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ENT Secrets > Chapter 46 - Pediatric ENT Anatomy, Embryology, Radiology > Flashcards

Chapter 46 - Pediatric ENT Anatomy, Embryology, Radiology Flashcards

1
Q

Foramen of Huschke

A

Also called foramen tympanicum
Anatomic variation
Anteroinferior aspect of EAC, posteromedial to TMJ
Gradually closes by age 5, occasionally persists
May predispose to spread of infection to infratemporal fossa

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2
Q

Adults vs Kids EAC shape

A

Adult: Sigmoid, as cartilaginous posterior/superior, and bony angles anterior/inferior. Pull helix posterosuperiorly

Infant: EAC nearly straight, nearly adult size/shape by age 9

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3
Q

Dimeric TM

A

When perf heals without fibrous (rigid) layer

more easily retracted, affects sound conduction

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4
Q

How much energy is lost transmitting sound from air to fluid?

A

99.9%

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5
Q

How does our inner overcome the impedance mismatch?

A

TM that is 21x larger than stapes footplate
ossicles create lever force of 1.3x
Allow near full transmission of all sound energy to inner ear

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6
Q

By how much do tensor tympani and stapedius dampen sound?

A

15 dB

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7
Q

Function of stapedial artery

A

Normally only present in fetal development to connect ICA, ECA
Goes through stapes, creates obturator foramen, gives stapes stirrup shape
If persistent, you have pulsatile tinnitus, CHL, absent ipsilateral foramen spinosum

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8
Q

Two most common congenital anomalies of ossicles

A

congenitally fixed stapes
incudostapedial discontinuity
Isolated stapes anomalies usually unilateral
Other ossicle abnormalities usually bilateral

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9
Q

4 nerves travelling in middle ear

A

Jacobsen- br of IX, across promontory, innervates middle ear mucosa and eustachian tube, PNS to parotid

Arnold- br of vagus, sensory to EAC, causes cough with exam

Chorda- medial to malleus, exit via petrotympanic fissure

Facial- may be dehiscent sup to oval window, or positioned in middle ear if congenitally malformed

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10
Q

Does facial nerve run superior or inferior to cochlear nerve?

A

Superior

7up/Cokedown

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11
Q

Tympanic segment of VII

A

geniculate ganglion to second genu

in medial wall of tympanic cavivty over round window, below bulge of L SC

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12
Q

Cochleariform process

A

ridge of bone
houses tendon of tensor tympani
landmark to denote tympanic portion of VII

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13
Q

Borders of sinus tympani

A

S: ponticulus
I: subiculum
may be a difficult area to extract cholesteatoma

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14
Q

What is the promontory?

A

bulge on medial surface of middle ear

prominence of basal turn of cochlea

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15
Q

Cochleovvestibular aplasia/Michel deformity

A

3rd week arrest, complete absence of cochlea, vestibular strctures

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16
Q

Cochlear Aplasia

A

late 3rd week arrest
absent cochlea
normal, dilated or hypoplastic vestibule

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17
Q

Common cavivty

A

4th week arrest

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18
Q

Incomplete Partition Type I

A 
arrest week 5
cystically enlarged cochlea
No internal architecture
dilated vestibule
enlarged IAC
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19
Q

Cochlear hypoplasia

A

6th week arrest
Separation of cochlear and vestibular structures
small cochlear bud

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20
Q

Incomplete partition type II (Mondini)

A

7th week arrest
cochlea has 1.5 turns
cystically dilated middle and apical turn
slightly dilated vestibule

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21
Q

Most common CT finding profoundly deaf child

A

Radiographically NL middle ear
malformation limited to membranous labyrinth, cannot be sean by IMG
90% of children with profound hearing loss

22
Q

Why children are more prone to nasoseptal hematoma

A

cartilage more pliable
less likely to fx
cartilage bends/buckles –> shearing force –> separation between perichondrium and cartilage –> bleeding within this space

23
Q

Development of paranasal sinuses

A

Ethmoid: most developed at birth

Maxillary: present (mm) at birth, grow rapidly first three years then again between 7-12

Frontal: not present at birth, develop as extensions of ethmoid air cells anterosuperiorly, growth starts at age 2 vertically, near adult size by early teens

Sphenoid: begins around 3-4, adult size by 12-15

24
Q

How many people do not develop any frontal sinuses? How many don’t develop one but do develop the other?

