Exam 1 Review Flashcards
Describe the CNS
Encased in the bones of the skull and vertebral column
Grossly consists of the brain (cerebrum, cerebellum, brainstem and subcortical structures) and spinal cord
Control center, integration, processing
Describe the PNS
Spinal nerves –31 pairs
Cranial nerves—12 pairs
Carrying information to and from the central nervous system
And the autonomic nervous system (ANS)
Involuntary, automatic
Higher mental processes
FRONTAL
Processes sensory information
Parietal
Processes visual information
occipital
Processes auditory information
temporal
Involved in consciousness
May be implicated in expressive aphasia
insula
Processes memory and emotion
limbic lobe
motor info going to muscles or glands
efferent/descending
sensory info going to receptor organs
afferent/ascending
cervical vertebrae and nerves
7 v 8 nerves
thoracic vertebrae and nerves
12
lumbar vertebrae and nervesf
5
sacral vertebrae and nerves
1 fused, 5 nerves
coccyx vertebrae and nerves
1
what are the 3 layers of meninges
dura, arachnoid, pia
what are the layers of the dura
Meningeal layer (attaches to arachnoid) and endosteal layer (this outer layer serves as the periosteum)
Dural layers are tightly attached to one another
Endosteal layer adheres to inside of the skull
what causes massive bleeding if a meningeal artery is torn.
high arterial blood pressure
what is the falx cerebri
dura that dips in and separates l and r hemisphere and doesn’t go all the way in because of the cc (connection bw two hemispheres
what is the protection of the CNS?
skin and scalp
vertebral colum and skull
meninges
describe the tentorium cerebelli
separates the cerebellum from the cerebral hemispheres
near cerebellum (tent over it)
helps keep parietal and occipital from squishing down on the cerebellum
holds these up to avoid this
below tectorium (cerebellum and bs) supratentorial
infratentorial
above tent (cerebral hemispheres)
supratentorial
the opening where the brainstem passes into the cerebrum
tent needs opening
BS passes up into cerebral hemispheres
tentorial notch
what type of lesions are better? supra or infra?
supratentorial lesions are better than infratentorial in the BS because all life sustaining things happens here and having a lesion can be fatal
why is the area of tentorial notch dangerous for concussions or head trauma?
area where concussion or head trauma - soft tissues are sheared at this notch against hard leather and can cause damage
Lies on the inner surface of the dura
Web-like
arachnoid
what is in the subarachnoid space
csf
what is the arachnoid trabiculae
collagenous (collagen fibers) strands connect the arachnoid and the pia for suspension
what is the arachnoid villa
pressure sensitive straws or one way valves; one way valve taking high pressure CSF into villi to go to the sinuses and then dumped into other sinuses and out through the jugular vein
closely adheres to the CNS tissue, following the gyri and fissures
pia
ARe there meninges in the sc?
All of the meninges cover the spinal cord too
Slight differences in how the dura and pia connect to the spinal cord, vertebrae and nerve roots
Spinal dura is a single layer
There is an epidural space in the spinal cord (the dura is not attached tightly to bone as in the skull)
don’t want something tightly attached to something that has movement if it was attached to bone in spinal cord, we were tear it every time we moved
Arachnoid layer and subarachnoid space are similar to those in the brain
what anchors the spinal cord
Lumbar cistern exists (pocket), denticulate ligament and filum terminale of pia and dural sheat
where can we do epidural injections without causing damage?
go into subarachnoid space in cauda equina and pull out CSF without damaging tissue in areas of lumbar cistern or filum terminale??
Spaces where the endosteal and meningeal layers of the dura separate
Cavities
venous sinuses
end in jugular vein to drain used blood and fluids from the brain (cranial vault)
Transverse sinus, straight sinus, sigmoid sinus and a few more
collects used blood
inferior saggital sinus
largest of venous system
superior sagittal sinus
what is the drainage system to carry blood and CSF away from the brain and to be recycled in the systemic blood flow.
venous system
what tissue makes side of sinuses?
