derivatives of pharyngeal pouch (1 First pharyngeal pouch ---distal portion widen into a sac-like structure- middle ear cavity, the branchial membrane form tympanic membrane or eardrum proximal part: remain/ narrow to form the pharyngotympanic or Eustachian tube 咽鼓管 鼓 舌 腭扁桃体窝---derivatives of pharyngeal pouch: ① First pharyngeal pouch: ---distal portion: widen into a sac-like structure￾middle ear cavity, the branchial membrane form tympanic membrane or eardrum ---proximal part: remain narrow to form the pharyngotympanic or Eustachian tube