Pharyngeal arches

Question 1

masseter mm (medial pterygoid, lateral pterygoid, temporalis)
Bones: maxilla and mandible

Answer 1

first pharyngeal arch - CN V2, V3

causes Pierre Robin sequence (micrognathia, glossoptosis, cleft palate, airway obstruction)

Question 2

stylopharyngeus mm - innervated by CN IX (posterior 1/3 of tongue)
Bones: greater horn of hyoid

Answer 2

third pharyngeal arch

Question 3

does not form adult structures

Answer 3

fifth pharyngeal arch

Question 4

cricothyroid mm, intrinsic mm of soft palate (eg levator veli palatini - innervated by CN X)
Bones: cricoid and thyroid cartilages

Answer 4

fourth; 6th pharyngeal arch

Question 5

mm of facial expression (buccinators, platysma, stapedius, stylohyoid, posterior belly of digastrics) - innervated by CN VII
Bones: stapes, styloid process, less horn of hyoid

Answer 5

second pharyngeal arch

Question 6

anterior 2/3 of tongue

Answer 6

first and second pharyngeal arch

Question 7

most mm of the tongue are innervated by CN XII except what?

Answer 7

Palatoglossus - innervated by CN X

Question 8

thymus

Answer 8

third pharyngeal POUCH

Question 9

22q11 (eg DiGeorge) is due to failure of which branchial pouches?

Answer 9

3rd and 4th

thymus and parathyroid not formed (T cell def and hypocalcemia respectively)

Question 10

Aortic arch derivatives: stapedial artery and hyoid artery

Answer 10

2 (S for second and stapedial)

Question 11

Aortic arch derivatives: Aortic arch, proximal part of R subclavian

Answer 11

4

Question 12

Aortic arch derivatives: pulmonary arteries and ductus arteriosus

Answer 12

6

Question 13

Aortic arch derivatives: Common carotid artery and proximal part of internal carotid

Answer 13

3 (C is 3rd letter of the alphabet)

Question 14

Aortic arch derivatives: Maxillary artery (branch of external carotid)

Answer 14

1 (maximal)

Question 15

Branchial Pouch: endoderm-lined structures of the ear

Answer 15

1

Question 16

Branchial Pouch: Superior parathyroid, parafollicular C cells of thyroid

Answer 16

4
Note: if you can’t find a parathyroid when performing a parathyroidectomy, explore near the thymus bc thymus and parathyroid are both derivatives of the 4th pharyngeal pouch

Question 17

Branchial Pouch: inferior parathyroids, thymus

Answer 17

3

Question 18

Branchial Pouch: lining of palatine tonsil

Answer 18

2

Question 19

mneumonic for branchial pouch derivatives

Answer 19

ear (1), tonsils (2), bottom (3)-to-top(4)

Question 20

Treacher Collins syndrome is due to defect in what pharyngeal arch?

Answer 20

1

Neural crest dysfunction –.> mandibular hypoplasia, facial abnormalities

Question 21

Genital embryology: What duct develops into the male internal structures

Answer 21

Mesonephric (Wolffian)

Question 22

Genital embryology: What duct develops into the female internal structures

Answer 22

Paramesonephric (Mullerian) duct

Question 23

Calcitonin-secreting cells develop in what part of the body during embryology?

Answer 23

ultimobranchial body and then migrate toward the midline into a parafollicular location in the thyroid gland.