Head and Neck development Flashcards

1
Q

Folding of embryo forms these two structures

A

primitive mouth (stomodeum) and forgut

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2
Q

What forms on either side in the floor of the pharynx during formation of foregut and stomodeum

A

Five pairs of pharyngeal arches

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3
Q

What do the pharyngeal arches consist of?

A

Mesodermal core covered by ectoderm, and lined by pharyngeal endoderm (EXCEPT the first)

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4
Q

Each arch appears as a swelling containing a cartilaginous rod form by?

A

Neural crest cells

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5
Q

Sequential swellings are separated by constrictions caused by these invaginations of the ectoderm. How many?

A

Pharyngeal clefts, 4

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6
Q

Evaginations of the endoderm. How many?

A

Pharyngeal pouches, 4

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7
Q

The narrow, constricted areas between clefts and pouches.

A

Pharyngeal membranes

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8
Q

In more primitive vertebrates, the membranes between clefts and pouches function for/form?

A

Gill slits or functioning gills. This doesn’t occur in humans, and are no longer necessary for breathing and filter feeding. Freed for other uses.

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9
Q

Muscle precursors derive from?

A

Paraxial somitomeres (recall paraxial mesoderm forms somites which go on to form myotome, dermatome, and sclerotome)

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10
Q

Arch 1 correlates with which CN?

A

CN V (Trigeminal, both)

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11
Q

Arch 2 correlates with which CN?

A

CN VII (Facial, both)

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12
Q

Arch 3 correlates with which CN?

A

CN IX (glossopharyngeal, both)

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13
Q

Arch 4 and 6 correlate with which CN?

A

CN X (Vagus, both)

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14
Q

Each cartilaginous rod that has migrated into the arch from rhombomeres make up these 4 important structures:

A

embryonic hindbrain, muscle precursors, aortic arch artery, and associated nerve

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15
Q

Transiently divided segment of the developing neural tube, within the hindbrain region in the area that will eventually become the rhombencephalon

A

Rhombomere, appear as a series of constricted swellings in the neural tube

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16
Q

What does the primitive mouth area is lined by what derived epithelium?

A

Ectodermal

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17
Q

The epithelial layer of the pharynx is derived from?

A

Endoderm

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18
Q

In humans the first arch cartilages persist as the Palatopterygoquadrate bars and Meckle’s cartilage (from maxilla and mandible process, respectively). What do their upper ends become?

A

The incus and malleus bones of the middle ear

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19
Q

Membrane bone from the neural crest mesenchyme develops and surrounded the remaining first arch cartilage to form these 4 bones:

A

Maxillary, Mandibular, zygomatic (cheek bones), and squamous temporal bones.

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20
Q

The first arch somitomeric mesoderm yields these 5 muscles:

A
  1. Muscles of mastication
  2. Tensor tympani
  3. Tensor veli palatini
  4. Anterior belly of digastric
  5. Mylohyloid
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21
Q

Second arch cartilage gives rise to these 3 bones:

A
  1. lesser cornu and upper rim of hyoid bone
  2. third ossicle of middle ear (stapes)
  3. styloid process
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22
Q

Muscles associated with second arch (4)

A

All muscles of facial expression including:

  1. platysma
  2. stylohyoid
  3. stapedius
  4. posterior belly of digastric
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23
Q

Third arch cartilage gives rise to this bone:

A

Greater cornu and lower rim of hyoid bone

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24
Q

The only muscle developed from third arch

A

Stylopharyngeous (innervated by CN IX)

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25
Q

What does the artery of the third arch give rise to?

A

Common carotid and base (first part) of the internal carotid

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26
Q

What do the fourth and sixth arches develop into? (1 with 5 parts)

A

laryngeal cartilage:

  1. thyroid
  2. cricothyroid
  3. arytenoid
  4. coniculate
  5. cuneiform
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27
Q

Muscles derived from the fourth arch mesoderm (3)

A
  1. Pharyngeal constrictors
  2. Cricothyroid
  3. levator veli palatine + other palatal muscles
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28
Q

Muscles derived from the sixth arch (2)

A
  1. intrinsic muscles of larynx

2. striated muscle of esophagus

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29
Q

Primary nerve [of vagus nerve] of the fourth arch derivative

A

superior laryngeal branch of vagus nerve

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30
Q

Innervation of the sixty arch muscles are from which nerve?

A

Recurrent laryngeal branch of the vagus nerve

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31
Q

The vagus nerve also contributes to innervation of the soft palate and pharyngeal constrictors through its contributions to what?

A

The pharyngeal plexus

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32
Q

What happens to the fifth arch?

A

In humans, it either never forms or is rudimentary and disappears

33
Q

The first pharyngeal pouch expands to form these two structures

A
  1. Tubotympanic recess- gives rise to tympanic cavity of the middle ear
  2. Pharyngotympanic tube (eustachian tube/auditory tube) connecting the middle ear cavity and nasal pharynx
34
Q

What does the pharyngeal membrane between the first clefts and pouches form?

A

The tympanic membrane (eardrum)

35
Q

What does the second pouch form?

A

The palatine tonsils

36
Q

The third pouch gives rise to what two regions?

A

A solid dorsal region and a hollow elongated ventral region

37
Q

Where does the thymus originate from?

