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Flashcards in 16. Pharyngeal Arches Deck (48)
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1

What week of development do the pharyngeal arches develop in?

4th/5th

2

What germ layer is found in the clefts?

Endoderm

3

What germ layer is found in the pouches?

Ectoderm

4

What is derived from the 1st pharyngeal arch?

Meckel's cartilage
Malleus and incus

5

What is derived from the 2nd pharyngeal arch?

Stapes
Styloid process
Stylohyoid ligament
Lesser horn of hyoid

6

What is derived from the 3rd pharyngeal arch?

Greater horn of hyoid

7

What is derived from the 4th pharyngeal arch?

Upper thyroid cartilage

8

What happens to the 5th pharyngeal arch?

Disappears

9

What is derived from the 6th pharyngeal arch?

Rest of the thyroid cartilage
Cricoid cartilage

10

What is derived from the 1st pharyngeal cleft?

External acoustic meatus

11

What happens if the 2nd, 3rd and 4th clefts don't disappear?

Cervical cysts
Presents as lumps under the sternocleidomastoid

12

What is it called if cervical cysts are open to the surface?

External branchial fistula

13

What do internal branchial fistulas open into?

Bed of palatine tonsils

14

What is derived from the 1st pharyngeal pouch?

Middle ear
Eustachian tube

15

What is derived from the 2nd pharyngeal pouch?

Palatine tonsils

16

What is derived from the 3rd pharyngeal pouch?

Inferior parathyroid
Thymus

17

What is derived from the 4th pharyngeal pouch?

Superior parathyroid
Ultimobranchial body

18

What does the ultimobranchial body become?

Parafollicular cells of the thyroid

19

What are 2 defects in the 1st arch?

Treacher Collins
Robin Sequence

20

What are the symptoms of Treacher Collins Syndrome?

Hypoplasia of maxilla, mandible and zygomatic arches
Associated with cleft palate and external ear defects

21

What are the triad of conditions in Robin Sequence?

Micrognathia
Glossoptosis
Cleft palate

22

What is micrognathia?

Poor growth of mandible

23

What is glossoptosis?

Posteriorly placed tongue

24

Name a syndrome of 3rd and 4th arch defects?

DiGeorge anomaly

25

What are the symptoms of DiGeorge anomaly?

No thymus or parathyroid glands
Persistant truncus arteriosus
Abnormal external ear
Micrognathia

26

What is the innervation of the 1st arch?

Mandibular

27

What is the innervation of the 2nd arch?

Facial

28

What is the innervation of the 3rd arch?

Glossopharyngeal

29

What is the innervation of the 4th to 6th arches?

Vagus

30

What is the blood supply to the 1st arch?

Maxillary