HLTH nervous system review Flashcards
anatomy of sutures
fibrous CT
choroid plexuses
areas of highly vascularized tissues in the ventricles that filter CSF
largest opening in the skull
forearm magnum which passes through the occipital bone
association area
refers to where sensory input is recognized and interpreted; ex. visual stimuli is identified here
dominant hemisphere meaning
is the side of the brain controlling language, which is usually the left side
broca’s area
motor speech area; located at the base of the premotor area of the left hemisphere
wernicke’s area
sensory speech area; located in the posterior temporal lobe
prefrontal cortex function
intellectual function, personality, and impulse control
basal nuclei
part of the extrapyramidal system and prevents excessive movements as well as accessory movements (ex. swinging arms while walking)
where is the limbic system located?
superior part of the brainstem
epithalamus
acts as a connection between the limbic system and other areas of the brain
2 arteries supplying the brain
internal carotid and vertebral
anterior cerebral artery
supplies the frontal lobe
middle cerebral artery
supplies the lateral sides of the temporal and parietal lobes
basilar artery
supplies the brainstem and cerebellum; this branches to form the left and right posterior cerebral artery
posterior cerebral artery
supplies the occipital lobe
circle of willis
provides an alternative source of blood when obstruction occurs in the vertebral or internal carotid arteries; surrounds the pituitary gland and optic chiasm
4 cranial nerves containing parasympathetic fibres
III, VII, IX, and X
where does the spinal cord end?
L1; below this is the cauda equina
lateral spinothalamic tract
ascending tract regulating temperature and pain
dermatone
is an area of sensory innervation of the skin by a spinal nerve
what cells create the myelin sheath?
schwann cells in the PNS and oligodendrocytes in the CNS
glial cells
supporting cells for neurons
astroglia
provide a link between neurons and capillaries, provide metabolic support, and help establish the blood-brain barrier
microglia
have phagocyte activity
ependymal cells
line ventricles and spinal cord and form choroid plexuses
where does neurogenesis usually occur?
in the hippocampus
electroencephalogram
measures brain waves and electrical activity
examples of cathecolimes
dopamine, norepinephrine, and epinephrine
most common inhibitory neurotransmitter in the brain
gamma-aminobutyric acid
most common inhibitory neurotransmitter in the spinal cord
glycine
serotonin role
is involved in mood, sleep, and emotions
histamine role
is involved in body temperature, emotions, and water balance
heart, blood vessel, and renin receptor
beta 1
skin, mucosa, and viscera receptors
alpha 1
skeletal muscle receptors
beta 2
respiratory system receptors
beta 2
what do alpha 1 receptors supply?
skin, mucosa, viscera, eye, sweat glands, digestive sphincters, and male genitalia
alpha 2 receptors
supply the digestive system
what receptors does norepinephrine act on?
alpha
what receptors does epinephrine act on?
alpha and beta
nicotinic receptors
are always stimulated by AcH and are part of the PNS
muscarinic
are either stimulated or inhibited by AcH and are part of the PNS
cholinergic blocking agents
block PNS activity
cholinergic or anticholinesterase agents
increase PNS activity
where are UMN located?
the motor cortex
where is the RAS found?
the midbrain
extrapyramidal tract function
modify and coordinate voluntary output and maintain posture
4 nerve plexuses
brachial, lumbar, sciatic, and cervical
saltatory conduction
involves the rapid AP along myelinated neurons
cholinergic fibers
refers to SNS preganglionic fibres that release AcH
adrenergic fibers
refers to SNS postganglionic fibres that release norepinephrine
local effects meaning
refers to damage in a localized area in which the effects are specific to that area; ex. damage to left frontal lobe results in damage to right arm
supratentorial lesions
occur above the tentorium cerebelli; this leads to specific dysfunction of an area
infratentorial lesions
occurs below the tentorium cerebelli or brainstem; lead to more generalized impairment due to nerves grouping together below this region
what determines levels of consciousness?
