Pharyngeal Arches--clinical info and misc. info

Question 1

What three structures are required for normal development of the upper lip?

Answer 1

Union of nasomedial prominence, nasolateral prominence and maxillary prominence

Question 2

How are the oral and nasal cavities separated?

Answer 2

The fusion of the palatal shelf and the median palatal & nasal septum separates oral and nasal cavities

Question 3

Signaling molecule associated with superficial location–palatal shelves and expressed early

Answer 3

Bone morphogenic proteins (BMPs)

Question 4

Signaling molecule associated with early induction of facial primordia, medial edge epithelia (palatal shelves)

Answer 4

Sonic hedgehog

Question 5

What is different about the action of Shh?

Answer 5

Instead of keeping layers apart, it fuses the epithelia

Question 6

Signaling molecule associated with tongue; what happens when this gene is mutated?

Answer 6

TBX22; mutation results in ankyloglossia–most cases sporadic, mutations in the T box transcription factor TBX22 may lead to heritable (X-linked) ankyloglossia with or without cleft lip, cleft palate

Question 7

Cause of median cleft lip

Answer 7

incomplete merging of the two medial nasal prominences therefore leading in most cases to various forms of bifid nose (with deep midline grooving of the nose)

Question 8

Mandibulo-facial dysostis
Underdevelopment of structures in arch 1
Downward slanting eyes, small mandible & malformed/absent ears
Autosomal dominant, chromosome 5; protein sorting during development

Answer 8

Treacher-Collin’s syndrome

Question 9

Micro/Retrognathia, glossoptosis & airway obstruction

Arch 1` deformity

Answer 9

Pierre Robin Sequence

Question 10

Muscles of the arches are _____ derived

Answer 10

mesodermally

Question 11

Is epiglottis from pharygeal arch? If not, where does it come from?

Answer 11

No, it comes from laryngeotracheal diverticulum

Question 12

Microdeletion (DGS critical region) on chromosome 22 at band 22q11.2
Hypoparathyroidism=hypocalcemia
Hypoplastic (underdeveloped thymus or absent) resulting in immune problems
Conotruncal heart defects (tetralogy of Fallot, interrupted aortic arch, ventricular septal defects, vascular rings)
Cleft lip and palate
Can also cause problems in frain fnx

Answer 12

DiGeorge’s Syndrome

Question 13

Anomolies in thyroid development

Answer 13

ectopic thyroid tissue or cysts along thyroglossal duct (midline structure); this is in contrast to cervical cysts which are remnants of pharyngeal clefts 2-4 and are found lateral to SCM