dura
describe an epidural hematoma
also called extradural and has “lemon”shape)
occurs if the meningeal arteries are torn
Most frequently after skull fractures (traumatic skull injury)
Bleeding between the periosteum (endosteal layer of the dura) and the skull bones
Death can occur within minutes if meningeal arteries are torn
above dura
bleeding bw dura and bone and pushes dura down to create pocket of blood here
happens with meningeal artery tears
this is the biggest concern with head trauma
describe subdural hematomas
“banana” shape)
from dural venous sinus or vein attachment at the sinus (blood is beneath the dura)
Rapid accelerations or decelerations of the head can cause the tearing of cerebral veins
May be acute with fast symptoms like an epidural hematoma or very slow in producing symptoms
underneath dura
head injury from motorcycle accident
can still cause problems like epidural but not as likely
describe subarachnoid hematomas
sometimes called subarachnoid hematoma
More common
Bleeding between the brain and the arachnoid (under the arachnoid)
Bleeding is generally from veins—less pressure
Can be from an artery
From severe blow to the head or from a rupturing blood vessel in the brain (i.e. a ruptured aneurysm)
are arteries or veins under more pressure?
arteries needs pressure to pump up but veins drain more so with gravity down
torn artery creates squirting artery
lemon shape bc the dura is adhering to bone and make a pocket
epidural hematoma
banana shape, following the contour of the subarachnoid space and cerebrum
subdural hematoma
List all the things that protect the CNS
Hard bony skull and vertebrae
Meninges
CSF for buoyancy and cushioning
weighs less when it is sitting in fluid, provides cushion, protects because it is cushioning and protect from chemical homeostasis
Protection from vibration, pressure, temperature
Chemical barrier—blood brain barrier
Regulation of temperature and function by the brain itself
what are the 3 major functions of the CSF
to keep the tissue buoyant, acting as a cushion
acts as a vehicle for delivering nutrients to the brain and removing waste
to flow between the cranium and spine and compensate for changes in intracranial blood volume
List the ventricles and the foramina and how the CSF is produced; and how it flows
CSF is produced by choroid plexus and flows from the 2 lateral ventricles through the interventricular foramina to the third ventricle and then through the cerebral aqueduct to the fourth ventricle and then out into the subarachnoid space
The CSF flows from the two lateral ventricles (one in each hemisphere) through the paired interventricular foramina of Monro (holes) to the single midline third ventricle of the diencephalon (thalamus). From the third ventricle, CSF flows through the tube-like cerebral aqueduct of Sylvius in the midbrain to the fourth ventricle of the pons and medulla
The CSF in the fourth ventricle can flow into the central canal which runs down the length of the spinal cord (This is usually closed in adults)
CSF exits the fourth ventricle via the two lateral foramina of Luschka and the single median foramen of Magendie to enter the cisterna magna of the subarachnoid space.
CSF circulates rostrally through the subarachnoid space to reach the superior sagittal sinus
It then enters the venous blood flow via giant vacuole transport (sucked up) through the specialized arachnoid villi. The CSF mixes with the blood in the sinuses and is carried to the jugular vein to be recycled and be removed from the brain
when will CSF flow into the superior sagittal sinus?
When the CSF pressure is higher than the venous pressure
one way valves
arachnoid villa
what is the cisterna magna
space under cerebellum; widest part of subarachnoid space under cerebellum
the major responsible bacterial organism (formerly Haemophilus influenzae but H. influenzae vaccines lowered this rate) for bacterial meningitis
Streptococcus pneumoniae
Most common cause of acquired postlingual profound SNHL and ossification of the labyrinth
bacterial meningitis
how does infection reach the inner ear?
through cochlear aqueduct (links subarachnoid space to basal turn of scala tympani
this explains why we see more high frequency hearing loss associated with it
HL associated with this occurs as early as 48 hours after infection
Disruption of CSF circulation
CSF pressure rises and ventricles expand
hydrocephalus
What can cause CSF?
Can be from excess CSF production, blockage of circulation or deficiency in reabsorption
what is the most common cause of hydrocephalus?
aqueductal stenosis - results from narrowing of cerebral aqueduct between the third and fourth ventricles in middle of the brain
what is communicating hydrocephalus?
