Embryology

Front 1

When does mesoderm develop?

Back 1

third week

Front 2

When does primitive streak appear?

Back 2

third week

Front 3

What is the name given for the third layer?

Back 3

mesoderm

Front 4

What layer gives rise to embryonic connective tissue of the facial region and to the cartilages of the branchial arches?

Back 4

Ectomesenchyme

Front 5

What is mesenchyme?

Back 5

At the end of the third week the paraxial mesoderm forms two solid rods of tissue one on each side of the central notochord.
These rods undergo segmentaion and form somites. During 4th week the somites begin to differentiate further forming dermatome, myocoels, myotome and sclerotome.
Sclerotome differntiates into connective tissues called mesenchyme.

Front 6

When does mesoderm develop?

Back 6

third week

Front 7

When does primitive streak appear?

Back 7

third week

Front 8

What is the name given for the third embryological layer?

Back 8

mesoderm

Front 9

What layer gives rise to embryonic connective tissue of the facial region and to the cartilages of the branchial arches?

Back 9

Ectomesenchyme

Front 10

What is mesenchyme?

Back 10

At the end of the third week the paraxial mesoderm forms two solid rods of tissue one on each side of the central notochord.
These rods undergo segmentaion and form somites. During 4th week the somites begin to differentiate further forming dermatome, myocoels, myotome and sclerotome.
Sclerotome differntiates into connective tissues called mesenchyme.

Front 11

What structures do the neural crest cells become into?

Back 11

components of peripheral nervous system including sensory ganglia, sympathetic neurons, Schwaan cells
meninges, and pigment cells

Front 12

How is ectomesenchyme differ to mesenchyme?

Back 12

mesenchyme is derived from mesoderm but ectomesenchyme is derived from neuro crest cells.

Front 13

What is Treacher Collin's Syndrome?

Back 13

interference in the migration of neural crest cells in the facial area

Front 14

Where is the origin of facial and neck muscles?

Back 14

Somites/somitomeres which migrate into the branchial arches or the frontonasal process

Front 15

What is the name for the developing oral cavity?

Back 15

Stomatodeum

Front 16

When does Stomatodeum appear?

Back 16

in the 4th week

Front 17

At first what is stomatodeum lined with?

Back 17

oral ectoderm

Front 18

What becomes of oral ectoderm later?

Back 18

give rise to the teeth and oral epithelium

Front 19

Which feature represents the wall that separates the gut from the mouth?

Back 19

buccopharyngeal membrane

Front 20

When does the neck start to develop?

Back 20

Fourth week of development

Front 21

What is the origin of the neck?

Back 21

brachial arches and the primitive pharynx

Front 22

Describe the origins of oesophagus, larynx and trachea.

Back 22

Caudal part of primitive pharynx forms oesophagus
Ventral outgrowth leads to larynx and trachea

Front 23

How many brachial arches are there originally?

Back 23

6

Front 24

How many brachial arches survive?

Back 24

5

Front 25

What are the components of a brachial arch?

Back 25

primitive striated muscle tissue
some nervous tissue
some vascular tissue
bar of cartilage in its mesodermal core

Front 26

What lines the branchial arches?

Back 26

ectoderm outside
endoderm inside

Front 27

Which arches are related to the formation of the face and which arches are for the neck?

Back 27

first two arches for the face
and the rest for the neck

Front 28

What is the name given for the 1st branchial arch?

Back 28

mandibular arch

Front 29

What is the name for the cartilage found in first pharyngeal arch?

Back 29

Meckel's cartilage

Front 30

What does 1st branchial arch become?

Back 30

bone: incus and malleus bones, maxilla, mandible
ligament: anterior ligament of malleus and the sphenomandibular ligament
muscles: muscles of mastication, tensor tympani, tensor veli palatini, mylohyoid and anterior belly of the digastric
nervous tissue: mandibular division of trigeminal nerve
vascular tissue: degenerates

Front 31

What is the name given to 2nd branchial arch?

Back 31

Hyoid arch

Front 32

Name the cartilage of the 2nd branchial arch.

Back 32

Reichert's cartilage

Front 33

What does 2nd branchial arch become?

Back 33

bone: Stapes, styloid process of the temporal bone, and some of the hyoid bone including the upper part of its body and the lesser cornu
ligament: stylohyoid ligament
muscles: Muscles of facial expression, stapedius, stylohyoid and the posterior belly of digastric
nervous: Facial nerve(VII)
vascular: degenerates

Front 34

What happens to the cartilage of third arch?

