brain (major structures and functions) Flashcards
what does the CNS first start out as? (brain embryology)
the neural tube
what is the lumen of the neural tube?
what is it filled with?
what does it become?
- neurocoel
- fluid
- eventually forms the brains ventricles
what 3 regions form at 4 weeks?
- prosencephalon
- mesencephalon
- rhombencephalon
what does the prosencephalon form?
- telencephalon
- diencephalon
what does the telencephalon form?
the cerebrum and the lateral ventricle
what does the diencephalon form?
the hypothalamus, thalamus, and the epithalamus
also the third ventricle
what does the mesencephalon form?
it becomes the midbrain
what does the rhombencephalon form?
- metencephalon
- myelencephalon
what does the metencephalon form?
the pons and cerebellum
what does the myelencephalon form?
the medulla oblongata
what are the major regions of the brain? (6)
- medulla
- pons
- midbrain
- diencephalon
- cerebellum
- cerebrum
general functions of the medulla oblongata
- relays info to the thalamus and the brainstem
- HR, BP, and digestion regulation
general functions of the pons
- relays info to the cerebellum and the thalamus
- somatic and visceral motor center regulation
pons (professor’s notes)
contains higher respiratory control centers
- apneustic
- pneumotaxic
apneustic pons
inhibits exhalation for inhalation
pneumotaxic pons
inhibits inhalation for exhalation
medulla (prof’s notes)
the medulla relays communication between the midbrain and the cerebellum
ex… you can’t maintain balance if your eyes are closed
balance = comes from cerebellum
eyes closed = comes from superior colliculi
general functions of the mesencephalon (midbrain)
- processes visual and auditory data
- maintains consciousness
- helps with reflexive somatic motor responses
visual = superior colliculi
auditory = inferior colliculi
midbrain (prof’s notes)
the reticular formation of the midbrain helps with maintaining consciousness
ex… when we’re walking down a dark alley and we’re scared, we become very alert
this is also an example of reverberation
general functions of the diencephalon
contains…
1. thalamus
2. epithalamus
3. hypothalamus
thalamus functions
- relays info from the cerebrum
- center for sensory information relaying
the spinothalamic tract runs through here
epithalamus functions
- contains the pineal gland
the pineal gland secretes hormones like melatonin and controls the secretion of FSH and LH from the pituitary gland
hypothalamus functions
- involved in emotions, thirst, and habitual activity
- involved in temperature control
- involved in circadian rhythm control
circadian rhythm control (prof’s notes)
in the morning, melatonin decreases and cortisol increases
the opposite is true for when you go to sleep
hypothalamus (prof’s notes)
the hormones released by the hypothalamus often control the release of hormones of the anterior pituitary gland
ex… corticotropic releasing hormone from the hypothalamus controls the release of cortisol from the ant. pituitary gland
general functions of the cerebellum
- coordinates complex somatic motor patterns
- adjustment of somatic motor centers for smooth movement
cerebellum (prof’s notes)
this basically controls balance and coordination
ex… to test balance, have one walk in a straight line
recall that communication with the corpus quadrigemina is maintained by the medulla
this also contains the vasomotor center (VMC) for blood vessel diameter control
general functions of the cerebrum
- conscious SKM regulation
- conscious thought
- intellectual thinking
- memory
cerebrum (prof’s notes)
contains the cortex which is grey matter
the junction between the grey and white matter are the pyramidal cells
the hippocampal gyrus is responsible for memory
what is the function of the ventricular system of the brain?
to filter and move CSF which brings nutrients and removes waste from the CNS
the 4 brain ventricles
- lateral ventricles (2x)
- third ventricle
- fourth ventricle
septum pellucidum
separates the 2 lateral ventricles
lateral ventricle horns
- anterior horn
- posterior horn
- inferior horn
pathway of CSF through ventricles
- CSF is made by the choroid plexus
- CSF is in the lateral ventricles
- goes through interventricular foramen to the third ventricle
- goes through the cerebral aqueduct to the fourth ventricle
fourth ventricle to the spinal cord
the lateral and median apertures let CSF into the subarachnoid space which CSF then enters the central canal
what are the two layers of the dura mater?
- endosteal
- meningeal
these layers surround the dural sinus
the endosteal layer is directly attached to the skull
what are the four dural folds?
- falx cerebri
- tentorium cerebelli
- falx cerebelli
- diaphragma sellae
what does the falx cerebri separate?
it separates the two hemispheres of the cerebrum by folding into the longitudinal fissure
what does the tentorium cerebelli separate?
it separates the cerebrum from the cerebellum by folding into the transverse fissure
what does the falx cerebelli separate?
it separates the two cerebellar hemispheres
what does the diaphagma sellae separate
it protects the pituitary gland from in the sella turcica
what do the arachnoid granulations do?
they maintain CSF volume and pressure by dumping excess CSF into the dural veinous sinuses
veinous sinuses bring blood to the jugular vein
high CSF pressure pathology (prof’s notes)
high CSF pressure presents with projectile vomiting, headaches and blurry vision
these are signs of meningitis
what can pass through the blood brain barrier?
