Anatomy PPT 1 Flashcards
brain is enclosed by:
cranium, a fixed bony cavity
brain is physically and functionally divided into two compartments
supratentorium
infratentorium
supratentorium contains
paired cerebral hemispheres and the diencephalon (composed of the thalamus and hypothalamus)
Each cerebral hemisphere is divided into four lobes
frontal
temporal
parietal
occipital
Cortical regions responsible for language are located in
the left hemisphere in almost all right-handed people and majority of left-handed people
Two primary regions responsible for language
Broca’s area
Wernicke’s area
Diencephalon is composed of
thalamus and hypothalamus
Thalamus acts as
sensory and motor relay station
directs information to various cortical structures
Hypothalamus:
lies below the thalamus
has autonomic and endocrine functions
is connected to the pituitary gland
primary neurohumoral organ
limbic system
cognitive function, memory consolidation, and emotional responses
Infratentorium
brainstem and cerebellum
Brainstem contains nuclei for cranial nerves
III to XII
Cerebellum responsible for:
proprioception, posture and gait
Frontal lobe:
motor cortex
parietal lobe:
somatic sensory cortex
occipital lobe:
vision cortex
temporal love:
auditory cortex and speech centers
cerebral cortex:
cognition, sensation, and movement
Hippocampus:
memory and learning
Amygdala:
emotion, appetite, responds to pain and stressors
Basal ganglia:
fine control of movement
midbrain:
auditory and visual tracts
pons:
autonomic integration
medulla:
autonomic integration
reticular activating system:
controls consciousness, arousal. and sleep
Archeocerebellum:
maintains equilibrium
Paleocerebellum:
regulates muscle tone
Neocerebellym:
coordinates voluntary muscle movement
Cranial nerve I:
olfactory, sensory
smell
Cranial nerve II:
optic, sensory
vision
Cranial nerve III:
oculomotor, motor eye movement (up), pupil constriction
Cranial nerve IV:
Trochlear, motor eye movement (down/in)
Cranial nerve V:
trigeminal, both
somatic sensation to face, anterior 2/3 tongue
muscles of mastication
Cranial nerve VI:
abducens, motor eye movement (out)
Cranial nerve VII:
facial, both
facial movement, eyelid closing, taste anterior 2/3 tongue
Cranial nerve VIII:
Vestibulocochlear, sensory
hearing and balance
Cranial nerve IX:
Glossopharyngeal, both
somatic sensation and taste to posterior 1/3 of tongue
Cranial nerve X:
vagus, both
swallowing
Cranial nerve XI:
spinal accessory, motor
shoulder shrug
Cranial nerve XII:
hypoglossal, motor
tongue movement
All nerves are part of the peripheral nervous system except:
CN 2
severe neuropathic facial pain comes from damage to:
CN 5
trigeminal neuralgia
Eye movement is controlled by
CN 3, 4, 6
injury to facial nerve causes:
Bell’s palsy
ipsilateral facial paralysis
Parasympathetic output carried by CN:
3, 7, 9, 10
Which CN is responsible for 75% of all parasympathetic activity?
Vagus (10)
Blood flow of the brain is supplied by four large arteries
two carotid and two vertebral arteries
Normal blood flow through the brain of the adult person averages
50 ml/100 grams brain tissue/minute
Normal blood flow through the brain of the adult person averages (in ml/min)
750 ml/min
The brain constitutes only about 2 percent of the body weight but receives _____ CO
15% of resting CO
Brain blood supply: anterior circulation receives blood from
internal carotid arteries
Brain blood supply: posterior circulation receives blood from
vertebral arteries
arterial systems communicate through arterial anastomoses that form
Circle of Willis
arteries that originate from the circle of Willis:
paired anterior, middle, and posterior cerebral arteries
Brain blood supply: ____ supplies the ipsilateral cerebral hemisphere
carotid artery
Brain blood supply: ____ supplies the structures of the posterior fossa
the vertebrobasilar system
What does the circle of willis do?
permits collateral blood flow
if a major vessel (right or left internal carotid arteries or basilar artery) becomes occluded
major vessels supplying the circle of Willis are
right and left internal carotids and the basilar artery. The basilar artery is supplied by
the right and left vertebral arteries.
