how to find primary key field name?

If I have a table name, I know how to find the primary key constraint
name, but see no way to find the primary key field name.

select constraint_name from information_schema.tabale_constraints where
table_name = <table_name> and constraint_type = 'PRIMARY KEY';

will return the constraint name, but given the table_name and the
constraint_name, how do I find the database column/field name associated
with that primary key?

J.V.