CVS Practice Test 2026 – The All-In-One Guide to Exam Success!

The optic nerve is not typically considered part of the mediastinum because it primarily functions within the cranial cavity, directly connecting the eyes to the brain. The optic nerve, or cranial nerve II, is involved in vision and transmits visual information from the retina to the visual cortex, located in the brain.

In contrast, the phrenic nerve, cardiac nerve, and vagus nerve are all associated with the structures found within the mediastinum. The phrenic nerve, for example, innervates the diaphragm, a crucial muscle for breathing located within the thorax. The cardiac nerve is part of the autonomic nervous system, influencing heart rate and function, while the vagus nerve has extensive connections throughout the thoracic and abdominal cavities, regulating various involuntary processes. Therefore, the optic nerve's primary role and location differentiate it from the other nerves that are directly involved in mediastinal functions.