2-craniofacial development-brainscape

Question 1

Cause of Oblique facial clefts (lips into nostril)

Answer 1

failure of maxillary prominence to merge with the corresponding lateral nasal prominence (therefore cleft lip arises even though the lateral nasal prominence does not give rise to the lip, lip is secondary to palate)

Question 2

Craniofacial aspects of Down’s Syndrome

Answer 2

Nasal bone is underdeveloped at week 16-20

Question 3

Describe formation of the mature thyroid gland

Answer 3

1) Primordial thyroid descends from foramen cecum 2) Descends as bilobed diverticulum 3) Initially attached to tongue by Thyroglossal duct (disappears) 4) By week 6 it descends in front of hyoid bone 5) At final position in front of trachea by week 7

Question 4

Development of the Nasal Pits

Answer 4

1) Deepen into surrounding NC cells & mesoderm (week 6) 2) Separated from oral cavity by oronasal membrane (week 7) 3) Oronasla membrane ruptures (midle week 7) 4) Primitive choana formed –> joins primitive nasal cavity with the oral cavity posterior to the primary palate

Question 5

Effect of anticonvulsant drugs (phenobarbital) on pregnant women

Answer 5

increase risk of cleft palate

Question 6

Facial Prominences

Answer 6

Two maxilary prominences Two mandibular prominences Frontonasal prominence

Question 7

Facial prominences derivatives

Answer 7

From the first pharyngeal arch: ectoderm externally and mesoderm/neural crest cells internally

Question 8

First growths of the tongue (and when)

Answer 8

From first pharyngeal arch at week 4: Two lateral lingual swellings and one medial tuberculum impar

Question 9

Five facial prominences that give rise to the nose and what they form

Answer 9

1) Frontal nasal prominence (Bridge) 2) Two merged medial nasal prominences (Crest and tip) 3) Two lateral nasal prominences (form the sides)

Question 10

Formation of nostrils

Answer 10

1) Nasal (olfactory) placodes on either side of frontal prominence form as a result of local thickening of the surface ectoderm 2) Nasal Pits form when the placodes invaginate (weeks 5-8) 3) Nasal Prominences form from the ridge of tissue overlying the nasal pits

Question 11

How does the thyroid develop?

Answer 11

Epithelial proliferation at base of pharynx between the tuberculum impar and the hypobranchial eminence at the foramen cecum

Question 12

How many dental buds in each jaw?

Answer 12

10

Question 13

Innervation of the tongue

Answer 13

Anterior (arch 1) = mandibular branch of trigeminal (V) Posterior 1/3 = Glossopharyngeal (IX) Extreme posterior = Superior Laryngeal branch of Vagus (X)

Question 14

Intermaxillary Segment

Answer 14

Caused by growth of maxillary prominence which caues fusion of medial nasal prominences, which deep to the surface leads to the intermaxillary segment which is composed of: 1) Labial component which forms the philtrum of upper lip 2) Upper jaw component (four incisor teeth here) 3) Palatal compartment (triangular primary palate)

Question 15

Later medial swellings of the tongue (when)

Answer 15

Copula: aka hypobranchial eminence ==> 2, 3, 4th arch Development of epiglottis: from posterior of arch 4

Question 16

Levothyroxine

Answer 16

synthetic version of thyroxine that can be presribed to obese patient if thyroxine deficiency led to obesity

Question 17

Neurocranium

Answer 17

Bone formation primarily endochondral ossification of paraxial and prechordal mesoderm and NC cells 1) Cartilaginous neurocranium 2) Membranous neurocranium

Question 18

Paranasal air surfaces (conchae)

Answer 18

Develop as diverticula of the lateral nasal wall and extend into maxilla, ethmoid, frontal, and spheroid bones *Increase SA to condition the air breathed in

Question 19

Sensory (taste) innervation of the tongue

Answer 19

Anterior 2/3 = Chorda tympani branch of facial nerve (CN VII) Posterior 1/3= Glossopharyngeal

Question 20

Stomodeum

Answer 20

Primitive oral cavity that is surrounded by the frontal prominences

Question 21

Subdivisions of the cranium

Answer 21

Neurocranium: Surrounds the brain Viscerocranium: Bones result of pharyngeal arch development

Question 22

Thyroglossal cysts

Answer 22

Cystic remnant of the thyroglossal duct that can lie at any point along the migratory pathway of the thyroid. If it is open to the outside byt he canal it forms a thyroglossal fistula

Question 23

Tissue origin of the thyroid gland

Answer 23

epithelial (endoderm) ==> NOT FROM POUCHES

Question 24

Viscerocranium

Answer 24

Bone formation primarily membrane ossification of NC cells with some mesoderm ossification 1) Cartilaginous viscerocranium 2) Membranous viscerocranium

Question 25

What are the tissue derivations of the tongue?

Answer 25

Mesoderm (musculature) surrounded by endoderm

Question 26

What are the two cells in the thyroid that are essential for the fetus?

Answer 26

1) Follicular cells 2) C-Cells

Question 27

What factors initially controls the growth of the tongue?

Answer 27

Underlying mesoderm and neural crest cells signal the overlying endoderm to proliferate

Question 28

What genes are involved with thyroid development?

Answer 28

TTF-1, PAX, BMPs, Noggin

Question 29

What is the fate of the original swellings of the tongue?

Answer 29

Lateral swellings overgrow the tuberculum impar and merge (weeks 5-10) to form the anterior 2/3 of the tongue

Question 30

What is the origin of the musculature of the tongue

Answer 30

mesoderm derived myoblasts that migrate from the occipital somite region

Question 31

What structures give rise to the upper lip?

Answer 31

two medial nasal prominences and the two maxillary prominences (not the lateral nasal prominences)

Question 32

When do milk teeth first form?

Answer 32

Week 8

Question 33

When do secondary teeth buds begin to form

Answer 33

week 15

Question 34

When does dental lamina and dental buds begin to form?

Answer 34

Week 6-7

Question 35

When does thyroid gland begin to funciton and what does it do?

Answer 35

Week 14-15 of development: Follicular cells within thyroid begin producting Colloid (source of Thyroxine & Triiodothyronine)

Question 36

When is the definitive palate formed and from what?

Answer 36

Internal growth of two maxillary prominences known as the palatine shelves (grow towards each other at week 7)

Question 37

Which bones in the face lack neural crest cells?

Answer 37

Thyroid Cartilage Cricoid Cartilage Malleus Incus