Craniofacial Growth & Development

Question 1

Organogenesis takes place during what weeks. What is this period?

Answer 1

week 3-8
Embryonic period (development of organs)
- critical time

Question 2

Gastrulation goes from ___ layers to ___ layers. What are these layers & what develops from them?

Answer 2

2 to 3

Embryonic ectoderm, mesoderm, endoderm
All structures in body develop from these 3 layers

Question 3

Vesicles during weeks 4 & 5

Answer 3

Week 4
Prosencephalon (forebrain)
Mesencephalon (midbrain)
Rhombencephalon (hindbrain)

Week 5
Prosencephalon (forebrain) → Telencephalon & Diencephalon
Mesencephalon (midbrain) → Mesencephalon
Rhombencephalon (hindbrain) → Metencephalon & Mylencephalon

Question 4

What neurological structures develop from the telencephalon, diencephalon, mesencephalon, metencephalon, & mylencephalon?

Answer 4

Telencephalon → Cerebrum
Diencephalon → eye cup, thalamus, hypothalamus, & epithalamus
Mesencephalon → Midbrain
Metencephalon → pons & cerebellum
Myelencephalon → medulla oblongata

Question 5

Briefly describe ectoderm, mesoderm & endoderm

Answer 5

Ectoderm = think things on the outside, nervous tissue
Mesoderm = think everything in the middle, CT, bones, skeletal muscle
Endoderm = think gut

Question 6

Dentin of the teeth is ___ derived. Enamel of teeth is ___ derived

Answer 6

Neural crest
Ectoderm

Question 7

Endoderm is closely associated w/ structures in the ___

Answer 7

neck

Question 8

Some neural crests can migrate to ___ & do what? Migration is determined by?

Answer 8

to face & do mesoderm like things even though they’re ectoderm

Basal cell lamina

Question 9

Neuralation order

Answer 9

Neural groove → median hinge point (neural crests coming together) → neural tube

Question 10

What are neural crest cell derivatives?

Answer 10

Pigment cells, schwann cell, satellite cell, unipolar & multipolar neuron, chromaffin cells, parasympathetic plexus, adrenal gland, sympathetic ganglion, dorsal root ganglion

Question 11

Weeks 4-8 are characterized by ___ differentiation

Answer 11

Somite
- differentiates into structures like limbs

Question 12

Craniofacial development occurs during ___ weeks. What are the 5 facial prominences?

Answer 12

5-8 weeks
frontonasal process, maxillary process (x2), & mandibular process (x2)

Question 13

What’s a philtrum?

Answer 13

The pinching of 2 maxillary processes

Question 14

Primary palate is formed at ___ weeks. When does it fuse?

Answer 14

5.5 weeks
Fuses 5-8 weeks

Question 15

How does the secondary palate fuse? At ___ weeks the palatine shelves elevate rapidly. At 10 weeks what happens?

Answer 15

As heart grows, it pushes head up, so tongue drops down, & palates can meet & fuse
7.5 weeks
Full fusion of shelves

Question 16

First pharyngeal Arch (“mandibular arch”) nerve, cartilage, vasculature, muscles

Answer 16

nerve: Trigeminal n. (CN V)
cartilage: Meckel’s cartilage
Vasculature: Maxillary aa. & external carotid aa.
Muscle: Muscles of mastication

Question 17

Skeletal derivatives of first pharyngeal arch

Answer 17

Malleus, incus, sphenomandibular ligament, Meckel’s cartilage, tympanic ring

Question 18

Second pharyngeal Arch (“hyoid arch”) nerve, cartilage, vasculature, muscles

Answer 18

Nerve: Facial n. (CN VII)
Cartilage: Reichert’s cartilage
Vasculature: Stapedial aa. & hyoid aa.
Muscles: Muscles of facial expression

Question 19

Skeletal derivatives for second pharyngeal arch

Answer 19

Stapes, styloid process, stylohyoid ligament, lesser horn of hyoid, part of body of hyoid

Question 20

Third pharyngeal Arch nerve, cartilage, vasculature, muscles

Answer 20

Nerve: Glossopharyngeal n. (CN IX)
Cartilage: Parts of hyoid
Vasculature: Common carotid aa. & internal carotid aa.
Muscles: Stylopharyngeus mm.

Question 21

Skeletal derivatives for third pharyngeal arch

Answer 21

Greater horn of hyoid, part of body of hyoid

Question 22

Fourth pharyngeal Arch nerve, cartilage, vasculature, muscles

Answer 22

Vagus n. (CN X)
Laryngeal
Right subclavian a. & aortic arch
Pharyngeal & laryngeal muscles

Question 23

Skeletal derivatives for fourth pharyngeal arch

Answer 23

Laryngeal cartilages

Question 24

How many pharyngeal pouches are there? What are they lined with?

Answer 24

4
Lined w/ endoderm

Question 25

What does the 2nd pouch turn into?

Answer 25

2nd pouch = palatine tonsil

Question 26

What does the 1st pouch turn into?

Answer 26

1st pouch = tympanic membrane

Question 27

What do the 4th pouch turn into?

Answer 27

4th pouch = parathyroid & ultimobranchial body

Question 28

Head & neck muscles get pulled into ___ arch

Answer 28

Pharyngeal

Question 29

Tongue develops around ___ weeks

Answer 29

4

Question 30

What swells in the 1st & 2nd swelling for the tongue?

Answer 30

1st swelling: tuberculum impar swells
2nd swellings: lateral lingual swellings

Question 31

The 3rd arch, in the tongue, gives rise to

Answer 31

mucous of tongue root (posterior ⅓)

Question 32

Define foramen cecum

Answer 32

point when thyroid begins to descend
- Thyroid starts in tongue & descends to neck

Question 33

What is the 1st & 2nd muscle to develop embryologically?

Answer 33

Heart = 1st
Tongue = 2nd

Question 34

Mandible develops in association w/ ___. It develops from ___

Answer 34

Meckel’s cartilage
Develops from 2 blastemas lateral to Meckel’s cartilage

Question 35

Mandible develops from ___ at ___ weeks

Answer 35

Periosteum at ~6 weeks

Question 36

TMJ growth is affected by

Answer 36

biomechanical loading associated w/ muscle action

Question 37

What does the 3rd pouch turn into?

Answer 37

3rd pouch = parathyroids & thymus