Week 3: ENT 1 (anatomy of the ear, history and examination)

Question 1

The ear is subdivided into 3 main parts:

Answer 1

1) the external ear 2) the middle ear 3) the inner ear

Question 2

referred ear pain explanation

Answer 2

• Branches of
  
  • Cervical spinal nerves
  • Vagus
  • Trigeminal (auriculotemporal n.)
  • Glossopharyngeal (tympanic n.)
• Small contribution from CNV II – vestibulocochlear)

e.g. someone with pathology affecting parts of the pharynx/larynx may manifest itself as pain from the ear

Question 3

Otalgia with a normal ear examination should leave you to suspect an alternative site of pathology

Answer 3

• Otalgia can be non-otological or otlogical in origin
• There are many non-ontological causes for otalgia
  
  • TMJ (temporal mandibular joint )dysfunction (CN Vc)
  • Disease of oropharynx (CN IX)
  • Disease of larynx and pharynx including cancers (CN IX and X)

Question 4

the external ear includes

Answer 4

• Pinna- outer curve of the ear
• External auditory meatus lined with skin air filled canal leading to the middle ear
• Supplied by the greater auricular nerve, lesser occipital and facial nerve

Question 5

the pinna

Answer 5

• Pinna consist of elastic cartilage thrown into folds and fibrofatty lobules
• Supplied by the greater auricular nerve, lesser occipital and facial nerve

Question 6

External auditory canal

Answer 6

• Oblique tube 3cm in length
• Outer 1/3 is cartilage, inner 2/3 is bony
• Ceruminous glands only exist in the outer 1/3 →wax
• Tympanic membrane from the medial boundary of the canal
• Nerve supply- auriculotemporal nerve and auricular branch of the vagus nerve
• Blood supply: Auriculotemporal branch of superficial temporal artery Posterior auricular branch of the external carotid artery

Question 7

external acoustic meatus

Answer 7

Skin lined cul-de-sac 2.5cm in length

• Sigmoid shaped
• Lined with keratinising, stratified squamous epithelium continuous onto lateral surface of tympanic membrane
• Embryology- EAM from cleft of the 1^st and second pharyngeal arches lined with ectoderm
• Cartilaginous outer 1/3
  
  • Hair
  • Sebaceous
  • Ceruminous (wax0 glands lined cartilage part
    
    • Barrier for foreign objects
• And bony inner 2/3 (petrous bone)

Question 8

self cleaning function of EAM

Answer 8

• Epithelial migration
• Surface of the skin moves laterally from the tympanic membrane towards the ear canal

Question 9

Middle ear

Answer 9

• Air filled cavity
• Pharyngotympanic tube (PT) intermittently opens→ allows air filled cavity of the PT equilibrate with air pressure in the Nasopharynx (NP)
• Ossicles
• Middle ear lined with pseudostratified columnar ciliated epithelium with goblet cells (resp epithelium)

Question 10

ossicles

Answer 10

• Malleus- largest and lateral process is attached to tympanic membrane
• Incus- head of malleus articulates with incus
• Stapes – two limbs (anterior crus and posterior crus) attached to oval window footplate

Question 11

The tympanic membrane

Answer 11

• forms the lateral boundary of the middle ear cavity. It is a circular shape and roughly 1cm in greatest diameter.
• Nerve supply- outer surface by the auriculotemporal nerve and the auricular branch of the vagus.
• The membrane is normally greyish/ pinkish in colour.
• When the membrane is examined with an otoscope, the concavity of the structure produces a cone reflex in the anteroinferior quadrant.
• The tip of the handle of malleus forms the deepest concavity of the membrane called the umbo, which is where the cone of light radiates from.
• The pars flaccida is the weakest and most flaccid area of the tympanic membrane.
  
  • It plays a vital role in the pathophysiology of cholesteatoma.
• The pars tensa forms the remainder of the tympanic membrane.

Question 12

Inner ear

Answer 12

• Fluid filled structures
• Located in the petrous part of the temporal bone
• Cochlear canal
  
  • Where action potentials are generated for sending signals to the brain to be perceived as sound
  • Fluid filled
• Semi-circular canals
  
  • 3
  • Orientated at 90 degrees to one another
  • Fluid filled
  • APs carried to the brain to be perceived as position and balancer

Question 13

two importnant structures of the inner ear

Answer 13

1. Vestibular apparatus
2. Cochlea
   
   • Both fluid filled tubes
   • Involved in hearing (cochlea) and balance (vestibular)

Question 14

cochlea

Answer 14

Fluid filled tube with specialised hair cells that generate AP when moved. Arranged in a spiral housed within the petrous part of the temporous bone. Cochlear duct sit inside the cochlear (allowed out petrous bone) that has specialised hair cells etc…

1. Movement at the oval window (by the movement of the ossicles causing movement on the footplate onto the oval window) causes movement of fluid in the cochlear duct
2. Waves of fluid cause movement of special sensory cells (stereocilia)→ generates AP via CN VIII (vestibulocochlear) → temporal region of brain

