Ent Textbook Liners (Chapter 1)

Front 1

What is incisura terminalis

Back 1

Area between crus of helix and Tragus which doesn't have cartilage.

Front 2

What can be used for reconstructive surgery of middle ear?

Back 2

1. Cartilage from tragus

2. Perichondrium from Tragus and concha

3. Fat from lobule

Front 3

Dimensions of External auditory canal

Back 3

1. 24 mm along it's post wall

2. Cartilagenous part: 8mm (outer 1/3rd)

3. Bony part: 16 mm (inner 2/3rd)

4. Isthmus: 6mm lateral to tympanic membrane

Front 4

Glands secreting wax

Back 4

1. Ceruminous

2. Pilosebaceous

Front 5

Name of deficiencies

Back 5

Fissures of santorini

Front 6

Where are furuncles formed and why

Back 6

Hair is confined only to the outer 1/3rd of canal, hence staph infections are seen only here

Front 7

Work of Anterior recess

Back 7

Acts as a cesspool for discharge and debris in case of infections

Front 8

Location of anterior recess

Back 8

Beyond isthmus, anteroinferior part of deep meatus

Front 9

Deficiency in anteroinferior part of bony canal

Back 9

Foramen of Huschke

Front 10

Dimensions of tympanic membrane

Back 10

1. 9-10 mm long

2. 8-9 mm wide

3. 0.1 mm thick

Front 11

Name of fibrocartlilagenous ring

Back 11

Annulus tympanicus

Front 12

What is Umbo?

Back 12

Central part of pars tensa tented inwards at level of tip of malleus

Front 13

Another name of pars flaccida

Back 13

Shrapnell's membrane

Front 14

Superior relation of EAC

Back 14

Middle cranial fossa

Front 15

Posterior relation of EAC

Back 15

1. Mastoid air cells

2. Facial nerve

Front 16

Inferior relation of EAC

Back 16

Parotid gland

Front 17

Anterior relation of EAC

Back 17

TMJ

Front 18

When and where is sagging seen?

Back 18

Seen in posterosuperior part of deeper canal

Noticed in acute mastoiditis

Front 19

Nerve supply of pinna

Back 19

1. Greater auricular

2. Lesser occipital

3. Auriculotemporal

4. Auricular branch of vagus

5. Facial nerve

Front 20

Other name of auricular branch of vagus nerve

Back 20

Arnold's nerve

Supplies concha and corresponding eminence

Front 21

Nerve supply of EAC

Back 21

1. Auriculotemporal

2. Auricular branch of vagus

3. Sensory fibres of (2)

Front 22

Nerve supply of tympanic membrane

Back 22

1. Auriculotemporal nerve

2. Auricular branch of vagus

3. Tympanic branch of vagus (Jacobson's nerve)

Front 23

Constituents of middle ear cleft

Back 23

Middle ear

Eustachian tube

Aditus

Antrum

Mastoid air cells

Front 24

Location of mesotympanum

Back 24

Opposite to pars tensa

Front 25

Location of epitympanum (attic)

Back 25

Above pars tensa but medial to Shrapnell's membrane

Front 26

Location of hypotympanum

Back 26

Below the pars tensa

Front 27

Roof and floor of middle ear

Back 27

Roof- tegmen tympani: separates TM from middle cranial fossa

Floor- thin plate of bone : separates TM from jugular bulb

Front 28

Anterior wall of middle ear

Back 28

Thin plate of bone : separates cavity from Internal carotid artery

Two openings:

1. Upper one: canal for tensor tympani muscle

2. Lower one: Eustachian tube

Front 29

Posterior wall of middle ear

Back 29

Lies close to mastoid air cells

Bony projection : Pyramid

Through the summit appears tendon of stapedius to get attached to neck of Stapes.

Front 30

Pyramid of middle ear

Back 30

Superior: aditus

Posterior: facial nerve

Depression in posterial wall lateral to pyramid: Facial recess/posterior sinus

Medial: Vertical part of 7th nerve

Lateral: Chorda tympani

Above: Fossa incudis

Front 31

Surgical importance of facial recess

Back 31

Direct access can be made through this to middle ear without disturbing posterior wall

Front 32

Medial wall of middle ear

Back 32

Formed by labyrinth

Bulge: promotory

Oval window

Round window

Front 33

Oval window

Back 33

Attached to the footplate of stapes

Above oval window: Canal for facial nerve

(Above this canal: Prominence of lateral semicircular canal)

Anterior to oval window: Processus cochleariformis

Front 34

Importance of Processus cochleariformis

Back 34

Marks the level of the first genu of the facial nerve which is an important landmark for surgery of the facial nerve.