the RAS and cerebral cortex
first sign of those with brain disorders
decreased level of resposiveness
what systemic disorders can suppress brain function?
acidosis and hypoglycemia
coma
is when the person is unconscious, motionless, does not respond to visual or verbal stimuli, but some reflexes are still maintained
terminal stage of a coma
loss of all reflexes, dilated pupils, and slow/irregular pulse and respirations
vegetative state
loss of awareness of mental function but brainstem functions continue
locked in syndrome
the individual is paralyzed but is aware and capable of thinking
brain dead criteria
flat EEG, absence of reflexes, absence of brainstem function, absence of respirations, and irreversible
what can cause temporary brain death?
hypothermia or drug overdose
damage to UMNs
causes hyperreflexia and spastic paralysis on the contralateral side
damage to LMNs
causes flaccid paralysis and absence of reflexes on the same side
decorticate responses
flexion of upper limbs, abducted arms, internal rotation of hands, and lower limbs are extended; common due to damage in the hemispheres
decerebrate responses
upper and lower limbs are extended, and the body is arched; commonly results from brainstem damage or systemic effects to the CNS
where is the somatosensory cortex located?
the parietal lobe
damage to the optic chiasm
vision is lost in both eyes
damage to the medial optic fibres
results in damage to the contralateral side
damage to the lateral optic fibres
results in damage to the ipsilateral side
damage to the optic tract or occipital lobe
vision is lost from the medial half of one eye and the lateral half of the other; overall effect is loss of vision on the side opposite to the damage
homonymous hemianopia
is damage to the optic tract or occipital lobe resulting in damage to the medial half of one eye and the lateral half of the other
diplopia
refers to double vision
aphasia
refers to an inability to process or comprehend language; 3 types: recessive, expressive, or global
dysphasia
refers to partial loss of processing or comprehending language
expressive aphasia
refers to damage to the broca’s area in the left frontal lobe; cannot create meaningful sentences
receptive aphasia
refers to damage to the wernicke’s area in the left temporal lobe; cannot understand the spoken or written words; still capable of speaking, but it is meaningless
global aphasia
refers to damage to both the broca’s and wernicke’s areas
fluent aphasia
pace of speech is normal but includes made up words; associated with damage to the wernicke’s area
nonfluent aphasia
slow and laboured speech with short phases; associated with damage to the broca’s area
dysarthria
refers to words not being articulated clearly and is a motor dysfunction
agraphia
impaired writing ability
alexia
impaired reading ability
agnosia
loss of recognition or association
what are seizures caused by?
spontaneous excessive discharge of neurons in the brain and may be due to bleeding, inflammation, or hypoxia
signs of seizures
temporary confusion, a staring spell, rapid jerking of arms and legs, unconsciousness, and fear or anxiety
tardive dyskinesia
is a neurological disorder caused by the longtime use of neuroleptic drugs (used for psychartitic and GI disorders) or antipsychotic drugs
signs of tardive dyskinesia
repetitive involuntary movements like grimacing, tongue protrusion, lip smacking, puckering and pursing, and rapid eye blinking
what disorders is increased ICP common in?
tumors, hemorrhage, cerebral edema, trauma, or accumulation of CSF
signs of increased ICP
headache, vomiting, decreasing level of consciousness, increasing BP, slow heart rate, and vision problems (including papilledema, fixed and dilated pupils, first in one pupil then in both, and ptosis)
papilledema
increased pressure of CSF causes swelling around the optic disc
compensation for increased ICP
increase venous return, shifting CSF into the spinal cavity, and vasodilation (which makes things worse), as well as systemic vasoconstriction and decreased respiratory rate
Cheyne–Stokes respirations
common with increased ICP and is alternating apnea and increasing and decreasing respirations
ptosis
means droopy eyelid and is common with increased ICP
where is lumbar puncture done?
