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