Embryology

Question 1

Which germ layer gives rise to the musculature of the face and neck?

Answer 1

Mesoderm

Question 2

During which weeks do the pharyngeal arches develop?

Answer 2

Week 4-5

Question 3

What does each pharyngeal arch consist of?

Answer 3

Core of mesenchyme assoc. with pharyngeal clefts + pouches
Neural crest cells
Cranial nerve
Artery

Question 4

The pharyngeal clefts externally/internally separate the pharyngeal arches (form ectoderm/endoderm lining)

Answer 4

The pharyngeal clefts externally separate the pharyngeal pouches (form ectoderm lining)

Question 5

The pharyngeal pouches externally/internally separate the pharyngeal arches (form ectoderm/endoderm lining)

Answer 5

The pharyngeal pouches internally separate the pharyngeal arches (form endoderm lining)

Question 6

There are 5 pharyngeal arches. The 5th pharyngeal arch does not develop in humans. True/False?

Answer 6

True
Arch 1, 2, 3, 4 and 6 exist only
(that’s how fcked up embryology is)

Question 7

Which cranial nerve is assoc. with pharyngeal arch 1?

Answer 7

CN V

Question 8

Which cranial nerve is assoc. with pharyngeal arch 2?

Answer 8

CN VII

Question 9

Which cranial nerve is assoc. with pharyngeal arch 3?

Answer 9

CN IX

Question 10

Which cranial nerve is assoc. with pharyngeal arch 4?

Answer 10

CN X (superior laryngeal branch)

Question 11

Which cranial nerve is assoc. with pharyngeal arch 6?

Answer 11

CN X (recurrent laryngeal branch)

Question 12

What skeletal components are assoc. with pharyngeal arch 1?

Answer 12

Maxillary: maxilla, zygoma, temporal bone
Mandibulary: mandible, Meckel’s cartilage, incus, malleus

Question 13

What skeletal components are assoc. with pharyngeal arch 2?

Answer 13

Stapes
Styloid process of temporal bone
Stylohyoid ligament
Lesser horn + upper hyoid

Question 14

What skeletal components are assoc. with pharyngeal arch 3?

Answer 14

Greater horn + lower hyoid

Question 15

What skeletal components are assoc. with pharyngeal arches 4 + 6?

Answer 15

Laryngeal cartilages

Question 16

What muscles are assoc. with pharyngeal arch 1?

Answer 16

Muscles of mastication
Mylohyoid
Tensor tympani
Tensor palatini

Question 17

What muscles are assoc. with pharyngeal arch 2?

Answer 17

Muscles of facial expression
Stapedius
Stylohyoid

Question 18

What muscles are assoc. with pharyngeal arch 3?

Answer 18

Stylopharyngeus

Question 19

What muscles are assoc. with pharyngeal arch 4?

Answer 19

Cricothyroid
Levator palatine
Pharyngeal constrictors

Question 20

What muscles are assoc. with pharyngeal arch 6?

Answer 20

Intrinsic laryngeal muscles

Question 21

Which pharyngeal cleft does the external auditory meatus develop from?

Answer 21

Cleft 1

Question 22

What happens to the 2nd-4th pharyngeal clefts?

Answer 22

Usually disappear; lose contact and form cervical sinus

Question 23

What does the 1st pharyngeal pouch develop into?

Answer 23

Middle ear cavity
Eustachian tube
(ultimately tympanic membrane)

Question 24

What does the 2nd pharyngeal pouch develop into?

Answer 24

Palatine tonsil

Question 25

What does the 3rd pharyngeal pouch develop into?

Answer 25

Inferior parathyroid gland | Thymus

Question 26

What does the 4th pharyngeal pouch develop into?

Answer 26

Superior parathyroid gland | Ultimobranchial body

Question 27

What are otic placodes?

Answer 27

Thickening/invagination of ectoderm at back of embryo

Question 28

What are otic vesicles?

Answer 28

Endocytosed otic placode that gives rise to inner ear | i.e. otic placode - otic pit - otic vesicle

Question 29

What 3 regions develop as part of the otic vesicle?

Answer 29

``` Endolymphatic duct sac Utricular portion (forms semicircular canals) Saccular portion (forms cochlea) ```

Question 30

List the 5 facial swellings present from week 4

Answer 30

Frontonasal prominence 2x maxillary prominences 2x mandibular prominences

Question 31

What is the stomodeum?

Answer 31

Site of the future mouth

Question 32

List the nasal swellings that develop on the frontonasal prominence in week 5

Answer 32

2x medial nasal swellings | 2x lateral nasal swellings

Question 33

What grows in the groove between the eye and the lateral nasal swelling?

Answer 33

Nasolacrimal duct

Question 34

What nasal features develop from the frontonasal prominence?

Answer 34

Bridge | Bony septum

Question 35

What nasal features develop from the medial nasal prominences?

Answer 35

Crest + tip of nose

Question 36

What nasal features develop from the lateral nasal prominences?

Answer 36

Alae (sides of nostrils)

Question 37

What does the primary palate form from?

Answer 37

Intermaxillary segment (formed by fusion of 2 medial nasal prominences)

Question 38

What does the labial portion of the intermaxillary segment give rise to?

Answer 38

Philtrum of upper lip

Question 39

What does the upper jaw component of the intermaxillary segment give rise to?

Answer 39

Carries 4 incisors

Question 40

What does the secondary palate form from?

Answer 40

Palatine shelves that grow downwards from maxillary prominences

Question 41

Is cleft palate more common in females or males?

Answer 41

Females | Failure of fusion of secondary palate

Question 42

Is cleft lip more common in females or males?

Answer 42

Males | Failure of fusion of primary palate