Pharyngeal Apparatus Flashcards

1
Q

What does the pharyngeal apparatus consist of?

A

Pharyngeal arches, grooves, pouches and membranes

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2
Q

Are the pharyngeal arches, grooves, pouches and membranes bilateral?

A

duh

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3
Q

When do the pharyngeal arches start to develop?

A

Early in the 4th week

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4
Q

What cell type migrates to form the pharyngeal arches?

A

NCC

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5
Q

What tissue types are within each arch?

A

Mesoderm and mesenchyme = middle
Ectoderm = external portion
Endoderm = internal portion

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6
Q

What does the endoderm in the arches do?

A

Regulates development of the arches

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7
Q

Describe the locations of the arches, grooves, membranes and pouches in relation to eachother

A

The arches make up the circular prominence and in between each arch is where you will find the grooves, pouches and membranes

  • The Pouches are internal
  • The grooves are external at the same level
  • The Membranes are in between a pouch and a groove
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8
Q

What forms the mesoderm in the pharyngeal arch?

A

Paraxial mesoderm

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9
Q

What forms the mesenchyme in the pharyngeal arch?

A

NCC

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10
Q

What will the mesoderm in the pharyngeal arch become?

A

Musculature

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11
Q

What will the mesenchyme in the pharyngeal arch become?

A

Cartilage and bony elements, smooth muscle and dermis

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12
Q

What will the lateral plate mesoderm create?

A

Endothelium

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13
Q

What will the prechordal plate mesoderm create?

A

Extraocular muscles

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14
Q

What are the 4 elements that each pharyngeal arch consists of?

A

Cartilagenous rods
Muscular components
Cranial nerves
Arteries

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15
Q

What do the cartilagenous rods of an arch create?

A

Form skeletal elements

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16
Q

What do the muscular components of an arch create?

A

Form head and neck musculature

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17
Q

What do the cranial nerves of an arch create?

A

Form sensory and motor components

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18
Q

Cartilage of PA1

A

Meckel’s cartilage

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19
Q

What does the dorsal, ventral and perichondrium portions of meckel’s cartilage create?

A

Dorsal - malleus and incus (ear bones)
Ventral - primordium of mandible
Perichondrium - anterior ligament of malleus and the sphenomandibular ligament

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20
Q

Where does the actual bony mandible form?

A

Lateral to the meckel’s cartilage and then the cartilage disintegrates

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21
Q

Cartilage of PA2

A

Riechert’s cartilage

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22
Q

What does the dorsal, ventral and perichondrium portions of Riechert’s cartilage create?

A

Dorsal - stapes and styloid process of temporal bone
Ventral - ossifies to form lesser horn of hyoid bone
Perichondrium - stylohyoid ligament

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23
Q

What does cartilage of PA3 create?

A

Greater horn of hyoid bone

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24
Q

What does cartilage of PA4 create?

A

Laryngeal cartilages and epiglottis (NCC derived)

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25
Q

What does cartilage of PA6 create?

A

Laryngeal cartilages

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26
Q

What forms the body of the hyoid bone?

A

Hypopharyngeal eminence

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27
Q

Where does most musculature originate from?

A

Paraxial mesoderm

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28
Q

What creates the extraocular muscles?

A

Prechordal plate mesoderm

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29
Q

What creates the tongue musculature?

A

Occipital myotomes

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30
Q

PA1 musculature

A

Muscles of mastication (temporalis, massater, medial and lateral pterygoids)

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31
Q

PA2 musculature

A

Muscles of facial expression and stapedius

occipitofrontalis, platysma, orbicularis oculi and oris, zygomaticus major and minor, buccinator

32
Q

PA3 musculature

A

Stylopharyngeus

33
Q

PA4 musculature

A

Cricothyroid and phayrngeal constrictors (superior, middle and inferior)

34
Q

PA6 musculature

A

Intrinsic laryngeal muscles

35
Q

What nerve supplies PA1?

A

Trigeminal – V2 and V3 (sensory and motor)

36
Q

What nerve supplies PA2?

A

Facial – CN VII (motor)

37
Q

What nerve supplies PA3?

A

Glossopharyngeal – CN IX (motor)

38
Q

What nerve supplies PA4 and PA6?

A

Vagus – CN X

39
Q

What nerves specifically supply PA4?

A

Superior laryngeal and recurrent laryngeal branches

40
Q

What nerve specifically supplies PA6?

