Pharyngeal Arches

Question 1

What are the 4 fundamental aspects of developmental biology?

Answer 1

Proliferation - cell growth
Pattern formation - cells grow in the right place at the right time
Morphogenesis - shape
Differentiation - different types of cells

Question 2

What is a dynamic interaction?

Answer 2

Happens quickly

Question 3

What is a reciprocal interaction?

Answer 3

One type of cell/tissue is in control of another

Question 4

What is a sequential interaction?

Answer 4

Timing of events

Question 5

Tissue interactions appear to be associated with at least 2 general types of phenomena Tissue interactions appear to be associated with at least 2 general types of phenomena, what are these?

Answer 5

Instructive
Permissive (facilitative)

Question 6

What is the instructive phenomena associated with tissue interactions?

Answer 6

the ability of one tissue to determine specific patterns of morphogenesis and differentiation that will develop in an associated tissue

Question 7

What is the permissive phenomena associated with tissue interactions?

Answer 7

the ability of an interacting tissue to provide certain conditions that is necessary for its committed partner tissue to progress to full expression of its pre-determined phenotype

Question 8

What is the tissue interaction governing cell differentiation and morphogenesis throughout embryonic development?

Answer 8

Secondary inductions

Question 9

What is an organ rudiment?

Answer 9

an organ or part incompletely developed in size or structure

Question 10

What is the organiser of differentiation to form specific structures in early embryology?

Answer 10

signalling centre

Question 11

What are the 3 true primary germ layers form outer to inner?

Answer 11

Ectoderm
Mesoderm
Endoderm

Question 12

What is the not true primary germ layer?

Answer 12

neural crest/ecto-mesenchyme

Question 13

what process brings about the primaru germ layers?

Answer 13

gastrulation

Question 14

What does the endoderm go on to form?

Answer 14

Many of the bodys inner linings
most of the GI tract, the lungs, liver, pancreas etc

Question 15

What does the ectoderm go on to form?

Answer 15

The bodys outer linings, including the epidermis, the skin (outer most layer) and hair

Question 16

What does the mesoderm go on to form?

Answer 16

The dermis of the skin, the heart, muscles, bones, bone marrow (therefore the blood) etc

Question 17

what week does the development of the pharyngeal arches start?

Answer 17

week 4/5

Question 18

What arch do they mandible and maxilla develop from?

Answer 18

pharyngeal arch 1

Question 19

What cartilage is found in pharyngeal arch 1?

Answer 19

Meckel’s cartilage

Question 20

What cartilage is found in pharyngeal arch 2?

Answer 20

Reichert’s cartilage

Question 21

How is meckel’s and reichert’s cartilage described?

Answer 21

as transient - it is almost completely disappeared/developed into other structures by week 20

Question 22

What is the stomadeum?

Answer 22

The precursor to the oral cavity

Question 23

what can be described as “a highly migratory cell population with the ability to acquire a broad spectrum of cell fates”

Answer 23

the neural crest

Question 24

What seperates the pharyngeal arches on the endodermal (internal) surface?

Answer 24

pouches

Question 25

What seperates the pharyngeal arches on the ectodermal (external) surface?

Answer 25

pharyngeal cleft

Question 26

The 2nd, 3rd and 4th clefts only form temporary cervical sinuses – which are then obliterated by what?

Answer 26

the rapidly proliferating second pharyngeal arch

Question 27

Which pharyngeal arch disappears extremely early in development

Answer 27

arch V (5)

Question 28

what are the 2 parts of the 1st pharyngeal arch?

Answer 28

the mandibular process and the maxillary process

Question 29

What cartilage is associated with the first pharyngeal arch?

Answer 29

Meckel's

Question 30

what nerve is associated with the first pharyngeal arch?

Answer 30

CNV

Question 30

What bones and ligaments does the meckel's cartilage associated with the 1st mandibular arch

Answer 30

bones - the incus and malleus ligaments - Sphenomandibular ligament and the sphenomalleolar

Question 30

what is the most common craniofacial abnormalities can be associated with the first pharyngeal arch?

