The primary function of the thorax is respiration. The ribs and the diaphragm move so that the thoracic cavity increases and decreases in size during the inspiratory and expiratory phases of respiration. It also probably aids in returning venous blood back to the heart because of the negative pressure produced with respiratory movements.
Secondarily it serves to protect the organs located within its cavity plus some organs of the abdominal cavity.
The main thoracic organs which you will examine in your dissection of the thorax are the: The other structures are:
Intro to Thorax Bony Boundaries of Thorax

Table of Contents for Thorax
Practice Exam