Embryology of the Head and Neck

Question 1

neurocranium

Answer 1

cartilaginous - cradles the base of the skull during 1st 10 weeks of development
membranous - flat bones start to form

Question 2

viserocranium

Answer 2

cartilaginous - 1st to 6th brachial arch cartilage

membranous - maxillary and mandibular prominences of the 1st branchial arch

Question 3

apert syndrome

Answer 3

premature fusion of coronal sutures

acrocephalic (tower skull) appearance

Question 4

carnioschisis

Answer 4

failure of occipital and parietal bones to completely form or close
associates w/ arrested brain development and rudimentary forebrain (anacephaly)

Question 5

microcephaly

Answer 5

small cranium due to early fusion of cranial sutures

Question 6

macrocephaly

Answer 6

enlarges cranium secondary to hydrocephaly

early fusion of the superior cranial sutures may result in conical cranium

Question 7

frontal prominence

Answer 7

forms forehead, dorsum and apex of nose
ectoderm forms the nasal placodes
nasal placodes will form nasal prominences from mesenchyme
L nasal prominence makes the ala
M nasal prominence makes the middle part of nose, upper lip, and philtrum
also makes up primary palate and nasal septum
nasal pits made from nasal placodes

Question 8

maxillary prominence

Answer 8

nasolacrimal groove - nasolacrimal duct

Question 9

oblique facial cleft

Answer 9

due to failure of the lateral nasal prominence and maxillary prominence to fuse
associated w/ cleft chin and partial fusion of the mandibular prominences
exposure of nasolacrimal duct

Question 10

mandibular prominence

Answer 10

fused during the 4th week to form the lower jaw and lip

Question 11

cleft chin

Answer 11

failure of fusion of the lower jaw and lip

Question 12

primary palate

Answer 12

from intermaxillary segment (fusion of medial nasal swellings)
made of mesoderm covered by ectoderm

Question 13

secondary palate

Answer 13

formed by palatine shelves

Question 14

anterior cleft deformity

Answer 14

failure of the medial nasal and maxillary swellings to fuse

Question 15

posterior cleft deformity

Answer 15

palatine shelves do not fuse

Question 16

median cleft lip and bifid nose

Answer 16

failure of medial nasal prominences to fuse
rare
associated w/ autosomal recessive

Question 17

macrostomia and microstomia

Answer 17

dysfunction of the maxillary and mandibular swellings

Question 18

I brachial arch

Answer 18

mm- mm of mastication 
n. - trigeminal (V) 
skeletal structures - incus and malleus 
a. - degenerates 
brachial groove - tympanic membrane, ext. auditory meatus

Question 19

II brachial arch

Answer 19

mm - mm of facial expression
n. - facial n (VII)
skeletal structures - stapes, hyoid bone
a. - degenerates
brachial groove - anomalus cyst or fistulas

Question 20

III brachial arch

Answer 20

mm - stylopharyngeus m
n. - glossopharyngeal (IX) 
skeletal structures - hyoid 
a. - stem of internal carotids
brachial groove - cervical sinus

Question 21

IV brachial arch

Answer 21

mm - pharyngeal and laryngeal mm 
n. - vagus (X) 
skeletal structures - laryngeal carilages 
a. - L aortic arch R subclavian 
brachial groove - cervical sinus

Question 22

VI brachial arch

Answer 22

mm - intrinsic mm of the larynx

n. - RLN

Question 23

treacher collins syndrome

Answer 23

impaired growth of the midface
deformities include small chin, enlarged nose, cleft palate, and possible cleft lip
conductive hearing loss due to underdevelopment of ossicles

Question 24

first brachial pouch

Answer 24

eustachian tube

tympanic cavity

Question 25

second brachial pouch

Answer 25

pharyngeal tonsil
palatine tonsil
lingual tonsil
tongue (root)

Question 26

third brachial pouch

Answer 26

inferior parathyroid gland (dorsal)
thymus (ventral)
tongue

Question 27

fourth brachial pouch

Answer 27

superior parathyroid gland (dorsal) 
ultimobranchial body (ventral)
parafollicular cells (thyroid gland)

Question 28

abnormal cysts produced by the lateral cervical sinus or first pharyngeal cleft

Answer 28

isolated cervical cyst
cervical cyst w/ external fistula
cervical cyst w/ internal fistula
cervical cyst w/ both internal and external fistula

Question 29

aural cyst

Answer 29

anterior to the ear

anomalous derivative of the 1st pharyngeal cleft

Question 30

lateral cervical cyst

Answer 30

anterior to the SCM

Question 31

development of thyroid

Answer 31

thyroid diverticulum evaginated and descends forming the thyroglossal duct which will make the pyramidal lobe

Question 32

thyroglossal ducts cysts and sinuses

Answer 32

develop from remnants of the early migration of thyroglossal duct

Question 33

anterior 2/3 of tongue

Answer 33

L lateral lingual swellings (Arch I) overgrows the median tuberculum impar
trigeminal n (GSA)
facial (SVA)

Question 34

posterior 1/3 of tongue

Answer 34

overgrowth of the copula (Arch II) by hypobranchial eminence (Arch III) 
glossopharyngeal  n (GVA and SVA)

Question 35

intrinsic mm of tongue

Answer 35

made from head myotomes 
hypoglossal n (GSE)