(E1) 1 - Head and Neck Development

Question 1

What are the superior and inferior borders of the head?

Answer 1

Superior most aspect of the skull (vertex) and the inferior border of the mandible.

Question 2

Components of the head anatomy

Answer 2

• cranial cavity
• ears
• orbit
• nasal cavity
• oral cavity
• nasopharynx
• oropharynx
• face and scalp

Question 3

Define the borders of the necks anatomy

Answer 3

Base of the skull and inferior border of the mandible to the superior thoracic aperture

Question 4

What are the internal structures of the neck?

Answer 4

Pharynx and larynx

Question 5

What is neuroectoderm derived from?

Answer 5

Neural tube and neural crest

Question 6

Where does the head and neck develop from?

Answer 6

Neural tube and neural crest cells drive the development

Question 7

What happens in development during the late 4th week?

Answer 7

The head and tail fold onto itself

Question 8

During what weeks does head and neck development take place

Answer 8

Weeks 4-8 (goal is to enlarge and then move structures towards the midline)

Question 9

What two things are the face and neck derived from?

Answer 9

Pharyngeal arches and frontonasal prominence (swelling)

Question 10

What does the frontonasal prominence give rise to?

Answer 10

Forehead and nose (nasal cavity, septum, primary palate and philtrum)

Question 11

What are the pharyngeal arches?

Answer 11

Six bilaterally paired arches that give rise to part of the face, oral cavity, pharynx, and neck

Question 12

What is the purpose of the pharyngeal arches?

Answer 12

Provides a structural scaffold for the face, palate, and anterior neck

Question 13

What does PA 1 split and give rise to?

Answer 13

Mandibular and maxillary prominences

Question 14

What does PA 2-6 give rise to?

Answer 14

Pharynx, larynx, and neck

Question 15

What do the pharyngeal arches support?

Answer 15

The lateral walls of the early pharynx

Question 16

What does Ectoderm give rise to?

Answer 16

Epithelium of the external face and neck, mucosa of part of the oral cavity

Question 17

In the ectoderm layer, what separates adjacent arches externally?

Answer 17

Pharyngeal grooves (clefts)

Question 18

Which germ layer is the central core of mesenchyme?

Answer 18

Mesoderm

Question 19

What is Mesoderm composed of?

Answer 19

Head mesoderm and ectomesenchyme (differentiated neural crest cells that migrate into head mesoderm)

Question 20

Which germ layer is the mucosal lining of the pharynx?

Answer 20

Endoderm

Question 21

Endoderm is the internal lining of all pharyngeal arches except which?

Answer 21

PA1

Question 22

What separates adjacent arches internally?

Answer 22

Pharyngeal pouches

Question 23

What does each pharyngeal arch contain?

Answer 23

• epithelial component
• an artery
• cartilage rod
• muscle
• sensory and motor nerves (neural tube and neural crest cells)

Question 24

What is the critical period for congenital defects?

Answer 24

4-8 weeks

Question 25

What does the frontonasal prominence give rise to?

Answer 25

Forehead, nose, nasal septum, philtrum, premaxilla of the upper jaw (4 incisors)

Question 26

What is the ROSTRAL boundary of the stomodeum?

Answer 26

Frontonasal prominence

Question 27

What is the LATERAL boundary of the stomodeum?

Answer 27

Bilateral maxillary prominence PA1

Question 28

What does the bilateral maxillary prominence give rise to?

Answer 28

Upper jaw, upper lip, cheek and palate (hard and soft)

Question 29

What is the CAUDAL boundary of the stomodeum?

Answer 29

Bilateral mandibular prominence PA1

Question 30

What does the bilateral mandibular prominence give rise to?

Answer 30

Lower jaw, lower lip and cheek

Question 31

What appears as a slight depression of surface ectoderm?

Answer 31

Stomodeum

Question 32

What germ layers make up the oropharyngeal membrane?

Answer 32

Surface ectoderm and endoderm

Question 33

What does the oropharyngeal membrane separate?

Answer 33

Each oral cavity (ectoderm) from the pharynx (endoderm)

Question 34

What happens to the oropharyngeal membrane around the 4th week?

Answer 34

Begins to degenerate creating an open connection between the oral cavity and the pharynx.

