Block 4 Embryo Flashcards

1
Q

pharyngeal apparatus consists of

A

pharyngeal arches, pouches, clefts (grooves), and membranes

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2
Q

each pharyngeal arch consists of

A

mesoderm (differentiates into muscles and arteries)

neural crest cells (differentiate into bone and connective tissue)

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3
Q

List the cranial nerves associated w/ each pharyngeal arch

A

1: CN V (trigeminal)
2: CN VII (facial)
3: CN IX (glossopharyngeal)
4: CN X (superior laryngeal)
5: CN X (recurrent laryngeal)

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4
Q

List the pharyngeal arches

A

1,2,3,4, and 6 (5 regresses)

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5
Q

List the pharyngeal pouches and what they’re made of

A

1,2,3,4

evaginations of endoderm that line the foregut

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6
Q

List the pharyngeal clefts/grooves and what they’re made of

A

1,2,3,4

invaginations of ectoderm located b/w each pharyngeal arch

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7
Q

List the pharyngeal membranes & what they’re made of

A

1,2,3,4

consists of ectoderm, intervening mesoderm and neural crest, and endoderm located between each arch

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8
Q

Fate of pharyngeal cleft/groove 1

A

develops into the external auditory meatus

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9
Q

Describe development of the thyroid gland

A

in the midline of the floor of the pharynx, endodermal lining of the foregut forms the thyroid diverticulum

the thyroid diverticulum migrates caudally, passing ventral to the hyoid bone and laryngeal cartilages. during this migration, the thyroid remains connected to the tongue by the thyroglossal duct, which is later obliterated

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10
Q

List arch 1 derivatives

A

mesoderm: muscles of mastication, mylohyoid, anterior belly of digastric, tensor veli palatini, tensor tympani
neural crest: maxilla, mandible, incus, malleus, zygomatic bone, squamous temporal bone, palatine bone, vomer, sphenomandibular ligament
CN V (trigeminal nerve)

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11
Q

List arch 2 derivatives

A

mesoderm: muscles of facial expression, posterior belly of digastric, stylohyoid, stapedius
neural crest: stapes, styloid process, stylohyoid ligament, lesser horn and upper body of hyoid bone
CN VII (facial N)

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12
Q

List arch 3 derivatives

A

mesoderm: stylopharyngeus, common carotid arteries, internal carotid arteries
neural crest: greater horn ad lower body of hyoid bone

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13
Q

List arch 4 derivatives

A
mesoderm: muscles of soft palate (except tensor veli palatini), muscles of pharynx (except stylopharyngeus), cricothyroid, cricopharyngeus, laryngeal cartilages, right subclavian artery, arch of aorta
 neural crest: none 
CN X (superior laryngeal)
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14
Q

List arch 6 derivatives

A
mesoderm: intrinsic muscles of larynx (except cricothyroid), upper muscles of esophagus, laryngeal cartilages, pulmonary arteries, ductus arteriosus
neural crest: none 
CN X (recurrent laryngeal nerve)
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15
Q

Pouch 2 develops into

A

epithelial lining of palatine tonsil crypts

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16
Q

Pouch 3 develops into

A

inferior parathyroid gland, thymus

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17
Q

Pouch 4 develops into

A

superior parathyroid gland

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18
Q

Groove 2-4 final state

A

obliterated

19
Q

Pharyngeal membrane 1 derivative

A

tympanic membrane

20
Q

Pharyngeal membrane 2-4 derivative

A

obliterated

21
Q

List the swellings that form the face

A

frontonasal prominence, maxillary prominence (pharyngeal arch 1), mandibular prominence (pharyngeal arch 1)

22
Q

Nasal Placodes

A

form nasal pits, then medial and lateral nasal prominence

23
Q

Nasolacrimal Groove

A

forms b/w maxillary prominence & lateral prominence; eventually forms nasolacrimal duct and lacrimal sac

24
Q

Intermaxillary palate

A

formed by fusion of nasal prominences at the midline; makes the primary palate

25
Q

Secondary Palate forms from

A

outgrowths of the maxillary prominences caulled palatine shelves (specifically, lateral)

26
Q

Describe the palate

A

primary and secondary palate fuse at the incisive foramen to form the definitive palate.

posterior part of the secondary plate eventually forms the soft palate & uvula and does not have bone

27
Q

First arch syndrome

result of
types

A

results from abnormal development of pharyngeal arch 1

treacher collins syndrome
pierre robin syndrome

28
Q

Treacher Collins Syndrome

A

mandibulofacial dysostosis

characterized by underdevelopment of the zygomatic bones, mandibular hypoplasia, lower eyelid colombras, malfomormed external ears

29
Q

Remnants of pharyngeal clefts 2-4

A

appear in the form of cervical cysts or fistulas found along the anterior border of the SCM

30
Q

Pharyngeal Fistula

A

occurs when pharyngeal pouch 2 & pharyngeal groove 2 persists, forming a patent opening b/w the tonsillar area to the external neck

found in the anterior border of the SCM

31
Q

Pharyngeal Cyst

A

occurs when parts of the pharyngeal grooves 2-4 that are normally obliterated persists, usually found by the angle of the mandible

32
Q

Ectopic Thymus, Parathyroid or Thyroid Tissue

A

result from abnormal migration of these glands

glandular tissue may be found anywhere along their path of migration

33
Q

Thyroglossal Duct Cyst

A

occurs when part of the thyroglossal duct persists and forms a cyst

most common in the midline near hyoid bone, but can also be at the base of the tongue (lingual cyst)

34
Q

Congenital Hypothyroidism

A

thyroid deficiency exists in the early fetal period; causes impaired skeletal growth and mental retardation

characterized by coarse facial features, sparse eyebrows, wide set eyes, broad nose

35
Q

Cleft lip results from (2)

A

maxillary prominence fails to fuse with medial nasal prominence

somitomeric mesoderm and neural crest fail to expand, resulting in persistent labial groove

36
Q

Cleft palate
involves
classification

A

involves neural crest cells

anterior or posterior, distinguished by incisive foramen

37
Q

anterior cleft palate

A

palatine shelves fail to fuse with the primary plate

38
Q

posterior cleft palate

A

palatine shelves fail to fuse with eachother and the nasal septum

39
Q

digeorge syndrome

A

pharyngeal pouches 3 & 4 fail to differentiate into the thymus and parathyroid glands

accompanied by facial anomalies resembling first arch syndrome

40
Q

Ankyloglossia

A

frenulum of the tongue extends to the tip of the tongue, preventing protrusion

41
Q

Cervical sinus

A

the common cavity for the pharyngeal clefts/grooves

42
Q

lateral cervical cyst

A

2nd pharyngeal arch fails to grow caudally over the 3rd and 4th arch; remnants of the 2-4th grooves remain in contact with the surface by a narrow drainage canal

43
Q

cranisynostosis

A

premature closure of the cranial sutures

44
Q

Describe the timeline for cranial suture closures

A

anterior fontanelle: closes by 9 to 18 months

sphenoidal and posterior: close during the first few months of life