During 4th week of embryonic development, five<unk>  arches grow into distinct parts of head and neck
All consist of arteries, nerves, muscle, skeletal tissue
If arches fail to fuse--> soft tissue<unk>  on lateral neck may form, called<unk> <unk> es include cysts (most common), fistulas, sinus tracts
2nd<unk> es most common
Branchial cleft anomaly
Reactive lymphadenopathy- most common
Vascular ring
Viral URI
Choanal atresia
EBV
Zygomatic arch fracture
CMV