Embryology

Question 1

Give some other names for pharyngeal arches

Answer 1

Pharyngeal apparatus

Bronchial arches

Question 2

When does the neural tube form?

Answer 2

Week 3

Question 3

By which time has the embryo folded?

Answer 3

End of week 4

Question 4

What tissues forms the core of the pharyngeal arches?

Answer 4

Mesoderm

Question 5

What are the pharyngeal pouches?

Answer 5

Inner pocketings of primitive gut tube

Endoderm lined

Question 6

What do the pharyngeal pouches develop into?

Answer 6

Middle ear

Parathyroids, thymus and palatine tonsils

Question 7

Where do the parts of the pharynx run from and to?

Answer 7

Nasal = base of skull to soft palate 
Oral = soft palate to larynx 
Laryngeal = posterior to larynx to inferior border of cricoid cartilage

Question 8

How many pharyngeal arches are there?

Answer 8

5 in total

1, 2, 3, 4 and 6

Question 9

What are pharyngeal clefts?

Answer 9

External pocketings of arches

Ectoderm lined

Question 10

What do we call the 3 vesicles of the brain?

Answer 10

Prosencephalon = forebrain
Mesencephalon = midbrain 
Rhombencephalon = hindbrain

Question 11

How many cranial nerves are there?

Answer 11

12 pairs

Question 12

Which cranial nerves innervate the pharyngeal arches?

Answer 12

V, VII, IX and X

Question 13

What is the face derived from?

Answer 13

The frontonasal prominence and the 1st pharyngeal arch

Question 14

Which arch gives us the muscles of mastication?

Answer 14

Pharyngeal arch 1

Question 15

Which nerve innervate pharyngeal arch 1?

Answer 15

Trigeminal nerve

Question 16

Which arch gives us the muscles of facial expression?

Answer 16

Arch 2

Question 17

Which nerve innervates pharyngeal arch 2?

Answer 17

Facial nerve

Question 18

What are the muscle derivatives of the 3rd arch?

Answer 18

Stylopharyngeus

Question 19

What are the muscle derivatives of the 4th arch?

Answer 19

Cricothyroid
Levator palatini
Constrictors of pharynx

Question 20

What are the muscle derivatives of 6th arch?

Answer 20

Intrinsic muscles of larynx

Question 21

What is the principle sensory nerve of the head?

Answer 21

Trigeminal nerve (V)

Question 22

What does the facial nerve pass through into the face?

Answer 22

Stylomastoid foramen

Parotid gland

Question 23

What is the stylopharyngeus muscle?

Answer 23

Between styloid process and pharynx
Elevates the larynx and pharynx
Dilates the pharynx to permit passage of large food bolus

Question 24

What nerve innervates the third arch?

Answer 24

Glossopharyngeal nerve (IX)

Question 25

Which arch does the vagus nerve innervate?

Answer 25

4th and 6th

Question 26

Where do the different cartilages come from?

Answer 26

Meckel's = 1st arch Reichert's = 2nd arch Cartilage of larynx = 4th and 6th arches

Question 27

What does Meckel's cartilage develop into?

Answer 27

Provides template for mandible | Malleus and incus

Question 28

What does Reichert's cartilage develop into?

Answer 28

Stapes Styloid process Hyoid bone

Question 29

What cartilages come from the 4th and 6th arches?

Answer 29

Thyroid Arytenoid Cricoid

Question 30

What is the artery of the 3rd arch?

Answer 30

Internal carotid artery

Question 31

What are the arteries of the 4th arch?

Answer 31

Arch of aorta and brachiocephalic

Question 32

What are the arteries of the 6th arch?

Answer 32

Pulmonary arch

Question 33

What does the 2nd pouch develop into?

Answer 33

Palatine tonsils

Question 34

What do the 3rd and 4th pouches develop into?

Answer 34

3rd and 4th dorsal = parathyroids | 3rd ventral = thymus gland

Question 35

What does the 1st pouch develop it?

Answer 35

Primitive tympanic cavity

Question 36

What does the 1st cleft develop into?

Answer 36

External auditory meatus

Question 37

Where does the Eustachian tube run from and to?

