10-31 L1 Development of pharyngeal arches

Question 1

craniosynostosis

Answer 1

due to premature closure of the sutures

(scaphocephaly, brachycephaly, trigoncephaly)

Question 2

In the pharyngeal arches the mesoderm is derived from what?

Answer 2

somites, somitomers and neural crest cells

Question 3

Name the structures that are derived from the first pharyngeal arch.

Answer 3

• maxillary swelling
• mandibular swelling
• malleus
• Incus

Question 4

NAme the structures that are derived from the second pharyngeal arch (reichert’s cartilage). (4-LSSS)

Answer 4

• Stapes
• Styloid process
• Stylohyoid ligament
• Lesser cornus of hyoid

Question 5

Name the strucutres that are derived from the third pharyngeal arch (2)

Answer 5

• greater cornu of hyoid
• body of hyoid

Question 6

Name the structures that are derived from the 4th and 6th pharngeal arches

Answer 6

• Thyroid cartilage
• Cricoid cartilage

Question 7

The stylopharyngeus m is dervied from what?

Answer 7

3rd arch

Question 8

ID the nerve innervation and muscles derivatives of the pharyngeal arches.

Answer 8

• 1st: Trigeminal, muscles of mastication
• 2nd: Facial, muscles of facial expression
• 3rd: Glossopharyngeal, stylopharyngeus m
• 4th (superior laryngeal): Vagus, muscles of pharynx
• 6th (Recuurent laryngeal): Vagus, muscles of larynx

Question 9

First arch syndromes

Answer 9

Underdevelopment of 1st arch derivatives (include Treacher Collins syndrome)

Question 10

Name the sensory innervation of mucosa

Answer 10

• CNV: anterior 2/3 of the tongue (GSA)
• CN IX: posterior 1/3 (GVA)
• CN X: supplies epiglottis (GVA)

Question 11

Name the taste innervation of the tongue

Answer 11

• Facial n (CN VII): supplies anterior 2/3
• Glossopharyngeal n (CN IX) posterior 1/3
• Vagus n (CN X): area over epilgottis

Question 12

Name the derivatives of the pharyngeal pouches

(composed of endoderm and surrounding meschenchyme (neural crest cells))

Answer 12

• 1st: middle ear
• 2nd: palatine tonsil
• 3rd: thymus and inferior parathyroid gland
• 4th: superior parathyroid gland, ultimobranchial body (neural crest) forms C cells of the thyroid gland

Question 13

thyroid gland is derived from what?

what does the trailing tissue form?

Answer 13

foramen ceucm

thryoglossal duct

Question 14

Thyroglossal cyst

Answer 14

cysts are remnants of thyroglossal duct

Question 15

The nasolacrimal duct develops from what?

Answer 15

develops as groove of ectoderm that pinches off from surface

becomes embedded in mesenchyme

Question 16

how do facial clefts occur?

Answer 16

when there is an incorrect fusion of facial eminecnes

Question 17

holoprosencephaly

what disease is associated with it?

Answer 17

a syndrome resulting from improper developemnt of the froebrain, causes facial anomalis

• fetal alcohol syndrome

Question 18

cleft palate

Answer 18

failure of fusion of palatal shelves

can be in hard or soft palate or both

cad be minor (muscles or tissue) or severe (bone)

Question 19

Pierre Robin syndrome (Robin sequence)

Answer 19

• micrognathia–>glossoptisis–>cleft palate
• micrognathia= underdeveloped mandible
• glossoptisis=tongue blocks the way of palate
• cleft palate results

Question 20

Isotretinoin (accutane) causes what?

Answer 20

vitamin A derivates such as isotretinoin (Accutane) causes severe birth defects

Question 21

Parotid gland and duct are derived from what

submandbiular and sublingual glands derived from what

Answer 21

• Parotid gland and duct= ectoderm
• submandibular & sublingual glands= endoderm (derived from invaginations of oral cavity)