Chapter 18: Brain
Hydrocephalus in adults
- keeps pressure within leading to brain damage because it leads to the compression of the brain blood vessels and crushes the soft nervous tissue
Directionality of CSF movement
-Lateral to the Third via interventricular foramen -Third to the Fourth ventricle via cerebral aqueduct
Outside to Inside head:
-Scalp -Epicranial aponeurosis -Loose CT and Periosteum-vascular CT that involves the bone -Cranium -Meninges-CT layers that separate the soft tissue of the brain from the skull -Dura Mater -Arachnoid Mater -Pia Mater-softest, most pliable, attaches to brain itself, on top of cerebral cortex, helps nourish brain cells
Occipital lobe
-after parietal lobe -visual association area -visual cortex -relation to perception of visual stimuli
Lateral ventricles extend from the
-anterior horn located in the frontal lobe to the posterior horn located in occipital lobe and extend to the Inferior horn of lateral ventricle located in temporal lobe -most of the lateral ventricles is located within the parietal lobe
Prefrontal cortex
-anterior to premotor cortex -area related to thinking, trouble solving, concentration, behavior, area where we have personality, morality and judgement
Cerebrum
-biggest part of our brain Gyrus (elevation) Gyri (group of elevation) Sulcus (shallow depression) Sulci, between gyri, gives us different lobes of our brain Fissure (a deep depression)
BBB is absent where?
-choroid plexus-No astrocytes -Hypothalamus -Pituitary gland-major endocrine gland release hormones directly in blood stream -Pineal gland -releases melatonin into blood stream
Peripheral nervous system:
-cranial nerves and spinal nerves -consists of whatever leaves the brain and spinal cord
ependymal cells
-glial cells responsible for producing the CSF , ciliated -function is to take nutrients from blood/blood plasma and make it into CSF
Pituitary gland
-hangs off of/connects to hypothalamus -major endocrine gland -hypothalamus controls the release of hormones by pituitary gland
Hypothalamus
-hypo means below -center of homeostasis -temperature control center -main visceral control center, continuously affects activity of autonomic motor neurons to keep the rate of activity of our internal organs proportional to what our body needs at that specific moment -involved with the thirst center and is known as the brain inner thermostat knows what temperature our body should be causing us to sweat and shiver
Thalamus
-largest nuclei in our brain, thalamus is a group of neuronal cell bodies in one specific area within the CNS
Cerebellum
-little brain, second largest part of our brain -coordination of repetitive body movements (dance, drive a car etc.)
What is the function of the medulla oblongata?
-located under the pons the part that connects the brain and spinal cord -relays sensory information to thalamus and to other portions of the brain stem -regulates reflex centers -autonomic centers for regulation of visceral function (cardiovascular, respiratory, and digestive system activities)
Parietal lobe
-posterior to central sulcus -related to sensations -Postcentral gyrus also called primary somatosensory cortex where we have sensation of the skin, muscles and joints
Arachnoid granulations
-projections that go into the into superior sagittal sinus -extensions of arachnoid mater
Blood Brain Barrier (BBB)
-regulates substances between our blood and the brain tissue -made up of capillary endothelial cells (cells that line inside of capillaries) surrounded by astrocytes (glial cell) -allows nutrients to go in and nourish the brain tissue such as glucose and oxygen -allows CO2 and wastes to get out of brain tissue
What is the function of the pons?
-relay station between cerebrum and cerebellum -regulates respiratory reflex center in medulla
Subarachnoid space
-space between the arachnoid mater and pia mater -true space -we find CSF flowing through which protects our brain creating liquid cushion for brain
Subdural space
-the space between the dura mater and arachnoid mater, -it is a potential space, it is filled with fluid if necessary -in the case if a subdural hematoma this is the space that gets filled with blood
Diencephalon
-top part of lollipop stick, completely inside of the cerebrum -divided into epithalamus, thalamus and hypothalamus
Choroid plexus
-vascularized membrane found inside all of the ventricles Plexus mean,a network
Temporal lobe
-we have auditory cortex and olfactory cortex relating to hearing and smell -if you pull back temporal lobe and look inside you find the insula inside the cerebrum
A normal adult replaces __________________ of CSF every 8 hours
150 millimeters
The CSF reduces the weight of the brain from
1500 grams to 50 grams, allows brain to float so it does not get crush on its own weight
______of CSF flows out through later and median apertures into the subarachnoid space
90%
What is the meninge that looks like a spider web?