A

5% for both

25
Q

Developmental frontal spaces where encephaloceles can form

A

Fonticulus frontalis - transient fontanelle between inferior frontal bone and nasal bone

Foramen cecum- passageway through skull base just posterior to where frontal sinus will eventually form

Prenasal space

These are possible paths for dermoid/enceph/glioma

26
Q

Why CT scan is not preferred for nasofrontal imaging in children <1 yo

A

First 6-8mo nasal frontal process, nasal bones, ethmoid are unossified, similar on CT to brain/nasal cart
May look like bony dehiscence with nasal secretions
Frontal process, nasal bones, crista galli lack fat in first 8mo, so look like brain on T1

So, use MRI for nasofrontal region in young kids

27
Q

Which muscles act on eustachian tube? Which is the main dilator

A

TVP - main dilator
TT
LVP
Salpingopharyngeus

28
Q

Function of TVP

A

Medial pterygoid –> palatine aponeurosis
V3 (medial pterygoid)
Tense soft palate, assists in elevating palate to prevent nasal regurg, provides stability for pharynx to elevate during swallowing

Attaches to lateral cartilaginous lamina of ET, so assists in dilation with swallow/yawn

29
Q

Function of tensor tympani

A

ET –> handle of malleus
medial pterygoid nerve (from V3)
pulls malleus medially to tense TM

30
Q

Function of LVP

A

petrous apex T bone/medial lamina ET –> palatine aponeurosis
CN X
Elevate soft palate to prevent nasal regurg of food

31
Q

Function of salpingopharyngeus

A

lower medial ET cart (makes posterior welt of torus tubarius)–> blend with palatopharyngeus to upper border thyroid cart
CN X
elevate pharynx/larynx with swallow, pull on torus tubarius

32
Q

How does ET differ between infants and adults?

A

Smaller, horizontal or 10 deg from horiz.
Angle affects function of TVP
Adult: larger, 45 deg

33
Q

Why are neonates obligate nasal breathers?

A

Larynx elevated with epiglottis in apposition to soft palate
Allows infant to drink and breathe simultaneously
Also means infants have difficulty breathing out of mouth

34
Q

How is pediatric airway different than adult?

A 
tongue larger in proportion to mouth
larynx more anterosuperior
pharynx smaller
epiglottis larger and floppier
trachea narrow, less rigid
35
Q

5 arteries to palatine tonsils

A 
dorsal lingual
ascending palatine (facial)
tonsillar br of facial
ascending pharyngeal (ECA)
lesser palatine (descending palatine)
36
Q

Venous drainage of palatine tonsils

A

peritonsilar plexus

lingual and pharyngeal veins, then to IJ

37
Q

Where is ICA in relation to tonsils?

A

2.5cm posterolateral

38
Q

Immune function of tonsils

A

sample pathogens
synthesis of humoral immunoglobulins
produces lymphocytes

39
Q

Effects of submucous cleft

A

abnormal palate motion
poor velopharynx closure
speech/swallow difficulty

40
Q

Which pharyngeal arches lead to SLN and RLN?

A

SLN - 4

RLN - 6

41
Q

Narrowest part of infant larynx

A

cricoid

42
Q

Narrowest part of adult larynx

A

rima glottis / glottic opening

43
Q

Significance of narrowest portion of infant airway being cricoid

A

Since narrowest portion is a rigid ring, ET tube too large may cause ischemic injury –> subglottic stenosis

44
Q

Which does RLN wrap around structures it wraps around?

A

6th arch: develops aortic arch and subclavian, as well as RLN
Wraps around aortic arch on L, subclavian on R

45
Q

What is associated with non-recurrent laryngeal nerve on R?

A

aberrant right subclavian artery

46
Q

Difference between external and internal laryngeal nerves

A

Both br of SLN
external innervates cricothyroid, inferior constrictor
internal sensation from supraglottic larynx (CN X does sensation below glottis)

47
Q

CHAOS

A

congenital high airway obstruction syndrome
failure of airway to recannulate during development of larynx (laryngeal atresia) or upper trachea
Very low survival if not ID’d prenatally
Unable to ventilate unless corresponding TEF

48
Q

Why having C-shaped cartilage in trachea is advantageous

A

needed rigidity to maintain airway throughout respiration

allows for larger boluses of food to pass through esophagus

49
Q

Blood supply to trachea

A

lateral pedicles from inferior thyroid, subclavian, supreme intercostal, internal thoracic, innominate, superior/middle bronchial

50
Q

Killian’s triangle

A

weakned area of pharyngeal wall
between inferior constrictor and cricopharyngeus
Pressure in lower pharynx plus impaired relaxation of cricopharyngeus during swallowing can lead to zenker’s diverticulum here

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