Ch 14: Brain-Cerebellum, Brain Stem, RF

Cerebrum

largest part of the brain

Divided into right and left hemispheres

Cerebellum

Inferior to cerebrum, posterior to brain stem, within cranial fossa

Brainstem

Midbrain, pons + medulla part of brain

Diancephalon

thalamus, hypothalamus, epithalamus part of brain

cerebrum and cerebellum

gray matter on surface (cortex) of brain

spinal cord

gray matter is deep to the white matter

hollow

much of the CNS is ____

ventricles

core spaces in the brain filled with CSF

central canal

core space in spinal cord

ectoderm

Embryology of the nervous system: NS develops from ________

neuroectoderm, neural plate

Embryology of the NS: 3rd week, dorsal streak of ___________ forms _______

primary vesicles

forebrain, midbrain, and hindbrain are all ________

initial three bulges that form from the early embryonic neural tube

prosencephalon

forebrain

mesencephalon

midbrain

rhombencephalon

hindbrain

telencephalon, diencephalon, midbrain, metencephalon, myelencephalon

secondary vesicles

the five key brain regions that develop from the three primary brain vesicles during early embryonic development

adult structures

cerebrum, thalamus, 3rd ventricle, midbrain, pons, cerebellum, and medulla oblongata are all _____________

telencephalon, diencephalon

secondary vesicle(s) of forebrain

midbrain

secondary vesicle(s) of midbrain

metencephalon, myelencephalon

secondary vesicle(s) of hindbrain

cerebrum, thalamus, 3rd ventricle

adult structures of forebrain

midbrain

adult structures of midbrain

pons, cerebellum, medulla oblongata

adult structures of hindbrain

inferior, myelencephalon

spinal cord develops from neural tube _______ to _________

3, CT

The meninges are __ layers of _ surrounding the brain and spinal cord

• special features related to production, circulaiton, and absorption of CSF

  • related to conveying venous blood

dura mater, arachnoid, pia mater

three things meninges is divided into

dura mater

tough, fibrous, outermost meninx layer

• double layer

• around the brain

• periosteal layer and meningeal layer = 2 layers fused over most of brain

periosteal layer

layer of dura mater: outer, adheres to skull bone forming periosteum

meningeal layer

layer of dura mater: inner, continouous w/dura mater of s.c.

dural sinuses

in certain areas of the dura mater, 2 layers are seperated forming ________

collect venous blood and empty into internal jugular veins

dural folds

places where the meningeal layer extends inward within fissures separating parts of the brain

falx cerebri

in longitudinal fissure between right and left cerebral hemispheres

falx cerebelli

dural midline fold separating the two cerebellar hemispheres

tentorium cerebelli

tent-like partition in the transverse fissure separating the occipital lobes from the cerebellum

arachnoid mater

middle meninx; sends down fibrous strands

subdural space

narrow space separating the arachnoid m. from the dura m.

close adhesion to dura

subarachnoid space

wider space separating the arachnoid m. from underlying pia m.

contains CSF

contains strands of arachnoid

pia mater

inner meninx; adheres closely to brain and s.c.

meningeal

in the spinal cord, only the _______ layer is present

20

brain receives __% of our blood

internal carotid, vertebral

blood flows to the brain via _______ as & ________ as

BBB

regulates substrate exchange between blood and brain

=astrocytes + tight junctions between capillary endothelial cells and cap. B.M.

• permeable to lipid soluble substrates and carrier transported substrates (ex. glucose)

• makes it difficult to administer some meds to brain

• trauma and inflammation can dama

CSF

clear liquid filling and surrounding the CNS

mechanical protection

function of CSF:

CSF is shock absorbing; buoyancy → effective weight of brain « actual weight

Homeostatic function

function of CSF: CSF pH affects pulmonary ventilation and blood flow; transports hormones

Circulation

function of CSF: CSF is a medium for minor exchange of nutrients and waste products between the blood and adjacent tissues

Choroid plexus

CSF is produced by the _______ within walls of each ventricle (capillaries covered by cuboidal epith.)

