ZOO 3731- CH 18 BRAIN
corpus callosum
-bundle of axons that connect the two hemispheres of the brain to allow for communication
BBB is absent in
-choriod plexus bc there are no astrocytes -hypothalamus bc it has receptors that need to sense the chemical composition of the blood -pituitary and pineal glands because their hormones need to be released directly into bloodstream
medulla oblongata
-connects brain and spinal cord -relay station between spinal cord and brainstem/thalamus -cardiac reflex center: regulate HR and BP -respiratory reflex center: regulate breathing pattern -partial center for consciousness -nuclei for cranial nerves VII-XII
granular layer of cerebellar cortex
-contains axons of Purkinje cells -tightly packed small neurons
cranial meninges
-continuous with spinal meninges -dura mater -arachnoid mater -pia mater
frontal eye field of cerebrum
-controls voluntary eye movements
trochlear nerve
-cranial nerve IV -moves eyeball up and down and outwards by innervating superior oblique
glossopharyngeal nerve
-cranial nerve IX -sensory function: taste posterior 1/3 of tounge, monitors oxygen and carbon dioxide levels in blood, monitors blood via baroreceptors and chemoreceptors -swallowing and saliva production -parotid glands and some myscles of pharynx
trigeminal nerve
-cranial nerve V 3 branches -opthalmic: sensory. superior orbital fissure -maxillary: sensation of upper teeth. foramen rotundum -mandibular:sensation of lower teeth AND motor mastication. foramen ovale
facial nerve
-cranial nerve VII -sensory function: sensation from anterior 2/3 of tongue -facial expression, production of tears and saliva by innervating lacrimal glands, submandibular glands, anf sublingual glands
vestibulocochlear nerve
-cranial nerve VIII -comes from inner ear -sensory function: hearing and equilibrium -adjusts sensitivity of hair cells
vagus nerve
-cranial nerve X comes from medulla -sensory function: taste in pharynx, monitors O2 and CO2 in blood and BP -related to autonomic control of organs in thoracic and abdominal cavities -regulates BP, respiratory rate, HR and digestive functions -longest cranial nerve
accessory nerve
-cranial nerve XI -swallowing and speech -innervates palate, pharynx, layrnx and upper back (sternocleidomastoid and trapezius
hypoglossal nerve
-cranial nerve XII -swallowing and speech
arachnoid granulations/villi
-extensions of arachnoid mater that go into superior sagittal sinus -allows CSF to reach the superior sagittal sinus and there it goes back into bloodstream due to fluid pressure
ventricles of the brain
-form and distribute CSF which transports water, glucose, gases, and ions throughout the CNS -fluid acts as a cushion to protect against physical damage
temporal lobe
-hearing and smell -auditory cortex -auditory association area -olfactory cortex -parallel to parallel sulcus
somatosensory association area
-helps understand size shape and texture
end of 3rd week of development
-hollow begins to swell at cepahlic end of the fetus forming three primary vesicles -prosencephalon, mesecephalon, and rhombencephalon
Purkinje layer of cerebellar cortex
-intermediate layer -contains Purkinje cell bodies
visual association area
-matches something you see to something you already know ie: matching someone's face to their name
hypothalamus
-part of diencephalon -center of homeostasis, controls body temperature, hunger, thirst. induces shivers and sweat to regulate body temp -regulates secretion of growth, metabolic, and reproductive hormones from pituitary gland via infundibulum -greatly affected from emotional state bc part of limbic system -highest control center for autonomic motor neurons to keep rate of activity of organs proportional to body's needs
thalamus
-part of diencephalon -contains largest group of neuronal cell bodies making it the largest nuclei of CNS -right and left thalamus have third ventricle in between and are connected by interthalamic adhesion -relays all sensory input except smell to other parts of the brain (95% of all sensory info) -provide crude perception of touch, pressure, pain, and temperature. -involved in some cognition, memory, and emotions
spinal cord
-processes reflexes -integrates excitatory and inhibitory nerve impulses -provides a "highway" for carrying sensory impulses to the brain and motor impulses from the brain to the spinal nerves
frontal lobe
-reasoning, planning, behavior, morality -precentral gyrus (primary motor cortex) -premotor cortex -prefrontal cortex
parietal lobe
-sensations -postcentral gyrus (primary somatosensory cortex) -somatosensory association area
Molecular layer of cerebellar cortex
-most superficial -contains dendrites of Purkinje cells
aqueduct of the midbrain (cerebral aqueduct)
allows communication between 3 and 4 ventricles
vermis
