16. Pharyngeal Arches

Question 1

What week of development do the pharyngeal arches develop in?

Answer 1

4th/5th

Question 2

What germ layer is found in the clefts?

Answer 2

Endoderm

Question 3

What germ layer is found in the pouches?

Answer 3

Ectoderm

Question 4

What is derived from the 1st pharyngeal arch?

Answer 4

Meckel’s cartilage

Malleus and incus

Question 5

What is derived from the 2nd pharyngeal arch?

Answer 5

Stapes
Styloid process
Stylohyoid ligament
Lesser horn of hyoid

Question 6

What is derived from the 3rd pharyngeal arch?

Answer 6

Greater horn of hyoid

Question 7

What is derived from the 4th pharyngeal arch?

Answer 7

Upper thyroid cartilage

Question 8

What happens to the 5th pharyngeal arch?

Answer 8

Disappears

Question 9

What is derived from the 6th pharyngeal arch?

Answer 9

Rest of the thyroid cartilage

Cricoid cartilage

Question 10

What is derived from the 1st pharyngeal cleft?

Answer 10

External acoustic meatus

Question 11

What happens if the 2nd, 3rd and 4th clefts don’t disappear?

Answer 11

Cervical cysts

Presents as lumps under the sternocleidomastoid

Question 12

What is it called if cervical cysts are open to the surface?

Answer 12

External branchial fistula

Question 13

What do internal branchial fistulas open into?

Answer 13

Bed of palatine tonsils

Question 14

What is derived from the 1st pharyngeal pouch?

Answer 14

Middle ear

Eustachian tube

Question 15

What is derived from the 2nd pharyngeal pouch?

Answer 15

Palatine tonsils

Question 16

What is derived from the 3rd pharyngeal pouch?

Answer 16

Inferior parathyroid

Thymus

Question 17

What is derived from the 4th pharyngeal pouch?

Answer 17

Superior parathyroid

Ultimobranchial body

Question 18

What does the ultimobranchial body become?

Answer 18

Parafollicular cells of the thyroid

Question 19

What are 2 defects in the 1st arch?

Answer 19

Treacher Collins

Robin Sequence

Question 20

What are the symptoms of Treacher Collins Syndrome?

Answer 20

Hypoplasia of maxilla, mandible and zygomatic arches

Associated with cleft palate and external ear defects

Question 21

What are the triad of conditions in Robin Sequence?

Answer 21

Micrognathia
Glossoptosis
Cleft palate

Question 22

What is micrognathia?

Answer 22

Poor growth of mandible

Question 23

What is glossoptosis?

Answer 23

Posteriorly placed tongue

Question 24

Name a syndrome of 3rd and 4th arch defects?

Answer 24

DiGeorge anomaly

Question 25

What are the symptoms of DiGeorge anomaly?

Answer 25

No thymus or parathyroid glands Persistant truncus arteriosus Abnormal external ear Micrognathia

Question 26

What is the innervation of the 1st arch?

Answer 26

Mandibular

Question 27

What is the innervation of the 2nd arch?

Answer 27

Facial

Question 28

What is the innervation of the 3rd arch?

Answer 28

Glossopharyngeal

Question 29

What is the innervation of the 4th to 6th arches?

Answer 29

Vagus

Question 30

What is the blood supply to the 1st arch?

Answer 30

Maxillary

Question 31

What is the blood supply to the 3rd arch?

Answer 31

Common and internal carotids

Question 32

What is the blood supply to the 4th arch?

Answer 32

Left: aortic arch Right: Subclavian

Question 33

What is the blood supply to the 6th arch?

Answer 33

Left: Ductus arteriosis and left pulmonary Right: right pulmonary

Question 34

What muscles arise from the 1st arch?

Answer 34

Muscles of mastication Mylohyoid Anterior digastric Tensor palati and tympani

Question 35

What muscles arise from the 2nd arch?

Answer 35

Muscles of facial expression Posterior digastric Stylohyoid

Question 36

Which parts of the tongue come from the 1st arch?

Answer 36

Lateral lingual swelling Medial swelling Tuberculum impar

Question 37

Which parts of the tongue come from the 2nd, 3rd and 4th arches?

Answer 37

Copula

Question 38

What does the epiglottis develop from?

Answer 38

Swelling from the 4th arch

Question 39

What is behind the swelling of the epiglottis?

Answer 39

Laryngeal orifice | Arytenoid swellings

Question 40

How is the anterior 2/3 of the tongue formed?

Answer 40

Lateral lingual swellings overgrow the tuberculum impar and merge

Question 41

What separates the anterior 2/3 of the tongue from the posterior 1/3?

Answer 41

Terminal sulcus

Question 42

Where does the thyroid develop?

Answer 42

Foramen cecum of tongue

Question 43

What fuses to form the palate?

Answer 43

Intermaxillary segment | Maxillary processes

Question 44

What are the issues with a cleft palate?

Answer 44

Food may go down the trachea | Nasal escape

Question 45

What prominences make up the face?

Answer 45

Facial, maxillary, mandibular, frontonasal and nasal

Question 46

How is the nose formed?

Answer 46

Maxillary processes grow medially Compress the nasal prominences in the midline Fuse together

Question 47

What forms the upper lip?

Answer 47

2 medial nasal prominences | 2 maxillary prominences

Question 48

What forms the lower lip and jaw?

Answer 48

Mandibular prominences