Embryology

Question 1

What are the three components of the pharyngeal apparatus

Answer 1

• Core pharyngeal arch (mesenchymal tissue)
• External pharyngeal cleft (ectoderm tissue)
• Internal pharyngeal pouch (endoderm tissue)

Clefs (external) and pouches (internal) line & separate arches

Question 2

Core pharyngeal arch (__________ tissue)

Answer 2

Mesenchymal

Question 3

External pharyngeal cleft (________ tissue)

Answer 3

Ectoderm

Question 4

Internal pharyngeal pouch (_________ tissue)

Answer 4

Endoderm

Question 5

Where does the pharyngeal arches develop from

Answer 5

Pharyngeal arches develop in the vertebrates

Question 6

When do the pharyngeal arches develop

Answer 6

Week 4 & 6

Question 7

How many pharyngeal arches are there

Answer 7

5 arches - 6 arches develop but number 5 ‘disappears’
So there is arch 1, 2, 3, 4 & 6

Question 8

What are the four components of the pharyngeal arches

Answer 8

(Skeletal) musculature
Connective tissue & smooth muscles
Cranial nerves
Arteries (branch of aortic arch

Question 9

Where do the skeletal muscles of the pharyngeal arch originate from

Answer 9

paraxial and lateral plate mesoderm

Question 10

Where do the smooth muscles & connective tissue of the pharyngeal arch originate from

Answer 10

Neural crest cells

Question 11

What innervates the 1st arch

Question 12

What bones are formed from the 1st arch

Question 13

What innervates the 2nd arch

Question 14

What bones are formed from the 2nd arch

Question 15

What muscles are formed from the 2nd arch

Question 16

What innervates the 3rd arch

Question 17

What bones are formed from the 3rd arch

Question 18

What muscles are formed from the 3rd arch

Question 19

What innervates the 4th arch

Question 20

What bones are formed from the 4th arch

Question 21

What muscles are formed from the 4th arch

Question 22

What innervates the 6th arch

Question 23

What bones are formed from the 6th arch

Question 24

What muscles are formed from the 6th arch

Question 25

What do the 2nd-4th clefts form

Answer 25

the cervical sinus (usually obliterates)

Question 26

What is the clinical relevance of the cervical sinus

Question 27

What does the 1st pouch form

Question 28

What does the 2nd pouch form

Question 29

What does the 3rd pouch form

Question 30

What does the 4th pouch form

Question 31

At what week does the tongue usually develop

Answer 31

4th week

Question 32

The tongue forms from two ________ swellings & one _________ swelling. The lateral swelling occurs from the ___ arch and forms the ________________________. The midline swelling forms from the ___ & ___ arch and forms the ____________ & __________.

Answer 32

The tongue forms from two lateral swellings & one midline swelling. The lateral swellings occur from the 1st arch and form the anterior 2/3rd of the tongue. The midline swelling forms from the 3rd & 4th arches and forms the posterior 1/3rd of the tongue (the copula) and epiglottis.

Question 33

What pharyngeal arch forms the anterior 2/3rds of the tongue & so what innervates it

Answer 33

1st arch - CN V3 (except for special sensory that it gets from chorda tympani)

Question 34

What pharyngeal arch(s) forms the posterior 1/3rd of the tongue & so what innervates it

Answer 34

3rd & 4th - CN IX

Question 35

Where do the tongue muscles originate from & so what innervates it

Answer 35

Occipital somites - Hypoglossal nerve (CN XII)

Question 36

What is the copula

Question 37

At what time in embryological development does the facial prominences appear

Answer 37

Week 4 & 5

Question 38

What are the 5 facial prominences

Answer 38

•Frontonasal prominence •PAIRED maxillary prominences •PAIRED mandibular prominences

Question 39

The nasal placode is part of the __________________. It is a thickened area of __________ that folds in on itself to ultimately form the _____________

Answer 39

The nasal placode is part of the frontonasal prominence. It is a thickened area of ectoderm that folds in on itself to ultimately form the nasal cavity

Question 40

The invagination of the nasal placode forms 4 swellings called the __________________________________.

Answer 40

The invagination of the nasal placode forms swellings called the (paired) medial & lateral nasal prominence.

Question 41

The medial nasal prominence forms the __________________________, _______________, ___________________ & ___________________

Answer 41

The medial nasal prominence forms the… - tip & crest of the nose, - nasal septum, - philtrum of the upper lipid, - primary palate

Question 42

The lateral nasal prominence forms the……….

Answer 42

Sides of the nose called the nasal alae

Question 43

What structures does the maxillary prominences form

Question 44

What structures does the mandibular prominences form

Question 45

What prominences make up the nose

Answer 45

Nasal bridge - frontonasal prominence Nasal septum - medial nasal prominences Nasal crest & tip - medial nasal prominences Nasal alae - lateral nasal prominences

Question 46

What prominences make the lip

Answer 46

Upper lip - maxillary & medial nasal prominences Lower lip - mandibular prominences

Question 47

What prominences make up the palate

Answer 47

Maxillary segment (majority) - Maxillary prominences Intermaxillary segment (anterior) - Medial nasal prominences

Question 48

What is the nasolacrimal groove

Question 49

What are the three portions in the palate

Answer 49

Labial (anterior), upper dentition, palate (posterior) portion

Question 50

What part of the palate fails to fuse in a unilateral palate defect extending into the nose

Question 51

What part of the palate fails to fuse in a unilateral palate defect Involving the lip & nose

Question 52

What part of the palate fails to fuse in a bilateral palate defect involving the cleft & nose

Question 53

What part of the palate fails to fuse in an isolated cleft palate defect

Question 54

What part of the palate fails to fuse in a cleft palate combined with unilateral anterior cleft lip defect

Question 55

What membrane breaks down the week 6 to allow communication between the oral cavity & nasal pit

Answer 55

Oronasal membrane

Question 56

Nasal cavity development

Answer 56

1) nasal placode => 2) forms nasal pit => 3) breakdown of oronasal membrane => 4) forms primitive choana (connection with oral cavity) => 5) forms definitive choana

Question 57

Palate development summary

Answer 57

palatine shelves of the maxillary prominence grow downwards then elevate before fusing with each other they then fuse anteriorly with the primary palate of the medial nasal prominence