510-03 Craniofacial Embryology

Question 1

As neurulation proceeds through the third week of development, the embryo elongates and folds in which two directions?

Answer 1

cephalocaudally (head + tail) and laterally (see figure 2-9 on slide 4)

Question 2

As the head and neck begin to form during the 4th-5th weeks of development, the embryonic ____ develops a series of external arches, clefts, and internal pouches that contain tissues that will develop into important nerves, blood vessels, bones, cartilage and other organs of the head and neck.

Answer 2

pharynx

Question 3

(T/F) Each pharyngeal cleft develops its own artery, nerve, muscle, and skeletal elements of the head and neck

Answer 3

False, each pharyngeal ARCH develops its own artery, nerve, muscle, and skeletal elements of the head and neck

Question 4

pharyngeal arches consist of bars of mesenchymal tissue separated by internal pharyngeal ____ and external pharyngeal ___.

Answer 4

pouches, clefts

Question 5

Pharyngeal pouches are lined by which germ layer?

Answer 5

endoderm

Question 6

Which structure gives rise to the middle ear cavity, eustachian tube, palatine tonsil, parathyroid glands, thymus and ultimobranchial bodies? (pharyngeal arches/ pouches/ clefts)

Answer 6

pharyngeal pouches

Question 7

Which pharyngeal cleft gives rise to the external auditory meatus?

Answer 7

the first cleft

Question 8

What structure does the first pharyngeal cleft give rise to?

Answer 8

external auditory meatus

Question 9

What structure is formed by the tracheo-bronchial diverticulum?

Answer 9

the lungs

Question 10

Outgrowths of the pharynx form ____ that will form structures in the head and neck

Answer 10

pouches

Question 11

What are 3 diffusible signaling molecules that help guide neural crest cell migration?

Answer 11

1) sonic hedgehog (Shh)
2) bone morphogenic proteins (Bmp)
3) fibroblast growth factors (Fgf)

Question 12

Development of head and neck tissues depend on migration of what kind of cells into the pharyngeal arches?

Answer 12

neural crest cells

Question 13

Migrating neural crest cells express genes that regulate differentiation of developing head and neck tissues by establishing gradients that are regulated by expression of ___ genes.

Answer 13

Hox genes

Question 14

Which arch develops into the mandible and maxilla?

Answer 14

first

Question 15

Which arch contains Meckel’s cartilage?

Answer 15

first

Question 16

Which ossicles are made due to Meckel’s cartilage?

Answer 16

Incus and malleus

Question 17

Which arch contains Reichert’s cartilage?

Answer 17

second

Question 18

What ossicle is made due to Reichert’s cartilage?

Answer 18

stapes

Question 19

The ____ that will eventually become the opening of the oral cavity is initially closed by a buccopharyngeal membrane in a 24 day embryo.

Answer 19

stomodeum

Question 20

The stomodeum that will eventually become the opening of the oral cavity is initially closed by a ______ membrane in a 24 day embryo.

Answer 20

buccopharyngeal

Question 21

What cellular process do the nasal placodes rely on in order to form into nostrils?

Answer 21

apoptosis

Question 22

Of the 6 pharyngeal arches, which ones produce significant body structures?

Answer 22

1-4

Question 23

What does the 6th pharyngeal arch contribute to?

Answer 23

laryngeal cartilage

Question 24

The cartilages of the first and second pharyngeal arches are derived from ______. The cartilages of the 3rd-6th arches are derived from ____.

Answer 24

neural crest cells, mesoderm

Question 25

(T/F) the cartilages of the 3rd-6th pharyngeal arches are derived from neural crest cells

Answer 25

FALSE

Question 26

Which arch contains thyroid cartilage?

Answer 26

4

Question 27

Which arch contains cricoid cartilage?

Answer 27

6

Question 28

Which arch forms into the temporal bone?

Answer 28

1

Question 29

Which arch forms into the hyoid bone?

Answer 29

3

Question 30

What is the process in which maxillary bones develop, where bone progressively replaces the embryonic connective tissue?

Answer 30

intramembranous ossification

Question 31

What are the 2 types of ossification?

Answer 31

intramembranous and endochondral

Question 32

The membranous bone of the developing mandible grows completely around the ___ ____ nerve and forms the ____ ___ that will contain the nerve.

