Ear Flashcards
Parts of ear
External
Middle
Dinner?
External ear components
Pinna
external auditory canal (acoustic meatus)
Middle ear components
Three Ossicles.
In order of decreasing size:
Malleus- tensor tempani muscle connection
Incus
Stapies- stapedius muscle connection
Stapes smallest bone of body
Inner ear components
Cochlea for hearing
Utricle and saccule for linear balance
Semicircular canals for angular balance
Which arch is external ear made up of?
Pinna- 1st pharyngeal arch
Rest- 2nd pharyngeal arch
External auditory canal made up of?
1st ectodermal cleft
Tympanic membrane made up of?
ALL 3 germ layers
1st ectodermal pouch makes?
Middle ear
Antrum
Eustachian tube
Ear ossicles made up of which pharyngeal arch?
Malleus + incus - ( + tensor tympani muscle) — 1st arch
Stapies + (stapedius muscle) 2nd arch
What is inner ear/cochlea made up of?
Neuroectoderm (Ottic placode)
When do pinna and cochlea completely develop?
20 weeks of intrauterine life
What are the congenital anomalies of external ears?
Incisura terminalis
Darwin’s tubercle
Bat ear
Microtia
Anotia
What is incisura terminalis?
It is a point at which the 1 and 2 pharyngeal arches merge.
If there is no fusion, a pre auricular sinus is formed.
There is no infection or complain.
What is Darwin’s tubercle?
It’s a conical elevation. Outer curve
Anomaly
What is bat ear deformity?
Inner curvature (anti helix) is absent
Plastic reconstruction at 6 to 7 years
Otoplasty
What is microtia and anotia?
Microtia- small pinna
Anotia- absence of pinna
What is the tip of malleus called?
Umbo
Oval window is attached to which bone?
Footplate of stapes
What are the four normal tympanic membrane landmarks?
1 lateral process of malleus
2 handle of malleus
3 light reflex (cone of light)
4 tip of umbo most important
Tympanic membrane parts
Upper part= Pars flaccida -2 layers
Lower part= Pars Tensa- 3 layers (fibrous layer aswell)
Pinna haematoma
Dx
Complications
Rx
Pt. Will present w Hx of trauma, boxer.
Pooling of blood between cartilage and pericardium due to trauma
Complications: post traumatic ear deformity— cauliflower/ boxers ear
Rx- incision and drainage/ aspiration. + pressure bandage.
Nerve supply of pinna
Greater auricular nerve
External auditory canal size
24 mm
Outer 1/3rd cartilage(8mm)
Inner 2/3rd bony
Rudimentary openings in external ear
fissure if Santorini in cartilaginous part
foremen of Hushke in bony part
Natural defects
Infection may reach parotid gland via
Nerve supply of roof and Ant. wall of EAC?
Auriculo-temporal branch of mandibular nerve
Nerve sup. of floor and Post. part of EAC?
Auricular branch of vagus nerve
Arnold’s OR Alderman’s nerve
Nerve sup. of postero-superior part of EAC?
Sensory branch of facial nerve
nerve of Winsberg
Ear syringing
50/60 ml warm water in posterosuperior direction.
•If cold water used, pt. Will experience vertigo
•In Antero-inferior direction— irritation of Arnold’s nerve (vagus) will cause:
-Cough reflex
-Sudden vasodilation leading to vasovagal syncope.
Localised external ear infection
Furuncle- infection of hair follicle
MCC- S. aureus
Rx- antibiotics + icthamamol glycerin packing (IG)
Diffuse external ear infection
Diffuse otitis externa
MCC = pseudomonas
tropical Singapore swimmers.
Rx-
only Antibiotics.
Elderly, diabetic, patient comes with complaints of severe earache, discharge and features of palsy. granulations in EAC.
Dx?
Malignant otitis externa
Malignant otitis externa
-Severe life threatening infection.
Common in immunocompromised (HIV, covid)
-MCC- pseudomonas
-Can spread in skull base — skull base osteomyelitis causing CN palsies
( 9.10.11.12 CN)
Most common CN involved in Malignant otitis externa
CN 7
Malignant otitis externa Rx
Broad spectrum antibiotics
3rd gen cephalosporins
for 6-7 weeks
(Ceftriazone.)
Wet newspaper appearance seen in which condition?
Otomycosis
Otomycosis
Dx
Rx
Fungal infection of the external ear
MCC- aspergillus niger
(Black newspaper appearance)
2nd-
Candida
(Cloudy white)
Main complaint- itching
Rx- aural toilet. Plus antifungal eardrops
Bullous Myringitis
Also called myringitis bullosa
Blebs or balloons over the tympanic membrane, a complication of infection.
Whitish appearance of tympanic membrane?
-Calcification or fibrosis of Tympanic membrane called tympanosclerosis
-Can be seen after infection
-Chalky white appearance
Tympanic membrane landmarks, not visible
Tympanic membrane sucked in
Retraction of tympanic membrane due to negative pressure generated inside the middle ear that creates a vacuum caused by blockage of eustachian tube.
Keratin deposition can also be seen in black colour
Child, slapped by teacher, has mild conductive hearing loss. Brought to OPD
Dx?
Traumatic tympanic membrane perforation
Traumatic Tympanic membrane, perforation
Rx?
Reassurance
Or Conservative
No infection so there will be no treatment as the tympanic membrane is self healing w/I 3-6 months
Self resolving condition
Middle ear also called?
Tympanum
Main function of middle-ear?
Impedance matching
What is impedance matching?
In inner ear, we have fluid called endolymph and perilymph.
When The sound reaches inside the inner ear, It will be diminished because of a change in medium as there is more resistance in fluid medium.
to overcome that, we need to amplify the sound.
usually done by the decreasing size of the ear ossicles along with the difference in the surface area of the tympanic membrane and the surface area of the oval window, causing amplification of sound.
Nerves along the petrous Apex?
5 and 6 CN
Roof of middle-age
Tegmen Tympani
above that is Dura matter of brain
above that temporal lobe of the brain
