Pharyngeal Arches

Question 1

pharyngeal cleft

Answer 1

external invagination of ectoderm

-4 clefts

Question 2

pharyngeal arches

Answer 2

core of mesenchyme
neural crest and paraxial mesoderm

each has own nerve and blood supply

6 total
#5 regresses

Question 3

neural crest

Answer 3

CT components

Question 4

paraxial mesoderm

Answer 4

gives rise to muscles

Question 5

pharyngeal pouches

Answer 5

internal evagination of pharyngeal endoderm

-4 pouches

Question 6

arch 1

Answer 6

trigeminal

Question 7

arch 2

Answer 7

facial

Question 8

arch 3

Answer 8

glossopharyngeal

Question 9

arch 4

Answer 9

vagus

Question 10

arch 5

Answer 10

mostly regresses

Question 11

arch 6

Answer 11

vagus - mostly recurrent laryngeal branch

Question 12

arch nerves

Answer 12

only ones with an SVE component**

Question 13

sensory info to face

Answer 13

trigeminal nerve

Question 14

divisions of pharyngeal arch 1

Answer 14

frontal prominence
maxillary process
mandibular ??

Question 15

bones of arch 1

Answer 15

viscerocranium and malleus and incus

also CT of face and dermis

Question 16

muscles of arch 1

Answer 16

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

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

Question 17

bones of arch 2

Answer 17

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

Question 18

muscles of arch 2

Answer 18

muscles of facial expression

also stapedius, stylohyoid, posterior belly of digastric

Question 19

facial nerve

Answer 19

nerve VII

arch 2

Question 20

bones of arch 3

Answer 20

greater horn and inferior portion of hyoid bone

Question 21

muscles of arch 3

Answer 21

stylopharyngeus

only pharynx muscle not innervated by vagus

Question 22

glossopharyngeal nerve

Answer 22

CN IX

arch 3

Question 23

bones of arch 4

Answer 23

with 6th arch - form all laryngeal cartilages

Question 24

arch 4 and 6

Answer 24

form laryngeal cartilages

Question 25

muscles of arch 4

Answer 25

muscles of pharynx | cricothyroid (in larynx)

Question 26

vagus nerve

Answer 26

CN X arch 4

Question 27

trigeminal nerve

Answer 27

nerve V | arch 1

Question 28

arch 6 bones

Answer 28

laryngeal cartilage (with arch 4)

Question 29

arch 6 muscles

Answer 29

``` laryngeal muscles (except cricothyroid) skeletal muscles of esophagus ```

Question 30

vagus nerve - recurrent laryngeal branch

Answer 30

CN X arch 6

Question 31

cleft 1

Answer 31

formation of external ear external acoustic meatus and part of tympanic membrane

Question 32

clefts 2-4

Answer 32

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

Question 33

cervical sinus

Answer 33

overgrowth of clefts 2-4 forms this sinus it can persist - clinically significant

Question 34

pouch 1

Answer 34

formation of middle ear and auditory tube also contributes to tympanic membrane

Question 35

pouch 2

Answer 35

stroma of palatine tonsil tonsillar fossa

Question 36

pouch 3

Answer 36

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

Question 37

pouch 4

Answer 37

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

Question 38

ultimobranchial body

Answer 38

migrate into substance of thyroid gland | become C cells

Question 39

thyroid development

Answer 39

from endoderm of proximal pharynx descends along pharynx into neck - remains connected to tongue via thyroglossal duct

Question 40

foramen cecum

Answer 40

superior opening of thyroglossal duct

Question 41

pyramidal lobe of thyroid

Answer 41

in 50% of individuals - remnant of distal thyroglossal duct

Question 42

parafollicular cells

Answer 42

C cells | from ultimobranchial body - pouch 4

Question 43

tongue development

Answer 43

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

Question 44

anterior tongue innervation

Answer 44

body | innervation via trigeminal (GSA) - from ectoderm

Question 45

somatic vs. visceral

Answer 45

ectoderm vs endoderm development

Question 46

posterior tongue innervation

Answer 46

root | innervation via glossopharyngeal (GVA) - from endoderm

Question 47

epiglottic tongue innervation

Answer 47

arch 4 | innervation vagus - GVA

Question 48

ectopic thyroid or parathyroid tissue

Answer 48

remnants of these glands along the course of their migration

Question 49

lateral cervical cysts

Answer 49

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

Question 50

thyroglossal cyst

Answer 50

remnant of thyroglossal duct -located on or near midline of neck*** can become infected and form cyst ALWAYS ALONG MIDLINE

Question 51

midline cyst

Answer 51

likely thyroglossal

Question 52

lateral cyst

Answer 52

likely lateral cervical cyst

Question 53

craniofacial defects

Answer 53

always with neural crest defects

Question 54

first arch

Answer 54

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

Question 55

neural crest defects

Answer 55

will almost always present with craniofacial defects treache collins, robin sequence, digeorge anomaly

Question 56

digeorge syndrome

Answer 56

CATCH-22