L3-L4
pressure of CSF in increased ICP
> 20 mm Hg
transtentorial (central) herniation
occurs when the hemispheres, diencephalon, and midbrain are displaced downwards, affecting respiration, the RAS, and the flow of blood and CSF
uncal (uncinate) herniation
occurs when the uncus of the temporal lobe is displaced downwards past the tentorium cerebelli, creating pressure on cranial nerve III, the posterior cerebral artery, and the RAS
cerebellar, or tonsillar (infratentorial), herniation
occurs when the cerebellar tonsils are pushed downward through the forearm magnum which compresses the brainstem and vital centres
pulse pressure
the difference between systolic and diastolic pressure; this increases with ICP from the decreased heart rate and cushing reflex
most common brain tumor
gliomas which result from glial cells; can be further subdivided, in which astrocytomas are the most common
where do secondary tumors of the brain usually spread from?
lung or breast cancer
what brain tumors are common in younger children?
cerebellar and brainstem
signs of brain tumors
morning headaches, visual problems, vomiting, lethargy, irritability, and seizures
2 origins of vascular brain disorders
ischemia or hemorrhage
global cerebral ischemia
can result from shock or cardiac arrest and results in loss of function and cerebral edema
transient ischemic attack
results from a temporary decreased blood flow to the brain due to an atherosclerosis, vasospasm, embolus, or loss of autoregulation; results in increased risk for a CVA/stroke
signs of a transient ischemic attack
short periods of muscle weakness, visual disturbances, confusion, aphasia, or numbness may occur
cerebrovascular accident
aka stroke; is an infarction of brain tissue due to a lack of blood and O2
how does the brain change with a stroke?
the brain tissue necrosis, inflammation develops, tissue liquifies creating a cavity, and a loss of function of that area develops; this is eventually replaced with scar tissue and cysts
3 types of CVAs
hemorrhage, embolus, and thrombus
most common cause of a CVA
atheroma in a large artery; these may also develop in cerebral arteries
thrombus CVA
is a gradually developing atheroma in a cerebral artery, in which the onset is gradual and causes localized effects
embolic CVA
is an atheroma that breaks away from a larger artery and lodges in a cerebral artery, causing a rapid onset and localized effects
hemorrhage CVA
is caused by hypertension and an atheroma, in which the onset is rapid and ICP increases, with widespread effects
what are the effects of blood in the brain?
vasospasm, electrolyte imbalance, acidosis, and cerebral edema
risk factors for a CVA
hypertension, hyperlipidemia, atherosclerosis, diabetes, SLE, past TIAs, age, heart disease, obstructive sleep apnea, and a combination of smoking and oral contraceptives
signs of a CVA
sudden weakness and tingling, often on one side of the face or arm, flaccid paralysis, temporary loss of speech and vision, severe headache, and dizziness
hemorrhage CVA signs
severe headache and confusion
treatment for CVA
immediate administration of clot busting agents like tissue plasminogen activator
cerebral aneurysms
are localized dilations in an artery at weak points and commonly occur at points of bifurcation in the circle of willis due to hypertension
result of a ruptured aneurysm
bleeding into the subarachnoid space and CSF, inflammatory response, irritation to nerves, increased ICP, and vasospasm
small leak from an aneurysm
is likely to cause a headache, photophobia, intermediate periods of dysfunction like speech, confusion, or weakness, and nuchal rigidity
nuchal rigidity
is a stiff or extended neck due to blood irritating spinal nerves and causing contractions of the neck; common with a small leak from an aneurysm
massive leak from an aneurysm
blinding headache, vomiting, visual problems, seizures, and loss of consciousness
meningitis
is a viral, bacterial, or fungal infection of the meninges in which the microbe can reach the brain through the blood, a nearby tissue, or trauma
how does the microbe reach the brain in meningitis?
they can bind to nasopharyngeal cells, cross the mucosa, attach to the choroid plexus and enter the CSF
how does the brain appear in meningitis?
