Development Flashcards Preview

ENT Advanced > Development > Flashcards

Flashcards in Development Deck (46):
1

In which week does the neural tube form?

3

2

Where are the oropharyngeal, nasal and the laryngeal parts of the pharynx?

Nasal - superior to soft palate Oropharynx - soft palate to larynx Laryngeal pharynx - posterior to larynx

3

What are the pharyngeal arches?

System of mesenchymal proliferations in the neck region of the embryo

4

How many arches are there in total and how are they numbered?

5 1, 2, 3, 4, 6

5

What is each arch associated with?

A nerve, artery and cartilage bar

6

What does the mesoderm of the pharyngeal arches give rise to?

Muscle, cartilaginous structures, CVS components

7

What does the ectoderm of the pharyngeal arch give rise to?

Epidermis of skin

8

How does the neural tube form?

Notochord signals overlying ectoderm to thicken to give a slipper shaped neural plate Edges elevate out of the plane of the disk and curl towards each other creating the neural tube

9

Which part of the neural tube forms the brain and what three sections can it be divided into?

The anterior part

Prosencephalon - forebrain

Mesencephalon - midbrain

Rhombencephalon- hindbrain

10

Where are most of the cranial nerves derived from and which are the exceptions?

Mid or hind brain I and II

11

What groups can the cranial nerves be classified into?

Somatic efferent

Special sensory

Nerves of pharyngeal arches

12

Which cranial nerves have mixed sensory and motor functions and supply the derivatives of the pharyngeal arches?

V - trigeminal 

VII - facial

X - vagus

13

Which cranial nerves have a relationship with the pharyngeal arch system?

Accessory (XI) Hypoglossal (XII)

14

What is the facial skeleton derived from?

The frontonasal prominence

First pharyngeal arch

15

Which pharyngeal arch are the muscles of facial expression derived from and therefore which nerve are they innervated by?

2

Facial nerve

16

Which pharyngeal arch are the muscles of mastication derived from and therefore which cranial nerve are they innervated by?

1 Trigeminal nerve (V) branch - the mandibular nerve

17

Which muscles does the third pharyngeal arch give rise to?

Stylopharyngeus

18

Which muscles does the 4th pharyngeal arch give rise to?

Cricothyroid Levator palatini Constrictors of the pharynx

19

Which muscles does the sixth pharyngeal arch give rise to?

Intrinsic muscles of the larynx

20

Which is the nerve of the first pharyngeal arch?

Trigeminal nerve (V)

21

Function of the trigeminal nerve?

Mixed

Principal sensory nerve of the head - skin and inside of mouth and nose

Motor: muscles of mastication, muscles derived from mandibular process

22

Which is the nerve of the second pharyngeal arch?

Facial (VII)

23

Function of the facial nerve?

Mixed Motor - muscles of facial expression and muscles from second pharyngeal arch Sensory - anterior two thirds of the tongue

24

Nerve of the third pharyngeal arch?

Glossopharyngeal (IX)

25

Function of the glossopharyngeal nerve?

Stylopharyngeus muscle

Sensory - posterior third of the tongue

26

Nerve of the fourth and sixth pharyngeal arches?

Vagus nerve (X) -4th arch branch is the superior laryngeal nerve -6th arch branch is the recurrent laryngeal nerve

27

What are the neural crest-derived cartilage bars of each of the pharyngeal arches?

1 = Meckel's

2 = Reichert's

4+6 = cartilages of the larynx

28

What can the first pharyngeal arch be divided into?

Maxillary and mandibular prominences

 

29

What does Meckel's cartilage go onto form?

Malleus and incus of the ear

Template for mandible which forms by membranous ossification

30

What does Reichert's cartilage go onto form?

Stapes in middle ear

Styloid process

Hyoid bone (part of it)

31

What does the cartilage of the third pharyngeal arch form?

Remainder of the hyoid bone

32

What do the cartilages of the 4th and 6th pharyngeal arches go onto form?

Epiglottis Thyroid, arytenoid, cricoid cartilages

33

Which artery is derived from each of the aortic arches?

1st and 2nd arch arteries disappear

3rd - internal carotid

4th - arch of aorta (L) and brachiocephalic trunk (R)

6th - pulmonary arch

34

Where do the aortic arches come from?

The aortic sac which lies in the floor of the pharynx

35

How many pharyngeal pouches are there?

4 pairs

36

Which part of the pharyngeal pouches give rise to organs?

The epithelial endodermal lining

37

What does pouch 1 give rise to?

Middle ear cavity

Eustachian tube

Lining of tympanic cavity

Tympanic membrane (ear drum)

38

What does pouch 2 give rise to?

Palatine tonsils Invaded by lymphoid tissue in third and fifth months

39

What does pouch three give rise to?

Inferior parathyroid

Thymus

40

What does pouch four give rise to?

Superior parathyroid

41

Which pouch is the parathyroid gland derived from?

3rd and 4th

42

How many pharyngeal clefts are there?

4, but only one contributes to a definitive structure

43

What is formed from the pharyngeal clefts? How?

External auditory meatus and part of the eardrum Dorsal part of the first cleft penetrates underlying mesenchyme and becomes the above

44

How are the clefts obliterated?

Second pharyngeal ARCH proliferates and covers third and fourth arches.

Merges with the epicardial ridge in the lower part of the neck.

Obliterates the other clefts

45

What can happen if the clefts are not obliterated?

Can have cysts or fistulae anywhere along the anterior border of the SCM

46

Where does the pharynx extend from and to?

Base of skull to inferior border of cricoid cartilage of the larynx