Question 35

What is the adult derivative demarcating the location of the oropharyngeal membrane?

Answer 35

Palatoglossal arch (fold)

Question 36

What is the palatoglossal arch?

Answer 36

Adult boundary between oral cavity and oropharynx

Question 37

Which germ layer forms the oral mucosa of oral cavity? (except floor of oral cavity)

Answer 37

Ectoderm

Question 38

What germ layer forms the mucosa lining pharynx and floor of the oral cavity?

Answer 38

Endoderm

Question 39

What is the muscular tube that extends from the base of the skull to C6?

Answer 39

Adult pharynx

Question 40

Describe the location of the nasopharynx

Answer 40

Posterior to the nasal cavity and superior to the soft palate

Question 41

Describe the location of the oropharynx.

Answer 41

Posterior to palatoglossal fold and between soft palate and epiglottis

Question 42

Describe the location of the laryngopharynx

Answer 42

Between epiglottis and inferior border of the cricoid cartilage

Question 43

What pharyngeal arches give rise to the adult pharynx?

Answer 43

PA 2-4 and 6

Question 44

Where is the early pharynx derived from?

Answer 44

The foregut

Question 45

What are pharyngeal pouches?

Answer 45

Separate PA internally, endoderm lined outpouchings (evaginations)

Question 46

What are pharyngeal grooves?

Answer 46

Separate PA externally

Question 47

What do pharyngeal pouches give rise to?

Answer 47

- Pharyngotympanic tube - palatine tonsils - parathyroid glands - thymus - parafollicular cells of thyroid gland

Question 48

What does the PA 1 groove do and give rise to?

Answer 48

Invaginates (ECTOderm derived) and external auditory meatus

Question 49

What do PA grooves 2-4 give rise to?

Answer 49

Overgrow each other and give rise to the smooth external appearance of the neck.

Question 50

What does PA1 - Meckel cartilage give rise to?

Answer 50

- Two auditory ossicles - provides template for lower jaw

Question 51

Is head mesoderm part of Meckel cartilage?

Answer 51

No - it provides the template for upper jaw

Question 52

What does PA2 - Reichert cartilage give rise to?

Answer 52

Auditory ossicle, styloid process and lesser cornu of hyoid bone

Question 53

What does PA3 - Arch cartilage give rise to?

Answer 53

Body and greater cornu of hyoid bone

Question 54

What does PA 4 and 6- Arch cartilage give rise to?

Answer 54

Thyroid and cricoid cartilages

Question 55

Where are muscular components derived from?

Answer 55

Head mesoderm

Question 56

PA1 gives rise to muscles of ...

Answer 56

mastication

Question 57

PA2 gives rise to muscles of ...

Answer 57

facial expression

Question 58

PA3 gives rise to muscles of ...

Answer 58

stylopharyngeus

Question 59

PA 4 and 6 gives rise to muscles of ...

Answer 59

pharyngeal constrictors and laryngeal musculature

Question 60

Where are cranial nerves derived from?

Answer 60

Neuroectoderm (tube and crest cells)

Question 61

What nerve supplies PA1?

Answer 61

Trigeminal CN V (5)

Question 62

What nerve supplies PA2?

Answer 62

Facial CN VII (7)

Question 63

What nerve supplies PA3?

Answer 63

Glossopharyngeal CN IX (9)

Question 64

What nerve supplies PA 4 and 6?

Answer 64

Vagus CN X (10)

Question 65

What cranial nerves carry taste and parasympathetics?

Answer 65

7, 9, and 10

Question 66

What are the outcomes of signaling events?

Answer 66

- migration - proliferation - differentiation - viability - fusion

Question 67

Describe the process of a signaling event in order

Answer 67

1. inductive cells (inducers) release a signal or ligand 2. ligand binds to a receptor on a competent cell 3. ligand-receptor interaction triggers and intracellular signal transduction pathway that activates or represses gene transcription

Question 68

Disruption during 0-4 weeks of embryonic development leads to what? - early embryonic period

Answer 68

Spontaneous abortion

Question 69

Disruption during 4-8 weeks of embryonic development leads to what? - late embryonic period

Answer 69

Critical period of orofacial, primary and secondary tooth defects