divides left and right hemispheres of cerebellum
cerebellar cortex
gray mater of cerebellum -contains cell bodies of Purkinje cells and has 3 layers
shallow depression
sulcus -separate lobes of the brain
normal adult replacement of CSF
150 mL q8h
dura mater
2 layers: -periosteal layer: attaches to inner surface of skull. layer felt within anterior fontanelle of baby. not in spinal cord -meningeal layer: covers brain and extends into vertebral canal as spinal dura mater
cerebellum
2nd largest part of brain communicates with brain via cerebellar peduncles
CSF pressure > venous pressure
CSF leaves subarachnoid space and is reabsorbed
abducens nerve
Cranial nerve VI. Movement of the eye laterally via lateral rectus
oculomotor nerve
The cranial nerve (III) that innervates the muscles that cause motion of the eyeballs except superior oblique and lateral rectus and intrinsic muscles -accommodation of lens and pupillary constriction
melatonin
affects sleep-wake cycles
central canal
allows communication between 4th ventricle and spinal cord 10% of CSF flows through here until the opening at the end of the spinal cord which allows it to go back to subarachnoid space
interventricular foramen
allows communication between lateral ventricles to third ventricle
crista galli
anchors brain -point of attachment in inferior anterior aspect of falx cerebri
prefrontal cortex
anterior to the premotor cortex -thinking, problem solving, concentration, behavior, personality, morality, judgement
premotor cortex
anterior to the primary motor cortex -planning of motor movement -relays a plan to the primary motor cortex to then have it sent to the skeletal muscles
CSF pressure < venous pressure
arachnoid villi will not allow CSF to pass into ventricular system
capillary endothelial cells lining BBB
attach to each other through tight junctions which does not allow passage of material between the cells -only lipid soluble compounds are capable of passing through
insula
behind temporal lobe when it is pulled back -location of gustatory cortex
subarachnoid space
between arachnoid mater and pia mater -space where CSF flows
subdural space
between dura mater and arachnoid mater -a potential space, meaning it doesnt normally exist but can if necessary ie: subdural hematoma
central sulcus
between frontal and parietal lobes
4th ventricle
between pons and cerebellum
superior sagittal sinus
between right and left cerebral hemispheres on superior side
dural venous sinus
cavity between the 2 hemispheres of the brain where dura mater membranes separate between the 2 hemispheres. -fills with venous blood to be drained into venous blood
CSF
cerebrospinal fluid -cushions brain -helps brain float within skull (buoyancy) -mixture of water, sugar, and electrolytes -prevents contact of neural tissue with surrounding bones -reduces weight of brain from 1500 g to 50 g
spinal nerves
cervical (8 pairs) thoracic (12 pairs) lumbar (5 pairs) sacral (5 pairs) coccygeal (1 pairs)
inferior cerebellar peduncle
communicates with medulla oblongata
superior cerebellar peduncle
communicates with mesencephalon, diencephalon, and cerebrum
middle cerebellar peduncle
communicates with pons
anterior commissure
connects the anterior parts of the cerebral cortex
epithalamus
contains pineal gland which secretes melatonin
Broca's speech area
controls movements required for speech
premotor area
controls repetitive skilled movements
primary motor area
controls voluntary contraction of muscles
commissure of fibers
corpus callosum + anterior commissure
longitundinal fissure
deep depression between left and right hemispheres of the cerebrum
tentorium cerebelli
dura mater folds that run along transverse cerebral fissure
dura septum
extensions of dura mater that go deep inside brain -subdivide cranial cavity -support brain and limits brain movement
deep depression
fissure
falx cerebri
folds of dura mater found along longitudinal fissure
falx cerebelli
folds of dura mater that are between left and right hemispheres of the cerebellum
folia of the cerebellum
folds of the cerebellum
prosencephalon
forebrain divides into telencephalon and diencephalon
astrocytes in BBB
form BBB and play role in providing nourishment to neurons
ependymal cells
glial cells responsible for producing CSF -take nutrients from blood (plasma nd blood components) and turn it into CSF
nuclei
group of neuronal cell bodies
projection fibers
groups of axons that link the cerebrum with other regions of the brain and spinal cord
elevation
gyrus (singular) -increase surface area of the cerebrum
pons
helps medulla control breathing via the respiratory reflex center in medulla -nuclei for cranial nerves V-VIII -relay station between cerebrum and cerebellum -plays role w cerebellum in coordinating movement
rhombencephalon