- lipid soluble material
- 3rd generation antibiotics
the BBB is continuous throughout the brain except for the following three areas?
- parts of the hypothalamus
- pineal gland
- parts of the 3rd and 4th ventricles
what are medulla’s relay functions?
since the medulla is continuous with the brain stem and spinal cord, all communication passes through the medulla
what are the 5 cranial nerves that innervate the medulla
CN’s 8, 9, 10, 11, and 12
*the cochlear branch of CN 8 only
12 = hypoglossus
11 = accessory
10 = vagus
9 = glossopharyngeal
8 = vestibulocochlear
what are the nuclei relay stations of the medulla
- olivary nuclei –> cerebellum relay
- nucleus gracilis and nucleus cuneatus –> somatic sensory relay to thalamus
what is the pyramidal decussation
the pyramids of the medulla is the region of cross over form motor neurons
what are the major reflex centers of the medulla? (think HR and RR)
- cardiovascular centers
- respiratory centers
what are the two cardiovascular centers?
- CIC (inhibitor)
- CAC (accelerator)
both centers provide nervous system control to increase or decrease the heart rate
what cranial nerves innervate the pons? (4x)
CN’s 5, 6, 7, and 8
5 = trigeminal
6 = abducens
7 = facial
8 = vestibular branch
what do cerebellar peduncles do?
they are the nuclei of the pons that relays to the cerebellum
aside from the corpus quadrigemina (superior and inferior colliculi) what else is part of the mesencephalon (midbrain)
- red nucleus
- substantia nigra
- cerebral peduncles
red nucleus function
integrates info between the cerebrum and cerebellum
substantia nigra function
regulates motor output of the basal nuclei
this tissue can affected in parkinsons
cerebral peduncles
consists of ascending and descending fibers (think spinothalamic and corticospinal)
substantia nigra and parkinsons
the substantia nigra controls muscle tone and fine movement which can affected by parkinsons
what does the hypothalamus consist of?
- the infundibulum (pituitary stalk)
- mammillary body
what does the hypothalamus do?
- subconscious SKM control
- HR, BP, RR, and digestive control
- secretion of hormones (supraoptic nucleus)
- emotion
- behavior
- thirst
- temp control
- circadian rhythm (suprachiasmatic nucleus)
what is the function of the mamillary bodies?
they are involved in feeding control
ex… swallowing, licking ice cream
what are the structures and contents of the cerebellum?
- vermis
- folia
- arbor vitae
- purkinje cells
what are purkinje cells?
these are cells analogous to the pyramidal cells of the cerebrum
they are at the junction between grey and white matter
what are the 3 cerebellar peduncles?
each cerebellar peduncle facilitates cerebellum communication with different parts of the brain stem
- superior –> to the midbrain
- middle –> to the pons
- inferior –> to the medulla
what lies behind the lateral sulcus?
the insula which processes taste and smell
what does the frontal lobe do?
controls SKM
what does the occipital lobe do?
the occipital lobe perceives visual stimuli
what does the parietal lobe do?
perceives touch, pressure, vibration, pain, temp and taste
what does the temporal lobe do?
perceives visual and auditory stimuli
what does the cerebral cortex do?
the cerebral cortex maintains higher order functions of the left and right cerebral hemispheres
specifically it integrates sensory stimuli and motor responses
what are the noteable centers of the cerebrum
- general interpretive area
- speech center (Broca and Wernicke)
- prefrontal cortex
- brodmann’s area
what does the general interpretive area do?
the general interpretive area is present on the left cerebral hemisphere and is the analytical center
what does wernicke’s area do?
wernicke’s area helps us discern spoken language
ex… I can distinguish that someone is talking to me in english
what does broca’s area do?
broca’s area regulates breathing patterns and speech vocalization
what does the prefrontal cortex do?
the prefrontal cortex performs complicated learning and reasoning functions
what are the 3 fiber types of the central white matter that connect the cerebrum and other parts of the brain?
- association fibers
- commissural fibers
- projection fibers
association fibers
includes arcuate and longitudinal fibers that connect different lobes together
commissural fibers
includes the anterior commissure which connects the two cerebral hemispheres
projection fibers
fibers that link the cerebrum to other parts of the brain and spinal cord
what are the basal nuclei?
this is grey matter imbedded in the white matter
general functions include..
1. SKM tone control
2. learned movement pattern coordination
3. info processing, integration and relay from the cerebral cortex
examples of basal nuclei
- globus pallidus
- putamen
- amygdaloid body –> initiates fear
- caudate nucleus
- claustrum
caudate nucleus, putamen, globus pallidus function
controls arm and leg cycles when walking
claustrum function
subconscious processing of visual information
amygdaloid body
part of the limbic system, initiates emotions such as fear
what is the function of the limbic system?
it’s primary function is for memory storage and retrieval, it can also establish emotional states
structures to note…
1. hippocampus
2. parahippocampal gyrus
3. cingulate gyrus
4. fornix
taxi driver example
since the limbic system is involved in memory storage, UK taxi drivers were found to have large hippocampuses because they need to memorize routes in the UK
