Nerve liable to get injured on removing the fish bone from pyriform fossa:-
Superior laryngeal nerve
Internal laryngeal nerve
External laryngeal nerve
Recurrent laryngeal nerve
Pyriform fossa is located on the side of epiglottis. It is supplied by Internal laryngeal nerve. Hence this nerve is liable to get injured while removing a fish bone from pyriform fossa. .
Pharynx, larynx and trachea and cranial nerves 3,4,6