Fill in the Blanks Anatomy of the TrunkOnline version Inglés I (Tp 1) by Carla Robert 1 trunk friction lungs superior Superior thoracic ribs diaphragm bones digestion posteriorly sternum pelvic abdomen The is the central part of the body . The abdomen is bounded superiorly by the . The abdomen is bounded by the vertebral column and its related muscles . The walls of the thoracic cavity are composed of the , the , and the intercostal muscles . The heart and the lungs lie within the cavity . mediastinum connects freely with the neck . The pleural cavities contain both . The mediastinum is the most important division because of its contents . The function of the pericardium and the pleura is to provide slippery surfaces so that the structures contained within can move without . The is the largest cavity . The cavity can be said to be part of the abdomen . The organs of are the principal internal organs contained in the abdomen . The abdominal cavity and the pelvic cavity are separated by .