the heart is a hollow ____________-shaped muscular pump within the ____________ cavity
Heart: The heart is a hollow, __cone__-shaped, muscular pump within the _thoracic_____ cavity. The average adult heart is __14_____ cm long and _____9______ cm wide. The heart lies in the ___mediastinum_____ under the sternum; its apex extends to the ___fifth_ intercostal space.t the base of the heart, the inner layer folds back to become the _parietal___ pericardium that lines the. tough outer layer. Between the two pericardia is a potential space called the __pericardial_ cavity and filled with _serous fluid.