_____ measures the pressure transmitted through the circle of Willis back to the carotid artery for which endarterectomy is proposed
stump pressure
A good stump pressure means:
that the brain will be perfused
adequately during the procedure.
Stump pressure of _____ are as reliable as EEG monitoring
> 40 mmHg
Metabolic factors contribute to cerebral blood flow regulation:
(1) carbon dioxide concentration
(2) hydrogen ion concentration
(3) oxygen concentration
increase in carbon dioxide concentration _______ cerebral blood flow
increases
A change in PaCO2of 1 mmHg roughly correlates to a change in CBF of
1-2 ml/100 g/min
PaCO2 _____ leads to maximal vasoconstriction & tissue hypoxia
<20
increase in hydrogen ion concentration (lactic acid, pyretic acid) will ____ CBF
increase
oxygen deficiency almost immediately causes ______
vasodilation to restore blood flow & O2 transport to the brain to normal (PaO2<50mmHg)
normal PaO2
50 mmHg
CBF is auto regulated well between MAP of
60-140 (or 60-160)
In people with HTN, auto regulation of CBF occurs in pressures up to:
160-180
CBF varies linearly between arterial carbon dioxide partial pressures (PaCO2) of:
20 to 80 mmHg
Cerebral blood flow remains constant above an arterial oxygen partial pressure (PaO2)
50 mmHg
Profound increase in CBF only at PaO2 of:
less than 50-60
PaO2 of 60+ has what effect on CBF?
no effect
CPP =
MAP - ICP
Normal CPP:
100 mmHg
CPP <50
EEG slowing
CPP 25-40
EEG flat
CPP <25
permanent brain damage
CBF 20ml/100g/min:
evidence ischemia
CBF 15ml/100g/min:
complete cortical suppression
CBF <15ml/100g/min:
membrane failure and cell death
Vessels that supply ischemic or atherosclerotic regions are
maximally dilated
Situations that cause cerebral vasodilation can cause
cerebral steal
steal flow from ischemia areas
Robinhood effect:
hyperventilation to constrict cerebral vessels that supply healthy tissue to redistribute to ischemic regions
Best practice regarding steal phenomena:
maintain normocapnia or mild hypocapnia (PaCO2 = 30-35)
Cerebrospinal fluid is secreted by
the ependymal cells of the choroid plexus within the ventricular system
Cerebrospinal fluid is secreted at rate of
30 ml/hr
CSF flows from the lateral ventricles of the cerebral hemispheres through the
foramen of Monro
After CSF flows through foramen on monro, it goes into
the third ventricle and through the aqueduct of Sylvius in the midbrain
After CSF flows through the aqueduct of Sylvius in the midbrain, it goes into
the fourth ventricle
CSF enters the subarachnoid space through
the medial foramen of Magendie and the paired lateral foramina of Luschka, openings posterior to the pons and anterior to the cerebellum
CSF drains into the venous blood via the
superior sagittal sinus
CSF is absorbed by
arachnoid granulations & arachnoid villi
CMRO2:
3-3.8 ml O2/100 g/min
Direct linear relationship of CMRO2 to CPP is called
coupling
As CMRO2 increases, CPP correspondingly
increases
relationship between CMRO2 and CBF can be modified by
anesthetics/anesthetic management
things that decrease CMRO2
all VAAs, barbiturates, and benzodiazepines
propofol, etomidate, hypothermia
VAA do what to CMRO2 and CPP?
decrease CMRO2
increase CPP
main energy substrate used by the brain
glucose
brain glucose consumption:
5 mg/100g/min
oxygen utilization by brain:
___ used for electrical activity
___ used for cellular integrity
60% electrical
40% cellular
(even if brain is silenced, it must consume O2 to support cellular integrity)
CMRO2 decreases by __% for every 1*C decrease in temp
7%
EEG suppression occurs at what temp?
18-20*C
mild hypothermia (32-24*C) for 12-24 hours may improve outcomes in what population?
its with anoxic brain injury, because it reduces O2 consumption
