Embryology Part 2 Flashcards

1
Q

How many brachial arches are there?

A

Six arches each possessing its own cartilage, nerves, vascular supply and muscles

First two are highly developed, the rest are poorly developed, The fifth atrophies

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2
Q

Which major structures compose the first mandibular arch?

A

Posterior portion of upper lip and cheeks
Posterior portion of the maxilla
Posterior 2/3 of the hard palate
Entire lower lip, mandibular arch and body of the tongue

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3
Q

Which structures are composed of Meckel’s cartilage? Which brachial arch is it a part of?

A

First brachial arch

Mental symphysis
Malleus and incus
Sphenomandibular ligament

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4
Q

What are the muscles of mastication? Which arch are they formed from?

A

Mandibular arch

Temporalis, masseter, medial and lateral pterygoid

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5
Q

What other muscles form from the first mandibular arch?

A

Anterior belly of the digastric muscle – Elevates the hyoid bone and mylohyoid muscle that forms the floor of the mouth
Tensor veli Palatine- soft palate
Tensor tympani-Tympanic membrane

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6
Q

Which nerve innervates all of the tissues of the face tongue and teeth?

A

Trigeminal nerve

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7
Q

Which major structure forms from the 2nd/hyoid arch?

A

Root of the tongue

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8
Q

What is Reichert’s cartilage and what Originates from it??

A

A continuous cartilaginous formation in the second brachial arch

 stapes/ear
Styloid process of temporal bone
Lesser cornu of the hyoid
Superior aspect of body of hyoid

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9
Q

Which muscles are formed from the second brachial arch?

A

Muscles of facial expression

Stapedius muscle
Styloid muscle
Posterior belly of the digastric

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10
Q

Which cranial nerve innervates the second brachial arch?

A

7th/facial

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11
Q

What major structure forms from the third brachial arch?

A

Posterior third of the tongue/root

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12
Q

Which cranial nerve innervates the third brachial arch?

A

9th/glossopharyngeal

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13
Q

Major structure of the fourth arch

A

Copula

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14
Q

Major structure of the sixth arch

A

Epiglottic eminence

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15
Q

What forms the oral cavity when the ectoderm invaginate’s?

A

Stomodeum

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16
Q

What is the first branchial arch divide into?

A

Posterior 2/3 of the maxillary process and the entire mandibular arch

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17
Q

Which direction does the mandibular process grow in? What does it form?

A

Grows medially and fuses at the midline

Forms the entire mandible/lower jaw and alveolar arch. Entire lower lip and lower cheeks

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18
Q

Which direction does the maxillary process grow? What does it form?

A

Grows mediately but does not meet

Formed the lateral sides of the upper lip, upper cheeks, lateral sides of the maxilla/alveolar bone. Lateral sides of the hard palate

(posterior 2/3)

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19
Q

How does the lateral nasal process grow and what does it form?

A

Grows laterally and fuses with the maxillary process

Forms the alae of the nose and nasal labial sulcus

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20
Q

How does the medial nasal process grow and what does it form?

A

Grows medially, inferiorly, interiorly and fuses

Forms the columella and tip of the nose, nasal septum

Inter-maxillary segment/pre-maxilla

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21
Q

How does the inter-maxillary segment/globular process grow and what does it form?

A

Grows inferiorly

Forms the philtrum of upper lip- Lateral borders fuse with the posterior 2/3 of the upper lip

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22
Q

When is fusion of the facial process is complete?

A

Complete by week eight

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23
Q

Between which weeks do the eyes form and migrate medially on face?

A

Is form at week six and migrate medially on the face at week 12

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24
Q

When do the ears form and where? When do they migrate superiorly onto the head?

A

Ears form on the low side of the neck at week eight and migrate onto the head at week 12

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25
Q

During which weeks does formation of the pre-maxilla/primary palate occur (anterior 1/3)?

A

Starts at week six and completes by week 12

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26
Q

What happens during primary palate formation during weeks five and six? What is formed?

A

Inter-maxillary segment/inferior aspect grows downward from right and left sides and fuses at the midline.

Forms the interior 1/3 of the alveolar ridge and hard palate

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27
Q

What happens during week seven of primary palate formation?

A

Lateral sides of the pre-maxilla fuse with the lateral Palatine shelves

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28
Q

What would failure of fusion of the maxillary process with the lateral borders of the center portion of the philtrum result in?

A

Cleft lip- week8

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29
Q

What happens during week six of secondary palate formation?

A

Lateral Palatine shelves form from the medial aspects of the maxilary processes

Grow mediallu than inferiorly due to tongue development

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30
Q

What happens during week seven of secondary pallet formation?

A

Tongue drops, Palatine shelves elevate and grow mediately and meet

31
Q

What happens during week eight of secondary palate formation?

A

Palatine shelves start to fuse at the midline and form the posterior 2/3 of the hard palate

32
Q

What happens during week 12/3rd month of secondary palate formation

A

Palate forms and fusion is complete

33
Q

What does the secondary palate and pre-maxilla fusing with the inferior aspect of the nasal septum give rise to?

A

Gives rise to the nasal cavities and developing paranasal sinuses

34
Q

When does tongue formation occur? Where does this occur and from which brachial arch?

A

Occurs from weeks 4 to 8 in the floor of the pharynx. Develops mainly from the first brachial arch but also from the second and third as well as a small portion from the fourth and sixth

35
Q

What part of the tongue forms from the first brachial arch?

