Besides containing the heart, thymus, and lymph nodes, the mediastinum serves as a thoroughfare for major nerves, vessels, and viscera. . .Besides containing the heart, thymus, and lymph nodes, the mediastinum serves as a thoroughfare for major nerves, vessels, and visceraBesides containing the heart, thymus, and lymph nodes, the mediastinum serves as a thoroughfare for major nerves, vessels, and viscera.