hindbrain divides into metencephalon and myelencephalon
sella turcica
holds pituitary gland and is encased by diaphragma sellae(fold of dura mater) -anchors dura mater to sphenoid bone
3rd ventricle
in diencephalon in between left and right thalamus
neurosecretory cells
in hypothalamus that secrete hormones (ADH and oxytocin) that are transported to the pituitary gland and then released into bloodstream
white mater of the cerebrum
inner layer of the brain -composed of myelinated axons
somatosensory association area of cerebrum
integrates body sensations to determine size, shape, and texture of objects and their orientation
prefrontal area of the cerebrum
integrative area for intellect, personality, cognition and judgement
common integrative area of cerebrum
interprets sensory information from all sources to provide for a suitable response
pyramidal cells
large neurons of the primary motor cortex that allow for conscious control of skeletal muscle movements
ventricles of the brain
lateral ventricles, third ventricle, fourth ventricle
directionality of CSF movement
lateral ventricles-3-4 -due to ciliated movements of ependymal cells
meningitis
may cause problems w reabsorption of CSF which can b fatal bc there is no connection bc of inflamed meninges
mesencephalon
midbrain -plays a role in moving eyes -processes sight and auditory data -reflexive motor responses
cranial nerves
olfactory(I), optic(II), oculomotor(III), trochlear(IV), trigeminal(V), abducens(VI), facial(VII), vestibulocochlear(VIII), glossopharyngeal(IX), vagus(X), accessory(XI), hypoglossal(XII)
median and lateral apertures
openings leading from the fourth ventricle to the subarachnoid space outside of the brain 90% of CSF flows through here
apertures
openings where CSF can leave ventricular system found at roof of 4th ventricle
hydrocephalus
overproduction of CSF obstruction in ventricular system problems with CSF reabsorption Tx: drain CSF through hole in ventricles into abdomen
blood brain barrier (BBB)
physiological barrier between the circulatory system and the central nervous system that establishes a privileged blood supply, restricting the flow of substances into the CNS -made up of capillary endothelial cells surrounded by astrocytes
optic chiasm
point at which optic nerve fibers cross in the brain
visual cortex
posterior to parieto-occipital sulcus -where you see
precentral gyrus
primary motor cortex -anterior to the central sulcus -sends nerve impulses down spinal cord towards muscle to initiate movement -pyramidal cells are found here
postcentral gyrus
primary somatosensory cortex -posterior to central sulcus -allows us to consciously feel sensations -sensations of skin, muscle, joints
carotid artery
provides oxygen rich blood to brain
gray mater of the cerebrum
referred to as the cerebral cortex -gets the color from the bodies of neuronal cells
midbrain
reflexive movements of eyeball, head, trunk in response to visual and auditory stimuli -nuclei for cranial nerves III-IV
brain stem
relays sensory and motor impulses between parts of the brain and spinal cord -mesencephalon -pons -medulla
association fibers
responsible for connecting areas of the cerebral cortex within the same hemisphere ie: arcuate fibers (look like arcs) longitudinal fasciculi (long bend fibers)
layers of physical protection of the brain
scalp - epicranial aponeurosis - periosteum of cranium - cranium - dura mater - arachnoid mater - pia mater
optic nerve II
sense of sight -only one that comes together, crosses and splits off between both hemispheres of brain in order to receive sensations on both sides simultaneously
olfactory nerve I
sense of smell -only cranial nerve exposed to the exterior and its the shortest -goes straight to brain as opposed to relaying info to the thalamus -form neuronal masses on sides of the crista galli -cribiform plate: where bundles of axons pass through
primary fissure
separate anterior and posterior lobes of cerebellum
transverse cerebral fissure
separates cerebrum and cerebellum
parieto-occipital sulcus
separates parietal and occipital lobes
parallel sulcus
separates temporal lobe from the others
arachnoid mater
spiderweb appearance bc of arachnoid trabeculae which are made up of collagen fiber -helps anchor cerebral blood vessels in place
jugular vein
takes away deoxygenated blood from the brain
diencephalon
thalamus, hypothalamus, epithalamus
choriod plexus
vascularized membrane found inside all 4 ventricles -surrounded by ependymal cells
lateral ventricles
ventricle 1 and 2 -extend from anterior horn to posterior horn and inferior horn -majority found in parietal lobe -do NOT communicate with each other because they are separated by septum pellucidum
occipital lobe
visual cortex and visual association area
arbor vitae
white mater of the cerbellum