A

Recurrent laryngeal branches

41
Q

What causes first arch syndromes?

A

Insufficient NCC migration during the 4th week of development

42
Q

What are the first arch syndromes?

A

Treacher-collins syndrome and Pierre-Robin sequence

43
Q

How is Treacher-Collins syndrome inherited?

A

Autosomal dominant

44
Q

What mutation causes Treacher-Collins syndrome?

A

Mutation in TCOF1 gene that results in decreased TREACLE protein which results in increased apoptosis of NCC!!

45
Q

Symptoms of Treacher-Collins syndrome?

A

Malar hypoplasia, downward slanting palpebral fissures, external, middle and internal ear deformations

46
Q

How is Pierre-Robin sequence inherited?

A

De novo

47
Q

Describe the Pierre-Robin sequence

A

Initial defect = small mandible (micrognathia)

  • Posterior displacement of tongue
  • Palate unable to fully close
  • BILATERAL CLEFT PALATE
48
Q

What is the final result of Pierre-Robin sequence?

A

bilateral cleft palate (and probs micrognathia)

49
Q

Where does the 1st groove/pouch lie?

A

Between the 1st and 2nd pharyngeal arches

50
Q

What does the 1st groove create?

A

External acoustic meatus

51
Q

What does the 1st pouch create?

A

Tubotympanic recess - - tympanic cavity and mastoid antrum

52
Q

What is created when the endoderm over the 1st pouch extends to the 1st groove?

A

Tympanic membrane is created

53
Q

What does the 1st membrane contribute to?

A

Tympanic membrane

54
Q

What happens to the grooves 2-4?

A

Overgrowth of the 2nd arch creates a cervical sinus that houses grooves 2-4; the cervical sinus is eventually filled with mesenchyme from PA2 and it will be obliterated along with grooves 2-4 = bye bye

55
Q

What does the 2nd pouch create?

A

Tonsilar sinus, tonsilar epithelium, lymphoid nodules of palatine tonsils

56
Q

What creates lymphoid nodules of palatine tonsils from the 2nd pouch?

A

Mesenchyme

57
Q

What does the dorsal and ventral portion of the 3rd pouch create?

A

Dorsal – inferior parathyroid gland

Ventral – thymus

58
Q

Where do the dorsal and ventral portions of the 3rd pouch go?

A

Migrate caudally

59
Q

What does the dorsal portion of the 4th pouch create?

A

Superior parathyroid gland

60
Q

What does the ultimobranchial body of the 4th pouch do?

A

Fuses with thyroid gland to create parafollicular cells

61
Q

What are the branchial anomalies?

A

External and internal cervical sinus, cervical cysts, cervical fistula

62
Q

Failure of 2nd groove and cervical sinus to obliterate and detected due to discharge of mucus

A

External cervical sinus

63
Q

Persistence of 2nd pouch that opens into tonsilar sinus

A

Internal cervical sinus

64
Q

Rememnants of cervical sinus and/or 2nd groove that includes slow growing, painless cysts in the neck below the mandible filled with fluid and cell debris

A

Cervical cysts

65
Q

Persistence of parts of 2nd groove and pouch that creates a canal that opens into tonsilar sinus and external side of neck

A

Cervical fistula

66
Q

What all does a cervical fistula pass through?

A

Subcutaneous neck tissue, platysma, carotid sheath and tonsilar sinus

67
Q

When does the thyroid gland begin to develop?

A

24 days post fertilization

68
Q

Where does the thyroid gland move?

A

Descends into neck as tongue grows, anteriorly to hyoid bone and laryngeal cartilages

69
Q

What connects tongue to thyroid gland?

A

Thyroglossal duct - eventually disintegrates

70
Q

Any thyroid tissue (functional) not in correct place

A

Ectopic thyroid tissue

71
Q

Thyroid gland forms but does not descend

A

Sublingual thyroid gland

72
Q

Can form in the tongue or neck, make sure it is not a functional thyroid gland (ectopic)

A

Thyroglossal duct cyst

73
Q

Which lobe is more commonly absent with thyroid hemiagenesis?

A

Left lobe

74
Q

What causes DiGeorge syndrome?

A

Breakdown of signaling from PA endoderm to NCC

75
Q

What symptoms can DiGeorge syndrome cause?

A

Agenesis of thymus and parathyroid glands, congenital hypoparathyroidism, cardiac abnormalities and shortened upper lip and nasal clefts