Development Of Pharyngeal Arches Flashcards

1
Q

What were pharyngeal arches originally called?

A

-brachial arches

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2
Q

Where are the pharyngeal arches?

A

-surrounds the foregut where the structures that develop into the upper respiratory and proximal digestive systems are located

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3
Q

How many pharyngeal arches are there?

A

6

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4
Q

What are the three principle components of the pharyngeal arches?

A
  • pharyngeal arch (skeletal, muscular, nerve, and artery component)
  • pharyngeal clefts (external)
  • pharyngeal pouches (internal)
  • CAP
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5
Q

Pharyngeal arches are formed by what

A

Neural crest

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6
Q

How is the face developed?

A
  • neural crest derived mesenchyme from the first and second arches migrates into the developing face
  • will give rise to binge and cartilage
  • muscle from mesoderm
  • associated with specific nerve and arteries
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7
Q

What forms the facial skeleton?

A

-neural crest cells

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8
Q

What forms the posterior portions of the neurocranium and basicranium?

A

-mesoderm

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9
Q

Coronal and sagittal sutures may contain what?

A

-neural crest

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10
Q

Anterior portion of the sphenoid and frontal bones are derived from what?

A

-neural crest

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11
Q

What skeletal elements are derived from arch 1?

A
  • neural crest -> cartilaginous rod (Meckel’s cartilage)
  • malleus and incus
  • Meckel’s cartilage -> mandible
  • sphenomandibular ligame-maxilla, zygomatic, and part of the temporal bone in the maxillary portion of the first arch
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12
Q

What comes from the first arch?

A
  • frontonasal region

- maxillary/mandibular prominences

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13
Q

Dorsal to the first arch is an elevation formed by the underlying ________ ________, the sensory ganglion for the nerve that supplies tissues derived from the first arch.

A

-trigeminal ganglion

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14
Q

What is required for normal development of the upper lip?

A

-Union of nasomedial prominence with the nasolateral prominence and maxillary prominence

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15
Q

Muscles of the arches are _______ derived.

A

Mesodermally

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16
Q

What muscles are derived from arch 1?

A
  • temporalis
  • massester
  • mylohyoid
  • ant. Belly of digastric
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17
Q

What muscles are derived from arch 2?

A
  • buccinator
  • orbicularis oris
  • post belly digastric
  • platysma
  • frontalis
  • orbicularis oculi
  • occipitalis
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18
Q

What muscles are derived from arch 3?

A

-stylopharyngeus

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19
Q

What muscles are derived from arches 4 and 6?

A
  • levator veli palatini
  • pharyngeal muscles
  • intrinsic muscles of larynx
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20
Q

What nerves are derived from arch 1?

A
  • trigeminal nerve, V

- mandibular division V3

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21
Q

What nerve is derived from arch 2?

A

Facial nerve, VII

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22
Q

What nerve is derived from arch 3?

A

Glossopharyngeal nerve, IX

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23
Q

What nerve is derived from arches 4 and 6?

A

-vagus nerve, X

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24
Q

When does cheilogenesis occur?

A

Week 5

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25
Q

What does the frontonasal prominence form?

A

-forehead, bridge of nose, medial and lateral nasal prominences

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26
Q

What does the maxillary prominence from?

A

-cheeks, lateral portion of upper lip

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27
Q

What does the medial nasal prominence form?

A

-philtrum of upper lip, crest and tip of nose

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28
Q

What does the lateral nasal prominence form?

A

-Alae of nose

29
Q

What does the mandibular prominence form?

A

-lower lip

30
Q

When does palatogeneis take place?

A

5-12 weeks

31
Q

When are BMPs expressed and for what?

A
  • expressed early

- superficial location-palatial shelves

32
Q

When is Shh expressed and for what reason?

A
  • early induction of facial primordia
  • medial edge epithelia-palatal shelves
  • this is different -> instead of keeping layers apart, now epithelia must fuse
33
Q

What does Tbx22 induce formation of?

A

Tongue

34
Q

What induces ankyloglossia?

A
  • mutations in T box transcription factor Tbx22

- can lead to heritable ankyloglossia with or without CL, CP

35
Q

What are oro-facial clefts?

A
  • separation or opening in a structure of the face: all skeletal elements derived from arch 1
  • cleft lip and cleft palate (hard, soft)
  • isolated or combined
  • unilateral or bilateral
  • genetic: either principal birth defect or symptom of hundreds of different syndromes
36
Q

What is median cleft lip/”hare lip”?

A

-due to the incomplete merging of the two medial nasal prominences, therefore leading to most cases (with deep midline grooving of the nose) to various forms of bifid nose

37
Q

What is a complete, unilateral cleft palate?

A
  • a complete cleft palate involves a cleft of the palate and the alveolus
  • open communication between oral and nasal cavities
  • bovine grafts are required
  • orthodontic treatment is required
38
Q

What is a complete, bilateral cleft palate?

A
  • leaves the premaxilla unattached, allowing it to grow forwards
  • premaxilla is unattached and carries the upper four central teeth
  • a double bone graft at the time the permanent teeth are erupting is required for this cleft
39
Q

What are lateral facial clefts?

A
  • macrostomia
  • hypoplasia or incomplete fusion of maxillary and mandibular prominences
  • large mouth (unit or bilaterally)
40
Q

What are classic arch 1 abnormalities?

A
  • Treacher-Collins syndrome

- Pierre Robin syndrome

41
Q

What is Treacher-Collins syndrome?

