A and P chapter 14 Brain and cranial nerves Flashcards
how much of the brain does the cerebrum constitute
83%
where are 50% of the brains neurons located
cerebellum
which parts of the brain are gray matter
cerebral cortex
basal nuclei
what makes up the white matter
bundles of axons and myelin
what are the 3 layers of embryonic tissue
endoderm
mesoderm
ectoderm
what does the ectoderm germ layer give rise to
nervous tissue
what are the brains protection
bone
meninges
cerebrospinal fluid
blood-brain barrier
what are the 3 meninges of the brain
dura mater
arachnoid mater
pia mater
describe the dura mater
double layer fused together except in spaces where it makes the dural sinuses
what are the dural sinuses for
collect venous blood from brain and direct it to the internal jugular veins
what is the dural septa
part of the dura mater that creates cranial cavity partitions
name the types of dural septa and describe them
dural septa part of dura mater
falx cerebri–> in longitudinal fissure; seperates 2 cerebrum
falx cerebelli–> on vermis of cerebellum; seperates halves of cerebelli
tentorium cerebelli–> in transverse fissure; separates cerebellum and cerebrum
describe the arachnoid mater
loose brain covering that does not dip into sulci/fissures
what is the subdural space
serous cavity that separates arachnoid and dura mater
what is the subarachnoid space
separates arachnoid and pia mater
what are arachnoid villi
a valve-like structure that protrudes through the dura mater into the sagittal sinus where CSF is absorbed into venous blood of the sinus
describe the pia mater
delicate layer with lots of tiny blood vessels
clings tightly to brain and does dip into all the grooves
where concussions happen
what are ventricles
spaces that make CSF in the brain
name the ventricles
R and L ventricles
3rd
4th
what ventricle connects to the cerebral aqueduct superiorly
3rd ventricle
what ventricle connects to the central canal that CSF flows down to the spinal cord
4th
what is the purpose of CSF
liquid cushion
floats brain in skull
nourishes brian and takes away waste
whats in CSF
sodium and chloride
potassium
calcium
glucose
protein
what is the purpose of the blood brain barrier
brain needs a constant environment to function (less variation in hormones and ions etc)
what easily passes through the blood brain barrier
water, glucose, amino acids, and some electrolytes
use facillitated diffusion to pass barrier
cant prevent anything lipid soluble from passing (fats, fatty acids, oxygen and carbon dioxide)
what can pass through blood brain barrier but takes work
sodium, potassium, chloride, urea, and creatinine, metabolic waste, proteins, and some drugs/toxins
blood brain barrier does not include
the hypothalamus
what is the downside to the blood brain barrier
some antibiotics and cancer meds cant pass through
where is the midbrain located
in between diencephalon and pons
where is the cerebral aqueduct located
runs through the center of midbrain and is surrounded by gray matter called the periaqueductal gray matter
what is the periaqueductal gray matter for
pain suppression
is an autonomic nervous system pathway
cranial nerves III and IV (oculomotor and trochlear) run through
what are cerebral peduncles
2 bulges on anterior that contain corticospinal motor tracts
what are the superior cerebellar peduncles for
connect midbrain fiber tracts to cerebellum
name the basal nuclei
corpora quadrigemina, substantia nigra, red nucleus
describe the corpora quadrigemina (basal nuclei)
largest of basal nuclei
superior colliculi–> visual reflex centers
inferior colliculi–> auditory relay, startle reflex
describe the substantia nigra (basal nuclei)
2 nuclei
high melanin content which is precursor to dopamine
makes dopamine
degeneration leads to parkinsons
describe the red nuclei (basal nuceli)
rich blood supply and iron pignment inside neurons (making it red)
involved in motor coordination
what are the functions of the pons
helps regulate normal breathing rhythm
sleep
posture
what is the purpose of the medulla oblongata
autonomic reflex center for body homeostasis
cardiac control
vasomotor control
respiratory rate and control
what are the pyramids in the medulla oblongata and what is decussation of them
two longitudinal ridges made by corticospinal fiber tracts
decussation of pyramids= crossing of the fibers from R to L or L to R
describe the reticular formation
loose web of gray matter that runs vertically through all levels of the brainstem
occupies space between white fiber tracts and brainstem nuclei
what is the purpose of the reticular formation
helps govern all somatic motor control
cardiovascular control
pain modulation
sleep/wake
habituation (ignore repetitive, inconsequential stimuli)
what are the two hemis seperated by in the cerebellum
vermis
what is the white matter in the cerebellum called
arbor vitae
what do cerebellar peduncles do
connect brainstem and cerebellum
what does the superior cerebellar peduncle do (midbrain)
connects to cerebral motor cortex via thalamic relays
what does the middle cerebellar peduncle do (pons)
one way communication from pons to cerebellum
what does the cerebellar peduncle do (medulla)
sensory info
muscle proprioception
balance
what are the functions of the cerebellum
sensory, linguistic, emotional function
non motor functionalities
planning, scheduling, emotional control
what brain structure encloses the 3rd ventricle
diencephalon
describe the thalamus structure
2 lobes connected by interthalamic adhesion
function of the thalamus
sorts out info and edits it and then sends it to other parts of brain to be executed
gateway to brain
role in motot control by signal replay betweeen cerebrum adn cerebellum
is a part of the limbic system= memory and emotional function
what is the function of the hypothalamus
main visceral control and body homeostasis
autonomic control center
emotional response “heart” of the limbic system
body temp reg., hunger reg., water balance, sleep/wake cycles
makes ADH and oxytocin
what is the infundibulum
stalk that connects with the pituitary
what are mamillary bodies
relay for olfactory tracts
what controls the pituitary glands secretions
hypothalamus
what structures in the epithalamus
pineal gland, posterior commissures, choroid plexus
what does the pineal gland do
makes melatonin and controls sleep and wake cycles (processes light info)
what do the posterior commissures do
link basal nuclei and limbic system
what does the choroid plexus do
secretes CSF
