Anatomy And Physiology Flashcards
What is anatomy?
What it is add what it does (function)
What is physiology?
How it does it
Superior?
Upper
Inferior?
Lower
Anterior?
Front
Posterior?
Back
Medial?
Middle
Lateral?
Towards the side
Inter?
In between
Anti?
Opposite
What is the pinna made up of?
Cartilage, epithelium & lobule
Which 3 nerves are located within the ear?
Cranial v, facial vii & vagus x
13 parts of the outer ear?
Helix, anti helix, crus of helix, superior crus of helix, inferior cross of helix (5)
Tragus and antitragus (2)
Scapphoid fossa and triangular fossa (2)
Lobule, inter tragic notch, Darwin’s tubicle and concha (4)
Characteristics of the EAM
2.5 cm long
7/8mm in diameter
4cc in volume
First third is cartilage 1.5mm thick
2nd 2/3’s is bone 0.5mm thick
Contains sebaceous and ceruminous glands
Has 2 distinct bends - isthmus narrowest point
Main function of the whole ear?
Transform acoustical energy into neural codes that are interpreted by the brain as sound
8 parts of the EAM?
Hairs
Sebaceous and ceruminous glands
Cartilage
Bone
Epithelium 1.5mm thick - start
Epithelium 0.5mm thick - finish
1st bend
2nd bend
What is cerumen?
Secretive sebaceous (oil), ceruminous (sweat) mix with dirt and debris to create Wax
Properties of Cerumen (7)
Colour variable
Water resistant
Hygro scopic
Acidic
Bacteriostatic
Lubricant
Migration - self cleaning
Parts of the TM (10)
Pars tensa pars flacidda
Annulus
Light reflex
Umbo
handle of Malleus
Short process of malleus
Long process of incus
Anterior malleal fold
Posterior malleal fold
TM made up of which 3 layers?
Squamous epithelium
Fibrous layer
Mucous membrane
Properties of the TM (8)
10mm high x 8mm wide 0.1 thick
Approx 55 degree angle
Concave - umbo max point of concavity
Translucent pearly grey
Handle of Malleus attached
Light reflex
Annulus
3 layers
What is the function of the outer ear?
CLAP
Collection
Localisation
Amplification
Protection
What is the resonance of the concha and EAM? What is their maximum amplification?
Concha resonates at 5500Hz
EAM at 2500Hz
Max amplification when combined is 3000Hz
(Increases signal by 15-20dB)
How does the pinna protect the middle ear?
Tragus - obstructs canal opening (objects/trauma)
Meatus: wax (protection against infection)
Hairs (filter/barrier)
2 bends (objects/trauma)
Sensitive bony section (cough reflex)
What is the function of the TM?
VATS
vibrates exactly in tune with incoming sound
Acoustic to mechanical energy
Transmits further into auditory system
Shield between outer and inner ear
Describe the Middle ear.
ME is an air filled chamber with a mucous membrane lining (lining continues in from 3rd layer of TM). It is surrounded by the Mastoid bone.
What makes up the ossicle chain?
Malleus, incus and stapes bones
Characteristics of the Eustachian tube
Approx 36mm long
Mucous membrane continuous with lining from tympanic cavity
1st 1/3 is cartilage
2nd 2/3 is bone
Tensor palatini muscle contracts to open and close the ET to allow EQUALISATION OF PRESSURE
links with NASOPHARYNX to drain mucous out of ME
Wheat does the stapes bone tap on?
The oval window - then comes the cochlea promontory and then the round window which leads into the inner ear.
What are the 3 muscles in the middle ear and their function?
Tensor tympani attached to MALLEUS and is next to TM. Also contracts to reduce head trauma (non acoustic reflex)
Stapedius muscle attached to stapes and also contracts to very loud sounds to protect inner ear.
Tensor palatini attaches to Eustachian tube and acts like a valve for drainage
Each muscle helps keep parts in place
Function of the middle ear?
TCAP
Transducer- converts acoustic to mechanical energy
Conduction - sounds from outer to inner ear
Amplifier - transformer, action, impedance mismatch mechanism
Why do we need equal pressure between outer and middle ear?
To allow effective conduction of sound to travel through. Otherwise sound will be compromised ie TM doesn’t vibrate as well
What is the function of the Eustachian tube?
Equalise pressure - either side of TM necessary for optimal hearing
Ventilation - tensor palatini muscle operates like a valve
Drainage - ET connects ME to nasopharynx for drainage of mucus
What is impedance?