pia and arachnoid layers become edematous, purulent exudate fills in spaces between sulci, and the brain appears flat, and the vessels supplying the brain are dilated
classic meningitis pathogen
neisseria meningitidis, or meningococcus
most common meningitis pathogen in infants
E coli
most common meningitis pathogen in young children
Haemophilus influenzae
most common meningitis pathogen in the elderly
Streptococcus pneumoniae
signs of meningitis
fever, chills, headache, back pain, stiff neck, photophobia, and signs of increased ICP; Kernig sign and Brudzinski sign may also be present
Brudzinski sign
neck flexion causes flexion of hip and knee
Kernig sign
resistance to leg extension when lying with the hip flexed
meningococcal infections signs
rose-colored petechial rash or extensive ecchymoses over the body, feeding difficulties, and high pitched cry in newborn
fulminant meningitis
means severe; signs are disseminated intravascular coagulation and hemorrhage of the adrenal gland; causes vascular collapse, shock, and death
abscess
is a localized infection, usually in the temporal or frontal lobes, causing necrosis and edema in the brain
what do abscesses result from?
spread of infection from the throat, ear, lung, or sinus
common organisms causing abscesses
staphylococci, streptococci, and pneumococci
signs of a brain abscess
signs of neurological deficits and increased ICP
encephalitis
is an infection, usually viral, of the CT in the brain and spinal cord, particularly of the basal ganglia
signs of an encephalitis infection
headache, stiff neck, lethargy, vomiting, fever, and seizures
types of encephalitis spread by mosquitoes
western equine encephalitis, st. louis encephalitis, and west nile fever
neuroborreliosis causative organsism
aka lyme; is a spirochete called Borrelia burgdorferi that is transmitted by tick bites
sign of a tick bite
red with a pale centre that gradually increases in size; called bulls eye
signs of neuroborreliosis/lyme
fever, headache, sore throat, dry cough, inflammation in large joints, cardiac arrhythmias, and neurological effects
herpes simplex encephalitis
can cause necrosis and hemorrhage in the brain, often affecting the frontal and temporal lobes
amoebic meningoencephalitis
is spread from the amoeba Naegleria fowleri that thrives in warm water and is usually fatal
rabies
transmitted by wild animal bites and causes inflammation and necrosis in the brainstem and basal nuclei
signs of rabies
headache, fever, nervous hyperirritability, seizures, difficulty swallowing, and impaired respirations
tetanus causative organism
clostridium tetani, a spore-forming bacillus
signs of tetanus
jaw stiffness, muscle spasms, difficulty swallowing, stiff neck, and eventually respiratory failure
poliomyelitis
is a highly contagious virus that attacks motor neurons of the spinal cord and brainstem, causing effects ranging from flulike symptoms to respiratory failure and paralysis
signs of poliomyelitis
fever, vomiting, headache, stiff neck, and flaccid paralysis
herpes zoster causative agent
varicella-zoster virus often following the primary infection of chickenpox
herpes zoster signs
affects a single cranial nerve or dermatome, causing pain, paresthesia, and a vesicular rash to develop in a unilateral line usually on the face or lumbar trunk
postpolio syndrome
occurs 10-40 years after the original polio infection causing progressive muscle weakness, atrophy, and pain; the more severe the original infection, the more severe PPS will be
pathophysiology of postpolio syndrome
surviving motor neurons later degenerate and die, due to creating new axon branches to serve muscle cells but couldn’t keep up
reye syndrome cause
is due to treating children with a viral infection, like influenza, with aspirin, causing changes in the brain and liver
signs of reye syndrome
lethargy, headache, vomiting, disorientation, hyperreflexia, hypoglycemia, hepatomegaly, and seizures
Guillain–Barré syndrome
is an inflammatory condition of the PNS which is thought to be an autoimmune response following viral infection, causing demyelination of motor nerves, then sensory nerves
how does Guillain–Barré syndrome progress?
