Development of head and neck

Question 1

In week 4, what proportion of the embryo is made up of the future head and neck?

Answer 1

Half of it

Question 2

What is the structure of the face of the embryo at week 4 of development?

Answer 2

No structure, completely undeveloped

Question 3

What is the structure of the head and neck of the embryo in early development?

Answer 3

Frontonasal prominence in the head

Pharyngeal arches

Question 4

Why is the frontonasal prominence named so?

Answer 4

At the front of the embryo

Where nose develops

Prominent because of developing brain behind it

Question 5

How many pharyngeal arches are there in the embryo in early development?

Answer 5

5 of them

but are numbered 1, 2, 3, 4, 6

Question 6

What is a pharyngeal arch made up of?

Answer 6

Mesenchymal proliferation
-mesoderm with some neural crest cells

Inner endoderm lining
Outer ectoderm lining

Question 7

What does the mesenchyme in the pharyngeal arch develop into?

Answer 7

Cartilage bar

Muscle

Artery

Question 8

What supplies a pharyngeal arch?

Answer 8

Each pharyngeal arch has its own blood supply

and is innervated by its own cranial nerve

Question 9

Which pharyngeal arch is the biggest?

Answer 9

1st pharyngeal arch

Question 10

How do the pharyngeal arches change in size?

Answer 10

Get smaller from the 1st pharyngeal arch to the 6th pharyngeal arch

Question 11

How does the number of derivatives of the pharyngeal arches change? Why?

Answer 11

Fewer derivatives from the 1st pharyngeal arch to the 6th pharyngeal arch
because they get smaller

Question 12

What are the parts of the 1st pharyngeal arch?

Answer 12

Maxillary zone

Mandibular zone

Question 13

Which cranial nerves innervate the pharyngeal arches?

Answer 13

CNs 5, 7, 9, 10

Question 14

Which cranial nerve innervates the 1st pharyngeal arch?

Answer 14

CN5 trigeminal nerve

Question 15

Which cranial nerve innervates the 2nd pharyngeal arch?

Answer 15

CN7 facial nerve

Question 16

Which cranial nerve innervates the 3rd pharyngeal arch?

Answer 16

CN9 glossopharyngeal nerve

Question 17

Which cranial nerve innervates the 4th pharyngeal arch?

Answer 17

CN10 vagus nerve

Question 18

Which cranial nerve innervates the 6th pharyngeal arch?

Answer 18

CN10 vagus nerve

Question 19

Which muscles does the 1st pharyngeal arch give rise to?

Answer 19

Muscles of mastication

Question 20

Which muscles does the 2nd pharyngeal arch give rise to?

Answer 20

Muscles of facial expression

Question 21

Which muscles does the 3rd pharyngeal arch give rise to?

Answer 21

Stylopharyngeus

Question 22

Which muscles does the 4th pharyngeal arch give rise to?

Answer 22

Pharyngeal muscles

Question 23

Which muscles does the 6th pharyngeal arch give rise to?

Answer 23

Laryngeal muscles

Question 24

What is the cartilage bar of the 1st pharyngeal arch called?

Answer 24

Meckel’s cartilage

Question 25

What bones does Meckel's cartilage develop into?

Answer 25

Malleus, incus Template for mandible

Question 26

What is the cartilage bar of the 2nd pharyngeal arch called?

Answer 26

Reichert's cartilage

Question 27

What bones does Riechert's cartilage develop into?

Answer 27

Stapes Upper part of hyoid bone Styloid process

Question 28

What bones does the cartilage bar of the 3rd pharyngeal arch develop into?

Answer 28

Rest of hyoid bone

Question 29

What does the cartilage bar of the 4th pharyngeal arch develop into?

Answer 29

Larynx cartilages - thyroid - cricoid - aretynoid

Question 30

What does the cartilage bar of the 6th pharyngeal arch develop into?

Answer 30

Larynx cartilages - thyroid - cricoid - aretynoid

Question 31

What is the blood supply of the 3rd pharyngeal arch?

Answer 31

Internal carotid artery

Question 32

What is the blood supply of the 4th pharyngeal arch?

Answer 32

Left side gives aortic arch Right side gives brachiocephalic trunk

Question 33

What is the blood supply of the 6th pharyngeal arch?

Answer 33

Pulmonary trunk

Question 34

What happens to the blood supply of the 1st and 2nd pharyngeal arches?

Answer 34

Disappear

Question 35

What is the name of the dent between pharyngeal arches in the endoderm?

Answer 35

Pharyngeal pouch

Question 36

What do the pharyngeal pouches develop into?

Answer 36

Glands of head and neck

Question 37

Which pharyngeal pouch is the biggest?

Answer 37

1st pharyngeal pouch | between the 1st and 2nd pharyngeal arches

Question 38

What does the 1st pharyngeal pouch develop into?

Answer 38

Eustachian tube Middle ear

Question 39

What does the second pharyngeal pouch develop into?

Answer 39

Palatine tonsils

Question 40

What do the third and fourth pharyngeal pouches develop into?

Answer 40

Third - inferior parathyroid gland, thymus gland Fourth - superior parathyroid gland

Question 42

What is the name of the dent between pharyngeal arches in the ectoderm?

Answer 42

Pharyngeal cleft

Question 43

What does the 1st pharyngeal cleft develop into?

Answer 43

External acoustic meatus

Question 44

What happens to the 2nd-6th pharyngeal clefts?

Answer 44

2nd pharyngeal cleft grows larger and downwards to cover and close up all the other clefts

Question 45

What is a branchial cyst?

Answer 45

Fluid-filled sac in the neck

Question 46

What is a branchial fistula?

Answer 46

Opening into neck

Question 47

How do branchial cysts present?

Answer 47

Swelling in neck

Question 48

Where are branchial cysts and fistulas located in the neck?

Answer 48

Anterior to the sternocleidomastoid muscle

Question 49

Where are pharyngeal arches located in the embryo?

Answer 49

Lateral walls of pharynx

Question 50

How does the development of the blood supply of the head and neck relate to the recurrent laryngeal nerve?

Answer 50

Explains why the right one turns under the right subclavian and why the left one turns under the aortic arch

Question 51

How do branchial fistulas form?

Answer 51

2nd arch pharyngeal cleft grew larger and donwards but didn't fully cover all the other clefts gives opening into neck

Question 52

How do branchial cysts form?

Answer 52

2nd pharyngeal cleft grew larger and downwards to cover all the other clefts but didn't fully close them up