What does a thoracotomy allow surgeons to access directly?

A thoracotomy is a surgical procedure that involves making an incision in the chest wall to gain access to the thoracic cavity. This allows surgeons to directly access structures within the chest cavity, such as the lungs, heart, major blood vessels, and other associated tissues. By performing a thoracotomy, surgeons can address conditions like lung cancer, cardiac issues, or traumatic injuries to the chest.

The other options focus on structures not related to the thoracic cavity. For instance, abdominal organs would require an abdominal incision rather than a thoracotomy. Brain tissue access typically involves a neurosurgical procedure like a craniotomy, which targets the cranial cavity. Muscle layers can be accessed through various general surgical procedures, but they do not specifically pertain to the thoracic cavity accessed through a thoracotomy. Thus, option C is clearly the correct choice as it directly relates to the purpose and outcome of the thoracotomy procedure.