Back 34

contributes to the hyoid bone

Front 35

What happens to the muscles of third arch?

Back 35

stylopharyngeus muscle

Front 36

What happens to the Nerves of third arch?

Back 36

glossopharyngeal nerve(IX)

Front 37

What happens to the artery of third arch?

Back 37

becomes common carotid artery and part of internal carotid artery

Front 38

Which two arches fuse together?

Back 38

4th and 6th

Front 39

What happens to the cartilages of 4th and 6th arch?

Back 39

contribute most of the laryngeal cartilages

Front 40

What are Laryngeal cartilages?

Back 40

thyroid
cricoid
arytenoid
corniculate
cuneiform

Front 41

What happens to the nervous tissues of 4th and 6th arch?

Back 41

4th: superior laryngeal branch of the vagus nerve (X)
6th: recurrent laryngeal branch of vagus (X)

Front 42

What happens to the arteries of 4th and 6th arch?

Back 42

4th: arch of the aorta on the left side and contributes to the right subclavian and brachiocephalic arteris
6th: contributes to the pulmonary arteries

Front 43

What happens to the 5th arch?

Back 43

it degenerates

Front 44

Differentiate between pharyngeal cleft and pouch.

Back 44

Pouch is the fold seen in the inside aspect and cleft is the fold seen from outside.

Front 45

What becomes of the first pharyngeal pouch?

Back 45

auditory tube and middle ear

Front 46

What becomes of the first pharyngeal cleft?

Back 46

external auditory meatus, and the tympanic membrane

Front 47

What becomes of the second pharyngeal pouch?

Back 47

tonsillar fossa between the palatoglossal and palatopharyngeal folds
which eventually becomes palatine tonsil

Front 48

What are the processes that are responsible for the facial development?

Back 48

frontonasal process
maxillary process
mandibular process

Front 49

The processes (frontonasal, maxillary, mandibular) of facial development originate from which pharyngeal arch?

Back 49

the first pharyngeal arch

Front 50

Describe the fusion of the arches to form the face.

Back 50

Frontonasal process forms nasal pits bilaterally. Both maxillary swellings move towards the center fuse with the frontonasal process superior to stomatodeum to form the upper lip. Mandibular swelling becomes the lower lip and the mandible.

Front 51

When is the secondary palate formed?

Back 51

week 7 or 8

Front 52

The secondary palate arise from which process?

Back 52

maxillary process

Front 53

What is the nerve of the primary palate?

Back 53

incisive branch of the long nasopalatine branch of the maxillary division of trigeminal nerve (V)

Front 54

What is the nerve of the secondary palate?

Back 54

Greater palatine branch of the maxillary division of V

Front 55

What is the name of the swelling in the midline of the mandibular process of the first brachial arch? What does it become?

Back 55

tuberculum impar
becomes the anterior 2/3 of the tongue

Front 56

What are the swellings are involved in the formation of the tongue?

Back 56

tuberculum impar
Lateral lingual swellings

Front 57

What do the swellings develop into?

Back 57

They merge together to become mucous membrane of 2/3 of the tongue.

Front 58

What nerve innervates the anterior 2/3 of the tongue?

Back 58

lingual nerve of mandibular division of V (sensory)
chorda tympani VII (taste)

Front 59

The nerve of the second arch contributes taste fibres to the anterior two-thirds of the tongue, via the ____ ____.

Back 59

chorda tympani

Front 60

The posterior part of the tongue arises from the ____ ____, a large midline swelling from the ____ pharyngeal arch, the nerve of which becomes the ____

Back 60

hypobranchial eminence
third
glossopharyngeal (IX)

Front 61

What nerves innervate the posterior part of the tongue?

Back 61

Glossopharyngeal (IX)

Front 62

How is the mandible formed?

Back 62

Two mandibular processes fuse in the midline to form a mandibular arch. The bone begins to form in the mesenchymal tissue lateral to the cartilage. The cartilage begins to disappear.

Front 63

How is Meckel's cartilage involved in the formation of the mandible?

Back 63

very little. It may contribute to positioning of the mental foramen.

Front 64

What are the five environmental factors that can affect the embryo development?

Back 64

infectious agent
ionising radiation
drugs
hormones
nutritional deficiencies

Front 65

The most common birth defect in the oral cavity is called...

Back 65

orofacial clefts

Front 66

Label

Back 66

a. buccopharyngeal membrane
b. primitive streak