Arachnoid mater
Inside ventricles we have?
CSF
when CSF reaches the fourth ventricle it can leave the ventricular system through which apertures?
Lateral aperture and Median aperture
What is capable of passing through the lipid bilayer?
Lipid soluble compounds
Cerebral cortex is divide into 3 layers:
Molecular layer is where we find dendrite of purkinje cells Purkinje layer is the intermediate layer where we find purkinje cell bodies Granular layer is the receptive layer where we find the axons of purkinje cells, we have tightly packed small neurons
What layer is found on the anterior fontanelle of a baby?
Periosteal layer
Where does the pituitary gland sit inside of?
Sella turcica What encases the sella turcica?,the diaphragma sellae Diaphragma sellae, -lines the sella turcica -Anchors dura mater to sphenoid bone -encases pituitary gland
The arachnoid valve works a
a one way valve
Precentral gyrus
also called primary motor cortex,in front of central sulcus, INITIATION of movement -region of the brain that sends the nerve impulses down the spinal cord towards the muscle when you want to make a movement -we find the pyramidal cells large which are the large neurons that allow the consciously control of skeletal muscle movements
Pineal gland
an endocrine that produces hormone called melatonin, that affects wake sleep patterns
Crista galli function
anchor brain
Premotor cortex
anterior to the primary motor cortex, related to PLANNING of motor movement Ex)thinking about grabbing a pen -premotor cortex send info to primary motor cortex
The third ventricle communicates with the fourth ventricle via the
aqueduct of mid brain also called cerebral aqueduct
Infundibulum
area that connects the hypothalamus to pituitary gland
What glial cell forms the BBB?
astrocytes
Cerebrum is part of our brain where we have the
awareness of our senses and can initiate the voluntary movements of our body
Central sulcus
between frontal lobe and parietal lobe
Parieto-occipital lobe
between parietal and occipital lobe
The fourth ventricle located
between the pons and cerebellum
CSF Superior sagittal sinus receives blood and CSf from?
blood from the cerebral veins and recieves CSF from the subarachnoid space via the arachnoid granulations
What do you not find in CSF?
blood proteins and red and white blood cells
Choroid
blood vessels
Corpus callosum
bundle of axons the decussate (cross) between two hemispheres and connect the two cerebrum hemispheres
The CSF give ____________to the CNS structures
buoyancy
Purkinje cells
cells responsible for our coordinated movements
the fourth ventricle of the brain communicates with the
central canal of the spinal cord
The remaining 10% continues to flow through a
central canal that runs through the entire spinal cord
The cerebellum communication with other regions of the brain happens via the
cerebellar peduncles -superior peduncles communicates cerebellum with mesencephalon, diencephalon and cerebrum -middle peduncles communicates cerebellum with the pons -inferior peduncles communicates cerebellum with medulla oblongata
Lateral Ventricles #1 and 2 located in the
cerebrum hemispheres
This directionality is due to
ciliated movement of ependymal cells
the lateral ventricles do not ___________ with each other
communicate there is no direct connection between the two,lateral ventricles
Association fibers are responsible for
connecting areas of the cerebrum cortex within the same hemisphere Ex)arcuate fibers and longitudinal fasciculi
What does the middle cerebellar peduncle do?
connects pons to cerebellum
The frontal lobe is related to
conscious control of skeletal muscles and trouble solving, reasoning and planning
Epithalamus
contains pineal gland Thalamus,- surrounds the third ventricle -right and left thalamus connected by interthalamic adhesion -relay station for all sensory info that comes through spinal cord and eyes and ears
What is a point of attachment in the inferior anterior aspect of the falx cerebri?
crista galli of ethmoid bone
If damage is in the brain stem it often means
death
Third ventricle located in the
diencephalon
Longitudinal fissure
divides right and left hemisphere of cerebrum
Tentorium cerebelli
dura mater fold located along transverse cerebral fissure (deep depression separating cerebrum from cerebellum)
Falx cerebelli
dura mater fold located between right and left hemisphere of cerebellum
Falx cerebri
dura mater fold located between right and left hemisphere of cerebrum, along the longitudinal fissure
What are the cranial meninges?
dura mater, arachnoid mater, pia mater
Blood vessels in the choroid plexus are surrounded by
ependymal cells
Dura septa
extensions of the dura mater that goes deep inside the brain
What are the commissural fibers?