This is when the lateral ventricles are still “communicating”/connected with the subarachnoid space and the problem is with reabsorption through the arachnoid villi or tentorial notch
pressure from outside - sas is pressing down on the tissues
occurs when flow is disrupted after it leaves the ventricles
what is noncommunicating hydrocephalus?
aka obstructive hydrocephalus
occurs when the flow of csf is blocked among one or more of the narrow passages connecting the ventricles
blockage could be due stenosis of the cerebral aqueduct or occlusion of the openings out of the 4th ventricle
balloons from inside - CSF stuck in ventricles
what are the symptoms of NPH?
abnormal gait, incontinence, memory problems, dementia
gait of individuals with NPH is distinct and appears as though their feet are glued to the floor as they try to ambulate; the gait has also been described as magnetic (Weiner, Constantini, Cohen, & Wisoff, 1995). NPH is one of the few reversible causes of dementia in older adults
describe NPH
usually a result from subarachnoid hemorrhage, head trauma, infection, tumor, or surgery complications
Generally in patients over 60
Usually idiopathic NPH
Slowly developing from gradual blockage of CSF
idiopathic
unknown cause
caused by drug or substance that interferes with development of the embryo or fetus
teratogenic
caused by dx, manner or tx of a physician
iatrogenic
what can nph be mistaken for?
Can be mistaken for Alzheimer disease or Parkinson disease
Can we treat NPH? if so, with what?
If NPH is correctly diagnosed and treated, the symptoms can resolve
Tx may be ventriculoperitoneal shunt
what are the two main divisions of the neurovasculature?
carotid circulation
vertebrobasilar circulation
ascends from left ventricle of heart
aorta
arise from aorta and subclavian arteries
common carotid and vertebral arteries
anterior supply
carotid
posterior supply
vertebral
arise from aorta
subclavian arteries
branch from subclavian and provide 20% of blood supply to CNS
vertebral arteries
branch off of subclavian on the right and aorta on the left
common carotid
begins at upper border of thyroid cartilage and ascends to reach base of the skull
internal carotid
enters at carotid canal (lacerum)
internal carotid
ophthalmic artery branches off from here and divides into many branches
internal carotid
also gives rise to middle cerebral arteries and anterior cerebral arteres and posterior communicating arteries
internal carotid
blood to brain eyes, etc
internal carotid
provide about 80% blood supply to telencephalon (hemispheres) and diencephalon (thalamus?)
internal carotid
arises opposite the upper border of thyroid cartilage, inclines backwards to space between neck and condyle of lower jaw and external auditory meatus
external carotid
divides into temporal and internal maxillary arteries
EC
supply neck face and base of skull
blood to face and mouth
EC
supplies areas of the cerebellum, medulla and choroid plexus of the 4th ventricle
Division of the vertebral arteries
PICA
one artery that runs along the anterior midline of the spinal cord
division of vertebral arteries
ventral spinal artery
Larger on the left
vertebral arteries
what arises off of the vertebral arteries?
Posterior (dorsal) spinal arteries
Anterior (ventral) spinal artery
PICA
what arises off of the basilar artery?
AICA
SCA
posterior cerebral arteries
what branch off of the basilar artery supply inferior portion of cerebellum including the flocculus
AICA
what branch off of the basilar artery supply superior cerebellum, much of the caudal midbrain and rostral pons
SCA
what branch off of the basilar artery , at the level of the midbrain, supply caudal diencephalon, medial occipital lobe and inferior temporal lobe
posterior cerebral arteries
how the circle of Willis is formed and what is its value/purpose?
The circle of willis forms anastomoses (natural communication between 2 blood vessels) between the internal carotid arteries and the vertebrobasilar system of arteries on the ventral side of the brain. It is made up of:
Anterior cerebral artery (left and right)
Anterior communicating artery
Internal carotid artery (left and right)
Posterior cerebral artery (left and right)
Posterior communicating artery (left and right)
The circle of Willis functions to support and provide blood supply between the anterior and posterior cerebral circulations, serving as backup routes for blood flow if one link is blocked or otherwise compromised. It prevents neurological damage from loss of blood.
