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Flashcards in Pharyngeal Arches Deck (56):
1

pharyngeal cleft

external invagination of ectoderm
-4 clefts

2

pharyngeal arches

core of mesenchyme
neural crest and paraxial mesoderm

each has own nerve and blood supply

6 total
#5 regresses

3

neural crest

CT components

4

paraxial mesoderm

gives rise to muscles

5

pharyngeal pouches

internal evagination of pharyngeal endoderm
-4 pouches

6

arch 1

trigeminal

7

arch 2

facial

8

arch 3

glossopharyngeal

9

arch 4

vagus

10

arch 5

mostly regresses

11

arch 6

vagus - mostly recurrent laryngeal branch

12

arch nerves

only ones with an SVE component**

13

sensory info to face

trigeminal nerve

14

divisions of pharyngeal arch 1

frontal prominence
maxillary process
mandibular ??

15

bones of arch 1

viscerocranium and malleus and incus

also CT of face and dermis

16

muscles of arch 1

muscles of mastication - temporalis, masseter, medial, lateral pterygoids)

also tensor tympani, tensor veli palatini, mylohyoid, anterior belly of digastric

17

bones of arch 2

stapes
styloid process of temporal bone
stylohyoid ligament, lesser horn and superior portion of body of hyoid

18

muscles of arch 2

muscles of facial expression
also stapedius, stylohyoid, posterior belly of digastric

19

facial nerve

nerve VII
arch 2

20

bones of arch 3

greater horn and inferior portion of hyoid bone

21

muscles of arch 3

stylopharyngeus

only pharynx muscle not innervated by vagus

22

glossopharyngeal nerve

CN IX

arch 3

23

bones of arch 4

with 6th arch - form all laryngeal cartilages

24

arch 4 and 6

form laryngeal cartilages

25

muscles of arch 4

muscles of pharynx
cricothyroid (in larynx)

26

vagus nerve

CN X

arch 4

27

trigeminal nerve

nerve V
arch 1

28

arch 6 bones

laryngeal cartilage (with arch 4)

29

arch 6 muscles

laryngeal muscles (except cricothyroid)
skeletal muscles of esophagus

30

vagus nerve - recurrent laryngeal branch

CN X

arch 6

31

cleft 1

formation of external ear

external acoustic meatus and part of tympanic membrane

32

clefts 2-4

second arch overgrows arch 3 and 4, burying clefts 2-4

33

cervical sinus

overgrowth of clefts 2-4 forms this sinus

it can persist - clinically significant

34

pouch 1

formation of middle ear and auditory tube

also contributes to tympanic membrane

35

pouch 2

stroma of palatine tonsil

tonsillar fossa

36

pouch 3

dorsal - inferior parathyroid glands (migrate)
ventral - thymus (migrate)

37

pouch 4

dorsal - superior parathyroid glands (migrate)
ventral - ultimobranchial body

38

ultimobranchial body

migrate into substance of thyroid gland
become C cells

39

thyroid development

from endoderm of proximal pharynx

descends along pharynx into neck - remains connected to tongue via thyroglossal duct

40

foramen cecum

superior opening of thyroglossal duct

41

pyramidal lobe of thyroid

in 50% of individuals - remnant of distal thyroglossal duct

42

parafollicular cells

C cells
from ultimobranchial body - pouch 4

43

tongue development

3 swellings form body of tongue
-anterior 2/3
-from 1st pharyngeal arch

root of tongue - posterior 1/3
-from 3rd arch endoderm

epiglottic region - from 4th arch

44

anterior tongue innervation

body
innervation via trigeminal (GSA) - from ectoderm

45

somatic vs. visceral

ectoderm vs endoderm development

46

posterior tongue innervation

root
innervation via glossopharyngeal (GVA) - from endoderm

47

epiglottic tongue innervation

arch 4
innervation vagus - GVA

48

ectopic thyroid or parathyroid tissue

remnants of these glands along the course of their migration

49

lateral cervical cysts

aka branchial cysts

cervical sinus - fails to regress
-found a long anterior border of SCM

50

thyroglossal cyst

remnant of thyroglossal duct
-located on or near midline of neck***

can become infected and form cyst

ALWAYS ALONG MIDLINE

51

midline cyst

likely thyroglossal

52

lateral cyst

likely lateral cervical cyst

53

craniofacial defects

always with neural crest defects

54

first arch

bones of face
-so abnormality of neural crest cells - craniofacial defects

55

neural crest defects

will almost always present with craniofacial defects

treache collins, robin sequence, digeorge anomaly

56

digeorge syndrome

CATCH-22