Deck 18: Development of the Pharyngeal Apparatus and Face

Question 1

A researcher discovers a gene that when knocked out causes the most common form of cleft lip seen in humans.Examination of the expression of this gene in embryos shows that it is expressed in the facial prominences that flank the area of cleft lip formation.What are these flanking prominences?

A) Maxillary and mandibular on one side
B) Maxillary and medial nasal on one side
C) Right and left lateral nasal
D) Right and left maxillary
E) Right and left medial nasal

Answer 1

B

Question 2

A premature infant is examined by a neonatologist at University hospital.Based on its facial features and a maternal history,the child is diagnosed with fetal alcohol syndrome.Fetal alcohol syndrome most dramatically affects derivatives of which pharyngeal arches?

A) First
B) Second
C) Third
D) Fourth and sixth

Answer 2

A

Question 3

The mesoderm forms which derivative of the pharyngeal apparatus?

A) Aortic arch muscle coats
B) Cartilaginous bars
C) Cranial nerves
D) Muscle plates

Answer 3

D

Question 4

A baby boy presents with Treacher Collins syndrome.A medical geneticist evaluates the boy and meets with both parents.She notices that the mother has mild Treacher Collins-like features.Which pharyngeal arch derivatives are most dramatically affected in this syndrome?

A) First
B) Second
C) Third
D) Fourth and sixth

Question 5

The muscles of the larynx are derived from which pharyngeal arches?

A) First
B) Second
C) Third only
D) Fourth and sixth only
E) Third, fourth, and sixth

Question 6

The thyroid gland starts to produce circulating hormones during which weeks of gestation?

A) 8-10
B) 10-12
C) 12-14
D) 14-16

Question 7

Fontanelles allow deformation of the skull during birth.How many fontanelles are present at birth?

A) 2
B) 3
C) 4
D) 5
E) 6

Question 8

The first pharyngeal arch forms on which day of gestation?

A) 20
B) 22
C) 24
D) 27
E) 31

Question 9

Derivatives of the second pharyngeal arches are innervated by which nerves?

A) Cervical spinal nerves
B) Facial nerves
C) Glossopharyngeal nerves
D) Trigeminal nerves
E) Vagus nerves

Question 10

A teenage boy who is taking Accutane® for severe acne meets a new girl at school and begins dating her.She too has acne,although mild,and asks her boyfriend to share his medicine with her.After a few weeks of dating they begin to have unprotected intercourse.Which embryonic cell population will be most endangered by Accutane® exposure if the girl becomes pregnant?

A) Pharyngeal groove/cleft ectoderm
B) Pharyngeal pouch endoderm
C) Pharyngeal arch mesoderm
D) Neural crest cells
E) Notochord cells

Question 11

The third pharyngeal pouches lie between which pharyngeal arches?

A) First and second
B) Second and third
C) Third and fourth
D) Fourth and sixth

Question 12

Which of the craniosynostosis syndromes is unusual in that it is X-linked,with females,but not males,being symptomatic?

A) Apert's syndrome
B) Pfeiffer syndrome
C) Craniofrontonasal dysplasia
D) Muenke syndrome
E) Saethre-Chotzen syndrome

Question 13

The third aortic arches lie between which pharyngeal grooves/clefts?

A) First and second
B) Second and third
C) Third and fourth
D) Fourth and sixth

Question 14

The secondary palate forms by fusion of which processes?

A) Lateral palatine with mandibular
B) Lateral palatine with maxillary
C) Medial palatine with mandibular
D) Median palatine with maxillary
E) Paired lateral palatine

Question 15

A child is diagnosed with DiGeorge syndrome due to a 22q11.2.1 deletion encompassing approximately 30 to 40 genes.Researchers have genetically inactivated these genes in mice to identify which are essential for pharyngeal arch development.Which two genes in the deleted area are now thought to be the key players in DiGeorge syndrome?

A) PAX9 and PAX1
B) TBX1 and CRKl
C) ENDOTHELIN 1 and FGF10
D) DLX5 and -6

Question 16

The cheeks are formed from which prominences?

A) Frontal
B) Lateral nasal
C) Mandibular
D) Maxillary
E) Medial nasal

Question 17

A new mom takes her baby son on an airplane trip.On descent,the child begins to cry vociferously,and does not quiet down until a few minutes after landing.At the next well-baby visit,the pediatrician explains that the eustachian tube in infants is very short and horizontally oriented,resulting in difficulty in clearing pressure from the middle ear.The eustachian tube forms from a persisting portion of a pharyngeal pouch that remains connected to the pharynx.Which pharyngeal pouch forms the eustachian tube?

