EMB: Pharyngeal arches

Question 1

What do the pharyngeal arches contribute to?

Answer 1

Nasal cavities, mouth, larynx, pharyn + neck

(1-4 + 6)

Question 2

What are pharyngeal arches made from?

Answer 2

NC

Question 3

What is the 1st pair of arcehs?

Answer 3

Primordial jaws

Question 4

What do arches 2-4 become?

Answer 4

future head + neck regions

Question 5

What contributes NC cells to the pharyngeal arches?

Answer 5

Rhombomeres (R1-7)

Question 6

What does each arch consist of?

Answer 6

core of mesenchyme (mostly) –> dervied from NC

covered extenally by ectoderm

internally by endoderm

Question 7

When do the pharyngeal arches (NC migration) begin?

Answer 7

4th week

Question 8

1st arch =

Answer 8

maxillary + mandibular prominences

Question 9

How does the cervical sinus form in the 1st arch?

Answer 9

PA2 overgrows PA3/4

It should dissapear

Question 10

What tissues does NCC form?

Answer 10

all connective tissue (bone) + dermis + smooth muscle

Question 11

What forms muscles?

Answer 11

Paraxial myogenic mesoderm

Question 12

What forms endotheliem?

Answer 12

Angioblasts

Question 13

What does each pharyngeal arch get?

Answer 13

An artery (from truncus arteriosus)

A cartilaginous rod

A muscualr component (form head/neck muscles)

A nerve (sensory or motor)

Question 14

What cartilage is in PA1? What does this form?

Answer 14

Meckel’s cartilage

Malleus + incus

Question 15

What cartilage is in PA2? What does it form?

Answer 15

Riechert’s Cartilage

Question 16

What does Richert’s cartilage form?

Answer 16

Dorsal = stapes + styloid process of temporal bone

Ventral = lesser horn of hyloid bone

Question 17

What does the 3rd arch cartilage form?

Answer 17

Greater horn of hyoid bone

And hypopharyngeal eminence forms hyoid bone

Question 18

What arches fuse together to make the larngeal cartilages?

Answer 18

arches 4 + 6

Question 19

What are muscular components derived from?

Answer 19

Paraxial mesoderm + prechordal plate

Question 20

What muscle does the firch arch form?

Answer 20

muscles of mastication (CN V)

Question 21

What muscles do the second arch form?

Answer 21

stapedius + muscles of facial expression

(CN VII)

Question 22

The 3rd arch forms which muscle?

Answer 22

Stylopharyngeus (CN IX)

Question 23

What muscles does the 4th arch form?

Answer 23

cricothyroid, levator veli palatini + constrictors of pharynx (CN X)

Question 24

What muscles do the 6th arch form?

Answer 24

intrinsic muscles of larynx (CN X)

Question 25

Which nerve supplies the first arch?

Answer 25

Trigeminal N.

Question 26

Muscles are supplied by \_\_\_\_\_\_.

Answer 26

Special visceral efferents

Question 27

Dermis + mucous membranes of head + neck are supplied by \_\_\_\_\_\_\_.

Answer 27

Special visceral afferents

Question 28

Which nerve supplies the 2nd arch?

Answer 28

Facial N.

Question 29

Which nerve supplies the 3rd arch?

Answer 29

glossopharyngeal N.

Question 30

Which nerve supplies the 4th-6th arches?

Answer 30

Vagus N.

Question 31

What do the arteries for the arches arise from?

Answer 31

Aortic sac

Question 32

Primordial pharynx is derived from the \_\_\_\_\_\_.

Answer 32

foregut

Question 33

What forms the tympanic membrane?

Answer 33

1st pharyngeal mmbrane + intervening membrane

Question 34

What does the 1st pharyngeal pouch (internal) expand into?

Answer 34

AUDITORY STRUCTURES (EAR) The tubotympanic recess + pharyngotypanic tube + part of tympanic membrane & cavity

Question 35

What does the 2nd pharyngeal pounch gives rise to?

Answer 35

LYMPHATIC STRUCTURES (TONSILS) tonsils + lymphoid tissue

Question 36

What does the third pharyngeal pouch give rise to?

Answer 36

1. Dorsal: \*\**Inferior* parathyroid gland 2. Ventral: **thymus**

Question 37

What does the 4th pharyngeal pouch give rise to?

Answer 37

*\*\*Superior* parathyroid gland

Question 38

What pharyngeal groove (external) forms the external auditory meatus?

Answer 38

1st pair

Question 39

Which grooves give rise to the cervical sinus?

Answer 39

2-4 If cervical sinus does not dissipate it causes birth defects

Question 40

What causs cervical (branchial) cysts?

Answer 40

cervical sinus and/or 2nd groove does not degrade and remains

Question 41

What forms the thyroid gland?

Answer 41

Thyroid primordium

Question 42

How is the thyroid connected to the tongue?

Answer 42

Thyroglossal duct

Question 43

Thyroid gland development

Question 44

If the thyroglossal duct persists, what does it become?

Answer 44

Foramen cecum

Question 45

What elongates to form the ultimopharyngeal body?

Answer 45

4th pouch

Question 46

What forms the parafollicular cells of the thyroid?

Answer 46

ultimopharyngeal body

Question 47

What syndrome is this?

Answer 47

First pharyngeal arch syndrome

Question 48

What causes first pharyngeal arch syndrome?

Answer 48

Abnormal development of the components of the 1st arch Malformation of eyes, ears, madible, + palate

Question 49

What are the different types first pharyngeal arch syndorme?

Answer 49

1. Treacher-Collins Syndrome (mandibulofacial dysostosis) 2. Pierre Robin Sequence

Question 50

What is wrong in this disease: Treacher-Collins Syndrome (mandibulofacial dysostosis)?

Answer 50

AD: TCOF1 gene Ribosome problem, can't make proteins Increased apoptosis of cranial NCC

Question 51

What causes Pierre Robin Sequence?

Answer 51

Hypoplasia of mandible causes micrognatia (small mandible) --\> results in bilateral cleft palate \*purpose of NC is to form jaws\*

Question 52

What is thyroid hemiagenesis?

Answer 52

unilateral failure of formation

Question 53

What is DiGeorge Syndrome?

Answer 53

wide range of NC problems --\> wide phenotypic variablity Agenesis of thymus + parathyroid glands Hypoparathyroidism, nasal clefts, cardiac NCC problem also