chapter 14 - brain and cranial nerves

gray matter

the seat of neurosomas, dendrites, and synapses, forms nuclei deep within brain

white matter

bundles of axons, lies deep to cortical gray matter, composed of tracts

ventricles

four internal chambers within the brain

choroid plexus

spongy mass of blood capillaries on the floor of each ventricle

fourth ventricle

small triangular chamber between pons and cerebellum, connects to central canal of spinal cord

third ventricle

narrow medial space beneath corpus callosum

ependymal cells

type of neuroglia that lines ventricles and covers choroid plexus, produce CSF

cerebrospinal fluid

clear, colorless liquid that fills the ventricles and canals of CNS

buoyancy, protection, chemical stability

what are the 3 functions of CSF?

brain barrier system

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

reticular formation

loose web of gray matter that runs vertically through all levels of the brainstem

somatic motor control, cardiovascular control, pain modulation, sleep/consciousness, habituation

what are the five main functions of the reticular formation?

cerebellum

largest part of hindbrain and second largest part of the brain, contains more than half of all brain neurons

motor coordination and locomotor ability

what are the main functions of the cerebellum?

diencephalon and telencephalon

what are the two parts of the forebrain?

thalamus

ovoid mass on each side of the brain perches at the superior end of the brainstem beneath the cerebral hemispheres

filters information

what is the main function of the thalamus?

hypothalamus

forms part of the walls and floor of the third ventricle

infundibulum

stalk attaching pituatary to hypothalamus

hormone secretion, autonomic effects

what are 2 functions of the hypothalamic nuclei

thermoregulation, food and water intake, sleep and circadian rhythms, memory, strong emotions

what are 5 functions of the hypothalamus

epithalamus

very small mass of tissue composed of the pineal gland and habenula

habenula

relays information from the limbic system to the midbrain

projection tracts

extend vertically between higher and lower brain and spinal cord 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 the cerebrum

cerebral cortex

covers surface of hemispheres

gray matter of the cerebrum

where is neural integration carried out?

cerebral cortex, limbic system, basal nuclei

where are the 3 places that cerebral gray matter is found?

stellate cells

have spheroid neurosomas with dendrites projecting in all directions, receive sensory input and process information on a local level

pyramidal cells

tall and conical with apex toward the brain surface, a thick dendrite with many branches with small, knobby dendritic spines

limbic system

important center of emotion and learning

cingulate gyrus, hippocampus, amygdala

what are the three components of the limbic system

cingulate gyrus

arches over corpus callosum in frontal and parietal lobes

hippocampus

in medial temporal lobe (memory function)

amygdala

immediately rostral to hippocampus (emotion function)

basal nuclei

masses of cerebral gray matter buried deep in the white matter, lateral to the thalamus

lentiform nucleus

putamen and globus pallidus together

primary sensory cortex

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

special senses

limited to the head and employ complex sense organs

vision, hearing, equilibrium, taste, smell

what are the special senses?

general senses

distributed over entire body and employ simple receptors

somesthetic association area

makes cognitive sense of the stimulus

somatotopy

point to point correspondence between an area of the body and an area of the CNS

basal nuclei

important motor functions like helping control intentional movements, repetitive movements like walking, and muscle memory

dyskinesias

movement disorders caused by lesions in the basal nuclei involving abnormal movement initiation

cerebellum

aids in learning motor skills, maintains muscle tone and posture, coordinates eye and body movements

wernickes area

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

brocas area

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

affective language area

usually in right hemisphere, lesions produce aprosody, flat emotionless speech

nonfluent (broca) aphasia

slow speech, difficulty in choosing words, using words that only approximate the correct word

fluent (wernicke) aphasia

speech normal and excessive, but uses senseless jargon, cannot comprehend written and spoken words

anomic aphasia

can speak normally and understand speech but cannot identify written words or pictures

cerebral lateralization

the difference in the structure and function of the cerebral hemispheres

left hemisphere

usually the categorical hemisphere, specialized for spoken and written language, sequential and analytical reasoning, breaks information into fragments and analyzes it

right hemisphere

usually the representational hemisphere, perceives information in a more integrated way, seat of imagination and insight, musical and artistic skill, perception of patters and spatial relationships

I, II, and VIII

what cranial nerves are sensory?

III, IV, VI, XI, XII

what cranial nerves are motor?

V, VII, IX, X

what cranial nerves are mixed?

olfactory nerve (I)

used to send the sense of smell to the brain

optic nerve (II)

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

oculomotor nerve (III)

controls the size of pupil and superior, inferior, and medial rectus and inferior oblique

trochlear nerve (IV)

controls movement of the eye, superior oblique

trigeminal nerve (V)

most important sensory nerve of the face, forks into three divisions

abducens nerve (VI)

movement of eye, lateral rectus

facial nerve (VII)

major motor nerve of facial muscles, taste on anterior two thirds of tongue, damage produces sagging facial muscles and disturbed sense of taste

vestibulocochlear nerve (VIII)

conducts sense of equilibrium and sound

glossopharyngeal nerve (IX)

used to control tongue, salivary glands, and swallowing muscles

vagus nerve (X)

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

accessory nerve (XI)

movement of sternocleidomastoid and trapezius

hypoglossal nerve (XII)

movement of tongue