Answer 32

inferior alveolar nerve, mandibular canal

Question 33

The ramus develops from a rapid spread of ossification away from Meckel's cartilage at a point marked by the ___ in an adult mandible

Answer 33

lingula

Question 34

The perichondrium of Meckel's cartilage becomes the _____ ligament

Answer 34

sphenomandibular

Question 35

The ___ cartilage develops as an independent piece of cartilage that fuses with the mandibular condyle. The ____ cartilage is a transient growth cartilage that disappears long before birth.

Answer 35

condylar, coronoid

Question 36

Most of the condylar cartilage is replaced by bone through ____ ossification

Answer 36

endochondral

Question 37

Mutations in the TCOF1 gene are responsible for most cases of treacher collins syndrome. The product of this gene is a protein called ___ , which is necessary for preventing apoptosis and maintaining proliferation in neural crest cells.

Answer 37

treacle

Question 38

Epibranchial placodes are specialized regions of surface ectoderm that invaginate to contribute to the formation of the sensory ganglia for which cranial nerves?

Answer 38

5, 7, 9, 10

Question 39

What are specialized regions of surface ectoderm that invaginate to contribute to the formation of the sensory ganglia for cranial nerves 5,7,9 and 10?

Answer 39

epibranchial placodes

Question 40

Which cranial nerve will supply tissues from the first arch, including muscles of mastication?

Answer 40

5 (trigeminal)

Question 41

Which cranial nerve will innervate the muscles of facial expression?

Answer 41

7 (facial)

Question 42

Which 2 cranial nerves will innervate muscles involved in swallowing?

Answer 42

9 (glossopharyngeal) + 10 (vagus)

Question 43

What is the fate of pharyngeal clefts 2,3 and 4?

Answer 43

They fuse to temporarily form a cervical sinus that eventually disappears

Question 44

What is derived from the first pharyngeal pouch?

Answer 44

tympanic membrane + eustachian canal

Question 45

What is derived from the second pharyngeal pouch?

Answer 45

palatine tonsils + tonsillar fossa

Question 46

What is derived from the third pharyngeal canal?

Answer 46

inferior parathyroid gland + thymus

Question 47

What is derived from the fourth pharyngeal canal?

Answer 47

superior parathyroid gland + ultimobranchial body (Parafollicular/C cells)

Question 48

What forms if the cervical sinus from clefts 2, 3, and 4 is not completely obliterated? Where?

Answer 48

lateral cervical cysts. On the lateral side next to the sternocleidomastoid muscle

Question 49

The thyroid gland originates from a midsagittal invagination of the pharyngeal epithelium at the ____ ____. This forms the ___ duct which closes after the thyroid tissue migrates to the trachea below the larynx.

Answer 49

foramen cecum, thyroglossal duct

Question 50

What kind of cyst occurs due to remnants of oral ectoderm tissue along the migration pathway from the foramen cecum towards the larynx and trachea?

Answer 50

thyroglossal cyst

Question 51

the human face develops of the growth of what 5 prominences? What structures does each one form?

Answer 51

1) frontonasal - forehead, bridge of nose, medial and lateral nasal prominences 2) maxillary - cheeks, lateral portion of upper lip 3) medial nasal- philtrum of upper lip, crest, and tip of nose 4) lateral nasal- alae of nose 5) mandibular - lower lip

Question 52

(T/F) all facial prominences are paired except for the frontonasal prominence

Answer 52

true

Question 53

Is cleft lip more common in males or females?

Answer 53

males

Question 54

Is isolated cleft palate related to maternal age?

Answer 54

no

Question 55

Does cleft palate occur more oftern in males or females?

Answer 55

females

Question 56

Partial unilateral and bilateral clefting of the lip results from the failure of which prominences to fuse? How about clefts involving the hard and soft palate?

Answer 56

- maxillary and medial nasal | - palatal shelves

Question 57

1) the body of the tongue develops from which arch? 2) the root of the tongue develops from which arch? 3) The epiglottis develops from which arch?

Answer 57

1) 1 2) 3 3) 4

Question 58

The body of the tongue develops from the ___ ___ swellings and the ___ ___ of the 1st arch growing together.

Answer 58

lateral lingual swellings, tuberculum impar

Question 59

The root of the tongue develops from the ___ of the 3rd arch

Answer 59

copula

Question 60

What is it called when the tip of the tongue is divided longitudinally due to a disturbance in the developmental process?

Answer 60

bifid tongue

Question 61

What is ankyloglossia of the tongue?

Answer 61

tongue-tie, decreases mobility of the tongue