Head & Neck Dev.

Question 1

what is acrania?

Answer 1

complete or partial absence of neurocranium

Question 2

what is acrania associated with?

Answer 2

meroencephaly (causes acrania)

Question 3

what is craniosynostosis?

Answer 3

prenatal fusion of cranial sutures that results in defects in the neurocranium

Question 4

what is scaphocephaly?

Answer 4

premature closure of sagittal suture (long, narrow, wedge-shaped cranium)

Question 5

what is brachycephaly?

Answer 5

premature closure of coronal suture (tower like cranium)

Question 6

what is plagiocephaly?

Answer 6

premature closure of coronal suture on one side only (twisted and asymmetrical cranium)

Question 7

what is trigonocephaly?

Answer 7

premature closure of frontal suture

Question 8

what is microcephaly?

Answer 8

small calvaria

Question 9

what causes microcephaly?

Answer 9

abnormal brain development in which the brain fails to grow

Question 10

congenital anomalies of craniovertebral junction cause?

Answer 10

• basilar invagination
• assimilation of the atlas
• atlantoaxial dislocation
• arnold-chiari malformation
• separated dens from axis

Question 11

how do external branchial sinuses form?

Answer 11

failure of second pharyngeal groove and cervical sinus to obliterate

Question 12

where does an external branchial sinus emerge?

Answer 12

anterior border of SCM (discharge of mucus)

Question 13

where do internal branchial sinuses open to?

Answer 13

tonsillar sinus or near palatopharyngeal arch (failure of 2nd pharyngeal pouch to disappear)

Question 14

normal remnant of 2nd pharyngeal pouch?

Answer 14

tonsillar sinus

Question 15

what is a branchial fistula?

Answer 15

abnormal canal that opens internally into tonsillar sinus and externally in the neck

Question 16

a branchial fistula passes through what structures?

Answer 16

• platysma

- between internal and external carotid arteries

Question 17

what is a piriform sinus fistula?

Answer 17

persistance of remnants of “ultimopharyngeal” body along its path to thyroid gland

Question 18

what is a branchial cyst?

Answer 18

remnants of cervical sinus or 2nd pharyngeal groove

Question 19

where are branchial cysts most often located?

Answer 19

lie free in neck inferior to angle of mandible & anterior border of SCM; parathyroid glands

Question 20

what is a branchial vestige?

Answer 20

cartilagenous or bony remnants of pharyngeal arch cartilages under the skin on the side of the neck

Question 21

where are branchial vestiges located?

Answer 21

anterior to inferior third of SCM

Question 22

how does first arch syndrome occur?

Answer 22

insufficient migration of neural crest cells into first arch

Question 23

infants with DiGeorge syndrome are born without what structures?

Answer 23

thymus and parathyroid glands

Question 24

what is DiGeorge syndrome characterized by?

Answer 24

• congenital hypoparathyroidism
• lots of infections
• cardiac anomalies

Question 25

why does DiGeorge syndrome occur?

Answer 25

third and forth pharyngeal pouches fail to differentiate into thymus and parathyroid glands

Question 26

how does an accessory thymus occur?

Answer 26

tissue breaks free from developing thymus as it shifts caudally in the neck

Question 27

where are ectopic sites for parathyroid glands?

Answer 27

inferiors can be near bifurcation of common carotid artery or in the thorax

Question 28

accessory parathyroid glands occurs because?

Answer 28

extra division of primordia of original glands

Question 29

absence of parathyroid glands occurs from?

Answer 29

failure of primordia to differentiate or from atrophy of a gland

Question 30

what is the most common metabolic disorder in neonates?

Answer 30

congenital hypothyroidism

Question 31

what can congenital hypothyroidism result in?

Answer 31

neurodevelopmental disorders and infertility if untreated

Question 32

how do thyroglossal duct cysts occur?

Answer 32

remnant of thryoglossal duct persists in tongue or inferior to hyoid bone

Question 33

how does a thryoglossal duct sinus occur?

Answer 33

infection of cyst leads to perforation of skin in median plane of neck

Question 34

where is an ectopic thyroid gland located?

Answer 34

along thyroglossal duct (most common is lingual area)

Question 35

why is it important to distinguish an ectopic thyroid gland from a thryoglossal duct cyst or accessory thyroid tissue?

Answer 35

to prevent accidental surgical removal of the thyroid

Question 36

what is thyroid hemiagenesis?

