8: Embryology 2 - face, palate and nasal cavities

Question 1

Which pharyngeal arches give rise to

a) the muscles of facial expression
b) the maxilla, mandible, zygoma and temporal bone
c) the muscles of mastication?

Answer 1

a) Pharyngeal arch 2

b) Pharyngeal arch 1

c) Pharyngeal arch 1

Question 2

Is pharyngeal arch 5 relevant?

Answer 2

No, doesn’t develop into anything

Question 3

Which cranial nerves supply the first pharyngeal arch and the second pharyngeal arch?

Answer 3

1st - CN V

2nd - CN VII

Question 4

What are the prominences which appear on the face in Week 4 of development?

Answer 4

Frontonasal prominence

2 maxillary prominences

2 mandibular prominences

Question 5

What form on the frontonasal prominence in Week 4?

Answer 5

Nasal placode

thickened ectoderm which gives rise to nasal structures

Question 6

What do the nasal placodes go on to form?

Answer 6

Nasal structures

including ofactory epithelium

Question 7

What developmental structures are found inferior to the mandibular prominences?

Answer 7

2nd and 3rd pharyngeal arches

Question 8

What space gives rise to the mouth?

Answer 8

Stomodeum

Question 9

Which nasal swellings form additional to the nasal placodes in Week 5?

Answer 9

2 medial nasal prominences

2 lateral nasal prominences

Question 10

What germ layer are the

a) medial nasal swellings
b) lateral nasal swellings
c) maxillary prominences

made up of?

Answer 10

a) Endoderm

b) Ectoderm

c) Mesoderm

Question 11

Why do the maxillary prominence and medial nasal prominence fuse sooner than “” and the lateral prominence?

Answer 11

Lateral nasal prominence and maxillary prominence form nasolacrimal groove

Question 12

What lies between the maxillary prominence and the lateral nasal prominence?

Answer 12

Nasolacrimal groove

Question 13

What do the nasolacrimal grooves develop into?

Answer 13

Nasolacrimal ducts

Question 14

What makes up the upper lip at 10 weeks?

Answer 14

2 maxillary prominences

2 medial nasal prominences

Question 15

What makes up the lower lip at 10 weeks?

Answer 15

2 mandibular prominences

Question 16

Which prominence makes up the bridge and septum of the nose?

Answer 16

Frontonasal prominence

Question 17

Which prominences make up the crest and tip of the nose?

Answer 17

Medial nasal prominences

Question 18

Which prominences make up the alae of the nose?

Answer 18

Lateral nasal prominences

Question 19

What external structure of the nose is formed by the fusion of the right and left medial nasal prominences?

Answer 19

Philtrum

Question 20

Which teeth are found in the intermaxillary segment?

Answer 20

4 incisors

Question 21

The intermaxillary segment (i.e the fused right and left medial nasal prominences) give rise to what structure of the nasal and oral cavities?

Answer 21

Primary palate

i.e the roof but not the lateral parts

Question 22

The intermaxillary segment gives rise to the primary palate.

What gives rise to the lateral parts of the palate?

Answer 22

Maxillary prominences

Question 23

How big is the primary palate compared to the secondary palate?

Answer 23

Much smaller in comparison

Question 24

What fuse to form the secondary palate?

Answer 24

Right and left palatine shelves of the maxillary prominences

Question 25

What structures fuse to form the palate?

Where do they come from?

Answer 25

Primary palate - from intermaxillary segment

Secondary palate - from left and right maxillary prominences

Question 26

What hole forms just posterior to the incisor teeth at the anterior part of the palate?

Answer 26

Incisive foramen

Question 27

What is found in the incisive foramen?

Answer 27

Blood vessels and nerves

Question 28

What forms at the posterior part of the palate?

Answer 28

Uvula

Question 29

What is a cleft?

Answer 29

Fissure or long opening

Question 30

What congenital abnormalities can occur if the prominences of the upper lip fail to unite properly?

Answer 30

Cleft lip

Cleft palate

Question 31

Why is cleft palate more common in females?

Answer 31

Growth of palatine shelves (which form secondary palate) is later in females

Question 32

What separates the oral and nasal cavities during development?

Answer 32

Oronasal membrane

Question 33

What is a nasal pit formed by?

Answer 33

Invagination of the nasal placodes

Question 34

What is the early communication between the nasal and oral cavities called?

In which direction does it move during development?

Answer 34

Primitive choranae

Posteriorly

Question 35

After the posterior movement of the primitive choranae, what is the passage between the nasal cavity and the pharynx called?

Answer 35

Definitive choanae