Development of head and neck Flashcards

1
Q

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

A

Half of it

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2
Q

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

A

No structure, completely undeveloped

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3
Q

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

A

Frontonasal prominence in the head

Pharyngeal arches

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4
Q

Why is the frontonasal prominence named so?

A

At the front of the embryo

Where nose develops

Prominent because of developing brain behind it

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5
Q

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

A

5 of them

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

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6
Q

What is a pharyngeal arch made up of?

A

Mesenchymal proliferation
-mesoderm with some neural crest cells

Inner endoderm lining
Outer ectoderm lining

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7
Q

What does the mesenchyme in the pharyngeal arch develop into?

A

Cartilage bar

Muscle

Artery

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8
Q

What supplies a pharyngeal arch?

A

Each pharyngeal arch has its own blood supply

and is innervated by its own cranial nerve

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9
Q

Which pharyngeal arch is the biggest?

A

1st pharyngeal arch

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10
Q

How do the pharyngeal arches change in size?

A

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

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11
Q

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

A

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

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12
Q

What are the parts of the 1st pharyngeal arch?

A

Maxillary zone

Mandibular zone

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13
Q

Which cranial nerves innervate the pharyngeal arches?

A

CNs 5, 7, 9, 10

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14
Q

Which cranial nerve innervates the 1st pharyngeal arch?

A

CN5 trigeminal nerve

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15
Q

Which cranial nerve innervates the 2nd pharyngeal arch?

A

CN7 facial nerve

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16
Q

Which cranial nerve innervates the 3rd pharyngeal arch?

A

CN9 glossopharyngeal nerve

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17
Q

Which cranial nerve innervates the 4th pharyngeal arch?

A

CN10 vagus nerve

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18
Q

Which cranial nerve innervates the 6th pharyngeal arch?

A

CN10 vagus nerve

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19
Q

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

A

Muscles of mastication

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20
Q

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

A

Muscles of facial expression

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21
Q

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

A

Stylopharyngeus

22
Q

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

A

Pharyngeal muscles

23
Q

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

A

Laryngeal muscles

24
Q

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

A

Meckel’s cartilage

25
Q

What bones does Meckel’s cartilage develop into?

A

Malleus, incus

Template for mandible

26
Q

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

A

Reichert’s cartilage

27
Q

What bones does Riechert’s cartilage develop into?

A

Stapes

Upper part of hyoid bone

Styloid process

28
Q

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

A

Rest of hyoid bone

29
Q

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

A

Larynx cartilages

  • thyroid
  • cricoid
  • aretynoid
30
Q

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

A

Larynx cartilages

  • thyroid
  • cricoid
  • aretynoid
31
Q

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

A

Internal carotid artery

32
Q

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

A

Left side gives aortic arch

Right side gives brachiocephalic trunk

33
Q

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

A

Pulmonary trunk

34
Q

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

A

Disappear

35
Q

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

A

Pharyngeal pouch

36
Q

What do the pharyngeal pouches develop into?

A

Glands of head and neck

37
Q

Which pharyngeal pouch is the biggest?

A

1st pharyngeal pouch

between the 1st and 2nd pharyngeal arches

38
Q

What does the 1st pharyngeal pouch develop into?

A

Eustachian tube

Middle ear

39
Q

What does the second pharyngeal pouch develop into?

A

Palatine tonsils

40
Q

What do the third and fourth pharyngeal pouches develop into?

A

Third - inferior parathyroid gland, thymus gland

Fourth - superior parathyroid gland

42
Q

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

A

Pharyngeal cleft

43
Q

What does the 1st pharyngeal cleft develop into?

A

External acoustic meatus

44
Q

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

A

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

45
Q

What is a branchial cyst?

A

Fluid-filled sac in the neck

46
Q

How do branchial cysts form?

A

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

46
Q

What is a branchial fistula?

A

Opening into neck

47
Q

How do branchial fistulas form?

A

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

47
Q

How do branchial cysts present?

A

Swelling in neck

48
Q

Where are branchial cysts and fistulas located in the neck?

A

Anterior to the sternocleidomastoid muscle

49
Q

Where are pharyngeal arches located in the embryo?

A

Lateral walls of pharynx

50
Q

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

A

Explains why the right one turns under the right subclavian

and why the left one turns under the aortic arch