Answer 37

Middle ear to nasopharynx

Question 38

What are the major features of the face?

Answer 38

Palpebral fissures Oral fissure Nares Philtrum

Question 39

What is a philtrum?

Answer 39

Groove on the upper lip

Question 40

The facial skeleton is derived from which cells?

Answer 40

Neural crest cells of 1st pharyngeal arch

Question 41

The muscles of mastication are derived from which cells?

Answer 41

Mesoderm of 1st pharyngeal arch

Question 42

What is the nerve of the 1st pharyngeal arch?

Answer 42

Trigeminal (V)

Question 43

What is the nerve of the 2nd pharyngeal arch?

Answer 43

Facial (VII)

Question 44

Which cells are the muscles of facial expression derived from?

Answer 44

Mesoderm of 2nd pharyngeal arch

Question 45

What are nasal placodes?

Answer 45

Dents in the frontonasal prominence (FNP) where the organ of special sense (olfaction) will develop

Question 46

What is the stomatodeum?

Answer 46

Small depression in head with buccopharyngeal membrane in centre Avascular membrane that ruptures to form the oral fissure

Question 47

What are the names of the 2 parts of the 1st pharyngeal arch?

Answer 47

Maxillary prominence | Mandibular prominence

Question 48

Which features have their origin from the FNP?

Answer 48

Forehead Bridge of nose Nose Philtrum

Question 49

Which facial features have their origin from maxillary prominence of 1 pharyngeal arch?

Answer 49

Cheeks Lateral part upper lip Lateral upper jaw

Question 50

What facial features have origin of mandibular prominence of 1st pharyngeal arch?

Answer 50

Lower lip | Lower jaw

Question 51

Where do medial and lateral nasal prominences form?

Answer 51

Either side of nasal placodes | 2 medial, 2 lateral

Question 52

Describe the development of the nasal prominences

Answer 52

Maxillary prominences grow medially pushing nasal prominences closer together Medial nasal prominences fuse with each other Medial nasal prominences fuse with maxillary prominences Creates the intermaxillary segment

Question 53

What compromises the intermaxillary segment?

Answer 53

Philtrum 4 incisors of upper jaw Primary palate

Question 54

What is the secondary palate derived from?

Answer 54

Palatal shelves | These derived from maxillary prominences

Question 55

What is the oronasal membrane?

Answer 55

CT that ruptures to give a connection between the nasal and oral cavity

Question 56

What does the nasal septum fuse with?

Answer 56

Secondary palate

Question 57

How does a lateral cleft lip occur?

Answer 57

Failure of fusion of medial nasal prominence and maxillary prominence

Question 58

How does a cleft lip and palate occur?

Answer 58

Failure of fusion of medial nasal prominence and maxillary prominence And failure of palatal shelves to meet in midline

Question 59

Eyes begin development in which week?

Answer 59

4

Question 60

How does the eye develop?

Answer 60

Optic vesicles grows to surface Makes contact with lens placode Placode invaginates to create a vesicle Forebrain forms the retina

Question 61

How do the eyes move from lateral to frontal?

Answer 61

As the facial prominence grows

Question 62

What is binocular vision?

Answer 62

Vision using 2 eyes | With overlapping fields of vision allowing good depth perception

Question 63

The external auditory meatus is derived from ...

Answer 63

1st pharyngeal cleft

Question 64

Where do ears initially develop?

Answer 64

Inferior to mandible in the neck | As mandible grows the ears move up

Question 65

Which placode leads to hearing and balance?

Answer 65

Otic placode

Question 66

What features might be seen in a child with foetal alcohol syndrome?

Answer 66

``` Smaller head (impaired brain development) Lower nasal bridge Smaller eye openings Flat midface Short nose Thin upper lip ```

Question 67

What parts of development are most sensitive to alcohol?

Answer 67

Neural crest migration | Brain development

Question 68

What is ARND?

Answer 68

Alcohol related neurodevelopmental disorder | Milder version of FAS - less alcohol consumed during the pregnancy

Question 69

What is the prevalence of FAS and ARND combined?

Answer 69

1 in 100 births