminate what portion of the body is being stimulated?
What two portions of the somatosensory homunculus are represented by the largest areas?
lips and fingertips
Where is the somatosensory association area, and what is its function?
just posterior to the primary somatosensory cortex - to integrate sensory information and understand what you are sensing
Where is the primary visual cortex, and what is its function?
extreme tip of occipital lobe (calcarine sulcus) - sight
Where is the visual association area, and what is its function
surrounding the primary visual cortex - recognize what is seen
Where is the primary auditory cortex, and what is its function?
superior margin of temporal lobe - hearing
Where is the auditory association area, and what is its function?
posterior to the primary auditory cortex - interpret sounds
Where is the olfactory cortex, and what is its function?
medial part of temporal lobe called the piriform lobe - smell
What is the olfactory cortex part of?
rhinencephalon (primitive brain)
Through evolution, the new functions of the rhinencephalon include what? What do we call this system?
memory and emotions - limbic system
Where is the gustatory cortex, and what is its function?
insula - taste
Where is the visceral sensory area, and what is its function?
insula - posterior to taste region - sense organs (full or upset stomach, full bladder...)
Where is the vestibular cortex, and what is its function?
posterior part of insula and adjacent parietal lobe - equilibrium
What do we call areas that receive input from multiple senses and send outputs to multiple areas?
multimodal association areas
What is the purpose of multimodal association areas?
give meaning, tie to previous experience, store as a memory
What are the three parts of the multimodal association areas, and what is the function of each?
1. anterior association area - also known as the prefrontal cortex - most complicated region - intellect, cognition, recall and personality
2. posterior association area - recognizing patterns and faces, locating us in space, and making a coherent whole of our senses
3. limbic association area - emotions and memory
What are the parts of the limbic association area?
cingulate gyrus, parahippocampal gyrus, and hippocampus
Which of the multimodal association areas is the last to develop, and what is the significance of this?
prefrontal cortex - abstract ideas, judgment, reasoning, persistence and planning all develop slowly and depend on feedback from the social environment
What happens with tumors or lesions in the anterior association area?
mental and personality disorders - loss of normal social restraints
What happens with tumors or lesions in the posterior association area?
won't wash or dress part of body because don't recognize it as self
What does the term cerebral dominance refer to?
the side dominant for language
In 90% of people, what does the left brain control?
language, math and logic
In 90% of people, what does the right brain control?
creativity, intuition, emotion
Most people with left cerebral dominance dominantly use what hand?
a reading disorder where otherwise intelligent people reverse letters and words - How is it related to cerebral dominance?
dyslexia - thought to be a processing disorder in one hemisphere
What are the three types of white matter tracts in the brain, and what is their function?
1. commissural - connect corresponding gray areas of the two hemispheres for coordinated function
2. association fibers - connect different parts of the same hemisphere (short and long)
3. projection fibers - tie the cortex to the rest of the nervous system - ascending and descending
What is the largest commissure?
projection fibers that form a compact band of white matter tracts between the thalamus and some of the basal nuclei - what are the fibers called as they radiate out to the cortex?
internal capsule - corona radiata
Name the 3 major bodies that make up the basal nuclei. What are they all called together? Why are they called this?
caudate nucleus, globus pallidus, and putamen - corpus striatum (look striped)
The putamen and globus pallidus are collectively called what?
What is the function of the basal nuclei?
unsure - regulate attention and cognition, start and stop movements, monitor movement intensity
Disorders of the basal nuclei controlling movement are linked to what two diseases?
Parkinson's and Huntington's
What is the thalamus? What is the function of the thalamus?
a collection of specialized nuclei - relay station for information coming in to the cerebral cortex - sorts, edits, and groups similar
Where is the hypothalamus, and what are its functions (7)?
below the thalamus - contains many nuclei that serve to control the viscera
1. autonomic control center
2. center for emotional responses - limbic system
3. body temperature control
4. regulates food intake
5. regulates water balance and thirst - antidiuretic hormone
6. regulates sleep/wake cycles - suprachiasmatic nucleus
7. controls the endocrine system by controlling the anterior pituitary
What are the tiny, paired nuclei that extend from the hypothalamus, and what is their function?
mammillary bodies - olfactory relay station
What important gland connects to the hypothalamus? What is the stalk of tissue connecting the two structures?
pituitary - infundibulum
What happens when the pituitary doesn't function?
body wasting/obesity, sleep disorders, dehydration, emotional imbalances, failure to thrive
Where is the epithalamus?
most dorsal part of diencephalon
What is the gland that extends from the back of the epithalamus, and what does it do?
pineal gland - secretes melatonin
What is the function of melatonin?
induce sleep and antioxidant
The brain stem is similar histologically to the spinal cord with what major exception?
gray matter nuclei embedded in white matter
What is the function of the brain stem?
