Topic 20 Central Nervous System PPT Part 2

the brain stem

structurally different from brain because it has deep gray matter surrounded by white matter

includes: midbrain, pons, medulla oblongata

brain stem: midbrain

coordinates head and eye movement when we visually follow a moving object or see something out of corner of eye

coordinates head reflex movement to unexpected auditory stimulus - startle reflex

brain stem - medulla oblongata

adjusts force and rate of heart beat, regulate breathing and blood pressure

brain stem - pons

helps to maintain normal rhythm of breathing

medulla oblongata: decussation

crossing over

the brain controls the opposite sides of the body

where the nerves that send or receive signals to the opposite side cross

the cerebellum

coordinate skeletal muscle contractions needed for the smooth movements

occurs subconsciously

application: injury level

abnormal posturing can occur when there is injury to the brain

decerebrate

more serious, damage to midbrain and lower

decorticate

damage to midbrain, cerebral hemispheres

the diencephalon

surrounded by the cerebral hemispheres

consists of 3 bilaterally symmetric structures: thalamus, hypothalamus, epithalamus

the thalamus

makes of 80% of diencephalon, where sorting out and information editing process occurs, relays sensory and motor signals to the cerebral cortex

the hypothalamus

caps the top of the brain stem

main control center of the endocrine and autonomic nervous system

vitally important to the homeostasis

the epithalamus

most dorsal portion of the diencephalon, pineal gland forms the bulk of the epithalamus

limbic system

group of structures in both cereal hemispheres and diencephalon

critical for memory function and feelings

limbic system: amygdala

links emotions to specific memories

responds to fear and anxiety

limbic system: hippocampus

organizes sensory and cognitive information into a new memory

basal ganglia

masses of gray matter deep within cerebral hemispheres

relay for motor impulses from cerebral cortex, subconscious control of movements

reticular formation

complex network of nerve fibers

controls levels of consciousness, filters incoming sensory information for importance

brain has 2 hemispheres

left and right sides are separated

corpus callosum

major pathway between hemispheres

cerebral white matter

deep to the gray matter of cortex

aids communication between cerebral areas and between cerebral cortex and lower CNS

white matter connection fibers

association, commissural, projection fibers

cerebral hemispheres

83% of brain mass

covered with gyri and sulci

fissures separate regions of brain

4 lobes in hemisphere

frontal, parietal, occipital, temporal lobe

frontal lobe

voluntary motor functions

planning, mood, smell, and social judgement

parietal lobe

receives and integrates sensory information

occipital lobe

visual center of brain

temporal lobe

areas for hearing, smell, learning, memory, emotional behavior

sensory association areas

interpret sensory information

somesthetic association area (parietal lobe)

position of limbs, location of touch or pain; shape, weight, and texture of an object

visual association area (occipital lobe)

identify things we see, faces recognized in temporal lobe

auditory association area (temporal lobe)

recall the name of a piece of music or identify a person by his voice

motor control

intention to contract a muscle begins in motor association area of frontal lobes

pre central gyrus relays signals to spinal cord

contralateral motor control

right hemisphere controls left side of brain, left controls right

language

includes reading, writing, speaking, and understanding words

wernickes area

permits recognition of spoken and written language and creates plan of speech

broca’s area

generates motor signals for larynx, tongue, cheeks, and lips

transmits to primary motor cortex action

aphasia

speech production and comprehension difficulties

lesion to broca = nonfluent aphasia

slow speech, difficulty in choosing words

lesion to wernicke = fluent aphasia

speech normal and excessive, but makes little sense

primary progressive aphasia

type of frontotemporal dementia, results from the degeneration of the frontal or temporal lobes of the brain

prefrontal cortex of frontal lobe

integrates information from sensory association, working memory, performs intellectual activities

cerebral lateralization

left and right hemisphere

left hemisphere - categorical hemisphere

specialized for spoken and written language, math and science reasoning, analyzing data

right hemisphere - representational hemisphere

perceives information, spatial relationships, patterns, special senses, music, imagination