Blood CSF barrier

formed by the tight junctions between the ependymal cells → decreases passage of harmful substrates from blood into the CSF

ventricles

the 4 CSF filled chambers of the brain (continuous)

lateral ventricles

2 large ventricles; one in each cerebral hemisphere

3rd ventricle

midsagittal plane ventricle; inferior to corpus callosum

4th ventricle

small change in shape between pons and cerebellum

CSF reabsorption rate

normally CSF production rate

CSF reabsorption rate

the normal CSF production rate is also the

hydrocephalus

If increase in CSF production OR decrease in reabsorption

enlarged head

If increase in CSF production OR decrease in reaborption in childhood

ventricular dilation, compressed brain tissue

If increase in CSF production OR decrease in reabsorption in older children or adults

concussion

temporary loss of consciousness at blow to head

headache, amnesia, confusion

contusion

brain bruise

subdural hematoma

serious accumulation of blood between the brain's surface and its outer covering

epidural hematoma

bleed between dura and skull, usually middle meningeal a. bleed; rapid

meningitis

inflammation of meninges; usually bacterial or viral infection, lumbar puncture for diagnois

brain stem

medulla, pons, and midbrain

produces programmed behaviors for survival

pathway for fiber tracts between spinal cord and cerebrum

sc, diancephalon

the brain stem is between the _______ and the _______

medulla

continuous w/superior part of spinal cord, but wider

also contains sensory nuclei and tracts

foramen magnum, pons

medulla starts at _____ and extends to _____

pyramids

2 large columns of motor neuron tracts on ventral surface of medulla

anterior median fissure

pyramids are separated by an __________

corticospinal tracts

pyramids contain _________ controlling voluntary limb movements

decussation of pyramids

at the junction of the medulla with the spinal cord, 90% of the corticospinal axons of the pyramids cross

opposite

each side of the brain controls voluntary movements on the ______ side of the body

olives

elevated areas of the medulla lateral to each pyramid

inferior olivary nuclei

olives contain ______ which send axons to cerebellum

VIII, IX, X, XI, XII

olives contain these cranial nerve nuclei:

olives

this part of the brain controls heart rate, respiration, bv diameter, coughing, swallowing, vomiting

pontine nuclei

pons contains ________ = a synaptic relay stations between the cerebrum and cerebellum

→ coordination of voluntary motor output

pons

contains ascending and descending tracts

contains “pneumotaxic” and “apneustic” areas to help control breathing

V, VI, VII, VIII

pons contains these cranial nerve nuclei

midbrain

between pons and diencephalon

contains the cerebral aqueduct (CSF from CN III→ CN IV)

made up of cerebral peduncles, substantia nigra, tegmentum, and tectum

cerebral peduncles

ventral surface of midbrain

contain corticospinal, corticopontine, and corticobulbar motor neuron tracts

substantia nigra

black nucleus between the peduncles and tegmentum

motor center containing dopamine neurons that extend to the basal nuclei → help control muscles activity (loss of these neuron ass. w/Parkinsons)

Tegmentum

contains “red nucleus” → rubrospinal tract

receive axons from cerebrum and cerebellum → some movement coordination

corpora quadrigemina

also known as tectum

corpora quadrigemina

dorsal surface of midbrain

contains 4 rounded bodies: superior and inferior colliculi

superior colliculi

upper pair of rounded bodies in tectum, some optic tract input → visual

inferior colliculi

lower pair of rounded bodies in tectum, involved in auditory reflexes

III, IV

corpora quadrigemina contain these cranial nerve nuclei

reticular formation

net-like arrangement of white and gray matter extending from the upper s.c., throughout the BS, and into the inf. diencephalon

regulate muscle tone

neurons in RF have both ascending (sensory) and descending (motor) functions:

somatic motor control

input

neurons in RF have both ascending (sensory) and descending (motor) functions:

autonomic ____

arousal

neurons in RF have both ascending (sensory) and descending (motor) functions:

_____

• ascending fibers activate the cerebral cortex

• Reticular activating system (RAS)

Reticular activating system

prevents sensory overload

helps arousal in RF

NO input from olfactory receptors

coma

damage to reticular activating system results in a ____

cerebellum

large, dorsal porjection in post. cranial fossa

posterior to medulla and pons

highly folded surface → increase in surface area

tentorium cerebelli

separates the cerebellum from occipital lobes → decrease P on cerebellum

vermis

2 lateral cerebellar hemispheres connected by

cerebellar cortex

superficial gray matter consisting of folds called folia separated by shallow sulci (grooves)

arbor vitae

tracts of white matter deep to gray matter in cerebellum

superior cerebellar peduncles

cerebellar connection: axons connecting to midbrain and thalamus

middle cerebellar peduncles

cerebellar connection: pons connection