Answer 30

treacher-collins syndrom

Question 30

what muscles are associated with the first pharyngeal arch?

Answer 30

body of the tongue, the muscles of mastication (temporalis, masseter, pterygoids), ABD, Mylohyoid, tensor tympani, tensor veli palatini

Question 30

what artery is associated with the first pharyngeal arch?

Answer 30

maxillary and internal carotid artery

Question 31

What is the name of the second pharyngeal arch?

Answer 31

hyoid arch

Question 32

What cartilage is associated with the 2nd pharyngeal arch?

Answer 32

Reichert's cartilage

Question 33

Reichert's cartilage is the precursor for what?

Answer 33

Stapes Lesser horn and superior hyoid body Styloid process, stylohyoid ligament

Question 34

The 2nd pharyngeal arch gives rise to what

Answer 34

thyroid gland and tonsils

Question 35

what muscles are associated with the 2nd pharyngeal arch?

Answer 35

muscles of facial expression and the posterior belly of digastric

Question 36

what nerve is associated with the 2nd pharyngeal arch?

Answer 36

CMVII

Question 37

What does the 3rd pharyngeal arch form?

Answer 37

- greater horn of hyoid - inferior hyoid body - root of the tongue - stylopharyngeus

Question 38

what nerve is associated with the 3rd pharyngeal arch?

Answer 38

CNIX (glossopharyngeal)

Question 39

What does the 4th pharyngeal arch form?

Answer 39

thyroid cartilage, pharynx and epiglottis muscles - pharyngeal constrictor and the soft palate

Question 40

what nerve is associated with the 4th pharyngeal arch?

Answer 40

CNX (vagus nerve) - superior laryngeal nerve

Question 41

What happens to the 5th arch?

Answer 41

it rapidly disappears early in development

Question 42

What does the 6th pharyngeal arch form?

Answer 42

cricoid and arytenoid cartilages larynx mauscles of the larynx

Question 43

what nerve is associated with the 6th pharyngeal arch?

Answer 43

Vagus nerve (CNX) - inferior laryngeal nerve

Question 44

what side of the arches are the clefts/grooves?

Answer 44

ectodermal surface

Question 45

What happens to the 2nd - 6rh clefts?

Answer 45

they are obliterated by the rapidly proliferating 2nd pharyngeal arch

Question 46

What side of the pharyngeal arches are the pouches?

Answer 46

the endodermal surface

Question 47

What does the 1st pouch form?

Answer 47

- eustachian tube - middle ear cavity - tympanic membrane

Question 49

what part of the first and second pouch is obliterated by the tongue?

Answer 49

the ventral part

Question 49

what does the 2nd pouch usually form

Answer 49

the tonsilar fossa

Question 50

what does the 3rd pouch form?

Answer 50

- Inferior parathyroid gland - Thymus

Question 50

what does the 4th pouch form

Answer 50

superior parathyroid gland

Question 51

what separates the pharyngeal pouches from the pharyngeal clefts/grooves

Answer 51

Double layered pharyngeal membrane (endoderm of the pouches contact the endoderm of the grooves) separates the pharyngeal pouches from the pharyngeal grooves/clefts

Question 51

what is the only cleft to give rise to a permanent structure in the adult, and what is this structure?

Answer 51

1st pharyngeal cleft/groove forms the auditory meatus

Question 52

What is the fate of the 2nd, 3rd and 4th pharyngeal clefts?

Answer 52

2nd, 3rd and 4th form temporary cervical sinuses, and are then obliterated by the rapidly proliferating 2nd pharyngeal arch

Question 53

after a while only what pharyngeal membrane exists? and what does it become?

Answer 53

1st pharyngeal membrane and it becomes the tympanic membrane

Question 54

What appears clinically if the 2nd pharyngeal arch fails to grow does sufficiently over the 2nd-4th cleft?

Answer 54

branchial fistula/cyst - almost a gil like appearance along the anterior border of the sternocleidomastoid

Question 55

What appears clinically if the parathyroid tissue fails to migrate?

Answer 55

Ectotopic thymic/parathyroid tissue - the parathyroid gland ends up closer to the mouth than it should be