What determines intelligence
number of active synapses among neurons
what is the typical brain volume and weight
1300cc
3 lbs
4 major regions of the brain
cerebrum
diencephalon
brainstem
cerebellum
folds in the brain
gyri
shallow depressions
sulci
6 week embryo order
telencephalon diencephalon mesencephalon metencephalon myelencephalon
telencephalon
cerebrum
diencephalon
diencephalon
mesencephalon
mesencephalon, forms a short section between the dicephalon and the pons
metencephalon
cerebellum and pons
myelencephalon
medulla oblongata
What determines the boundaries of the brains cavities
bends and creases that occur in the developing brain
gray matter
motor neuron and interneuron cell bodies
dendrties
branching axon terminals
unmyelinated axons
white matter
derives color from the myelin in the myelinated axons
also contains dendrites and associated neurogiial cells
inner region of white matter is called:
medulla (marrow)
what protects and isolates the brain
bony cranium
meninges (connective tissue membranes)
cerebrospinal fluid
blood brain barrier
meninges
3 connective tissue layers that separate the soft tissue of the brain from the bones of the cranium
pia mater
delicate mother, innermost of cranial meninges, highly vascular, follows every contour of brains surface
arachnoid
internal to dura mater, delicate web of collagen and elastic fibers
also contains the subarachnoid space
what lies between the arachnoid and the overlaying dura mater
subdural space
dura mater
tough mother, most external, tough dense irregular connective tissue with 2 fibrous layers, strongest of the meninges
2 layers of the dura mater
meningeal layer (deeper of the 2) periosteal layer
blood filled spaces
dural venous sinuses
dural venous sinuses
large veins that drain blood from the brain and transport the blood to the internal jugular veins
epidural space
contains arteries and veins that nourish the meninges
not actually a space
can become a spce due to trauma
cranial dural septa
double layers of dura mater
separate specific regions of the brain and provide stabilization
4 cranial dura septa
- falx cerebri
- tentorium cerebelli
- falx cerebelli
- diphragma sellae
falx cerebri
largest
sickle shaped
extends off of crista galli
tentorium cerebelli
contains the tentorial notch to allow passage of the brainstem
falx cerebelli
sickle shaped, divides the left and right cerebellar hemispheres
diphragma sellae
smallest, forms roof over the sella turcica of the sphenoid bone
brain ventricles
cavities within the brain that are derived from the lumen of the embryonic neural tube
4 brain ventricles
- 2 lateral ventricles
- 3rd ventricle
- 4th ventricle
lateral ventricles
in cerebrum,separated by septum pellucidum
third ventricle
located in diencephalon, communicates with lateral ventricle
fourth ventricle
between pons and cerebellum, merges with central canal
cerebrospinal fluid
clear liquid that circulates in the ventricles and subarachnoid space
functions of the cerebrospinal fluid
buoyancy
protection
environmental stability
CSF buoyancy
reduces weight by 95%
CSF protection
provides liquid cushion
CSF environmental stability
transports nutrients, chemical messengers, removes waste
CSF formation
formed by choroid plexi, filtrate of plasma that contains proteins and salts
blood brain barrier
protects nervous tissue
where the blood brain barrier is reduced or missing
choroid plexi
hypothalamus
pineal gland
cerebrum
location of conscious thought processes and the origin of all complex intellectual functions
cerebrum is the center for what
intelligence, reasoning, sensory perception, thought, memory, judgment, voluntary motor, visual, and auditory activities
what is the outer gray layer of the cerebrum called
cerebral cortex
inner white layer of the cerebrum
cerebral medulla
What separates the paired cerebral hemispheres
longitudinal fissure
largest white matter tract
corpus callosum, provides main method of ommunication
five lobes
frontal parietal temporal occipital insula (not visible from the surface)
frontal lobe
voluntary motor functions concentration verbal communication decision making planning personality
parietal lobe
general sensory functions
temporal lobe
hearing
interpreting speech and language
smell
occipital lobe
process incoming visual info
stores visual memories
insula
can be seen by pulling aside the temporal lobe
memory
interpretation of taste
injury to the cerebrum after a blow to the head
coup-contrcoup
diencephalon
between inferior regions of teh cerebral hemispheres, including the epithalamus, thalamus, and hypothalamus
epithalamus
houses pineal gland
pineal gland
secretes the melatonin which helps regulate day-night cycles (circadian rhythm)
thalamus
oval masses
final relay point for all sensory info except for the sense of smell
hypothalamus
infundibulum heart rate, blood pressure, digestive activities, respiration hormone secretino thermostat emotional response controls hunger/thirst sleep/wake cycle
bidirectional passageway
brainstem
mesencephalon
superior portion
visual and auditory reflexes
control of posture and movement
pons
relay impulses
regulate breathing
medulla oblongata
all communication between brain and spinal cord involves nerve fibers tracts that go through here
cardiac center
vasomotor center
respiratory center
coughing, sneezing, salvation, gagging, vomiting
cerebellum
second largest part of the brain and develops from the metencephalon
outer layer of cerebellum
cerebellar cortex
inner layer of cerebellum
arbor vitae
functions of cerebellum
smooth movement muscle contraction muscle memory coordination of muscle movement equilibrium and posture muscle tone attention processing language, music and other stimuli
reticular formation
loosely organized core of gray matter
regulate muscle tone
RAS-maintain a state of awareness or consciousness
RAS
reticular activating system
limbic system
emotions
border around diencephalon
motivationnal and mood states
odors can provoke emotions here
Rostrocaudal brain deterioration