A) First
B) Second
C) Third
D) Fourth
E) Fifth

Question 18

The superior parathyroid gland arises from which structure?

A) First pharyngeal cleft
B) First pharyngeal pouch
C) Second pharyngeal pouch
D) Third pharyngeal pouch
E) Fourth pharyngeal pouch
F) Second pharyngeal cleft

Question 19

A child is diagnosed with Treacher Collins syndrome,which results from a mutation in the gene TCOF1 encoding the protein TREACLE.What embryonic tissue is the most affected by this mutation?

A) Endoderm
B) Surface ectoderm
C) Neural crest cells
D) Mesoderm
E) Notochord

Question 20

Craniosynostosis,the premature closure of the sutures,is usually due to increased signaling of which pathway?

A) FGF
B) BMP
C) SHH
D) NOTCH
E) WNT

Question 21

Which signaling molecule patterns the cranial-caudal axis of the hindbrain?

A) Wnts
B) Bmps
C) Hedgehog
D) Retinoic acid
E) Fgfs

Question 22

Van der Woude syndrome is predominantly characterized by which defect?

A) Premature suture closure (i.e., craniosynostosis)
B) Defective outgrowth of the facial processes (i.e., cleft lip and palate)
C) Narrowing of the facial prominences (i.e., holoprosencephaly)
D) Failure of cranial neural tube closure (i.e., exencephaly)

Question 23

The third pharyngeal arch artery gives rise to which adult blood vessel(s)?

A) Internal and external carotids
B) Common carotids and roots of internal carotids
C) Corticotympanic artery
D) Ductus arteriosus
E) Initial sprouts of pulmonary arteries

Question 24

The muscles of mastication,excluding the tongue muscles,arise from the mesoderm of which structure(s)?

A) First pharyngeal arches
B) Second pharyngeal arches
C) Occipital somites
D) Neural crest cells
E) Notochord

Question 25

The stylopharyngeus muscle is innervated by which nerve?

A) Trigeminal
B) Vagus
C) Facial
D) Glossopharyngeal
E) Oculomotor

Question 26

The muscles of facial expression arise from the mesoderm of which structure(s)

A) First pharyngeal arches
B) Second pharyngeal arches
C) Occipital somites
D) Neural crest cells
E) Notochord

Question 27

Researchers have shown that the Hox genes are important for patterning the pharyngeal arches.Which of the Hox genes is essential for the specification of the second pharyngeal arch and when genetically inactivated in mice,result in the homeotic transformation of the second pharyngeal arch into one with first pharyngeal arch identity?

A) Hoxa1
B) Hoxa2
C) Hoxa3
D) Hoxb1
E) Hoxb2

Question 28

Researchers have shown that the mandibular prominence can be transformed into the maxillary prominence by the genetic inactivation of two homeobox transcription factors in mice.What are these two factors?

A) Msx1 and -2
B) Barx1 and Msx1
C) Dlx1 and -2
D) Dlx5 and -6
E) Dlx2 and -5

Question 29

Mutations in the growth factor SONIC HEDGEHOG would be expected to result in which birth defect?

A) Cleft lip
B) Cleft palate
C) Craniosynostosis
D) Holoprosencephaly
E) Mandibulofacial dysostosis

Question 30

Neural crest cells migrate from the hindbrain in distinct streams.How many neural crest cells streams are there in the hindbrain?

A) 2
B) 3
C) 4
D) 5
E) 7

Question 31

The oropharyngeal membrane ruptures to create the continuity between the developing gut and oral cavity during which week of gestation?

A) 4
B) 5
C) 6
D) 7

Question 32

At birth what is the approximate ratio of the facial skeleton to the cranial vault?

A) 1:3
B) 1:5
C) 1:7
D) 2:1
E) 2:3

Question 33

The developing hindbrain is segmented into rhombomeres,which are characterized by the differential expression of members of the Hox family of transcription factors.Researchers have shown that some members of the Hox family are crucial for the specification of the rhombomeres.When Hoxa1 is genetically inactivated in mice,which rhombomeres are affected?

A) r1 and r2
B) r3 and r4
C) r4 and r5
D) r6 and r7

Question 34

Both cleft lip and palate have a genetic component,which results in differences in the frequency of cleft lip and palate in females and males.Does cleft lip occur more often in females or males?

A) Males
B) Females

Question 35

Fate mapping studies of neural crest cell migration have been carried out in chicks,quails,and mice.These studies have shown that the neural crest cells that populate the second pharyngeal arch arise from which level(s)of the brain?

A) Midbrain only
B) Midbrain and rhombomere 1
C) Rhombomeres 1 and 2
D) Rhombomere 4
E) Rhombomeres 5 and 6