Embryo Of H&N

Question 1

What is Apert Syndrome? What can it lead to?

Answer 1

Form of microcephaly in which premature fusion of the cortical sutures occurs

Can lead to acrocephaly (towering skull)

Question 2

What is macrocephaly secondary to?

Answer 2

Hydrocephaly

Question 3

What is cranioschisis (acrania)?

Answer 3

Failure of the occipital and parietal bones to form/close

Question 4

What are fontanelles?

Answer 4

Soft spots part of the infant human skull, aka sutures, allow for rapid stretching and deformation of neurocranium as the brain expands faster than the surrounding bone can grow

Question 5

What is craniosynostosis?

Answer 5

Premature ossification of sutures

Question 6

What are the 4 sutures?

Answer 6

Anterior, posterior, occipital, sphenoidal

Question 7

What invades Arch I and where.. To form muscles of facial expression? What n innervates these muscles?

Answer 7

Mesenchyme from Arch II invades the maxillary and mandibular swellings/processes

Facial n

Question 8

What are the brachial Arch innervations?

Answer 8

Arch I: trigeminal n
Arch II: facial n
Arch III: glossopharyngeal n
Arch IV: vagus
Arch VI: RLn (of X)

Question 9

What Arch are muscles of mastication from?

Answer 9

Arch I, innervated by trigeminal

Question 10

What does the frontal prominence of Arch I form? What is it innervated by?

Answer 10

Forehead, dorsum and apex of nose

Innervated by V1 of trigeminal (ophthalmic n)

Question 11

Where are the nasal placodes located? What do they become?

Answer 11

Frontal prominence of Arch I

Nasal placodes –> medial and lateral nasal prominences –> nasal pits –> nasal sacs (primitive nasal cavity) and septum

Question 12

What is the landmark that divides the primary and secondary palates?

Answer 12

Incisive foramen, marks zones for ant and post cleft palates

Question 13

Which palate contains the hard and soft regions?

Answer 13

Secondary

Question 14

What causes anterior cleft deformity? What does it lead to?

Answer 14

Failure of medial nasal prominence (from frontal) and maxillary prominences to fuse

Cleft lip and palate

Question 15

What causes a posterior cleft deformity? What’s the result?

Answer 15

Palatine shelves from maxillary prominence don’t fuse (secondary palate doesn’t form)

Cleft palate

Question 16

What causes a median cleft lip and bifid nose?

Answer 16

Failure of medial nasal prominences to fuse

Question 17

What is agathnia?

Answer 17

Agenesis of mandibular swellings

Question 18

Macrostomia/Microstomia is what?

Answer 18

Dysfusion of the maxillary and mandibular swellings

Question 19

Treacher Collins Syndrome is what? What are the s/sx?

Answer 19

Aka first Arch syndrome, leads to impaired growth of the midface

Small chin, enlarged nose, cleft palate and cleft lip, bilateral hearing loss

Question 20

What are aural and lateral cervical cysts?

Answer 20

Cysts located along the brachial arch development pathway. May have fistulas associated with them. Aural or ant to SCM.

Question 21

What pharyngeal pouch is associated with the eustachian tube and tympanic cavity?

Answer 21

1st pouch

Question 22

What pharyngeal pouch is associated with the root of the tongue?

Answer 22

2nd pouch

Question 23

What pharyngeal pouch is associated with the body of the tongue?

Answer 23

3rd pouch

Question 24

What is the blood supply associated with Arch 3?

Answer 24

Stem of internal carotids

Question 25

What’s the blood supply associated with Arch 4?

Answer 25

Subclavian and aortic arch

Question 26

What is the innervation to the anterior 2/3rds of the tongue?

Answer 26

GSA: trigeminal n (lingual, of V3)

SVA: facial n (chorda tympani)

Question 27

What’s the innervation to the posterior 1/3 of the tongue?

Answer 27

Glossopharyngeal n (SVA and GSA)

Vagus is part of SVA

Question 28

What’s the innervation of the intrinsic mm of the tongue?

Answer 28

Hypoglossal (CN XII)

Question 29

What are the components of the viscerocranium?

Answer 29

Cartilaginous –> brachial arches

Membranous, from the neocranium –> maxillary and mandibular prominences of the first brachial arch

Question 30

Oblique facial cleft caused by?

Answer 30

Failure of fusion along nasolacrimal groove between lateral nasal prominences and maxillary prominences.

Question 31

Why does a cleft chin occur?

Answer 31

Failure of mandibular prominence fusion around W4