What areas are supplied by the anterior cerebral artery?
longitudinal fissure from frontal to back of parietal
What areas are supplied by the middle cerebral artery?
sylvian/lateral fissure, primary a1, temporal lobe
What areas are supplied by the posterior cerebral artery?
occipital lobe to lower gyri of temporal lobe
Where does the labyrinthine artery branch off from other arteries? Details of blood supply to the labyrinthine structures of the AVS
Internal auditory or labyrinthine arteries- directly from basilar artery or from anterior inferior cerebellar artery
Lab A. -> C.C. & AVA -> AVA to L SCC, S SCC, & Utricle -> C.C. to PVA & Main Coch. -> M.C. to spiral ganglion, Organ of Corti & Stria Vasc. -> PVA to P SCC & Saccule
describe the blood supply to the SC
comes off the vertebral arteries
posterior spinal arteries
2 run down back of SC
anterior spinal artery (2 from vertebrals)
one anterior runs along the anterior midline of the sc
what are chronic conditions that affect blood flow?
high cholesterol
diabetes
a foreign body (blood clot) that travels within the body and can constrict blood flow (could be detached thrombus)
embolus
a blood clot, a lesion attached to the inner vessel wall, can block partially or fully the flow of blood. (attached)
thrombus
can a thrombus can break off and turn into an embolus?
yes
what is a plexus?
a large network of blood vessels
large amounts of blood escapes into surrounding tissues without clotting
can have symptoms like strokes
an escape of blood through ruptured or unruptured vessel walls
hemorrhage
small amounts of blood that escape into surrounding tissues causing bruising
a localized mass of blood outside of blood vessels that is relatively or completely confined within an organ or tissue, a space or potential space; the blood is usually clotted
hematoma
most common cause of neurological deficits
Cerebrovascular (blood flow to cerebral structures) disease and accidents
necrotic region of tissue
infarct
what can strokes lead to if blood supply is not restored?
infarct
abrupt incident of vascular insufficiency
stroke
loss of blood supply due to mechanical blockage
ischemic stroke
what can cause an ischemic stroke?
thrombus or embolus
blood is blocked for a little bit and then gets broken up and clears itself allowing blood to flow through again
TIA
Is a stroke more dangerous in the infratentorial or supratentorial region?
more dangerious in infratentorial because BS has life managing functions (automatic things) and can go into a coma or life threatening injuries. Supra can just affect a little of something.
localized dilation of a blood vessel
wall is weak and can rupture
can be corrected surgically if detected while small
aneurysms
occur were cerebral arteries branch off of the circle of willis
considered subarachnoid hemorrhage (when ruptures, blood spills into the space bw skull and brain)
berry aneurysm
Describe the signs of a stroke
B = Balance: Sudden loss of balance
E = Eyes: Loss of vision in one or both eyes
F = Face: Face droops on one side
A = Arms: Arm drops when both arms are raised
S = Speech: Speech is slurred or sounds different
T = Time: Time to get help immediately
What is angiography?
medical imaging technique used to visualize the inside, or lumen, of blood vessels and organs of the body, with particular interest in the arteries, veins, and the heart chambers
what arteries from EC supply the outer ear?
posterior auricular arteries
anterior auricular arteries
where does blood supply for peripheral ear structures come from
labyrinthine artery that comes from basilar or AICA directly off vertebral basilar
how do we make vertebral basilar and carotid connect?
with communicating arteries (posterior - come right off of IC, anterior )
why do we care about the circle?
provides alternative routes for blood to circulate if there is a blockage elsewhere
safety valve
will slowly widen over time
doesnt work well for fast occlusions
Ophthalmic artery branches off this and divides into the many branches
artery passes into the orbit via the optic canal.
internal carotid
Divides into temporal and internal maxillary arteries
Branches—supply the neck, face and base of skull
external carotid
what branches of EC supply middle ear?
the occipital and/or posterior auricular arteries
The deep auricular artery, a branch of the maxillary artery.
what branches of IC supply inner ear
labyrinthine artery, arising from either the anterior inferior cerebellar or the basilar artery
what is the bbb and why is it important
when arteries go down to arterials and capillaries to feed brain tissues, there are tight junctions
large macromolecules cannot go through because things like viruses are these and this helps restrict access to the tissues
controls the movement of substances from the general extracellular fluid of the body to the extracellular fluid of the brain
strict def: tight junctions of endothelial cells that line capillaries in CNS
helps to protect cns
Arachnoid barrier layer
CSF-Brain interface
interface because fluid bathes the brain
what is Arteriovenous malformations and why does it cause a problem
tangle of blood vessels that connects arteries and veins in the brain
causes problem because arteries are supposed to bring blood in and veins take it out and here they go together and not do their job
can rupture due to delicate walls
happens during development
cavities formed by the endosteal and meningeal layers of the dura mater
venous sinuses
the drainage system to carry blood and CSF away from the brain and to be recycled in the systemic blood flow.