fibers that connect the two cerebrum hemispheres Anterior commissure and corpus callosum
Transverse cerebral fissure
fissure (deep depression) between cerebrum and cerebellum
Ventricles
fluid filled cavities
Folia of cerebellum
folds of cerebellum equivalent to cerebrum gyri
Projection fibers
groups of axons link the cerebrum with other regions of the brain
In insula we find the __________
gustatory cortex which gives us the perception of taste
Meningitis
inflammation of meninges -causes increased amount of CSF
Where is CSF located?
inside the ventricles of the brain, inside central canal of spinal cord and surrounding brain and spinal cord
All ventricles are
interconnected
the veins of the brain empty themselves into the sinuses which deliver the blood to the
internal jugular vein in the neck
right and left thalamus are connected by the
interthalamic adhesion
The lateral ventricles communicates with the third ventricles via the
interventricular foramen
Intracranial pressure (ICP)
is the pressure exerted by fluids such as cerebrospinal fluid (CSF) inside the skull and on the brain tissue.
The hypothalamus is wired to the
limbic system the part of the brain involved in behavioral and emotional responses Ex) if we are upset it affects hypothalamus and causes it to make autonomic motor neurons to speed up our heart rate and raise our blood pressure, if relaxed BP goes down and heart rate
the reabsorption of the CSF involves the
meninges
Brainstem:
mesencephalon (midbrain), pons, medulla oblongata
What is another name for mesencephalon?
midbrain
White matter is composed of
myelintaed axons
Gray matter is composed of
neuronal cell bodies
If the CSF pressure is less than the pressure of the venous pressure the arachnoid villi will
not let the blood pass into the interventricular system
Dura mater is formed by what two layers:-Periosteal layer (closer to the skull) attaches to inner surface of skull
only found in brain -Meningeal layer (closer to arachnoid mater) extends into vertebral canal as the spinal dura mater
Each cerebral hemisphere controls the ___________ side of the body
opposite
Hypothalamus links the nervous system and the endocrine system via the
pituitary gland
hydrocephalus
results from -overproduction of CSF -obstruction within ventricular system -problems with CSF reabsorption
What happens when the two dura layers separate?
results in blood filled space dura venous sinus
If someone has a stroke on the primary cortex of the left hemisphere the person will develop an impairment on the _____________ of the body
right side
Primary fissure
separates anterior and posterior lobe of cerebellum
Lateral sulcus
separating temporal lobe from all other lobes
Lateral ventricles are separated by a partition called
septum pellucidum
Superior sagittal sinus
sinus we have between the right and left cerebral hemispheres in the superior side
Hydrocephalus happens in newborns because
skull bones are not fused yet -there is increased pressure causing head to become very large
What are the functions of the mesencephalon?
some extrinsic eye muscles, sight and auditory processing, associated reflex
Dura venous sinus
space filled with venous blood, majority of blood from brain drains into
Medulla oblongata is the place that makes the link between our
spinal cord and the brain regions
If the CSF pressure is greater than the venous pressure of the superior sagittal sinus the CSF will be
squeezed out of the subarachnoid space flowing into the blood stream and get reabsorbed
There is an opening at the bottom of spinal cord where CSF comes out and enters the
subarachnoid space
95% of sensory information goes through the ____________ and forwarded to where it's supposed to go
thalamus
what is the largest nuclei we have in the CNS?
thalamus has largest mass of neuronal cell bodies in the CNS
What do we have under the cranium?
the dura mater
The jugular vein that drains blood out of our brain gets the blood supply from
the dura venous sinuses
Infundibulum
the structure that connects the pituitary gland and the hypothalamus
Meningitis causes problems with reabsorption because
there is no communication between where the CSF is made and where it is reabsorbed causing Intracranial pressure to raise which is fatal
between the right and left thalamus we have the
third ventricle and the two thalami surround the 3rd ventricle
Capillary endothelial cells are attached by
tight junctions which block the passage of material between the cells
Treatment for hydrocephalus is
to drain CSF by making a small hole in ventricle and drain the CSF form ventricle in a place in the abdominal cavity
Cerebellum right and left hemisphere are separated by the
vermis
CSF is made up of
water, sugar, and electrolytes (gatorade)
When our blood pressure is low
what does the hypothalamus release?,antidiuretic
Cerebellar Cortex
when gray matter is on the surface, where we find neuronal cell bodies of Purkinje cells
Nuclei
when we have a group of neuronal cell bodies within the CNS
Cortex
when we have collection of neuronal cell bodies in the surface of the CNS
Arbor vitae
white matter of cerebellum, looks like tree of life