Front 35

Sinus tympani

Back 35

It is medial to pyramid

bounded by the subiculum below and the ponticulus above

Front 36

Lateral wall of middle ear

Back 36

Formed largely by the tympanic membrane and to a lesser extent by the bony outer attic wall called scutum.

Hint 36

Front 37

What is a scutum

Back 37

Bony outer attic wall is called scutum.

Front 38

Boundaries of mastoid antrum

Back 38

Roof- tegmen antri (separates from middle cranial fossa)

Laterally- 1.5 cm thick plate of bone

Marked externally on surface of mastoid by Mac Ewen's (supremeatal) triangle

Hint 38

Front 39

Different types of mastoid

Back 39

Depending on development of air:

1. Well-Pneumatized or Cellular

2. Diploetic

3. Sclerotic or acellular

Front 40

Different type of mastoid 2

Back 40

Depending on the location

1. Zygomatic cells

2. Tegmen cells

3. Perisinus

4. Reterofacial

5. Perilabyrinthe

6. Peritubular

7. Tip

8. Marginal

9. Squamosal

Front 41

What is Korner's septum?

Back 41

Mastoid develops from petrous and squamous bones.

The petrosquamosal suture may persist as bony plate, separating superficial squamousal cells from deep petrosal cells - called as Korner's septum

Front 42

Surgically importance of Korner's septum

Back 42

Korner’s septum is surgically important as it may cause difficulty in locating the antrum and the deeper cells; and thus may lead to incomplete removal of disease at mastoidectomy.

Mastoid antrum cannot be reached unless the Korner’s septum has been removed.

Front 43

Inferior route for draining petrous apex

Back 43

Inferior- most common

Approach through:

1. Infralabyrinthine- Access is through mastoid.

2. Infracochlear- Access is through the ear canal.

Front 44

Footplate of Stapes is held by

Back 44

Annular ligament in oval window

Front 45

Intratympanic muscles

Back 45

1. Tensor tympani

2. Stapedius

Front 46

Attachments of Intratympanic muscles

Back 46

1. Tensor tympani attaches to the neck of malleus and tenses the tympanic membrane.

2. Stapedius- attaches to the neck of stapes and helps to dampen very loud sounds thus preventing noise trauma to the inner ear.

Front 47

Nerve supply of Intratympanic muscles

Back 47

Tensor tympani- develops from 1st arch

Supplied by branch of mandibular nerve (V3).

Stapedius- develops from 2nd arch

Supplied by branch of CN VII

Front 48

Tympanic plexus is formed by

Back 48

Lies on promontory

(i) Tympanic branch of glossopharyngeal.

(ii) Sympathetic fibres from the plexus round the internal carotid artery.

Front 49

What does tympanic plexus supply

Back 49

Innervation to the medial surface of the tympanic membrane, tympanic cavity, mastoid air cells and the bony eustachian tube.

It also carries secretomotor fibres for the parotid gland.

Front 50

Course of secretomotor fibres of tympanic plexus to the parotid:

Back 50

Inferior salivary nucleus → CN IX → Tympanic branch → Tympanic plexus → Lesser petrosal nerve → Otic ganglion → Auriculotemporal nerve → Parotid gland.

Front 51

Chorda tympani nerve

Back 51

Carries taste from anterior two-thirds of tongue and supplies secretomotor fibres to the submaxillary and sublingual salivary glands.

Front 52

Lining of Eustachian tube

Back 52

Pseudostratified columnar- Cartilagenous part

Columnar- Bony part

It is lined by ciliated epithelium.