Answer 36

unilateral failure of formation of thyroid lobe (usually left lobe)

Question 37

what congenital tongue anomalies are associated with down's syndrome?

Answer 37

fissuring of tongue and hypertrophy of lingual papillae

Question 38

cysts in the tongue come from where?

Answer 38

thyroglossal duct

Question 39

lingual cysts cause what?

Answer 39

pharyngeal discomfort and dysphagia

Question 40

where do lingual fistulas open to?

Answer 40

from thyroglossal duct to foramen cecum into oral cavity

Question 41

what is ankyloglossia?

Answer 41

short lingual frenulum that interferes with protrusion of tongue

Question 42

is surgery required to fix ankyloglossia?

Answer 42

no. normal stretching usually does the trick

Question 43

how does macroglossia occur?

Answer 43

generalized hypertrophy of developing tongue from lymphangioma (lymph tumor)

Question 44

what syndrome is macroglossia usually found in?

Answer 44

downs syndrome

Question 45

what is microglossia associated with?

Answer 45

micrognathia (underdeveloped mandible/recession of chin) and limb defects (Hanhart syndrome)

Question 46

what is glossoschisis?

Answer 46

bifid or cleft tongue (incomplete fusion of tongue)

Question 47

how does atresia of nasolacrimal duct occur?

Answer 47

failure of nasolacrimal duct to canalize

Question 48

when are maxillary sinuses fully developed?

Answer 48

when all permanent teeth have erupted (early adulthood)

Question 49

are frontal and sphenoid sinuses present at birth?

Answer 49

no

Question 50

what forms the frontal sinus?

Answer 50

anterior ethmoidal cells grow into frontal bone ---> frontal sinus

Question 51

what forms the sphenoidal sinus?

Answer 51

posterior ethmoidal cells grow into sphenoid bone

Question 52

the growth of the paranasal sinuses are important for?

Answer 52

altering size and shape of face and adding resonance to voice

Question 53

how do anterior cleft anomalies occur?

Answer 53

deficiency of mesenchyme in maxillary prominences and median palantine process

Question 54

how do posterior cleft anomalies occur?

Answer 54

defective development of secondary plate and growth problems of lateral palantine processes (no fusion)

Question 55

what is a unilateral cleft lip?

Answer 55

failure of maxillary prominence on one side to unite with medial nasal prominence

Question 56

what causes a persistant labial groove?

Answer 56

failure of mesenchymal masses to merge and proliferate

Question 57

what is a simonart band?

Answer 57

bridge of tissue connecting incomplete unilateral cleft lip

Question 58

what is a bilateral cleft lip?

Answer 58

failure of mesenchymal masses in both maxillary prominences to unite with medial nasal prominences

Question 59

a bilateral cleft lip affects which muscle?

Answer 59

orbicularis oris

Question 60

what is a median cleft lip?

Answer 60

failure of medial nasal prominences to merge and form median palatal process

Question 61

median cleft of lower lip is caused by?

Answer 61

failure of mandibular prominences to merge

Question 62

what does a cleft uvula look like?

Answer 62

fishtail appearance

Question 63

what is a distinguishing landmark between anterior and posterior cleft anomalies?

Answer 63

incisive fossa

Question 64

clefts of primary/anterior palate?

Answer 64

failure of lateral palatal processes to fuse with primary palate

Question 65

clefts of secondary/posterior palate?

Answer 65

failure of lateral palatine processes to fuse with each other and nasal septum

Question 66

clefts of primary and secondary palate?

Answer 66

failure of lateral palatine processes to fuse in primary plate, with each other, and with the nasal septum

Question 67

cleft lip/palate are especially associated with which syndrome?

Answer 67

trisomy 13

Question 68

what is congenital microstomia?

Answer 68

small mouth

Question 69

why does congenital microstomia occur?

Answer 69

excess merging of mesenchymal masses in maxillary and mandibular prominences of first pharyngeal arch

Question 70

why would a single nostril form?

Answer 70

if only one nasal placode forms

Question 71

what's a bifid nose?

Answer 71

medial nasal prominences don't merge which causes nasal bridge to be bifid

Question 72

oblique facial clefts cause what?

Answer 72

nasolacrimal ducts to be open grooves

Question 73

bilateral facial clefts result in?

Answer 73

macrostomia