Embryology Of The Pharyngeal Apparatus Flashcards

1
Q

What are the grooves made of?

A

Ectoderm

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2
Q

What are the pouches made from?

A

Endoderm

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3
Q

What are the pharyngeal membranes made of?

A

Ectoderm from groove
Endoderm from pouch
Mesenchyme from core

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4
Q

What is the core of pahryngeal arches made of?

A

Mesoderm and Mesenchyme

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5
Q

When do the pharyngeal arches form?

A

4th week

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6
Q

What do the 1st pair arches form?

A

Primordial jaws

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7
Q

What is the purpose fo the pharyngeal arches?

A

Support lateral walls of the primordial pharynx

Give rise to prominences of tissue that contribute to craniofacial development

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8
Q

What does the NCC derived Mesenchyme form from arches?

A

All CT in head as well as dermis and smooth muscle

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9
Q

What does the paraxial mesoderm do?

A

Populate each arch to form PA musculature

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10
Q

What does the lateral plate mesoderm do?

A

Angioplasty to endothelium

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11
Q

What does the Prechordal plate mesoderm do?

A

Extraocular musculature

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12
Q

What do arch artery arise from? What are they remodeled into?

A

Truncus arteriosus of primordial heart

Remodeled into great arteries of thorax and head/neck

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13
Q

What is a cervical cyst?

A

Remnant of cervical sinus (from 2- 4 grooves)

Persists and forms a slowly enlarging, painless, free-lying cyst in neck

Can accumulate fluid and cellular debris derived from desquamation of the epithelial linings

Mobile, typically painless, unattractive, drained or surgically excised

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14
Q

What is a cervical sinus?

How is it detected?

A

Failure of 2nd pa groove and cervical to go away

Detected due to discharge of mucus

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15
Q

What is a cervical fistula?

A

Abnormal canal that opens into tonsillar sinus and externally in the side of neck

Persistent of parts of 2nd groove and pouch

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16
Q

How is the thymus formed?

When is it complete?

A

From PA 3 endoderm (pouch)

Comprised of epithelial cords that grow into surrounding Mesenchyme forming lobules

They then become arranged around a central point forming thymic corpuscles

Thymus growth and development is still going on during childhood

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17
Q

How does the thyroid gland develop?

A

First endocrine gland to develop

From a median endodermal thickening in the floor of primordial pharynx

Descends into neck with tongue growth

Is conjected to tongue by narrow tube

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18
Q

How is the thyroid conjected to tongue during its descent down the throat?

What will this become?

A

Thyroglossal duct

Remnant is seen as foramen cecum

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19
Q

What happens to the 3rd pouch?

A

Caudally migrates due to growth of brain and cardiac regions

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20
Q

What will fuse with the Thryoid gland? What does it give rise to?

A

Ultimobranchial body

Gives rise to parafollicular cells (make c-cells)

21
Q

What is first pharyngeal arch syndrome?

Present with?

Results from what?

A

Abnormal development of components of the first arch

Malformation of eyes, ears, mandible, and palate

Results from insufficient migration of NCC to 1st arch during wk. 4

22
Q

What is Treacher Collins Syndrome?

Genetic wise? What does this cause?

A

First PA syndrome

Malar hypoplasia
Defects of external ears and lower eyelids

Autosomal dominant disorder with mutation in TCOF-1, truncated protein

Causes for increased apoptosis of cranial NCC

23
Q

What is Pierre Robin sequence?
How does it occur?
Present?
Initiating defect?

A

1st PA syndrome

Occurs de novo

Hypoplasia of manidble, cleft palate, defects of eyes and ears

Small mandible is the initiating defect

24
Q

What is agenesis of the thyroid gland?

A

Absence of a thyroid gland or one of its lobes

25
Q

What is thyroid hemiagenesis?

A

Unilateral failure of formation

Left lobe more commonly absent

26
Q

What is DiGeorge Syndrome?

Occurs from what?

Classic triad associated with it?

A

Agenesis of thymus and parathyroid glands

Occurs from breakdown of signaling form PA endoderm to NCC

22q11 chromosomal deletion

Loss of thymus, loss of parathyroid gland, congential heart defects

CATCH 22 (Congenital hypoparthyroidism, abnormal face, cardiac problems, hypocalcemia)

27
Q

What is a brachial cleft cyst?

When are they first noticed?

Will it move?

A

Present as a neck mass

First noticed when they become infected
Fistula to skin may develop and ooze pus

Mass does not move with swallowing (=not thyroid)

28
Q

What is a thyroglossal duct cyst?

A

Midline neck mass that MOVES

29
Q

What forms from the:

1st groove? What is it made of?

A

External acoustic meatus

Ectoderm

30
Q

What forms from the:

2nd-4th groove? What is it made of?

A

Cervical sinus

Ectoderm

31
Q

What forms from the:

1st arch? What is it made of?

A
Meckel’s Cartilage
Malleus
Incus
Mandible
Sphenomandibular L. 
Anterior L. Of the mandible 

NCC

32
Q

What forms from the:

2nd arch? What is it made of?

A

From NCC

Reichert’s cartilage

Stapes

Styloid process of temporal bone

Lesser Cornu of hyoid bone

Stylohyoid L.

33
Q

What forms from the:

3rd arch? What is it made of?

A

NCC

Greater Cornu of hyoid
Body of hyoid

34
Q

What forms from the:

4th arch? What is it made of?

A

NCC

Epiglottis

35
Q

What forms from the:

6th arch? What is it made of?

A

NCC

Laryngeal Cartilages

36
Q

What forms from the:

1st arch muscles? What is it made of?

A

Mesoderm

Muscles of mastication

37
Q

What forms from the:

2nd arch muscles? What is it made of?

A

Muscles of facial expression

38
Q

What forms from the:

3rd arch muscles? What is it made of?

A

Mesoderm

Stylopharyngeus m.

39
Q

What forms from the:

4th arch muscles? What is it made of?

A

Cricothyroid M.

Levator Veli Palatini

Pharyngeal Constrictors

40
Q

What forms from the:

6th arch muscles? What is it made of?

A

Mesoderm

Intrinsic Ms. of the Larynx

41
Q

What forms from the:

1st pouches? What is it made of?

A

Endoderm

Tympanic cavity
Mastoid antrum
Eustachian tube (Pharyngotympanic tube)

42
Q

What forms from the:

2nd pouches? What is it made of?

A

Endoderm

Tonsillar sinus
Lymphoid tissue

43
Q

What forms from the:

3rd pouches? What is it made of?

A

Endoderm

Inferior parathyroid glands
Thymus

44
Q

What forms from the:

4th/6th pouches? What is it made of?

A

Endoderm

Superior parathyroid gland

Ultimobranchial body

45
Q

What CN is associated with the:

1st arch?

A

CN V

46
Q

What CN is associated with the:

2nd arch?

A

CN VII

47
Q

What CN is associated with the:

3rd arch?

A

CN IX

48
Q

What CN is associated with the:

4th/6th arch?

A

CN X

49
Q

What forms from the:

1st pharyngeal membrane? What is it made of?

A

Endoderm, ectoderm, Mesenchyme

Tympanic Membrane