Chapter 14: Intro to the brain and brainstem

gray matter

neurosomas, dendrites and synapses, dull color due to little myelin, surface layer, processes info, forms nuclei deep within brain

white matter

bundles of AXONS, transmission matter, transmits info, composed of tracts or bundles of axons connect one part of the brain to the other

ventricles

four internal chambers within the brain, hollow cavities help move fluid, two lateral ventricles (left and right)

interventricular foramen

tiny pore that connects to third ventricle

choroid plexus

spongy mass of blood capillaries on the floor of each ventricle, generates cerebrospinal fluid

ependymal

type of neuroglia that lines ventricles and covers choroid plexus, produces cerebrospinal fluid

cerebrospinal fluid

clear, colorless liquid that fills the ventricles and canals of the CNS, bathes its exernal surface

ependymal cells

modify the filtration of blood plasma so CSF has more sodium and chloride then plasma

Functions of CSF

buoyancy, protection, chemical stability

buoyancy

allows the brain to attain considerable size without being impaired by its own weight, brain doesn't touch the cranium floor

protection

CSF protects the brain from striking the cranium when head is jolted

chemical stability

flow of CSF rinses away metabolic wastes from nervous tissue and homeostatically regulates its chemical environment

the flow of CSF

from areas of high pressure to low pressure

brain barrier system

regulates what substances can get from the bloodstream into tissue fluid of the brain,

blood-brain barrier

protects blood capillaries throughout brain tissue, tight junctions between ENDOTHELIAL cells that form the capillary walls, highly permeable

endothelial cells

exclude harmful substances from passing to the brain tissue while allowing nesessary ones to pass

blood-CSF barrier

protects brain at the choroid plexus, forms tight junctions between the EPENDYMAL cells,

medulla oblongata

begins at foramen magnum of skull,

reticular formation

loose web of gray matter that runs vertically through all levels of brainstem, connections with many areas of the cerebrum

somatic control

voluntary, adjust muscle tension to maintain tone, balance, and posture, relay signals from eyes and ears to cerebellum, gaze centers, central pattern generators

cardiovascular control

cardiac and vasomotor centers of medulla oblongata

pain modulation

some pain signals ascend through reticular formation, some descending analgesic pathways begin in the reticular formation

sleep and consciousness network

reticular formation plays a central role in consciousness, alertness and sleep

habituation network

reticular activating system modulates activity in cerebral cortex so that it ignores repetitive, inconsequential stimuli

cerebellum

largest part of the hindbrain, right and left hemispheres, contains more than half of all brain neurons, motor coordination, locomotor ability,

folia

superficial cortex of gray matter with folds

arbor vitae

branching white matter

forebrain

diencephalon, telencephalon

diencephalon

thalamus, hypothalamus, epithalamus

thalamus

ovoid mass on each side of the brain perched on the superior end of the brainstem beneath the cerebral hemispheres, gateway to cerebral cortex, motor control, memory and emotional functions of the limbic system

hypothalamus

forms part of the walls and floor of the third ventricle, relays signals from the limbic system to the thalamus, control center of autonomic nervous system and endocrine system, food and water intake, sleep, emotional behavior and sexual response

epithalamus

very small mass of tissue composed of pineal gland and habenula (relay from the limbic system to midbrain)

cerebrum

largest part of brain, sensory perception, thought, judgement and voluntary motor actions, two cerebral hemispheres, white matter

frontal lobe

abstract thought, explicit memory, mood, motivation, foresight, planning, decision making, social judgement, speech production

insula

taste, pain, visceral sensation, consciousness, emotion and empathy, cardiovascular homeostasis

parietal lobe

taste, somatic sensation, sensory integration, visual processing, spatial perception, language processing, numerical awareness

occipital lobe

visual awareness, visual processing

temporal lobe

hearing, smell, emotion, learning, language comprehension, memory consolidation, verbal memory, visual and auditory memory, language

tracts

bundle of nerve fibers in the CNS

projection tracts

extend vertically between higher and lower brain and spinal core centers

association tracts

connect different regions within the same cerebral hemisphere

commissural tracts

cross from one cerebral hemisphere to the other allowing communication between two sides of cerebrum, corpus callusum

