Embryology

Question 1

what forms the definitive endoderm and mesoderm?

Answer 1

invagination of the epiblast through the primitive streak

Question 2

what are the three parts of the mesoderm?

Answer 2

paraxial
intermediate
lateral plate

Question 3

when do the pharyngeal arches develop?

Answer 3

weeks 4 and 5

Question 4

what are the five pharyngeal arches?

Answer 4

1
2
3
4
6

Question 5

what are the three components of the pharyngeal apparatus?

Answer 5

core pharyngeal arch
external pharyngeal cleft
internal pharyngeal pouch

Question 6

where are clefts and pouches found on the pharyngeal apparatus?

Answer 6

separate the arches

clefts external
pouches internal

Question 7

what are the two processes formed by the first arch?

Answer 7

maxillary

mandibular

Question 8

what does the maxillary process of the first arch form?

Answer 8

maxilla

zygomatic bone

Question 9

what does the mandibular process of the first arch form?

Answer 9

meckel’s cartilage

Question 10

what does meckel’s cartilage give rise to?

Answer 10

incus
malleus
mandible
squamous portion of temporal bone

Question 11

what is the cartilage of the second pharyngeal arch?

Answer 11

reichert’s cartilage

Question 12

what are the skeletal derivatives of the third arch?

Answer 12

greater horn of hyoid

lower part of hyoid bone

Question 13

what are the skeletal derivatives of arches 4 and 6?

Answer 13

laryngeal cartilages

Question 14

what nerve supplies arch 1?

Answer 14

trigeminal

Question 15

what nerve supplies arch 2?

Answer 15

facial

Question 16

what nerve supplies arch 3?

Answer 16

glossopharyngeal

Question 17

what nerve supplies arches 4 and 6?

Answer 17

vagus

Question 18

what is another name for a cervical cyst?

Answer 18

a branchial cyst

Question 19

what causes a cervical cyst?

Answer 19

the cervical sinus not fully closing by birth

Question 20

where are cervical cysts usually found?

Answer 20

along the anterior border of the sternocleidomastoid

Question 21

what does the first pharyngeal cleft form?

Answer 21

the EAM

Question 22

what do the 2-4th pharyngeal clefts form?

Answer 22

second arch grows over them creating a space called the cervical sinus

disappears by birth

Question 23

what does the first pharyngeal pouch form?

Answer 23

tympanic membrane
middle ear
eustachian tube

Question 24

what does the second pouch form?

Answer 24

palatine tonsil

Question 25

what does the third pouch form?

Answer 25

inferior parathyroids

thymus

Question 26

what does the fourth pouch form?

Answer 26

superior parathyroid gland

ultimobranchial body

Question 27

when does the first form of the tongue appear?

Answer 27

the four weeks

Question 28

what pharyngeal arch forms the initial tongue?

Answer 28

1st

Question 29

how does the initial tongue appear?

Answer 29

two lateral swellings

one midline swelling

Question 30

what is the border between anterior and posterior tongue called?

Answer 30

terminal sulcus