Lecture 40: Embryo of Head and Neck

Question 1

What are the two fates of invaginating epiblasts during gastrulation

Answer 1

1. Intraembryonic mesoderm (fill space between epiblast and hypoplast)
2. Endoderm (replace hypoblast)

(Remaining epiblasts becoming ectoderm)

Question 2

The presence of ___ induces thickening in the adjacent ectoderm

Answer 2

Notochord

Question 3

What are the two longitudinal ridges that form in neural plate

Answer 3

neural folds

Question 4

What structure is between neural folds

Answer 4

Neural groove

Question 5

What are neural crest cells

Answer 5

Crests of neural folds that grow towards each other and then continue to proliferate and migrate away from neural folds/tube to develop in many regions of the embryo

Question 6

What drives lateral folding

Answer 6

Growth of somites

Question 7

What drives craniocaudal folding

Answer 7

Longitudinal growth of the cranial and caudal ends of the neural plate

Question 8

What separates the pharynx from the oral cavity in development

Answer 8

Craniocauudal folding

Question 9

What are pharyngeal arches

Answer 9

Parried bulges along the wall of the developing pharynx

Question 10

What forms the outer surface of the pharyngeal arches

Answer 10

Ectoderm

Question 11

What forms the middle surface of the pharyngeal arches

Answer 11

Mesenchyme from the paraxial and lateral plate mesoderm

Question 12

What cells are present in the middle of pharyngeal arches

Answer 12

Neural crest cells

Question 13

What are the 5 arches

Answer 13

1,2,3,4, 6

Question 14

The mesoderm of the pharyngeal arches become most of the muscles of the ___

Answer 14

Head

Question 15

What is responsible for forming the skeleton of head and neck

Answer 15

Neural crest cells

Question 16

What nerve innervates Arch 1

Answer 16

Trigeminal CN V

Question 17

What nerve innervates Arch 2

Answer 17

Facial CN VII

Question 18

What nerve innervates arch 3

Answer 18

Glossopharyngeal CN XI

Question 19

What nerve innervates arch 4

Answer 19

Cranial laryngeal on vagus CN X

Question 20

What nerve innervates arch 6

Answer 20

Caudal laryngeal nerve on vagus CN X

Question 21

What are the two processes that make up the first pharyngeal arch

Answer 21

maxillary and manidbular processes

Question 22

What is the cartilage of the the 1st arch

Answer 22

Merkel’s cartilage

Question 23

What two structures derive from merkel’s cartilage

Answer 23

Malleus and incus

Question 24

Mesenchyme derived from neural crest cells form bones of ___ and ___

Answer 24

Mandible and lower face

Question 25

Mesoderm derived mesenchyme of the first arch produces the dermis of the ___ and ___ associated with ____ and ____

Answer 25

Face and muscles associated with mandible and ear

Question 26

What structures does the trigeminal nerve innervates in the first arch

Answer 26

Muscles of mandible (mastication), tensor tympani and tensor veil palatini and the skin of the face

Question 27

The cartilage of the 2nd arch articulates with what

Answer 27

Merkels cartilage of 1st arch

Question 28

Cartilage of the second arch becomes what two structures

Answer 28

Hyoid apparatus and the stapes

Question 29

What are the muscles of the second arch

Answer 29

Stylohyoideus, caudal DI gastric, stapedius, muscles of facial expression

Question 30

What bones are in the 3 arch

Answer 30

Thyrohoid and basihyoid

Question 31

What muscle is in 3rd arch

Answer 31

Stylopharyngeus

Question 32

What cartilages are in 4th arch

Answer 32

Laryngeal

Question 33

What muscles are in 4th arch

Answer 33

Cricothyroid and pharyngeal

Question 34

Arch 6 contains what muscles

Answer 34

Intrinsic laryngeal muscles (except cricothyroid)

Question 35

What structures are between the arches

Answer 35

External: cleft Internal: pouches

Question 36

The first pouch and cleft form between what

Answer 36

First and second arch

Question 37

The cleft becomes ____

Answer 37

External auditory canal

Question 38

The first pouch becomes what two structures

Answer 38

Tympanic cavity and pharyngotympanic tube

Question 39

Invagination of the 1st cleft and 1st pouch continue deep until surfaces join at what structure

Answer 39

Tympanic membrane

Question 40

The tonsils are a derivative of what pouch

Answer 40

Pouch 2

Question 41

Glands are a derivative of what pouch

Answer 41

Pouch 3

Question 42

What pouch contributes to C cells of thyroid gland

Answer 42

Pouch 4

Question 43

The cervical sinus is from what arch

Answer 43

Arch 2

Question 44

Failure of the cervical sinus to develop results in what in adults

Answer 44

Cervical cysts

Question 45

Failure of arch 2 to fuse with the distal lateral cervical tissue results in ___ that may connect to cervical cysts

Answer 45

Fistulas

Question 46

The nasal placode results from thickening of what structure

Answer 46

Ectoderm

Question 47

What is the stomodeum

Answer 47

Primitive oral cavity

Question 48

Completion of the secondary palate results in fusion of what two structures

Answer 48

Palatine shelves and nasal septum

Question 49

Several swellings from the floor of the developing oral pharynx contribute to the development of the ___

Answer 49

Tongue

Question 50

What two swellings come from the first arch

Answer 50

Lateral lingual and tuberculum impar

Question 51

copula swelling comes from what arches

Answer 51

2,3,4

Question 52

The epiglottal swelling comes from what arch

Answer 52

4