sequence of events that occurs when the cerebrum pushes down through the tentorial incisure because of head trauma
steps of rostrocaudal brain deterioration
- pressure builds, CSF is squeezed out
- hypoxia (loss of oxygen)
- unconsciousness
- decorticate posturing
- decerebrate posturing (last reversible stage)
- brain death
most common serious disease of the CNS
cerebrovascular accident (stroke)
causes of cerebrovascular accidents
thrombus formation
intrecerebral hemorrhage
aneurysm
fatty plaque build up
hemiplegia
contralateral paralysis of body (result of stroke)
I
olfactory
olfactory
sensory
chemoreceptors
smell
II
optic
optic
sensory
enter optic foramen converge to form optic chiasm
meninges travel along here
III
oculomotor
oculomotor
motor
internal muscles constrict the eyeball
trauma can cause same side paralysis
IV
Trochlear
Trochlear
motor
in mesencephalon
downward and lateral movement of eyeball
V
trigeminal
Trigeminal
both sensations of touch, temperature and pain ophthalmic branch maxillary branch (photic sneeze reflex) mandibular branch (dental anasthesia) chewing
VI
abducens
abducens
motor
moves eye laterally
VII
facial
facial
both
facial expression
taste (sweet)
stimulate salivary glands
VIII
vestibulocochlear
vesibulocochlear
sensory
vestibular branch- balance
cochlear branch-hearing
IX
glossopharyngeal
glossopharyngeal
both
stimulate swallowing
bitter taste on posterior portion of the tongue
X
vagus
vagus
both
longest cranial nerve
innervates most muscles of pharynx and larynx
receives input from EAC and eardrum, pharynx, larynx, heart, lungs, esophagus, abdominal organs
XI
accessory
Accessory
motor
innervates pharynx
innervates trapezius
XII
hypoglossal
hypoglossal
motor
innervates muscles of tongue
damage can lead to diffiuclty of speech
tapering inferior end of spinal cord
conus medullaris
inferior to the conus medullaris, group of axons
cauda equima
thin strand of pia mater that is the anchor
filum terminale
cervical enlargement
inferior cervical region of the spinal cord contains the neurons that innervate the upper limb
lumbosacral enlargement
innervates the lower limbs
31 pairs of spinal nerves
c1-c8 t1-t12 l1-l5 s1-s5 co
outermost to innermost structures and space that encircle the spinal cord
vertebra epidural space dura mater subdural space arachnoid subarachnoid space pia
what is the epidural space made up of
loose connective tissue, blood vessels, adipose connective tissue
what is found in the subarachnoid space
cerebrospinal fluid
peripheral white matter of spinal cord
myelinated axons
neural communication to and from brain
central gray matter of spinal cord
dendrites and cell bodies
spinal reflexes
has central canal filled with CSF
dermatome
specific skin segment supplied by a single spinal nerve (except c1)
referred visceral pain
pain or discomfort from one organ is mistakenly referred to a dermatome
nerve plexus
network of interweavinf spinal nerves t2-t12 and s5-co1 do not for plexuses
cervical plexus
deep to the neck
c1-c4
*phrenic nerve
brachial plexus
upper limbs
c5-t12
major nerves from the brachial plexus
axillary nerve median nerve musculocutaneous nerve radial nerve ulnar nerve
lumbar plexuses
l1-l4
nerves of the lumbar plexus
femoral nerve (medial) obturator nerve (supramedial)
sacral plexus
l4-s4
nerves of sacral plexus
sciatic nerve (largest)
tibial nerve
common fibular nerve
the neural canal develops into what
central canal
trauma above c3
death by asphyxiation innervation to the intercostal muscles and innervation to the diaphragm are lost
trauma between c4 and c7
quadriplegia
what happens if c3 and c4 are intact after trauma
phrenic nerve functions and will be able to breath on their own
trauma between t1 and l1
paraplegia of lower extremities
amount of blood pumped from one ventricle per minute is called
cardiac output
two blood vessels
arteries
veins
arteries
away from heart
arterioles
carry blood high in oxygen
veins
towards the heart
low in oxygen
great vessels
blood vessels leaving the hear, large in diameter
unidirectional flow`
no backflow prevented by valves
right side pump
directs blood to the lungs for gas exchange
left side pump
blood to body tissues for nutrient and respiratory gas delivery
blood pressure
alternate cycles of heart wall contraction and relaxation (minimal blood pressure is needed)
2 circulations
pulmonary
systemic
pulmonary circulation
right side of heart
pulmonary arteries-poorly oxygenated blood to lumgs
pulmonary veins-high oxygen to lungs
systemic circulation
left side
all named blood vessels that carry blood to all peripheral organs and tissues
sac that contains the heart
pericardium, double layered serous lining
two parts of pericardium
outer= fibrous
inner=serous
2 layers of serous pericardium
parietal layer (in) visceral layer (out)
potential space between parietal and visceral
pericardial cavity
pericardial cavity
serous fluid lubricates membranes, prevents friction
bleeding in the pericardial cavity can lead to:
cardiac tamponade- pulsus paradoxus, jugular vein disention
3 layers of heart
epicardium
myocardium
endocardium
epicardium
outermost
visceral layer
becomes fattier with age
myocardium
middle
thickest
heart attacks occur here
endocardium
internal
covers external surfaces of the heart valve
contiguous with endothelium
hollow chambers
smaller atria
larger ventricles
atria
thin walled chambers
auricle
right atrium
receives blood from systemic circuit
left atrium
receives blood from pulmonary circuit
pulmonary trunk
carries blood from right ventricle into the pulmonary circuit
aorta
conducts blood from the right ventricle into the systemic circuit
valves
lined with endothelium, allow blood to only travel in one directino
fibrous skeleton
between atria and ventricles, dense irregular connective tissue
functions of fibrous skeleton
separates atria and ventricles
anchors heart valves
electrical insulation (not randomly spread impulses)
framework
right atrium
receives blood from systemic circulation