Embryology

Question 1

Week 1

Answer 1

preimplantation phase
-fertilization to implantation

Question 2

Week 2

Answer 2

implantation complete
- fertilized egg > zygote > cells continue to divide > becomes blastocysts > then embryo

Question 3

Week 3-8

Answer 3

Embryotic Phase
- the blastocysts is a cluster of dividing cells and consists of 3 embryotic germ layers

Question 4

3 Embryotic germ Layers

Answer 4

Ectoderm - outer layer
Mesoderm - middle layer
Endoderm - inner layer

Question 5

Week 4

Answer 5

Primitive Oral Cavity
-aka stomodeum

Question 6

oropharynx

Answer 6

-consists of primitive oral cavity and area of the foregut (pharynx)
-At 4 weeks the oral pit appears, aka stomodeum; positioned between the foregut and the developing heart
-oral pit will become the oral pocket and then the oral cavity

Question 7

Developing Face Processes
4th week

Answer 7

primitive mouth forms
-frontal process
-maxillary process
-mandibular proocess

Question 8

Developing Face processes
5th week

Answer 8

-Nasal placodes appear in the upper border of lip (become nostrils)
-frontal area becomes frontonasal process
-eyes appear

Question 9

Developing Face Process
6th week

Answer 9

Nose
-median nasal process - philtrum
-lateral nasal process - ala

Question 10

Developing Face Process
7th week

Answer 10

-face begins to look more human
-eyes and nose have moved
-upper lip has fused

Question 11

medial and lateral palatal processes

Answer 11

-palate separates oral cavity from nasal cavity
-palate comes from primary palate (medial palatine process)
-palate comes from secondary palate (lateral palatine process)
-during 8th week, palatal shelves are pushed together

Question 12

Tongue

Answer 12

• Body and base oof tongue are separated by V shaped grove (terminal sulcus)
  -posterior to the terminal sulcus -lingual sulcus (dorsal surface)
  -lingual tonsil forms part of Waldeyer’s Ring

Question 13

Thyroid Gland

Answer 13

-thyroid tissue moves to neck during development
-during movement, thyroid gland attaches to the tongue by epithelial cord - thyroglossol duct
-evidence> foramen ceacum

Question 14

malfunctions

Answer 14

facial and palatal cleft
-cleft lip
-facial lip
-hairlip cleft
-mandibular cleft
-palatal cleft

Question 15

rathke’s pouch

Answer 15

turning out of the roof of the mouth
-eventually becomes pituitary

Question 16

Globular process

Answer 16

becomes philtrum

Question 17

Pharyngeal arch 1

Answer 17

-mandibular arch
-maxilla, mandible, muscles of mastication, (masseter, medial and lateral pterygoid, temporalis) nerves, vessels

Question 18

Pharyngeal Arch 2

Answer 18

Hyoid arch
-will form muscle/nerves, vessels, hyoid bone
-

Question 19

Pharyngeal Arch 3

Answer 19

pharyngeal muscles, glossopharyngeal nerve
(tongue)

Question 20

Pharyngeal arches 4+6

Answer 20

arches fuse to form laryngeal cartilages
-muscle/nerve of larynx and pharynx