Front 53

Lining of Tympanic membrane

Back 53

Anterior and inferior- ciliated columnar

Posterior part- cuboidal

Front 54

Lining of epitympanum and mastoid air cells

Back 54

Flat, non-ciliated epithelium

Front 55

Major Blood supply of middle ear

Back 55

1. Anterior tympanic branch of maxillary artery - which supplies tympanic membrane.

2. Stylomastoid branch of posterior auricular artery - which supplies middle ear and mastoid air cells.

Front 56

Minor blood supply of tympanic membrane

Back 56

1. Petrosal branch of middle meningeal artery.

2. Superior tympanic branch of middle meningeal artery.

3. Branch of artery of pterygoid canal.

4. Tympanic branch of internal carotid.

Front 57

Where do veins supplying middle ear drain into?

Back 57

Pterygoid venous plexus

Superior petrosal sinus

Front 58

Lymphatic drainage of middle ear

Back 58

Front 59

Recesses in vestibule of bony labyrinth

Back 59

1. Spherical - lodges the saccule

2. Elliptical - lodges the utricle

Front 60

What passes through aqueduct of vestibule?

Back 60

Endolymphatic duct

Front 61

What is Crus Commune?

Back 61

The nonampullated ends of posterior and superior semicircular canals unite to form a common channel called crus commune.

Front 62

What is modiolus?

Back 62

The bony cochlea is a coiled tube making 2.5 to 2.75 turns round a central pyramid of bone called modiolus.

Front 63

Components of bony cochlea

Back 63

(a) Scala vestibuli

(b) Scala tympani

(c) Scala media or the membranous cochlea

Front 64

What is helicotrema?

Back 64

It is an opening through which scala vestibuli and scala tympani (filled with perilymph) communicate with each other at the apex of cochlea.

Front 65

What is scala Vestibuli closed by?

Back 65

By the footplate of stapes which separates it from the air-filled middle ear.

Front 66

What is scala tympani closed by?

Back 66

By secondary tympanic membrane

Front 67

Constituents of membranous labyrinth

Back 67

It consists of the cochlear duct, the utricle and saccule, the three semicircular ducts, and the endolymphatic duct and sac.

Front 68

Walls of Cochlear duct/scala media/membranous cochlea

Back 68

1. Basilar membrane

2. Reissner's membrane

3. Stria vascularis

Front 69

Cochlear duct is connected to saccule via

Back 69

Ductus reuniens

Front 70

What is macula?

Back 70

The sensory epithelium of the utricle is called macula and is concerned with linear acceleration and deceleration.

Front 71

What is Crista ampullaris?

Back 71

The ampullated end of each semicircular duct contains a thickened ridge of neuroepithelium called crista ampullaris.

Front 72

Surgical importance of Endolymphatic sac

Back 72

It is exposed for drainage or shunt operation in Ménière’s disease.

Front 73

Perilymph is rich in?

Back 73

Sodium ions

Front 74

Endolymph is rich in

Back 74

Potassium ions

Front 75

Endolymph is secreted by

Back 75

It is secreted by the secretory cells of the stria vascularis of the cochlea and by the dark cells.

Front 76

Blood supply of labyrinth

Back 76

labyrinthine artery, which is a branch of anterior-inferior cerebellar artery but sometimes from the basilar.

Front 77

Divisions of labyrinthine artery

Back 77

Front 78

Venous drainage of labyrinth

Back 78

1. Internal auditory vein

2. Vein of cochlear aqueduct

3. Vein of vestibular aqueduct

which ultimately drain into inferior petrosal sinus and lateral venous sinus.

Front 79

Development of Tragus and pinna

Back 79

Tragus develops from the tubercle of the first arch while the rest of the pinna develops from the remaining five tubercles of the second arch.

Front 80

What forms preauricular sinus

Back 80

Faulty fusion between the first and the second arch tubercles causes preauricular sinus or cyst

Front 81

External auditory meatus develops from

Back 81

First branchial cleft

Front 82

Pinna is fully developed by

Back 82

20th week

Front 83

External ear canal is fully developed by

Back 83

28th week gestation

Front 84

Middle ear cleft develops from

Back 84

Endoderm of tubotympanic recess

Front 85

Development of ossicles

Back 85

Malleus and incus- Mesoderm of 1st arch

Stapes- second arch

Footplate and and annular ligament - derived from the otic capsule

Front 86

What forms otocyst/auditory vesicle?

Back 86

Ectoderm in the region of hindbrain thickens to form an auditory placode, which is invaginated to form auditory vesicle or the otocyst.

Front 87

Development of ear in nutshell

Back 87