venous sinuses
Briefly describe the drainage system of the venous sinuses
Veins of the cerebral cortex dump into the venous sinuses
Sinuses such as the superior sagittal sinus (SSS), sigmoid sinus, straight sinus, inferior sagittal sinus, straight sinus, and cavernous sinuses also dump into the overall system for drainage
Then to internal jugular veins and basilar venous complex around the base of the brain
Is plasticity a good thing?
yes, able to reorganize f the blood, like the circle of willis, if something can accommodate a change for the benefit of the brain
what is the great cerebral veil of galen
it is formed by the joining of the paired internal cerebral veins (the major deep veins) and it joins the inferior sagittal sinus to form the straight sinus
What are the functions of the skin?
Covering—about 2mm thick and weighs about 6 pounds
Skin is largest organ—has more than two tissues
Waterproof—to keep water in
Barrier from foreign invasion
Bacteria, viruses, fungi, protozoa, chemicals
Protects from ultraviolet rays
Heat control
Sensory receptors
Vitamin D/Hormone production
Excretion
how does our skin protect against UV?
melanocytes produce melanin
absorbs UV light
how does our skin protect with heat control?
as sweat evaporates it lowers the body temperature
sweating to reduce hyperthermia
vascular changes
autonomic
red or pink skin; Smooth muscle in blood vessels of the skin relax/open, allow more blood to enter the skin
vasodilation
Contraction of arrector pili to trap air and make insulation layer; and smooth muscle in blood vessels of the skin to reduce blood flow and keep heat in
sensory reception
vasoconstriction
ABCDE’s of Melanoma
A- Asymmetry
B – uneven borders (melanoma) or smooth (benign)
C – color (like brown, tan or black)
D – diameter (larger than 1/4 inch)
E - evolution (changing in size, shape, elevation, color or new symptom)
squamous outer most layer with dead/keratinized cells also called the horny layer and innermost layer is the stratum germinativum
epidermis
where cells are still dividing (mitosis) and there are melanocytes (produce the color in the skin)
stratum germinativum
dense connective tissue - collagenous and elastin fibers
dermis
what is contained in the dermis?
Blood vessels—pink/blushing from dilation, blue (cyanosis) from lack of oxygen
Nerves
Lymph
Smooth muscle
Sweat glands
Hair follicles
Sebaceous glands
aka subcutaneous
fatty tissue (adipose)
attaches dermis to muscle or bone and is considered the superficial fascia
hypodermis
where do hypodermic needle injections occur?
hypodermis
give examples of accessory structures of the skin
hair
shaft is visible
root in the epidermis
hair follicle in epidermis and dermis
arrector pili muscles - involuntary, autonomic nervous system activation
goose bumps
nails
modification of leathery epidermal cells with hard keratin
lunula - crescent at proximal end of each nail (white free end)
air mixed with keratin
cuticle is a layer of epidermis extending over the nail
glands
what are the glands of the skin?
sebaceous, sweat, ceruminous
what are the purpose of sebaceous glands
oil
lubrication for glossy and pliable skin and shiny hair
what is the purpose of sweat glands
to cool and secrete minimal waste
most abundant in hands and feet
or sweat and heat regulation
eccrine sg
scent/odor (in armpits and genitalia)
appocrine sg
has sodium chloride (salty) - urea, uric acid, ammonia, other organic substances
sweat
what is the function of the ceruminous gland
modified apocrine sweat glands (has contributions from sebaceous glands)
lubricates and protects the ear canal
how does cerumen protect the ear canal
Only in the dermis of the external auditory canals
Cerumen traps foreign material like dust and pathogens
Continuously produced and migrates out of canal
what is the purpose of skin receptors
purpose is to sense the external environment
touch, pressure, vibration, temp, pain
vibration
pacinian corpuscle
touch
meissner corpuscle
merkel endings
pressure
ruffini ending
touch/movement of hair
hair receptors
pain, temperature, itch, touch
free nerve endings
what are the 6 prominent types of mechanoreceptors
Encapsulated—Pacinian corpuscle, Meissner corpuscle, Ruffini ending
Nonecapsulated –Hair receptors, Merkel endings, free nerve endings
what are our special senses?