Question 15

Vestibular apparatus

Answer 15

1. Fluid movement (generated by position and rotation of head)
2. Converted into APs (CNVIII) → perceived as position sense and balance

Question 16

Inner ear pathology presents with a combination of

Answer 16

1. Hearing loss
2. Tinnitus
3. Disturbances in balance and vertigo (specific to inner ear)

Question 17

Mechanism of hearing

Answer 17

• Auricle and external auditory canal focuses and funnels sound waves towards the tympanic membrane which vibrates
• Vibration of TM causes vibration across chain of ossicles (amplifies) and ends in vibration of the foot of the stapes on the oval window
• Fluid filled cochlea duct
  
  • Within the duct is the organ of corti – where we found the stereocilia
  • Vibration created by ossicles leads to waves in the channels of fluid which lead to movement of stereocilia (nerve cells) AND TRIGGERS AP IN COCHLEAR PART OF CN VIII
  • Generate sound
  • PRIMARY AUTITORY CORTEX= TEMPORAL LOBE

Question 18

History taking in ENT

Answer 18

Before starting

• Wash hands
• Introduce self and ensure patient is comfortable
• Maintain good eye contact

Structure

• PC
• HPC
  
  • SOCRATES
  • Relevant targeted list of questions for PC related to ears, nose and throat
  • Previous episodes
    
    • Any recent ear infections and were there any complications e.g. perforation, middle ear effusion
    • Recent upper resp tract infection e.g. rhinitis and sinusitis
    • Attempts at cleaning the ears with cotton swabs or sharp objects
    • Recent trauma to head, neck or ears
  • • PMH
  • Birth history is important for ear conditions in children
  • Chronic illnesses: diabetes, hypertension, asthma, immunocompromised state
  • Ear surgeries
  • Dental status: recent dental procedures and hygiene
  • Head and neck tumours
  • Problems in the neck and temporomandibular joint
• Drug history- inc counter medication and vaccination
• Allergies
• Family history of ear problems
• Social history
  
  • Ask questions about quality of life
  • Smoking
  • Alcohol
  • Occupation e.g. ototoxicity from chemicals, noise pollution
  • Barotrauma e.g. recent air travel or undersea diving are potential causes of hemotympanum in the absence of external trauma
  • Problems in the neck and temporomandibular joint
  • Recent travel or contact with sick people
• Systems review- also enquire about any tendency to bruise or bleed easily

At end of history

• Summarise patients history to them
• Clarify that you understand them
• Ask if there is anything else they would like to mention
• ICE

Question 19

overview of examination of the ear

Answer 19

INSPECT

OTOSCOPE

HEARING TEST

Question 20

Before starting ear exam

Answer 20

• Wash hand
• Introduce self and make sure patient comfortable
• Ask about any pain or tenderness
• Patient should be position on chair and place yourself to the side of patient
  
  • Children should be sat across the parent/nurse lap, with the side of the ehad held to the chest by the carers hand
  • Flailing arms can be secured with the cares other hand
  • Examine opportunistically and incorporate play as part of the examination

Question 21

inspection of the ear

Answer 21

Inspect each ear individually starting with the normal ear.

• Front
  
  • Size
  • Symmetry of the pinna
  • Differing degrees of protrusion
  • Is there an obviously abnormal pinna
• Preauricular
  
  • Inspect for scars (previous parotidectomy or middle ear surgery), swelling (infection, parotid tumour), erythema (infection/inflammation), sinuses, pits, fistualae
• Pinna
  
  • Signs of erythema, swelling (infection, haematoma) or tenderness
• Post auricular
  
  • Move pinna anteriroly to inspect behind the pinna
  • Not any scars
  • Acute and/or painful swelling suggests infection (mastoiditis or lymphadenitis)

Examine the other eat and note difference

Question 22

otoscopy method

Answer 22

• Ensure the otoscope has good magnification and illumination. Use the largest speculum that will fit comfortable in the external auditory canal (EAC)
• Start with the “normal” ear
• Gently pull the pinna upwards and backwards to straighten the ear canal to best visualise the tympanic membrane. In children, pulling the pinna downwards and backwards may provide better visualisation
• Hold the otoscope like a pencil and use your little finger as a fulcrum against the cheek to avoid injury should the patient move suddenly
• Inspect systematically

Looking at: external auditory canal, tympanic membrane, ossicles

Question 23

otoscopy: external auditory canal

Answer 23

wax or discharge, erythema, swelling (infection, trauma)

Question 24

otoscopy: tympanic membrane

Answer 24

• Normal light reflex
• Colour of drum (normal is greyish and translucent)
• Pink/red can mean infection/inflammation
• White plaques can indicate tympanosclerosis
• Position of drum
  
