Final answer:
A transthoracic mediastinotomy is typically not entered through an incision in the sixth intercostal space, but rather through an incision above the sternum or between the fourth or fifth intercostal spaces, making the statement false.
Step-by-step explanation:
The statement that a transthoracic mediastinotomy is entered by an incision in the sixth intercostal space is false. In general, a mediastinotomy, which is a surgical procedure used to gain access to the mediastinum, is more commonly performed through an incision above the sternum or between the fourth or fifth intercostal spaces, not the sixth. The mediastinum contains critical structures such as the heart, great vessels, trachea, esophagus, and lymph nodes. Furthermore, the heart, a central mediastinal structure, rests higher within the thoracic cavity.
The base of the heart is level with the third costal cartilage, and the tip of the heart, or apex, is situated near the junction of the fourth and fifth ribs. Therefore, an incision at the sixth intercostal space would generally be too low for optimum access to the mediastinum for the purposes of mediastinotomy. The sixth intercostal space is located between the sixth and seventh ribs.