<prompt> Internal thoracic artery is a branch of -1st part of subclavian artery2nd part of subclavian artery3rd part of subclavian arteryThyrocervical trunk  <response>: Ans. is a i.e., 1st part of subclavian artery Ref: BDC Vol III 5the p. 179Branches of subclav ian artery :-o 1st Part - Vertebral artery, internal thoracic artery, thyrocervical trunk, and on left side costocervical trunk,o 2nd Part -On right side costocervical trunk,o 3rd Part - Dorsal scapular artery. 