physio neuroanatomy pt 2.

circle of willis formed by

2 internal carotid arteries

basilar artery formed by

2 vertebral arteries

right internal carotid and left vertebral artery control

blood flow

blood pressure is maintained by

constant through central control and carotid reflex

when arterial BP falls below 70mmHG

cerebral blood flow is compromised cause orthostatic hypotension or surgical shock

cerebrovascular resistance

circulation may be reduced by 50%

polycythemia

high concentration of RBC in blood making blood thick and less able to travel through vessel and organs, kind of blood cancer

when MAP falls

cerebral arterioles dilate → resistance decrease

when MAP rises

cerebral arterioles constrict → resistance increase

MAP

mean arterial pressure

ICP

intracranial pressure

cerebral perfusion pressure

MAP -ICP

does autoregulation have its limits?

yes

severe hypotension/elevated ICP can

reduce cerebral perfusion

physiological control and major factors of cerebral blood flow

BP/CPP, arterial CO2, arterial O2, blood viscosity

is an issue arrises in BP/CPP, arterial CO2, arterial O2, blood viscosity what can occur

orthostatic hypotension, shock, intracranial hypertension, hyperventilation, polycythemia

cerebral capillaries have unique characteristics that ______ permit passage of substances through ______ between _________

do not, junctions, endothelial cells

what are brain capillaries surrounded by

endfeet of astrocytes

what can cross the cerebral capillaries with ease

water, CO2, O2

what can cross the cerebral capillaries but it is slow

exchange of other substances

capillaries in the brain are of ____________ which have _______ between endothelial cells _______ passage of small molecules

non fenestrated type, tight junctions, permitting

blood brain barrier is a highly selective

semipermeable border of endothelial cell that prevent solute in circulating blood

BBB is formed by

endothelial cells of capillary wall, astrocyte, pericytes in basement membrane

BBB system allows

passage of small molecule by passive diffusion

BBB restrict passage of

pathogens, solutes, large/hydrophilic molecules into CSF

cells of BBB actively transport

metabolic products using specific transport proteins

BBB also restricts passage of

peripheral immune factors

circumventricular organs are

areas in brain and around hypothalamus where BBB doesnt exist

areas in brain where BBB doesnt exist

posterior pituitary, pineal body, area postrema, supraoptic crest, subfornical organ

what are clinical implications of the BBB

kerniterus and crigler-najjar syndrome, breakdown in fection/irradiation/tumors, breakdown by increase in BP, penetration by drugs

spinal cord is

column of nervous tissue continous with brain and begin outside cranial cavity

31 segments of spinal cord include, how many cervical

8

31 segments of spinal cord include, how many thoracic

12

31 segments of spinal cord include, how many lumbar

5

31 segments of spinal cord include, how many sacral

5

31 segments of spinal cord include, how many coccygeal

1

what is function of spinal cord

conduction of info from and to brain, integrative center for reflexes

integrative center for reflex consist of

patellar, withdrawal, evacuation

patellar reflex

knee jerk

withdrawal reflex

skeletal muscle

evacuation reflex

urinary bladder and large intestine

ascending tract of spinal cord

carry sensory info to the brain

decending tract of spinal cord

conduct motor impulse from brain to muscle and gland

corticospinal in descending tract

conduct impulse from brain cortex to spinal cord, controls voluntary movements

reticulospinal in descending tract

brain to muscle and sweat gland, muscle tone and sweat

vestibulospinal in descending tract

equilibrium and posture

rubrospinal in descending tract

muscle coordination and posture control

tectospinal in descending tract

head and eye movements

which part of the decending tracts are pyramidal

corticospinal

which part of the decending tracts are extrapyramidal

reticulospinal, vestibulospinal, rubrospinal, tectospinal

spinal cord injuries

flaccid and spastic paralysis

flaccid paralysis

loss of muscle tone and atrophy from damage to motor pathways

spastic paralysis

increase muscle tone with no atrophy, lack of muscle control, damage to motor pathways

parts of brain

brain stem, diencephalon, cerebellum, cerebrum

brain stem is composed of __________ and ___________ and has 3 major parts

white matter, grey matter

what are 3 major parts of brain stem

medulla oblongata, pons, midbrain

the pons nuclei

facial and trigeminal, vestibular, respiratory, raphe

midbrain consist of

corpora quadrigemina and red nucleus

reticular formation of brain stem is part of brain RAS which controls

sleep, wakefulness, focus, filer, perceptual association

how many cranial nerves are there

12

olfactory (CN1)

arise from olfactory bulb on ventral portion of frontal lobe of brain

optic (CN2)

arise from retina to brain via optic foramen

oculomotor (CN3)

parasympathetic fiber supply ganglion to sphincter of iris and ciliary muscle

trochlear (CN4)

supply muscle with moves the axis of vision downward and inward

trigeminal (CN5)

3 division: 1= opthal / 2= maxillary / 3= mandibular-sensory fiber

abducens (CN6)

supply lateral rectus muscle that rotate eyeball outward

facial (CN7)

fiber supply skeletal muscle of ear, face, scalp, parasympathetic fiber to membrane and gland of pharynx, palate, nasal cavity, etc.

acoustic/vestebulocochlear (CN8)

vestebular and cochlear nerves

glossopharyngeal (CN9)

motor to pharynx, sensory from pharynx/soft palate/tongue/tonsil/auditory tube, etc.

vagus (CN10)

pass to muscle of pharynx, soft palate, sensory from pharynx/larynx/trachea/esophagus/throacic/abdominal viscera

spinal accessory (CN11)

muscle of larynx and jaws

hypoglossal (CN12)

muscle of tongue

important hypothalamus structures

optic chiasma, infundibulum, pituitary gland, mammillary body

function of hypothalamus

control body temp, regulate water/electrolyte balance, basic drive of hunger/thirst/sexual activity, control movement and glandular secretion of stomach/intestine, control and production of hormone that stimulate release various pituitary hormone, regulate sleep/wakefulness

cerebellum consist of

cerebellar cortex and nuclei (dentate/fastigal/globose emboliform)

cerebellum function

coordination of skeletal muscle activities

lobes of cerebrum

frontal, parietal, temporal, occipital

function of cerebral cortex

motor area, sensory area, association area

sensory cortex include

somatosensory, visual, auditory, olfactory cortex

somatosensory function

localize touch, process body

visual function

process visual input from visual fields

auditory function

analyse pitch, timing, and sound features

olfactory function

processess odor identity

a unilateral primary auditory cortical lesion rarely cause

complete deafness bc auditory pathways project bilaterally

cerebral dominance

left hemisphere, dominant side in humans

left hemisphere is dominant to humans bc

verbal inguistic consist of broca’s area and wernickes area

broca’s area (left frontal lobe)

area of speech allow us to speak properly

wernickes area and brocas area help us

speak and learn by hearing

basal ganglia comprised of

caudate nucleus, putamen, globus pallidus, subthalmic nucleus, substantia nigra, red nucleus, corpus striatum, lentiform nucleus

limbic system also known as

rhinencephalon and visceral brain

limbic system comprised of

amygdala, hypothalmic nuclei, hippocampus

amygdala

small nuclei that regulate fear and emotional processing

hypothalmic nuclei

associated with thirst, hunger, sex appeal

hippocampus

seed of learning and memory