Ex 19

Brain and Cranial Nerves

Meninges RevisitedDura Mater

tough outermost coveringcreates sinuses and ligaments

Arachnoidclosely associated with the durasubarachnoid space contains the CSF and cerebral vasculaturearachnoid villi, transfers CSF from subarachnoid space to venous vasculature

Pia Materdelicate tissue over brainattached by astrocytesblood vessels lie on top of it

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Meninges RevisitedDura Mater differences

two layersouter fibrous

fused to periosteuminner fibrous

two layers can separate to create spaces called venous sinuses

collect most of the blood from the braindrain into the internal jugular vein

Meninges RevisitedDural Ligaments

folds of inner dural layer that act to support the brain

Falx Cerebribetween hemispheressuperior & inferior sagittal sinus

Tentorium Cerebellibetween cerebrum and cerebellumtransverse sinus

Falx Cerebellibetween cerebellar hemispheres

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VentriclesSpaces within the brain filled with CSF

2 lateral ventricles3rd ventricle4th ventricle

CSF is created in the ventricles in structures called choroid plexilateral ventricles connected through the interventricular foraminathe third and fourth ventricles are connected through the cerebral aqueductCSF gets into the subarachnoid space through the median and lateral aperturesremember that CSF gets back into the blood through the arachnoid villi

Ventricles

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Area of brain devoted to higher level functions

gray matter (outside)neural cell bodies, dendrites, unmyelinated axons, support cells

white matter (inside)tracts of information

corpus callosuminternal capsule

nucleiislands of grey matter

Cerebrum

Divided into right and left hemispheresHemispheres divided into lobes:

Frontal LobeParietal LobeTemporal LobeOccipital Lobe

Cerebrum

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CerebrumFissures: deep grooves in the cerebrum

longitudinal fissurebetween hemispheres

transverse fissurebetween cerebrum and cerebellum

CerebrumSulci: shallow depressions in gray matter

Central Sulcusdivides frontal and parietal lobes

Lateral Sulcusdivides the temporal from the parietal lobes

Gyri: ridges in gray matter to increase surface area

precentral gyrusprimary motor cortex

postcentral gyrussomatosensory area

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Functions of the lobesFrontal Lobe

motor, speech (l. lobe), personality

Parietal Lobesensation (except smell, language

Temporal Lobehearing, smell, language

Occipital Lobevision

Cerebrum

Diencephalon

ThalamausHypothalamusEpithalamus

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DiencephalonThalamus

bulges into the 3rd ventriclepaired, oval areas of grey matter and white matter tractsacts as a relay station for sensory input

DiencephalonHypothalamus

nucleimajor regulation

mamillary bodiesprocess olfactory sensations

pituitaryhormonal regulationattached via the infundibulum

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Diencephalon

Functions of Hypothalamuscontrols somatic motor activities at the subconscious levelcontrols autonomic functioncoordinates activities of the nervous and endocrine systemssecretes hormonesproduces emotional and behavioral drivecoordinates voluntary and autonomic functionsregulates body temperaturecoordinates circadian cycles of activity

DiencephalonEpithalamus

pineal gland

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Basal GangliaBasal Ganglia

control motor movements that don’t require much thought: arm swinging, muscle tone, smiling.sets muscle tone

defects in dopamine regulation in these structures results in Parkinson’s disease

Diencephalon & Basal GangliaCorpus Callosum

area where axons cross over

Caudate Nucleus

Putamen

Globus Pallidus

Thalamus

tail of caudate nucleus

corpus callosum

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Cerebellumfine tunes and coordinates motor movements

people with cerebellar deficiencies have problems with balance and position

Cerebellar Hemispheres

Vermix

CerebellumArbor Vitae

tracts of white matter in the cerebellum

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Brain Stem

Mesencephalon (midbrain)

Pons

Medulla Oblongata

MidbrainLies inferior to thalamusCorpora Quadrigemina

superior colliculireflexes for vision such as tracking and pupillary reflexes

inferior colliculiauditory pathways to the thalamusresponsible for startle reflex

CV III and IV arise from midbrainMidbrain also acts as motor relay and does some processing of motor informationCerebral peduncles

motor pathways on anterior side of midbrain

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MidbrainLies inferior to thalamusCorpora Quadrigemina

superior colliculireflexes for vision such as tracking and pupillary reflexes

inferior colliculiauditory pathways to the thalamusresponsible for startle reflex

CV III and IV arise from midbrainMidbrain also acts as motor relay and does some processing of motor informationCerebral peduncles

motor pathways on anterior side of midbrain

PonsPons

“bridge”one of the first relay areas for motor informationcontains apneustic and pneumotaxic areas

modify activity of medullar respiritory areas

CN V, VI, VII and VIII

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MedullaMedulla

pyramidsdecussation of pyramids

olivary nucleicardiovascular center, rhythmicity area, embarrassing bodily functions area: vomiting, coughing, sneezingCN VIII-XII

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