stellate cells

cerebral cortex cells, spheroid neurosomas with dendrites projecting in all directions, receive sensory input and process info on a local level

pyramidal cells

cerebral cortex, tall and conical with apex toward thee brain surface, thick dendrite with many branches with small knobby dendritic spines

limbic system

important center of emotion and learning

cingulate gyrus

arches over corpus callous, in frontal and parietal lobes

limbic system

important center of emotion and learning, cingulate gyrus, hippocampus, amygdala, one in each cerebral hemisphere, centers for both gratification and aversion

basal nuclei

masses of cerebral gray matter buried deep in the white matter, lateral to the thalamus, receivers input from the midbrain and motor areas of the cortex, send signals back, involved in motor control INCLUDES: caudate nucleus, putamen, globes pallidus

integrative functions of the brain

focus mainly on the cerebrum, higher brain functions (sleep, memory, cognition, emotion, sensation, motor control, language), interactions between cerebral cortex and basal nuclei

primary sensory cortex

sites where sensory input is first received and one becomes conscious of the stimulus

primary visual cortex

bordered by visual association areas: make cognitive sense of visual stimuli

special senses

limited to the head and employ relatively complex sense organs

visual primary cortex

posterior region of occipital lobe

visual association area

anterior and remaining occipital lobe

primary auditory cortex

superior region of the temporal lobe and insula

auditory association area

temporal lobe deep and inferior to primary auditory cortex, recognizes spoken words

association cortex

seat of consciousness of our body movements and orientation in space, roof of the lateral sulcus near lower end of the central sulcus

gustatory

taste, signals received by the primary gustatory cortex in inferior end of the postcentral gyrus of the parietal lobe

olfactory

smell, signals received by the primary olfactory cortex in the medial surface of the temporal lobe and inferior surface of the frontal lobe

general senses

distributed over entire body and employ simple receptors, touch, pressure, stretch, movement, heat, cold and pain

somesthetic association area

caudal to the post central gyrus and in the roof of the lateral sulcus

motor association (premotor) areas

where the intention to contract a muscle begins, where we plan our behavior, neurons compile a program for the degree and sequence of the contraction, plan transmitted to the pre central gyrus

dyskinesias

abnormal movement caused by lesions in the basal nuclei

wernicke area

recognition of spoken and written language, posterior to lateral sulcus, usually in left hemisphere

broca area

inferior prefrontal cortex usually In the left hemisphere, generates motor program for the muscles of the larynx, tongue, cheeks and lips for speaking and for signing

affective language area

right hemisphere, lesions produce aprosody, flat emotionless speech

cerebral lateralization

the difference in the structure and function of the cerebral hemispheres

left hemisphere

categorical hemisphere, spoken and written language, analytical reasoning, breaks information into fragments and analyzes it

right hemisphere

creative hemisphere, imagination and insight, musical and artistic skill, comparison of sights, smells and tastes

cranial nerves

carry fibers between brainstem and ipsilateral receptors and effectors, carry sensory information

olfactory nerve (I)

used to send sense of SMELL to the brain

optic nerve (II)

used to send visual signals to the brain via the optic chiasma

oculomotor nerve (III)

control the size of the pupil and movement of eye

trochlear nerve (IV)

controls movement of eye

trigeminal nerve (V)

provides motor movement and sensory info for different aspects of your face

Abducens Nerve (VI)

movement of eyeball

Facial Nerve (VII)

motor nerve of facial muscles, facial expressions, salivary glands, taste on anterior 2/3rds of tongue

vestibulocochlear nerve (VIII)

conducts sense of equilibrium and sound

glossopharyngeal nerve (IX)

used to control tongue, salivary glands and swallowing muscles

vagus nerve (X)

swallowing, speech, most extensive distribution of any cranial nerve, major role in the control of cardiac, pulmonary, digestive, and urinary function

accessory nerve (XI)

movement of sternocleidomastoid and trapezius

hypoglossal nerve (XII)

movement of TONGUE