  • Retracted (cholesteatoma, infection)
  • Bulging (infection), perforation

Question 25

otoscopy: ossicles

Answer 25

malleus, incus and stapes can sometimes be seen if perforation

Question 26

**Pneumatic otoscopy**

Answer 26

**-** can be used to assess tympanic membrane (this modified otoscope has an air-tight seal when placed in the ear canal and a rubber bulb (similar to that of a sphygmomanometer) which the user can squeeze which alters the pressure within the ear canal)

Question 27

**Hearing tests**

Answer 27

* **Pure tone audiogram** * **Field speech testing** * **Webers and rinnes tests**

Question 28

**Free field speech testing**

Answer 28

* Free field testing is a good screening tool for hearing loss * Use of masking improves the accuracy of testing: * Rub the tragus of the contralateral ear whilst performing this to prevent sound being heard in the contralateral non-test ear * Use polysyllabic phrase (number or letter) e.g. ‘C5’, ‘37’ or motivational phrases in children e.g. ball, sweets, crisps * Test normal ear first. * Perform, in order of intensity at 60cm (arms length) and 15cm: whisper, conversational speech, loud voice. * Patient should be able to repeat \>50% of the letters/numbers correctly.

Question 29

Webers and Rinnes test

Answer 29

These tests assess air conduction (AC) and bone conduction (BC) and are used to help delineate whether hearing loss is sensorineural (SNHL)or conductive (CHL) in origin.

Question 30

Webers

Answer 30

* Vibrating 512Hz tuning fork applied firmly to the midline of the forehead, apex of head (see Figure 4) Ask the patient if he/she can hear a tone in the right ear, left ear or centre of the head * The “louder” ear may be due to conductive hearing loss in that ear (sound travels through the bone), or sensorineural hearing loss in the other ear * You can work out which this is by performing Rinne’s test.

Question 31

Rinnes test

Answer 31

* Place vibrating tuning fork with base on mastoid process (position 1, testing bone conduction). See Figure 5 * Then move the tuning fork so its prongs are adjacent to (but not touching) the external auditory meatus (position 2, testing air conduction). * Ask patient to tell you which is louder, when the fork is placed behind the ear or in front of the ear * Position 2 is louder than position 1 in the normal ear (Positive Rinne), as an intact hearing apparatus of the external and middle ear amplifies sound. * When position 2 is quieter than position 1, (Negative Rinne), this indicates external or middle ear disease affecting the air conduction

Question 32

summary of webers and rinnes

Answer 32

Question 33

pure tone audimetry

Answer 33

Pure tone audiometry is a subjective test that aims to evaluate the quietest sound that can be heard with each ear at various frequencies i.e. the hearing threshold. Hearing is usually reported on the decibel scale, which is a logarithmic scale. In general, a whisper from 1m has an intensity of 30dB, normal conversational voice is 60dB, shouting equates to about 90dB and discomfort can be felt at around 120dB.

Question 34

technqiue of audiometry

Answer 34

* The audiometer is a machine which provides pure tone sounds at varying frequencies * *The test must be conducted in a soundproof room and the subject should not be able to see the machine or the tester adjusting the controls as this may influence the results.* * Before conducting the test, the ears must be examined to exclude an active infection, foreign body or occluding wax. The patient then wears headphones to test air conduction followed by a bone vibrator placed on the mastoid process to test bone conduction * **Air conduction** is tested at 250, 500, 1000, 2000, 4000 and 8000 Hz while **bone conduction** is tested at 500-4000 Hz. * Masking helps to deal with cross hearing, which occurs from bone conduction to the contra-lateral cochlea. * It involves presenting a sound to the non-test ear (masking noise) to prevent it from detecting the sound being presented to the test ear

Question 35

interpreting audiometry

Answer 35

Hearing Disability is defined as: * Normal hearing is defined to be 20dB or better. * Mild hearing loss is between 21-40dB. * Moderate hearing loss is between 41-70dB. * Severe hearing loss is considered to be 71-90dB. * Profound hearing loss is worse than 90dB.

Question 36

audiogram example

Answer 36

Question 37

**Physiology of the ET**

Answer 37

* Connects middle ear (ossicles) into the post nasal space * Lining = mucosal * Usually closed in healthy individual, but opens regularly when you swallow or chew * Opening the tube allows: * Mucus to drain out of the ear * Allows air to move from the post-nasal space (atmospheric pressure) and middle ear this equilibrates the pressure

Question 38

**ET blockage** *

Answer 38

* More common in children * Small diameter of eustachian tube * More horizontal * More coughs and cold * Large adenoids * When blocked * Ear pressure cannot equilibrate with atmospheric pressure * Mucus cannot drain out of the middle ear

Question 39

healthy TM is

Answer 39

slightly concave- cone of light

Question 40

**If the pressure in the middle ear decreases**

Answer 40

retraction of the TM- otitis media with effusion (not getting pressure equilibrating- air in middle ear space gets reabsorbed → leaving mucosal fluid- negative middle ear pressure)

Question 41

**If pressure in the middle ear increases**

Answer 41

- bulging – acute otitis media (inflammatory exudate produced by mucosa increased air pressure)