Development L3 - Oral Development biology: Arches

Question 1

In which week would you expect to see the appearance of pharyngeal arches

Answer 1

pharangyeal arches appear in 4th and 5th week.

Question 2

where do neural crest cells migrate from to reach the pharyngeal arches

Answer 2

they migrate from the back of the developing head

Question 3

how are the pharyngeal arches separated internally and externally

Answer 3

arches are separated by

clefts/grooves - externally

pouches - internally

Question 4

neural crest cells migrate to the lower face to undergo proliferation and differentiation. which gene mediates neural crest cells.

Answer 4

hox gene

Question 5

name the arches

Answer 5

pharyngeal arch 5 is misisng becuase it is removed very early on in embryo development.

Question 6

pharyngeal arches consists of ectoderm and endoderm germ layers.

however these germ layers are located in specific locations on the pharyngeal arches. where are they located?

Answer 6

Ectoderm is located on the outside of the pharyngeal arches

Endoderm is located in the inside of the pharyngeal arches except for the 1st arch

Question 7

what is the name given to the 1st pharyngeal arch and which processes are present

what is the name of the special cartilage present in 1st p arch

which two bones does this cartilage form

which two ligaments does this cartilage form

Answer 7

1st p arch is mandibular arch which houses the mandibular and maxillary processes

the special cartilage present is the meckels cartilage

the two bones the meckels cartilage devlops is the incus and malleus, which are two bones of the ear

the two ligaments produced are the sphenomandibular and the sphenomalleolar

Question 8

which muscles, nerve and arterties does the 1st pharyngeal arch give rise to

Answer 8

the 1st pharangyeal arch is called the mandibular arch. so the muscles, nerve and blood supply will be generally associated with that arch.

muscle of mastication = temporalis, masseter, pterygoids, mylohyoid, anterior body of digastric

nerve = trigeminal

artery = maxillary and carotid arteries

Question 9

what is the name given to the 2nd pharyngeal arch

Answer 9

hyoid arch

Question 10

which muscles, nerve, cartilage and gland does the 2nd pharyngeal arch give rise to

Answer 10

cartilage = reicherts cartilage, which gives rise to stapes, lesser horn and superior hyoid body, styloid process and stylohyoid ligament

muscles = facial expression and posterior belly digastric

nerve = facial VII

gland = thyroid gland and tonsil

Question 11

what are the arrows pointing to

Answer 11

clefts

Question 12

the 2nd - 6th clefts disappear due to the proliferation of which arch

Answer 12

2nd arch (hyoid arch)

Question 13

what is the arrow pointing to

Answer 13

pouch

Question 14

the eustacian tube

middle ear cavity

tympanic membrane

ventral part obliterated by the tongue, would be found in which pouch

1st, 2nd or third pouch

Answer 14

1st pouch

Question 15

the tonsillar fossa

ventral part obliterated by the tongue, would be found in which pouch

1st, 2nd or third pouch

Answer 15

2nd pouch

Question 16

which pouch would house the inferior parathyroid gland and thymus

1st, 2nd or 3rd pouch

Answer 16

3rd pouch

Question 17

which pouch would house the superior parathyroid gland

1st, 2nd, 3rd or 4th pouch

Answer 17

4th pouch

Question 18

the vagus nerve is present in which pouch

Answer 18

4th pouch

Question 19

the glossopharyngeal nerve is present in which pouch

Answer 19

third pouch

Question 20

the internal carotid artery is present in which pouch

Answer 20

third pouch

Question 21

the right subclavian artery and aorta are present in which pouch

Answer 21

pouch 4