A

Ventral regions of the third pouches

38
Q

Solid cords that break their connection with the pharynx migrate bilaterally and eventually form what?

A

The thorax, fuse into a single gland

39
Q

Where does the inferior parathyroid gland originate from?

A

The dorsal region of the third pouch

40
Q

Which pouch in addition to the third pouch has dorsal and ventral regions?

A

The fourth pouches

41
Q

What two important structures does the fourth pouch form?

A
  1. Superior parathyroid (dorsal)

2. Ultimobranchial body (ventral)

42
Q

Of neural crest origin, these cells give rise to the calcitonin secreting C cells of the parafollicular thyroid

A

Ultimobranchial body (small organ found in the neck region)

43
Q

The last 3 pharyngeal clefts usually disappear and become covered by the second arch, however the first cleft becomes these two structures:

A
  1. external acoustic meatus (ear canal)

2. External layer of tympanic membrane

44
Q

This develops by proliferation of cells in the floor of the pharynx between the first and second pouches

A

Thyroid gland

45
Q

The most common congenital malformation of the head and neck

A

Unilateral cleft lip (failure of one of maxillary prominence to fuse with medial nasal prominence of same side)

46
Q

Cleft palate, a defect distinct from cleft lip, is usually classified as anterior or posterior, distinguishable by their relationship to what?

A

The incisive foramen

47
Q

First arch syndrome, the lumping together of first arch, is usually a result from failure of what?

A

Failure of neural crest cells to migrate into the arch

48
Q

DiGeorge Syndrome

A

complex constellation of anomalies caused by deletion of chromosome 22 (first arch anomalies, immunological deficiencies with thymus, deficiencies of thyroid and parathyroid glands, cardiovascular anomalies)

49
Q

Common denominator for DiGeorge syndrome

A

Impaired neural crest migration into the third and fourth arches

50
Q

The hard palate is formed in how many stages?

A

2

51
Q

This segment contributes to the upper lip (philtrum) and a jaw component carrying the incisor teeth, forming the triangular primary palate

A

Intermaxillary segment (has deep palatal compartments)

52
Q

What forms the secondary palate?

A

Formed by paired outgrowth of the maxilla

53
Q

Ventrally, what undergoes endochondrial ossification to form the hard palate?

A

Mesenchymal condensations

54
Q

Posteriorly, what condenses to form the soft palate?

A

Myogenic mesenchyme

55
Q

Expansion of the face continues after birth by development and expansion of

A

paransal sinuses

56
Q

Paransal sinues (air filled spaces) develop as diverticular of the lateral nasal wall and invade and expand within which 4 bones?

A
  1. Maxillary
  2. Ethmoid
  3. Sphenoid
  4. Frontal
57
Q

Mandibulofacial dysostosis, genetic basis, inherited as autosomal dominant (first arch syndrome)

A

Treacher Collins

58
Q

The tongue develops from which arch?

A

1, 3, and 4

59
Q

What forms the intrinsic and extrinsic muscles of the tongue?

A

migrating occipital somite mesoderm

60
Q

What innervate the muscles in tongue derived from occipital somites?

A

hypoglossal nerve CN XII

61
Q

The mucosa of the anterior two-thirds of the tongue receives general sensory innervation from which nerve?

A

CN V

62
Q

The posterior third of the tongue received its innervation for both general and taste from which nerve?

A

CN IX (glossophyrangeal)

63
Q

A small area on the dorsal most part of the root or pharyngeal part of tongue receives general and taste sensation from?

A

superior laryngeal branch of CN X (vagus)

64
Q

Taste to the anterior two-thirds is from what nerve?

A

Chorda tympani branch of CN VII (facial)

65
Q

Most recent evidence is that taste buds form independtly in this, but survive only if what are present?

A

Form in lingual epithelium, need nerves to survive

66
Q

All “glossus” muscles (muscles of palate) are innervated by CN XII, except for this muscle

A

Palatoglossus

67
Q

The five facial swellings

A

An unpaired frontonasal prominence on anterior end of developing embryo, and paired maxillary and mandibular prominences (form from growth and division of the paired first pharyngeal arches)

68
Q

The five prominences form this major facial feature

A

The nose

69
Q

What forms the bridge of the nose?

A

The frontonasal prominence

70
Q

Formation of the tongue

A

Pharyngeal arches 1, 3, and 4

71
Q

The thyroid develops from an invagination of the tongue endoderm between what two structures? Later indicated by what foramen?

A

Tuberculum impar and copula linguae. Foramen cecum

72
Q

Through where does the thyroid migrate to its porper position?

A

Thyroglossal duct

73
Q

Unilateral cleft lip can result from these two factors:

A
  • maxillary prominence fails to fuse with medial nasal prominence
  • underlying somitomeric mesoderm and neural crest fail to expand, resulting in a “persistent labial groove”
74
Q

What does the intermaxillary segment form?

A

The philtrum of the lip, the incisors (4), and the primary palate

75
Q

Palatine shelves

A

outgrowths of maxillary prominences

76
Q

The secondary palate forms from outgrowths of these structures

A

palatine shelves, maxillary promimences

77
Q

palatine shelves project downward on either side of tongue but later attain a horizontal postition and fuse along the ________ to form the ______

A

palatine raphe, secondary palate

78
Q

Where do the primary and secondary palates fuse? to form what?

A

incisive foramen, definitive palate