10 or 12 cranial nerves root here
What does the term peduncle mean? What are the cerebral peduncles?
little feet - two vertical columns of white matter tracts above the pons
What is the corpora quadrigemina? How does the corpora quadrigemina get its name?
nuclei that protrude from the dorsal midbrain - 4 domes - quadruplets
What is the periaqueductal gray matter, and what is its function?
gray matter around cerebral aqueduct - pain suppression, link between fear perceiving area (amygdala) and fight or flight response, contains nuclei for oculomotor and trochlear nerves
What is the fear-perceiving center called?
What are the parts of the quadrigemina and their functions?
superior colliculi - visual reflex center for tracking
inferior colliculi - auditory relay and startle reflex
What is the substantia nigra? Where is it located? What is its function?
nuclei in side of midbrain - makes dopamine
Why is the substantia nigra so dark?
What is the purpose of the melanin in the substantia nigra?
precursor to dopamine production
What is the ultimate cause of Parkinson's disease?
degeneration of dopamine producing neurons in substantia nigra
What is the red nucleus? Where is it located? What is its function?
gray matter deep to substantia nigra in the reticular formation that function as a relay for some motor neurons
Why is the red nucleus red?
blood supply and iron pigment
What is the meaning of the word pons? Why does it have this name?
bridge - conduction tracts between midbrain and medulla
What are the numerous nuclei in the pons called, and what is their function?
pontine nuclei - connect motor cortex and cerebellum, serve as part of reticular formation, maintain normal breathing rhythm
the middle portion of the brain stem, anterior bulge
the most inferior part of the brain stem
What are the longitudinal ridges on the medulla called? What is their function?
pyramids - corticospinal tracts (descending)
the crossing of the corticospinal tracts or pyramids at the junction between the medulla and spinal cord - What does this explain?
decussation of the pyramids - explains why right side of brain controls left side of body and left brain controls right body
oval swellings lateral to the pyramids that contain nuclei that relay sensory information about the stretch of muscles and joints
a measure of the electrical activity of the brain using electrodes
EEG - electroencephalogram
patterns of electrical activity in an EEG
What generates brain waves?
How are brain waves measured?
Hertz - Hz
What is a Hertz?
1 wave or cycle per second
What is amplitude?
the height of a wave or the depth of a trough
Name, and describe the four major patterns of brain waves.
1. alpha - 80=-13 HZ, regular and rhythmic, low amplitude, calm and relaxed state of wakefulness
2. beta - 14-30 Hz, rhythmic but not as regular, higher frequency, mentally alert and concentrating
3. theta - 4-7 Hz, irregular, common in children, uncommon in awake adults
4. delta - 4HZ or less, high amplitude, deep sleep, under anesthesia, may indicate brain damage in awake adults
brain waves that are 4HZ or less, high amplitude, deep sleep, under anesthesia, may indicate brain damage in awake adults
brain waves that are 80=-13 HZ, regular and rhythmic, low amplitude, calm and relaxed state of wakefulness
brain waves that are 14-30 Hz, rhythmic but not as regular, higher frequency, mentally alert and concentrating
brain waves that are 4-7 Hz, irregular, common in children, uncommon in awake adults
What four factors can change brain waves?
age, stimulation, disease, chemical state
What are EEGs useful at diagnosing?
epilepsy, sleep disorders, brain function
a flat EEG is clinical evidence of what?
a flood of electrical activity that interferes with brain function
epilepsy - seizure
List 5 things that can cause seizures.
trauma, stroke, infection, high fever, tumors, genetic factors
What are the two main kinds, and how are they different?
1. absence (petit mal) - goes blank for a few seconds where not everyone will notice
2. tonic-clonic (Grand mal) - intense convulsions
What sometimes precedes a seizure, and how can it be helpful?
aura - light, smell, or taste hallucination that allows the person to lie down
What is a difference after the absence or tonic-clonic seizures?
tonic clonic seizures leave the person disoriented
What can control epilepsy?
anticonvulsive drugs or vagus nerve stimulator
What 3 factors indicate consciousness?
1. ability to initiate movement
2. perception of sensation
3. higher mental functioning
What are the 4 degrees of consciousness?
2. drowsy (lethargy)
a brief loss of consciousness (2 terms)
fainting or syncope
How is sleep different from a coma?
Sleeping people use almost as much oxygen as people who are awake, and they can be aroused by stimulation.
Give 5 things that can cause a coma.
1. blow to the head
4. metabolic disturbance - hypoglycemia
6. liver or kidney failure
What are the two major types of sleep?
REM and non-REM
What happens during the first part of our sleep?
brain waves decline, respiration, blood pressure and heart rate decline
What happens when we are in REM sleep?
alpha waves appear, digestion is inhibited, BP, respiratory rate,and heart rate increase, use more oxygen than when awake, dream
When do most nightmares and night terrors happen?
NREM stages 3-4