A

Anterior 2/3 (body) Of tongue

36
Q

Which swellings merge together to form the body of the tongue?

A

Tuberculum impar

Lateral lingual swellings

37
Q

What forms the median lingual sulcus?

A

Fusion of the lateral lingual swellings and corresponding deep fibrous band

38
Q

What fuses together to form the root of the tongue?

A

Copula and epiglottic eminence

39
Q

Which arches does the posterior 1/3 of the tongue form from?

A

Second and third with a small portion from the fourth and sixth

40
Q

What is the sulcus terminalis?

A

March the fusion between the body and the route of the tongue. V-shaped roof on the dorsal surface, Apex points posteriorly

41
Q

What is the foramen cecum?

A

Origin of the thyroid gland

42
Q

When will tongue formation infusion be complete by?

A

Week eight

43
Q

What effect on the developing fetus can alcohol consumption have?

A

Fetal alcohol syndrome

Growth efficiencies and mental disabilities. Similar facial features to children with down syndrome

44
Q

What effect on development does the use of tetracycline during pregnancy have?

A

Has affects during tooth development. Can affect primary or permanent teeth causing intrinsic yellow to gray brown stain

45
Q

What effect can polychlorinated biphenyl’s have on the developing fetus?

A

Growth deficiencies and mental disabilities. Small premium, impaired visual recognition, poor short-term memory, low verbal skills

46
Q

 Infections that can affect the fetus

A

Rubella- cataracts, cardiac defects and deafness

Syphilis – hutchinson incisors and mulberry molars, blindness, deafness and paralysis

47
Q

Effects of radiation on the embryo or fetus

A

What was deficiencies and mental disabilities: cell death commicromosome damage, delayed mental and physical growth

48
Q

Congenital defects affecting the Dentition

A

Down syndrome, epodermal dysplasia, treacher-Collins syndrome

49
Q

What effect does down syndrome have on the dentition?

A

Hypertrophy of lingual papillae

High incidence of periodontal disease, delayed eruption, hypodontia, microdontia

50
Q

What effect does ectodermal dysplasia have on the dentition?

A

Hypodontia and loss of alveolar ridge. Protuberant lips with loss of vertical dimension due to alveolar bone loss

51
Q

What effect does Treacher Collins syndrome have on the Dentition?

A

High vaulted palate, palatal clefts and malocclusions

52
Q

What causes spinal bifida?

A

Neural tube defect, failure of neural tube to fuse

53
Q

What causes a cleft lip?

A

Partial or complete failure of inter-maxillary segment and maxillary process to fuse

Unilateral or bilateral

Most common in males

54
Q

What causes a cleft chin?

A

Failure of depression to fill in at mandibular midline

55
Q

What causes an oblique facial cleft?

A

Failure of lateral nasal process and maxillary process to merge

Void in nasolacrimal Groove

56
Q

What causes macrostomia and microstomia?

A

Failure of closure or over closure of maxillary and mandibular processes

Exceptionally large or small mouth opening

57
Q

What causes Fordyce granules?

A

Entrapment of sebaceous glands during fusion of maxillary and mandibular processes

Entrapped ectopic sebaceous glands located at retromolar areas, labial mucocutaneous junctions and commissures

58
Q

What causes a cleft palate?

A

Premaxilla and/or secondary palate fail to fuse with the nasal septum and/or failure of pre-maxilla to fuse with secondary palate in canine area

59
Q

What is the appearance and treatment of cleft palate?

A

Crippling communication between oral cavity and nasal cavity; may be partial or complete

May involve the maxillary ridge, bilateral or unilateral with displaced or missing teeth

60
Q

What causes a cleft uvula?

A

Uvula fails to completely fuse at the midline

61
Q

What causes a median maxillary/anterior alveolar cleft?

A

Pre-maxilla fails to completely fuse at the midline forming a very large diastema that may be fixed with orthodontics

62
Q

What is Bifid tongue?

A

Cleft in tip of tongue caused by the lateral lingual swelling‘s failing to merge in the midline

63
Q

What is microglossia?

A

Under development/hypertrophy of musculature of the tongue

64
Q

What is macroglossia?

A

Over development/hypertrophy of musculature of the tongue

65
Q

What is aglossia?

A

Absence of the tongue

Defect involving the first, second and third brachial arches

66
Q

What is ankyloglossia?

A

Very short lingual Frenum

Individual cannot lift tongue to roof of mouth

67
Q

What may cause fissural cysts of the oral region?

A

During fusion of embryonic processes, epithelial cell rests may become entrapped. Entrapped cells have the potential to form cysts

68
Q

Nasopalatine cyst

A

Lies near or in the incisive canal

69
Q

Median Palatine cyst

A

Lies on the fusion line between the lateral palatine shelves of the maxillary process

70
Q

Globulomaxillary cyst

A

Lies on the fusion line between the pre-maxilla and the maxillary process (between lateral and canine)

71
Q

Dermoid/epidermoid cyst

A

Lies in the floor of the mouth. Submandibular or sublingual areas

72
Q

Brachial cleft cyst

A

Usually lies between the second and third brachial arches. Below the angle of the mandible, along the interior border of the SCM)

73
Q

What are the muscles of mastication? Which arch are they formed from?

A

Mandibular arch

Temporalis, masseter, medial and lateral pterygoid