branchial arches

Question 1

describe development of arches

Answer 1

from 4th to 7th weeks. Cranial to caudal.

Question 2

what does the ectomesenchyme and paraxial mesoderm of head give rise to generally?

Answer 2

connective tissue and bone; muscles associated with arches and endothelial cells

Question 3

describe recurrent laryngeal arches

Answer 3

Arch 6 artery on r side disappears while L side persists as ductus arteriosus. The RLN wraps around R. subclavian on R and duct art. on left

Question 4

describe what becomes of grooves

Answer 4

first becomes EAM. second arch overgrows others and forms a sinus which can persist

Question 5

where does the pinna come from

Answer 5

ant. half from bottom of arch one. Post. half from top of arch 2

Question 6

what is the basis for most anomalies

Answer 6

persistence of structures that normally disappear

Question 7

branchial cysts, sinuses, fistulas

Answer 7

anterior border of SCM. Remnants of SECOND pharyngeal GROOVE

Question 8

DiGeorge syndrome

Answer 8

failure of 3rd and 4th pouches to differentiate into thymus and parathyroid

Question 9

treacher-collins syndrome

Answer 9

zygomatic underdevelopment, downward palpebral fissures, malformed inner and outer ear

Question 10

pierre-robin

Answer 10

mandibular underdevelopment, cleft palate, eye and ear defects

Question 11

Fetal alcohol syndrome

Answer 11

affects almost all facial primordia