A mediums resistance to movement
Low impedance - moves easily
High impedance - requires more force to move through medium ie water more difficult than air
What are the 3 mechanisms of the ME to mitigate impedance mismatch?
Aeral ratio
Leverage action
TM characteristics
Explain the areal ratio in relation to the impedance mismatch
TM is 14 x larger than oval window condensing sound pressure into smaller area - SPL is then increased although sound is not louder.
Explain leverage action in relation to impedance mismatch
Malleus is 1.15 x longer than incus which is equal to a 1:1.3 pressure increase
Explain TM characteristics in relation to impedance mismatch
Conical shape of TM helps condense increasing SPL towards stapes and oval window
How much do the 3 impedance mismatch mechanisms increase SPL by?
22 times greater - the combined nature increases the SPL sufficiently to move the sound from the air of the ME through the fluids of the inner ear.
Explain the acoustic reflex
This is the stapedius muscle contracting in response to loud sounds (70-80dB above their hearing threshold) which reduces movement to the ossicles which become tense. This is attempting to protect the inner ear from the excessive, potentially damaging, sound.
This is always bilateral but not instantaneous hence sounds can damage ie explosions
Explain the non acoustic reflex
Occurs when the tensor tympani muscle (located next to TM and supports malleus) contracts in response to a puff of air on the cornea likely in response to head trauma.
Name outer ear disorders caused by trauma and their treatment?
Cauliflower ear - damage to cartilage
Haematoma - rupture of blood vessels
Treatment - drainage and pressure dressing
Name the 3 infective infections and describe them and their treatments.
Viral - swelling redness, decongestants and steroids
Bacterial - pain rash blisters. Anti biotics, Analgesics tropical lotions
Fungal - itchy dry skin inflammation
Anti fungal cream
Name the 3 reactive infections and their treatment
Eczema dry red scaly skin - moisturise steroids
Psoriasis red itchy snake skin autoimmune (body attacks itself) moisturise steroids
Dermatitis dry flaky skin - avoid irritant
What is otitis externa?
General term given to any infection or inflammation of the outer ear including EAM
Describe acute otitis externa and it’s treatment
Painful bacterial infection caused by scratches etc pain itching blocked sensation and discharge
Treatment cleaning antibiotics ear drops analgesics
Describe chronic otitis externa, its symptoms and treatment
Prolonged or recurring otitis externa
Itching fullness HL ear pain yellow discharge foul smelling debris in EAM
red and possibly narrow EAM due to swelling which can thicken and cause permanent narrowing
Treatment thorough cleaning tropical antibiotics and steroids for inflammation
Describe examples of otitis externa
Symptoms and treatment
Shingles - viral infection very small spots Symptoms can also include facial palsy and SN loss
Perichondritis - infection of perichondrium by bites, piercings etc
Symptoms redness pain swelling
Treatment antibiotics and steroids warm compress drainage analgesics
What is neoplasia? include treatment
A new growth, malignant or benign. Includes tumours, lesions
Treatment can include removal of pinna - if both pins removed major effect on Localisation
Radiotherapy if malignant
Name genetic/hereditary conditions of the outer ear plus treatments
Anotia- absent ear
Microtia- Malformed ear
Both like to affect EAM usual bilateral
Treatment: surgery - prosthetics autologous reconstruction alloplastic reconstruction
Bat ears
Pre-auricular tags/pits
Name a trauma disorder of the EAM
Lacerations, stitch if required
Name infections of the EAM with symptoms and treatment
Otomycosis - fungal infection of the ear usually in EAM
Colour maybe white, brown or black spores with irritation and otalgia (pain)
Treatment via meticulous cleaning anti fungal creams ear drops
Furunculosis - infection of the hair follicles and shows as a spot or boil in EAM very painful but doesn’t affect hearing
Treatment is rare but antibiotics or possibly surgical removal
Referred pain
What does ectomy, otomy and oplasty mean?
Ectomy - removal
Otomy - incision
Oplasty - reconstruction
What does myring and tympan refer to?
Myring relates to TM only
Tympan relates to whole ME cavity
What does suppuration refer to?
It is the production of pus
Describe the terms progressive, sudden and rapid
Progressive - deteriorates over time
Sudden - over 3 day period
Rapid - in last 3 months
What is the difference between the terms cochlea and retro cochlea?
