pharyngeal arches Flashcards

1
Q

pharyngeal arch 1 CN

A

CN V

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2
Q

pharyngeal arch 2 CN

A

CN VII

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3
Q

pharyngeal arch 3 CN

A

CN IX

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4
Q

pharyngeal arch 4 CN

A

CN X

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5
Q

pharyngeal arch 1 aortic arch, gives rise to?

A

Aortic arch I: becomes maxillary aa

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6
Q

pharyngeal arch 2 aortic arch, gives rise to?

A

aortic arch 2; gives rise to hyoid and stapedial aa which normally go away with development

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7
Q

pharyngeal arch 3 aortic arch, gives rise to?

A

aortic arch 3; common cartoid and proximal internal carotid aa

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8
Q

pharyngeal arch 4 aortic arch, gives rise to?

A

aortic arch 4; right subclavian and the aorta

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9
Q

mm dereived from pharyngeal arch 1

A
masticory
tensor tympani 
mylohyoid 
tensor palatini veli 
anterior digastric
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10
Q

mm dereived from pharyngeal arch 2

A
facial expression mm
stylohyoid 
platysma 
post digastric 
stapedius
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11
Q

mm dereived from pharyngeal arch 3

A

stylopharyngeus

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12
Q

mm dereived from pharyngeal arch 4

A

pahrygeal and laryngeal mm

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13
Q

skeletal derivatives of arch 1

A
malleus 
incus 
sphenoman ligament 
meckel's cartilage-mandible 
tympanic ring
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14
Q

skeletal derivatives of arch 2

A

stapes
styloid
lesser horn of hyoid
stylohyoid ligament

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15
Q

skeletal derivatives of arch 3

A

greater horn

body of hyoid

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16
Q

skeletal derivatives of arch 4

A

laryngeal cartilages

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17
Q

pharyngeal groove/cleft vs pouch

A

groove/cleft: outside of where two arches meet

pouch: inside of where two arches meet

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18
Q

first pharyngeal groove (where arches 1 and 2 meet) becomes?

A

external ear/ external auditory meatus

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19
Q

2nd, 3rd, 4th pharyngeal grooves become?

A

cervical sinuses: temporary, pathology if not resorbed

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20
Q

1st pharyngeal pouch becomes (where arches 1 and 2 meet)?

A

middle ear and eutaschian tube

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21
Q

2nd pharyngeal pouch becomes (where arches 2 and 3 meet)?

A

supratonsilar fossa

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22
Q

3rd pharyngeal pouch becomes (where arches 3 and 4 meet)?

A

thymus and inf PTG

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23
Q

4th pharyngeal pouch becomes (where arches 4 and 5 meet)?

A

sup PTG

post brachial body

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24
Q

when does the pharyngeal region form

A

around the 4th week

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25
Q

pharyngeal complexes

A

Blocks of mesenchymal tissue separated externally by
pharyngeal clefs (grooves) and internally by pharyngeal pouches.
The pharyngeal complexes are crucial for normal
formation of the neck & face.

26
Q

components of pharyngeal arches

A
Pharyngeal arch (skeletal, muscular, nerve & artery components) 
 Pharyngeal clefts (external)
 Pharyngeal pouches (internal)
27
Q

processes and names of the first arch

A

the first (mandibular) arch has two processes - the
maxillary and the mandibular (really 3 if you include the
frontonasal).

28
Q

which arches form face/neck? can be observed externally?

A

The first two pharyngeal arches develop into facial
and neck structures that can be observed externally, the other
arches do not.

29
Q

neural crest migration to the arches

A

 Neural-crest migrates into the arches
 The migrating neural crest cells differentiate into the skeletal element of each arch,
 Branches of specific cranial nerves, which are derived from neuroectoderm, migrate into each pharyngeal arch.

30
Q

Development of the Arterial System

A

 6 pair of aortic arches, one for each arch
 Connect aortic sac/TA to dorsal aortae
heart developing ventricle and atria

31
Q

structures found in each pharyngeal arch

A

 Skeletal element
 Muscles
 A branch of a specific cranial nerve
 Artery

32
Q

skeletal elements of arch 1

A

 The migrating neural crest in the first arch induce the formation of a cartilaginous rod
(Meckel’s cartilage).
 The more posterior portion differentiates and becomes ossified into the malleus and the incus.
 The more anterior portion of Meckel’s cartilage serves as a scaffolding for intramembranous bone formation of the mandible.
In between the two middle ear bones and the mandible, the sphenomandibular ligament forms, connecting the first arch skeletal elements.
 In addition, the maxilla, zygoma and part of the temporal bone form in the maxillary portion of the first arch.

33
Q

skeletal elements of arch 2

A

 The skeletal elements of the second arch initially appear as a bar of cartilage (Reichert’s).
 The posterior portion differentiates into the stapes & the styloid process of the temporal bone.
 The anterior portion differentiates into the lesser horns (cornu) and the superior portion of the hyoid bone. In between these elements, the stylohyoid ligament is formed.

34
Q

Skeletal elements –

Arches 3,4 & 6

A

The skeletal elements of the third pharyngeal arch are the greater horns (cornu) and inferior portion of the hyoid bone.

Skeletal elements of the fourth-sixth pharyngeal arches differentiate into all the laryngeal cartilages (thyroid, arytenoid, corniculate, cuneiform, and cricoid), except the epiglottis (comes from the laryngeotracheal diverticulum)

35
Q

general rule for what mm come from each arch?