what are the lobes of the cerebrum
frontal
parietal
occipital
temporal
insula
describe location and function of the frontal lobe
rostral to central sulcus
voluntary motor functions, motivation, planning, memory, moodm emotion, social judgement, aggression
describe location and function of the parietal lobes
between central sulcus and parieto-occipital sulcus
integrates general senses, taste, and some visual info
describe location and function of the occipital lobe
caudal to parieto-occipital sulcus
primary visual center of brain
describe location and function of the temporal lobes
lateral and horizontal; below lateral sulcus
functions in hearing, smell, learning, memory, some aspects of vision and emotion
describe location and function of the insula lobe
deep to lateral sulcus
helps understand spoken language, taste and integrating info from visceral receptors
what is the tissue composition of the cerebral cortex
interneurons only, neuron cell bodies, dendrites, glial cells, blood vessels– no fiber tracts
what percent of brain is the “conscious mind”
40% and only gray matter
what are the 3 functional areas of the cerebral cortex
motor–>voluntary functions
sensory–>allows conscious awareness of sensation
associational–>integrates info (makes info whole so we can give it meaning)
what do commisural fibers in the cerebral cortex do
horizontal fiber tracts that communicate between 2 hemispheres (connect gray areas and allows them to work as a unit)
what is the corpus callosum
a commisural fiber tract (largest of them actually)
what are association fibers
horizontal fiber tracts that connect different parts of the same hemisphere
what are projection fibers
vertical fiber tracts that connect cortex to nerves in body
nerves from left side of body cross in the brain stem and shoot towards the right brain and vice versa
what is the internal capsule
in regard to projection fibers
compact band in the brain stem
what is the corona radiata
in regard to projection fibers
superior to internal capsule, fibers radiate through white matter in fan like pattern
no motor function happens unless what brain structure is involved
basal nuclei (though not directly connected to the motor cortex)
what structures are in the corpus striatum (basal nuclei)
caudate nucleus
putamen
what is the amygdala
basal nuclei
what is the globus pallidus
basal nuclei
what is the role of basal nuclei
complex and repetitive behaviors
practiced behaviors
modify voluntary motor activity
issue in nuceli causes too much or too little movement
what is the function of the amygdala
primal fear and aggression
not impacted by alzheimers
what neurotransmitters are inhibitory in the basal nuclei and associated areas
GABA and dopamine
what neurotransmitters are excitatory and inhibitory in the basal nuclei and associated areas
ACh, norepinephrine, serotonin, and enkephalin
what neurotransmitters are excitatory in the basal nuclei and associated areas
Glutamate
pathways provide most fo the excitatory signals within the basal nuclei
what is huntingtons disease
disorder of the basal nuclei, loss of GABA secreting neurons in the nuclei, loss of ACh neurons in many parts of brain
spastic paralysis (uncontrolled motor output)
dementia and paranoia in later stages
what do the limbic system and the reticular activating system have in common
networks of neurons that span across many different parts of the brain
what is the limbic system do and where is it
emotional brain (bridge between conscious and subconscious brain, center for gratification, psychosomatic illness here)
forebrain
what is the reticular activating system and where is it
an alert system
brain stem
what location are within the limbic system
amygdala, hippocampus, hypothalamus, thalamus
describe where reticular activating system is and what it does
in brainstem, loosely clustered gray matter neurons in white matter
keeps cortex alert and concious, whole brain arousal
allows us to move stimuli to the background (ignore it)
if severely injured here like twisting of brain stem=comatose
what does EEG mean and what does it do
electroencephalogram
records patterns of brain waves
what is induced paralysis where BP is lowered, ATP is restored, and damage is repaired
sleep
what is REM sleep
rapid eye movement sleep
semi awake state searching for daylight
restful sleep
what are the cognitive functions in the association areas of the cortex (parietal lobe, temporal lobe, frontal lobe)
parietal lobe–> helps perceive and attend to stimuli
temporal lobe–> helps identify stimuli
frontal lobe–> helps us think about the world, plan, and execute appropriate behaviors
what would damage to the parietal lobe cause in regard to cognitive function
contralateral neglect (unaware of objects on opposite side of body)
what would damage to the temporal lobe cause in regard to cognitive function
agnosia (inability to recognize, identify familiar objects; like cannot recognize faces)
what would damage to the frontal lobe cause in regard to cognitive function
personality disorders and socially inappropriate behaviors
what is amnesia
defects in declaritive memory; inability to describe past events
what is procedural memory
example would be ability to tie ones shoes
what is anterograde amnesia
unable to store new info
what is retrograde amnesia
person cannot recall things known before injury
what is skill memory
muscle memory
what are some brain structures involved in memory
hippocampus
cerebellum
amygdala
what do the primary functional areas in the cerebral cortex do
specifically responsible for perception and control
sensory and motor
what do the secondary functional areas in the cerebral cortex do
interpret and modify what happens in the primary areas
motor and sensory
where is the primary somatosensory cortex and what does it do
postcentral gyrus of parietal lobe
receives info from somatic sensory receptors in skin and proprioceptors in skeletal muscle, joint, tendons
where is the secondary somatosensory association cortex and what does it do
posterior to primary somatosensory cortex
integrates somatic sensory input so you can recognize/understand what you are sensing
where are the visual areas and what do they do
extreme posterior of occipital lobe
primary recieves info from retinas, surrounding association areas interpret the info
where are the auditory areas and what do they do
temporal lobe by lateral sulcus
info about pitch, rhythm, and volume (sound memories)
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