Cochlea relates to sensory, mostly hair cell, damage
Retro is neural, damage to auditory nerve or the brain
Describe acute suppurative otitis media ASOM and it’s different stages and treatment
It is the infection of the mucosal lining of the ME cavity often by sending the ET from the nasopharynx but also via blood supply or EAM if TM perforated/grommet.
Stage 1 - arrival of infection
Stage 2 - redness mucosal lining swells dilation of blood vessels negative pressure TM can retract no light reflex
Possible HL if TM not vibrating properly
Stage 3 - suppuration increased pain feeling of fullness TM bulges outwards under pressure from the pus build up infection spreads to TM
Stage 4 - resolution either TM ruptures/perforates or intervention ie myringotomy (incision) drainage of pus
Treatment - antibiotics (for infection) nasal decongestant (open ET) analgesics for pain relief potential myringotomy
Describe chronic suppurative otitis media CSOM
Occurs because of untreated or unresolved ASOM and recurs/long lasting
Often with a persistent discharge and conductive HL
irreversible change to structure/function of ME potential destruction of ossicles and or TM
What are the 2 types of perforation that can result from ASOM?
Safe (central) no risk discharge flows out
Unsafe (marginal) higher up attic perforation discharge cannot escape infection can spread including to mastoid potential mastoiditis
Perforations can also be caused by trauma
Describe a cholesteatoma including treatment
Most frequently encountered process associated with UNSAFE (marginal) disease.
Usually unilateral and likely develops due to a weak pars flaccida
A blocked ET sees the weakened area (likely pars flaccida) drawn inwards to form a retraction pocket (dimple) in TM
discharge collects in the pocket to become an INFECTED septic sac.
The sac increases in size filling the ME and often corrodes the ossicles
If untreated may progress to mastoid air cells to meninges around brain causing meningitis
Treatment - if small clean via suction if large surgically removed mastoidectomy and or ossiculoplasty to reconstruct ossicles
Regular cleaning
Antibiotics if infection progresses
Describe acute non-suppurative otitis media including symptoms and treatment
Sudden appearance of fluid (non-infectious) in the ME
Result of ET failing to aerate ME resulting in negative pressure which appears to encourage outpouring of non infected golden yellow watery fluid from mucosal lining of ME
Symptoms unilateral hearing loss blocked up feeling ear pressure mild ear ache
Treatment self resolves but if persists decongestants drain fluid from ME
Aeration via MYRINGOTOMY/grommet
Describe chronic non-suppurative otitis media including symptoms and treatment
Found more often in children (glue ear)
Likely caused by ET dysfunction or bacterial infection following incompletely resolved ASOM
Thick sticky mucous
Lack lustre membrane grey/yellowish or blue in hue
Possible dilated blood vessels
Significant HL bilateral up to 40dBHL
Treatment self resolves
Nasal decongestants
MYRINGOTOMY/grommet (to aerate equalise pressure)
Adenoidectomy/tonsillectomy to improve ET function
Describe tympanosclerosis
Chalky looking patches of the TM signifies previous ear disease usually following unresolved acute otitis media and, in particular, insertion of grommets
Deposits plaques of collagen
Calcification of tissue
Usually no HL
Describe trauma based perforations
Results from violent changes in air pressure within EAM ie explosion, slap to ears but also foreign bodies or wax syringing
HL depends where perforation is on TM and how large
Treatment is to keep clean to prevent secondary infection. Should heal by self - large ones may require myringoplasty (reconstruct TM)
Explain Barotrauma perforation
Air or water pressure causes ET dysfunction as cannot equalise pressure. ET stays temporarily closed preventing air flow so TM can retract (negative pressure)
Symptoms pain dulled hearing temp HL tinnitus
Treatment is simply to avoid the barotrauma!
Describe otosclerosis including treatment
Abnormal bony growth around stapes footplate.
Genetic/hereditary condition which results in the calcification and stiffness of ME ossicles.
Defective gene yet presents later in life
If it fixates or restricts footplate of stapes will initially show as conductive HL (Audiometry shows Carhart’s notch)
Growth can invade cochlea and patient develops SN loss albeit less common
Treatment:
Stapes mobilisation - break bony growth around stapes to allow it to move
Stapedectomy - most common, remove stapes and replace with prosthetic
Drug/dietary supplement - sodium fluoride to slow down prevent bony growth
HA to mitigate any HL
Describe a glomus tumour
Most common neoplasia of ME
A common presentation of this tumour is pulsatile tinnitus due to its highly vascular nature
Conductive HL due to mass in ME which impedes passage of sound.
