Trigger is the only object of Object Related DBMS applications which gets executed implicitly. Other objects such as Procedures, Functions, Tables, Indexes should be created and executed explicitly

You cant call Trigger from Stored Procedure, as Trigger are created on table and get fired implicitly.

Triggers are like events which are fired on some operation on table (Insert, Update and Delete)

But you can call stored procedure to from trigger, but do remeber it should not be recursive.

You can't call trigger from the stored procedure.

Trigger implicitely fires when you perform any manipulation on the table(like Insert,Update,Delete).

Suppose you have written a procedure for updating the record of the Table. When your procedure will execute,Your created trigger will also fire because it automatically fires when any operation performed on the table.