Embryo

Question 1

pharyngeal arches: which parts are muscles, arteries, bone, and CT derived from?

Answer 1

muscles, arteries: somitomeric mesoderm

bone, CT: neural crest cells

Question 2

what are the pharyngeal pouches?

Answer 2

evaginations of endoderm lining foregut

Question 3

what are the pharyngeal grooves?

Answer 3

invaginations of ectoderm b/w each arch

Question 4

which nerve is associated with each arch?

Answer 4

arch 1: trigeminal (5) 
arch 2: facial (7)
arch 3: glossopharyngeal (9)
arch 4: vagus (10) - superior laryngeal 
arch 6: vagus (10) - recurrent laryngeal

Question 5

what is derived from arch 1? (5 muscles/groups of muscles, 8 bones, 1 ligament, 1 cartilage)

Answer 5

• muscles of mastication
• mylohyoid
• anterior digastric
• tensor veli palatini
• tensor tympani
• maxilla
• mandible
• incus
• malleus
• zygomatic
• squamous part of temporal
• palatine
• vomer
• sphenomandibular ligament
• Meckel’s cartilage

Question 6

what is derived from arch 2? (4 muscles/groups, 3 bones, 1 ligament, 1 cartilage)

Answer 6

• facial expression muscles
• posterior digastric
• stylohyoid
• stapedius
• stapes
• styloid process
• stylohyoid ligament
• lesser horn/upper body of hyoid
• Reichert’s cartilage

Question 7

what is derived from arch 3? (1 muscle, 2 vessels, 1 bone)

Answer 7

• stylopharyngeus
• common carotid aa.
• internal carotid aa.
• greater horn/lower body of hyoid

Question 8

what is derived from arch 4? (4 muscles/ groups, 1 cartilage, 2 vessels)

Answer 8

• soft palate muscles (except tensor veli palatini)
• pharynx muscles (except stylopharyngeus)
• cricothyroid
• cricopharyngeus
• laryngeal cartilages
• R subclavian a.
• arch of aorta

Question 9

what is derived from arch 6? (2 muscles/groups, 1 cartilage, 2 vessels)

Answer 9

• intrinsic larynx muscles (except cricothyroid)
• upper esophageal muscles
• laryngeal cartilages
• pulmonary aa.
• ductus arteriosus

Question 10

what is derived from pouch 1?

Answer 10

• epithelial lining of auditory tube and middle ear cavity

- mastoid air cells

Question 11

what is derived from pouch 2?

Answer 11

epithelial lining palatine tonsil crypts

Question 12

what is derived from pouch 3?

Answer 12

• inferior parathyroid gland

- thymus

Question 13

what is derived from pouch 4?

Answer 13

• superior parathyroid gland

- ultimobranchial body

Question 14

what is derived from groove 1?

Answer 14

epithelial lining of external auditory meatus

Question 15

what is derived from grooves 2,3,4?

Answer 15

obliterated

Question 16

what is derived from membrane 1?

Answer 16

tympanic membrane

Question 17

what is derived from membranes 2,3,4?

Answer 17

obliterated

Question 18

embryonic origin of thyroid

Answer 18

endoderm - thyroid diverticulum

Question 19

embryonic origin of tongue?

Answer 19

• ant 2/3: median tongue bud + 2 distal tongue buds (associated w/ arch 1)
• post 1/3: copula + hypobranchial eminence (associated w/ arches 2,3,4)

Question 20

embryonic origin of face

Answer 20

from 3 swellings:

1. frontonasal prominence
2. maxillary prominence (arch 1)
3. mandibular prominence (arch 1)

Question 21

embryonic origin of mouth

Answer 21

stomodeum (ectoderm) + cephalic end of foregut (endoderm) - these meet at oropharyngeal membrane

Question 22

embryonic origin of olfactory epithelium

Answer 22

thickening of ectoderm of nasal placode in roof of each nasal cavity

Question 23

which epithelium comes from ectoderm?

Answer 23

• oral part of tongue
• hard palate
• sides of mouth
• lips
• parotid gland + ducts
• Rathke’s pouch
• enamel

Question 24

which epithelium comes from endoderm?

Answer 24

• pharyngeal part of tongue
• floor of mouth
• palatoglossal fold
• palatopharyngeal fold
• soft palate
• sublingual gland + duct
• submandibular gland + duct