A
  • mandibulo-facial dysostosis
  • underdevelopment of structures associated with arch 1
  • downward slanting eyes, small mandible, and malformed/absent ears
  • autosomal dominant
  • protein appears to assist in protein sorting during development
  • prenatal testing
42
Q

What is Pierre Robin syndrome?

A
  • micro/retrognathia
  • glossoptosis
  • airway obstruction
  • treatment is surgery
43
Q

What skeletal elements are derived from arch 2?

A
  • initially bar of cartilage -> Reichert’s cartilage
  • stapes and styloid process of temporal bone
  • lesser horns/cornu and superior portion of the hyoid bone
  • stylohyoid ligament
44
Q

What are the skeletal elements of arches 3,4, and 6?

A
  • 3: greater horns/cornu and inferior portion of the hyoid bone
  • 4,6: laryngeal cartilages (thyroid, arytenoid, corniculate, cuneiform, and cricoid) except epiglottis
45
Q

Arteries from arch 1

A

Maxillary arteries

46
Q

Arteries arch 2

A
  • stapedial artery

- hyoid artery

47
Q

Arteries arch 3

A
  • common carotid arteries

- proximal portion of the internal carotid arteries

48
Q

Arteries arch 4

A
  • connects to aorta forming the aortic arch

- right side forms proximal portion of right subclavian artery

49
Q

Arteries arch 5

A

-rudimentary and do not develop into any known vessels

50
Q

Arteries arch 6

A
  • proximal: right and left pulmonary arteries

- distal: left aortic arch -> ductus arteriosus

51
Q

What is the derivative of. Pharyngeal cleft 1?

A

-external auditory meatus

52
Q

What is the derivatives of pharyngeal cleft 2-4?

A

Neck

53
Q

What is the derivative of pharyngeal pouch 1?

A
  • middle ear auditory tube and endoderm forms the lining of the middle ear
  • between the first pouch and cleft is the tympanic membrane
54
Q

What is the derivative of pharyngeal pouch 2?

A
  • supratonsillar fossa
  • underneath endoderm of the second pouch develops tonsil are crypts and differentiates into lymphoid tissue called the palatine tonsils
55
Q

What is the derivative pharyngeal pouch 3?

A
  • thymus

- parathyroid gland

56
Q

What is the derivative of pharyngeal pouch 4?

A
  • thymus
  • parathyroid gland
  • ultimobranchial body
57
Q

What can remnants of pharyngeal clefts 2-4 form?

A

-can appear in the form of cervical cysts or fistfuls found along the anterior border of the sternocleidomastoid muscle

58
Q

Cells from the ultimobrachial body differentiate into parafollicular cells (C cells) that produce calcitonin.

A

: )

59
Q

What is DiGeorge syndrome?

A
  • micro deletion on DGS critical region on chromosome 22
  • characterized by hypoparathyroidism, which results hypocalcemia
  • hypoplastic thymus or absent thymus which results in problematic immune system
  • conotruncal heart defects
  • cleft lip and/or palate
  • problems with development and function of the brain
60
Q

When does the tongue develop?

A

During the 4th week, anterior and posterior tongue have different mechanism

61
Q

What does the tongue differentiate from?

A

-1st, 2nd, 3rd pharyngeal arches and migration of muscles from the occipital somites

-anterior: arises from 1st arch formed from 3 masses (2 lateral lingual swellings and the tuberculum impar)
+lateral; lingual swellings enlarge, merge with each other and overgrow the tuberculum impar to form the oral part of the tongue

62
Q

How does the base of the tongue develop?

A
  • develops mainly from 3rd arch -> initially indicated by midline elevation that appears behind the tuberculum impar
  • tissue from arches 3 and 4 overgrow and second arch to become continuous with the body of the tongue
  • the site of union between base and body is the sulcus terminalis
63
Q

What is the origin, sensory innervation, and taste bud innervation of the anterior two thirds of the tongue?

A

Origin: median tongue, lateral lingual swellings

Sensory: lingual nerve, branch of trigeminal nerve

Taste bud: facial nerve

64
Q

Origin, sensory innervation, taste bud innervation of posterior one third of tongue

A

Origin: hypophyseal eminence

Sensory: glossopharyngeal nerve

taste bud: glossopharyngeal nerve, vagus nerve

65
Q

How is the thyroid gland formed?

A
  • not derived from any pharyngeal pouches
  • arises from midline of thyroid diverticulumthat forms from the endoderm in the flood of the pharynx just caudal to the 1st pharyngeal arch -> differentiate into follicular cells of the thyroid gland
  • diverticulum elongates but remains connected to tongue by thyroglossal duct -> is obliterated, foramen cecum in the midline at their terminal sulcus
  • endodermal mass of cells invaginate a into underlying mesoderm, creating the thyroid diverticulum that is positioned 2/3 and posterior 1/3 of developing tongues
  • thyroid diverticulum grows inferiorly, often between the skeletal elements of the 2nd and 3rd arches
  • it then migrates to a position anterior to the upper portion of the developing trachea
66
Q

What can anomalies in thyroid develop result in?

A

-ectopic thyroid tissue and/or cysts present along the course of the thyroglossal duct, which is a midline structure

67
Q

What is a thyroglossal duct fistula?

A

-thyroglossal duct cyst may rupture and present as a draining sinus, which has been erroneously called a thyroglossal fistula, although communication with foramen cecum is extremely rare

68
Q

When do the pharyngeal arches appear?

A

-four weeks of development