If large enough can cause vertigo, facial palsy and SN HL
Otoscopy - pinna: what are we looking for?
Shape
Skin condition
Piercings
Scars
Distinguishing marks
Otoscopy - EAM, what are we looking for?
Tragal hair
Size shape
Wax
Bends
Skin migration
Skin conditions
Infection
Discharge
Irritation
Otoscopy - TM: what are we looking for?
Colour
Patches
Perforations
Grommets
Retracted bulging
Infections
What type of hearing loss is associated with the inner ear?
Sensorineural loss
Describe the door Mat effect of the inner ear
All sound will enter and travel down the basilar membrane. At the base (entrance) is where higher frequencies are encoded but all frequencies will still cross it. High frequency loss is associated with old age due to the wear and tear on the base end of the BM
Describe the inner ear
A liquid filled area contained within a membranous labyrinth surrounded by a bony labyrinth all lying within a PETROUS bone, the area contains 3 parts:
The vestibule - controls posture
Semi circular canals - balance
The cochlea - hearing
What are the characteristics of the cochlea?
Conical snail shell bony structure
36mm L 10x5 mm
Spiral 2.75 turns around a modiolus (central axis)
Osseous (bony) spiral lamina
Membranous lining
Oval (attached to stapes) and round windows (allows movement of fluid) also attached.
What are the 3 longitudinal channels within the cochlea and what fluid are they contained within?
SCALA VESTIBULI (at top)
SCALA TYMPANI (bottom)
Both surrounded by PERILYMPH fluid and communicate with one another a the HELICOTREMA
SCALA MEDIA runs along outside of cochlea and surrounded by ENDOLYMPH fluid.
What is the relevance of each fluid to electrical charge?
Perilymph fluid contains little potassium so NO electrical charge.
Endolymph fluid is high in potassium ions pumped in by the STRIA VASCULARIS so has a high electrical charge.
What are the 2 main membranes contained within the inner ear and where are they located?
REISSNER membrane forms floor of Scala VESTIBULI and ceiling of Scala MEDIA.
BASILAR membrane forms floor of Scala MEDIA and ceiling of the Scala TYMPANI
Narrow and taut at the base (high freq)
Wide and flaccid at the apex (low freq)
Where are the inner and outer hair cells located and what are their characteristics?
Both are located on the BASILAR membrane and part of the central heating organ - ORGAN of CORTI.
INNER HAIR CELLS (IHC’s)
Sensory and passive - SN loss
Shaped like ten ping bowling bowl
3500 per cochlea
Single row
Transduces mechanical energy to neural activity
AFFERENT - to brain
OUTER HAIR CELLS (OHC’s)
Active and mechanical
12500 per cochlea
3 rows
Test tube shaped
Impacts sensitivity of cochlea
EFFERENT - from brain
What is the outer hair cell function?
Amplification - more vibration for softer sounds
Limitation - less vibration for loud sounds
Fine tuning - causes wave to concentrate on a smaller group of IHC’s (causing them to fire off nerve impulses)
A loss of OHC function results in an inability to hear quieter sounds
Where is the organ of corti and what is its central function?
Located within the cochlea and on the BASILAR membrane, it is the central organ for hearing.
This is where the hair cells are located with the stereo cilia on top of the hair cells that bend and respond to fluid motion.
What is shearing?
As hair cells ebb and flow with fluid motion, they cause the tectorial membrane to either come towards or away from the hair cells (in effect shearing them).
This shearing causes the hair cells to open allowing potassium to flow in turning the cells from a negative charge to a positive charge.
This releases neuro transmitters which send sound signals to nerve cells and then the brain.
What are the 2 essential processes that take place within the cochlea?
TRANSMISSION - transfers sound from Oval window to organ of Corti
TRANSDUCTION - converts mechanical energy (vibrations) into electrical-chemical energy (action potential).
Also functions as a frequency resolution - breaking sound up into its component frequencies,
What is Bekesy’s traveling wave theory?
This theory demonstrates that a traveling wave of motion along the BM reaches a maximum amplitude (displacement)
Position of maximum amplitude varies with the frequency of the signal (frequency resolution)
Low frequency - peak near apex
High frequency - peak near base
Frequency determines where the peak is, once reached the vibration dies out rapidly.