Hearing (audition) & Balance
Vision
Olfaction
Taste (gustatory sensations)
cells that detect stimuli and produce receptor potentials
sensory receptors
what are inner hair cells?
specialized mechanoreceptors
Mechanical displacement
mechanoreceptors
Temperature change
thermoreceptors
Pain –Tissue damage
nociceptors
Chemicals
chemoreceptors
light
Photoreceptors
Receptor distribution in the skin in not uniform—why?
some areas are more densely innervated than others
like lips and fingertips as opposed to the back
test by two point discrimination
minimum distance by which two stimuli can be separated and still perceived as two stimuli
sensory area of skin that is going into specific spinal segment of nerves
dermatome
C2 Derm
occiput
C3 Derm
scalp around ear, pinna & other craniofacial
including scalp around the ear, pinna, lateral cheek over angle of the jaw, submental region and lateral and anterior aspects of upper neck
C4 Derm
posterior neck and upper shoulder
C6, C7, C8: hand derm
C6: thumb
C7: index and middle fingers
C8: ring and little fingers
T1 Derm
upper thorax and anterior surface of upper extremity
T4 Derm
nipple zone
T5 derm
inferior angle of scapula
f
T10 Derm
umbilical zone
L4 Derm
lateral thigh, anterior surface of knee, and medial leg, great toe
L5 derm
middle three toes, sole of foot, and great toe
S1 Derm
back of leg, little toe, heel and lateral foot
S2 Derm
genitalia and back of thigh
A muscular segment; one of the zones into which the muscles of the trunk, especially in fishes, are divided
myotomes
partial paralysis or weakness
paresis
can occur when upper motor neurons are damaged like in a stroke
results if all roots innervating a particular muscle are destroyed
paralysis
Will spinal cord lesions affect control of bladder and bowels?
YES because they are controlled and innervated by low spinal cord segments (S2, S3, S4)
connective tissues that separate muscles
sclerotomes
what is Waardenburg
genetic and congenital
mutation in changes of the melanocytes
this changes pigmentation in skin, hair and eyes
pale eyes/different colors, white patch of hair/early grey patches, patches of white or dark on skin
can have moderate to profound HL and balance issues
red patches, thick, scaly, can bleed when scraped
hyperactive stratum germinativum
psoriasis
uncontrolled growth in epidermal layer
human papillomavirus
warts
herpes simplex virus
fluid filled blisters
cold sores
Staphylococcus aureus bacteria, small blisters, highly contagious (face and can spread)
impetigo
staph infection of hair follicle or gland with pus
furuncle/boil
localized edema in epidermis
red/pale and itchy
elevated
urticaria/hives
what are external ear canal conditions
external otitis
bacterial or fungal
swimmers ear
bacterial
otomycosis - fungal
nectrotizing (malignant) external otitis
what are features of the skin of the ear canal
cerumen glands
hair angled to protect
outer layer of ™ same as skin tissue
epithelial migration
what is proprioception
respond to changes in position of the body or its parts
where are receptors
In the skin
Muscles
Joints
And viscera (organs of the digestive, respiratory, urogenital and endocrine systems—and the spleen, the heart and the great vessles—the internal organs)—these might be specifically classified as visceral sensory instead of somatosensory
Detect muscle length
muscle spindles
detect muscle tension
golgi tendon organs
Respond to joint position and movement
joint receptors
how proprioception related to as and vs?
how we keep our balance
what is Resting membrane potential
high sodium outside the cell and high potassium concentration inside the cell, approximately -70 millivolts inside the cell
what is the sodium potassium pump
counterbalances this leakage (At rest Na+ leaks into the cell and K+ leaks out) moving 3 Na+ out and 2 K+ in (3:2 ratio)
Na+/K+ ATPase pump—active/uses energy
Maintains and re-establishes the resting membrane potential (balance necessary)
describe a receptor potential
Local and graded
Amplitude modulated (more volt change for a larger stimulus, etc.)
Carry info about location and nature of stimulus
By the type of receptor, location and where it projects to in the CNS
Intensity coded by amplitude of the receptor potential, the threshold of the receptors and how many (whole hand touching vs one finger)
Duration coded by the duration of the receptor potential and
Slowly adapting—continue to respond but at a diminished level throughout the duration of the stimulus
Rapidly adapting- signal the beginning and end of a stimulus
Combinations of receptors cover the full range of information that needs to be encoded