A

mm inn by nerve of that arch

1: CNV
2: CNVII
3: CNIX
4: CNX

36
Q

Terminal branches of maxillary artery are associated with?

A

the first pharyngeal arch.

37
Q

 Tissues of the second pharyngeal arch are supplied by? (aa)

A

the stapedial artery, which regresses.

38
Q

 The common carotid artery and root of internal carotid artery are associated with?

A

with the third pharyngeal arch.

39
Q

The ductus arteriosus and roots of pulmonary arteries are associated with which arches?

A

the fourth-sixth pharyngeal arches.

40
Q

treacher-collins

A

 Mandibulo-facial dysostosis

 Underdevelopment of structures associated with Arch 1.

41
Q

Pierre Robin Sequence

A

Micro-/Retrognathia=glossoptosis (pushes tongue back) to cause airway obstruction

42
Q

pharyngeal clefts become?

A

The first pharyngeal cleft deepens and forms the external auditory
meatus and canal. This is the only cleft that gives rise to an adult
structure. The second-fourth clefts become overgrown by the
second pharyngeal arch and, thus, become enclosed as a cervical
sinus. Normally, this cervical sinus regresses.

43
Q

ectopic thyroid

A

thyroid develops at the foramen cecum and will migrate to its adult position
may have misplaced thyroid tissues along this route or still present on the tongue=lingual thyroid

44
Q

formation of the eustachian tube

A

The first pouch increases in size and migrates towards the first pharyngeal cleft. As the pouch and cleft
approach each other, the auditory (pharyngotympanic or eustachian) tube is formed and the endoderm of the first pouch forms the lining of the middle ear (tympanic cavity).

45
Q

tympanic membrane formation

A

At its most distal end, endoderm of the first pouch becomes approximate to the ectoderm of the first pharyngeal cleft with only a small amount of mesoderm separating them. This is the site of the tympanic membrane.

46
Q

second pharyngeal pouch becomes? what forms beneath it?

A

site of the tonsillar fossa in the adult
Underneath the endoderm of the second pouch develops pit-like depressions (tonsillar crypts) mesoderm differentiates into lymphoid tissue that is called the palatine tonsils.

47
Q

Pharyngeal Pouch 3 develops?

A

Dorsally, the posterior endodermal region develops into bilateral inferior parathyroid glands (III), which
migrate toward the posterior aspect of the inferior pole of the thyroid gland.

Ventrally, the anterior endodermal region of the third pouch differentiates bilaterally into thymus gland tissue.

Each part migrates inferiorly and fuses with its counterpart in the midline, and the united gland migrates inferiorly to the superior mediastinum of the thorax.

48
Q

how can the inferior PTG form more superior than the superior PTG?

A

inf will migrate further down and eventually be inf to the sup PTG

49
Q

Pharyngeal Pouches 4-5 develop?

A

The posterior endoderm develops into superior parathyroid glands that migrate to the posterior aspect of the thyroid gland.

The anterior endoderm of the fourth pouch develops an ultimobranchial body that migrates to the thyroid gland. Cells from the ultimobranchial body differentiate into parafollicular cells (C cells) that produce calcitonin.

The endoderm of the fifth pharyngeal pouch contributes to the formation of the ultimobranchial body

50
Q

Digeorge syndrome

A

failure of the thymus gland to develop from the third pharyngeal pouch

51
Q

adult derivatives of pharyngeal pouch 1

A

Auditory (pharyngotympanic, eustachian) tube, middle ear (tympanic
cavity), part of the eardrum (tympanic membrane)

52
Q

adult derivatives of pharyngeal pouch 2

A

Tonsillar crypts

53
Q

adult derivatives of pharyngeal pouch 3

A

Inferior parathyroid glands

Thymus gland

54
Q

adult derivatives of pharyngeal pouch 4

A

Superior parathyroid glands

Ultimobranchial body

55
Q

adult derivatives of pharyngeal pouch 5

A

Ultimobranchial body

56
Q

anterior 2/3 of the tongue development

A

Median tongue bud; overgrown by lateral lingual swellings, fusion indicated by the median sulcus

57
Q

posterior third of the tongue development

A

Mesoderm of the second pharyngeal arch forms a central process (copula)

It is overgrown by a central process from the third and fourth pharyngeal arches, the hypopharyngeal (hypobranchial) eminence, which develops into the posterior one-third of the tongue.

58
Q

between the anterior and posterior tongue?

A

terminal sulcus

59
Q

mm of the tongue development and inn

A

Muscles of the tongue develop from the mesoderm of the occipital myotomes that migrate into the developing tongue. Branches of the hypoglossal nerve (CN XII) follow the migrating occipital myoblasts and thus innervate the intrinsic muscles of the tongue

60
Q

formation of the thyroid gland

A

The endodermal mass of cells invaginates into the underlying mesoderm, creating the thyroid diverticulum that is positioned between the anterior two-thirds and posterior one-third of the developing tongue.

The thyroid diverticulum grows inferiorly, often between the skeletal elements of the second and third pharyngeal arches.

It then migrates to a position anterior to the upper portion of the developing trachea.

connection between origin of thyroid diverticulum and the thyroid gland is called the thyroglossal duct and normally regresses over time, if not thyroglossal duct cyst