What is temporal resolution?
A pattern of firing nerve fibres that is in someways analogous to the sound stimulus
For example: if 1kHz presented to the ear, a pattern of nerve impulses that repeats 1000 times per second will travel to the brain.
What is the endocochlea potential?
It is the positive voltage of 80-100 millivolts seen in the cochlea endolymphatic spaces
What is the resting/standing potential?
No sound. Hearing requires minimum of 80 mv of electrical charge to hear sounds.
Hair cell potential 60mv
Perilymph potential 0mv
What are evoked potential?
The cochlea microphonic - an electrical signal in the outer hair cell, same waveform of incoming frequency
Action potential (total activity) measurement of impulses in the nerve fibres within the cochlea - passing via the 8th nerve to the auditory cortex.
What is the summating potential?
Inability of the stria vascularis to maintain 80mv in the endolymph when subjected to long and intense signals.
What is the function of the inner hair cells?
CODING THE FREQUENCY - specific frequency causes maximum displacement at a particular point on BM.
TEMPORAL CODE - pattern of firing nerves ie 1kHz impulses 1000 times per second
CODING THE INTENSITY - higher intensity of stimulus the greater the number of nerve impulses
What are the pre-inspection questions for otoscopy?
Do you have any ear related symptoms such as pain, discharge or discomfort?
Have you previously ever had ear related surgery?
Are you happy for me to proceed? (CONSENT)
Remain still, face forward, don’t speak but if to wish me to stop just raise your hand.
What is NIHL? noise induced hearing loss
Result of inadequate communication in high noise generally within a work place resulting in:
Degraded production
Accidents and injuries
Noise induced hearing loss
What is DPNE in relation to NIHL? How do we measure it?
DAILY PERSONAL EXPOSURE LEVEL
Industry calculates an equivalent continuous noise level over 8hrs - DPNE level.
What is the legislation relating to NIHL and the employer/employer responsibilities?
Control of noise at work regs 2005
Health and safety act 1974
Employer: measure DPNE levels
Supply and maintain equipment
Control noise exposure
Training & ensure correct use
Employee: cooperate wear PPE look after it, report any safety or hearing issues.
What is the DPNE measured in? What is it measuring?
DB(a) A-weighted decibels
Expression of loudness perceived by the human ear.
Decibel value for sounds at low frequency are reduced as the human ear is less sensitive below 1kHz than high frequencies
As a weighted scale cannot add or subtract in usual way ie:
90dB(a) + 90dB(a) = 93dB(a) not 180.
A 3dB(a) increase is a doubling of sound intensity - what increase is required for dB perception in hearing?
A 10dB increase is needed to be perceived as twice the intensity in the human ear.
What are the 3 levels of action required to monitor DPNE levels?
LAV lower action value:
DPNE - 80dB(a)
Single peak - 135dB(a)
UAV upper action value:
DPNE 85dB(a)
Peak 137dB(a)
ELV Exposure limit value
DPNE 87dB(a)
Peak 140dB(a)
ELV takes into account reduction to exposure provided by PPE
What are the 3 key HL factors relating to noise exposure?
The sound level/intensity (how loud)
Proximity
Exposure time
If noise exposure is cumulative, how does this inform dB(a) increases?
For every 3dB(a) increase we half the exposure time of the level before.
Starts at 85dB(a) Max 8 hours
88. 4 hours
91. 2 hours
And so on.
What hearing protection options are there?
Ear plugs
Personalised/mould plugs
Ear defenders ‘Muffs’
Electronic ear protectors ‘in the ear’
What are the effects of the cumulative effect of NIHL?
Hair cell damage.
Louder the noise, longer the exposure = greater chance of permanent damage.
Intensity, proximity and duration
What are the 3 types of NIHL? what is there characteristic?
NIHL - high intensity long duration
HIGH FREQUENCY SN HL
ACOUSTIC TRAUMA high intensity short duration - conductive or SN loss
BLAST injury sudden very loud exposure - conductive and SN loss
What are the 5 BSA audiogram descriptors for hearing loss?
Unilateral or bilateral?
Symmetrical or asymmetrical?
Flat/sloping/reverse slope?
Mild/moderate/severe or profound?
Conductive/SN or mixed loss?
What are the dBHL levels for mild to profound losses?
Mild. 20-40dBHL
Moderate. 41-70
Severe. 71-95
Profound. 95 plus
