Ear anatomy and embryology

Question 1

Inner ear is located in
Ear is in

Roof of ext, middle and inner ear

Internal acoustic meatus connects inner ear to which cranial fossa

Which cn passes through int acoustic meatus

Answer 1

Petrous part of temporal bone
Temporal bone
,
Anterior plate of petrous bone
posterior plate separates it from posterior cranial fossa

Posterior cranial fossa

7 nd 8

Question 2

Acoustic neuroma

Answer 2

Tumour Arises from the internal acoustic meatus then it goes intracranially, so there can be diplopia due to 6 cn involvement( upper pole of tumour, cn 5 , 6 involved)
Lower pole involve 9,10 ,11

Cn 6 arises at the junction of pons and medulla ( quite posteriorly) nd has the
Longest intracranial course may be involved in many conditions

Question 3

Pathology of petrous apex cn involved

Sigmoid sinus

Answer 3

5 and 6

Posterior boundry of mastoid exit through juglar foramen and continues in neck as internal juglar vein

Question 4

Base of skull foramen
1 optic canal
2 superior orbital fissure 
3 foramen rotundum
4 foramen ovale
5 foramen spinosum
4 foramen lacerum
5 internal acoustic meatus 
6 juglar foramen
7 hypoglossal canal

Answer 4

Optic nerve, opthalmic artery
Cn 3,4,6,5(opthalmic branch)
Cn 5( maxillary branch)
Cn 5( mandibular branch)
Middle meningeal artery and vein
Greater petrosal nv( passes over the foramen)
cn 7,8
Cn 9, 10, 11
Cn 12

Question 5

Meiners disese

Answer 5

Apex of organ of corti ( responsible forr low frequency sensation) is affected early in meiners disease

Base of organ of corti senses sound at high frequency

Question 6

Arcuate eminence

Posterior semicircular canal
Lateral semicircular canal

Answer 6

Projection of superior semicircular cannal into roof of inner ear( base of skull)
If arcuate eminence ( roof) is absent - superior semicircular canal dehiscence syndrome aka third window syndrome

Bulges posteriorly towards the mastoid
Bulges laterally towards the middle ear

Question 7

Bonny labyrinth develops from

Membranous labrynth develops. From

Answer 7

Mesoderm from enchonderal ossification ( first develops into cartilage then into bone)
Sub ectoderm

Question 8

Oval window

Answer 8

’ Connects middle ear to vestibule of inner ear

Otosclerosis- fixation of oval window →no vibration transmission
Utricle and saccule overstimulation by oval window hypermobility or utricle and saccule dilationlation leads to proximity of u nd s towards the oval window leading to to vertigo ( utricle and saccule dilation— meiners , syphlis— hypermobility)

Question 9

Secondary tympanic membrane

Answer 9

Round window -connecting middle ear to scala tympani
Significance of round window- sound transmission shering action on organ of corti

Electrodes transmission to inner ear via round window in cochleaer implant (round window is the path of choice for middle to inner transmission eg steroids , gentamicin )

Question 10

Connection of Brain to inner ear

Answer 10

Internal acoustic meatus
Cochlear aqueduct ( CSF → perilymph)
Meningitis can lead to labrynthitis

Question 11

Congenital abnormality of inner ear

Answer 11

Michael Aplasia → absent
Mondini → cochlea /sm has 1 1/2 turns only
Alexander →deformity of basal turn high frequency sound affected
Schiebie → deformity of saccule and cochlea (sc)

Question 12

Endolymphatic sac

Orientation of semicircular canals

Answer 12

Lies between 2 layers of dura ( menengeal and endosteal)

Lateral lies inside posterior and superior and posterior have a common opening called crus commune

Question 13

Internal and middle ear development

Answer 13

From brachial arches
Ectodermal lining _ external auditory canal develops from first cleft( only cartilagenous part present at birth , pinna develops from the same cartilage-defect in formation of pinna is called meatal atresia—hearing loss— Tt BAHA invasive surgery-reconstruction done after 6years of age in children by costal rib cartilage )

Mesodermal arch _ first arch: malleus, incus _ second arch: supra structure of stapes

Endodermal pouch: tubotympanic recess - proximal part: Eustachian tube
- distal part: middle ear, mastoid antrum

Question 14

Calluaral fistula

Answer 14

All the cleft during the formation of external auditory canal develops in the neck
The lateral part fuses and the medial part leads to formation of EAC
If lateral part remains unfused it leads to formation of an opening in neck called a callural fistula

Question 15

Mc site of preauricularsinus

Answer 15

Junction of tragus and helix

Question 16

1-Crowbecks sign
2-Griesinger sign
3-tragal sign
4- Hennebert sign 
5- lighthouse sign( pulsatile otorrhoea)
6- pulsation/ browns sign ( pulsation and blanching )
7- pulsatile tinnitus
8- Phlep s sign ( absence of crest of bone b/w ICA and JV)
9 Reservoir sign/ tea pot sign ( pus in mastoid refilling while drainage)
10- Gradenigo’s triad
11-Delta sign/ Empty triangle sign
12-tobey ayer/ Queckenstedt’s test
13-Schwatz sign / flamingo pink sign
14- schwatz surgery
15- red reflex/ rising sun app
16 red TM/ cartwheel app
17 vanderhoeve syndrome
18- kernigs sign
19- Brudzinski singn
20- hitzelberger sign
21 -double ring/ halo/ target sign
22 -double density sign
23-  Holman miller sign
24- Dodd’s/ crescent sign
25- irwin moore sign
26- Moure sign 
27- Boyce sign 
28  -Boyce position
29- roses position
30 bryce sign

Answer 16

1-Papilledema in eye on compresssing and releasing the IJV
2-Swelling of mastoid due to mastoid emissary vein obstruction in lateral sinus thrombosis
3- furuncle of EAC
4-congenital syphlis, some cases of meiners ,SSCD
5- ASOM; acute mastoiditis
6,7,8- Glomus
9- mastoiditis
10- triad of petrositis- inv of cn V, palsy of VI nv and ear discharge
11- lateral sinus thrombosis osis due to obstruction walls apper like empty triangle
12- lateral sinus thrombosis inc in csf when press and release the IJV
13- active otosclerosis ( n appearance in otosclerosis is pearly white )
14- acute mastoiditis( opening of mastoid air cells nd pus removal)
15 glomus
16 ASOM
17 osteogenesis imperfecta association with otosclerosis and blue sclera
18 meningitis complication of CSOM
19- meningitis
20-acoustic neuroma/ vestibular schwannoma- hypoesthesia in EAC inv sensory part of facial nv
21. Csf rhinorrhea
22. Allergic fungal sinusitis
23- angiofibroma ( post wall of mazxillary antrum pushed anteriorly)
24- antrichoaanal polyp ( column/ crescent of air seen when bulge doesnot arise from post pharyngel wall whersas in angiofibroma where bulge arise from post pharyngeal wall it is not seen)
25-chronic tonsillitisOn pressing anterior pillar there is expulsion of cheesy material
26- post cricoid CA , laryngeal crepitus is heard on holding and moving the larynx
27 zenkers diverticulum pharyngeal pouch gurgling sound of swelling
28. Direct laryngoscopy bronchoscopy oesophagoscopy
29- tonsillitis, adenoidectomy, tracheostomy
30. Laryngocele on pressingswelling hissing sound

Question 17

Meiners
Reverse meiners
Dipalcusis

Answer 17

Triad of vertigo followed by deafness and tinnitus
Deafness and tinnitus preceed vertigo
Ears perceive sound at different frequencies see in meiners