inflammation and degeneration of nerves begins in the legs, and ascends to involve the spinal nerves of the trunk and neck; can be dangerous if respiratory muscles are affected
Guillain–Barré syndrome signs
progressive muscle weakness and lack of reflexes, parthesthia, muscle aching, vision and speech may be impaired, or even swallowing and respiration in serious cases
concussion
is reversible damage to the brain caused by injury, causing excessive movement of the brain, which can result in temporary confusion, memory loss, and headaches
amnesia
means memory loss
contusion
is bruising of the brain which may result from rupture of a small vessel and edema
closed head injury
is when the skull is not fractured but the brain tissue is injured and vessels may rupture
open head injury
involves fractures or penetrations of the brain by sharp objects
compound fractures
occur when the brain is exposed to the environment, in which risk of infection is high
depressed fractures
involve the displacement of a bone below the skull that compresses the brain tissue; blood supply is impaired and pressure is exerted on the brain
basilar fractures
occur at the base of the skull and often cause blood and CSF to leak through the nose or ears
contrecoup injuries
occur when an area contralateral to the injury is injured due to the brain bouncing off the skull
primary brain injuries
are direct injuries that involve lacerations and crushing of the brain structures
shearing injury
refers to the lobes against each other
secondary brain injuries
result from complications like hemorrhage, edema, vasospasm, hematoma, or infection; this is characterized by the development of additional injurious factors
hematoma
is a collection of blood under the tissue that results from a rupture
epidural hematoma
results from bleeding between the dura and the skull, usually caused by tearing of the middle meningeal artery in the temporal region
subdural hematoma
develops between the dura and the arachnoid, usually the result of a tear in a small vein
hygroma
refers to CSF leaking into the subdural space
subarachnoid hematoma
develops between the arachnoid and pia and is associated with bleeding at the base of the brain
intracerebral hematoma
results from contusions or shearing injuries and often develop several days after injury
complications of hematomas
leads to pressure on local structures and increased ICP, blood cells may undergo hemolysis, and this results in osmotic pressure draws more fluid into this area, exacerbating these effects
otthrea
refers to CSF leaking from the ear
rhinorrhea
refers to CSF leaking from the nose
possible signs of a head injury
seizures, cranial nerve damage, otthea or rhinorrhea, otorrhagia, fever, and stress ulcers
otorrhagia
is blood leaking through the ear at a fracture site
where do most spinal cord injuries occur?
at areas that provide more mobility and less support, ex. C1-C7 and T12-L2
what do cervical spine injuries often result from?
hyperflexion or hyperextension of the neck
types of spinal cord injuries
hyperflexion, hyperextension, compression fractures, dislocation of the vertebrae, and penetration injuries
types of vertebrae fractures
compression, wedge, dislocation, or simple
wedge fracture meaning
displaced angular section of bone
bruising of the spinal cord
will result in temporary bleeding and edema
efffects of cervical spinal cord injuries
inflammation can extend upwards, interfering with phrenic nerve innervation, thus affecting respiration; can also impair vasomotor tone, blood pressure, body temperature, and bladder and bowel emptying
spinal shock
occurs in the initial period following injury when conduction of impulses through nerves ceases, causing impairment at, slightly above, and below the level of injury
signs of spinal shock
varies depending on the level, but includes no reflexes, no control of skeletal muscle, and impaired autonomic function, including bladder and bowel
tetraplegia/ quadriplegia
paralysis of all four limbs
paraplegia
paralysis of the trunk and lower limbs
autonomic dysreflexia
can result from injury at the cervical level, and includes the triggering of a massive sympathetic response that cannot be controlled by the brain; usually is triggered by a distended bladder or debictus ulcers
signs of autonomic dysreflexia
vasoconstriction, increased heart rate, severe headache, and visual impairment
complications of autonomic dysreflexia
stroke and heart failure
complications of spinal cord injuries
decubitus ulcers, contractures, muscle spasms, impaired respiratory and urinary function, and impaired sexual function/reproduction
A criteria for a spinal cord injury
no motor or sensory function in the sacral reigons
E criteria for a spinal cord injury
motor and sensory function are normal
is sensory or motor function gained back first from spinal cord injuries?
sensory
leading cause of death for spinal cord injuries
pneumonia, second is renal failure
heart conditions that may cause a CVA
problems with the left ventricle, endocarditis, MI, prosthetic valves, and atrial fibrillation
