Which of the following veins is found within the brain's systemic veins?

The correct response focuses on the Great Cerebral Vein, known for its role within the cerebral circulation. This vein is significant as it drains blood from various areas of the brain and ultimately conveys it into the venous system surrounding the brain. It is specifically part of the venous drainage system of the brain, which is crucial for maintaining proper intracranial pressure and ensuring the removal of metabolic waste products from cerebral tissues.

The Superior Sagittal Vein is also associated with the brain's venous system, but it is not the Great Cerebral Vein itself, which has a more direct function in draining blood from deep structures of the brain. The Internal Jugular Vein, while related to cranial venous drainage, is located outside the skull and serves as a channel carrying blood from the head and neck back to the heart. Lastly, the Femoral Vein is located in the thigh and is not related to the brain's venous system at all, as it drains blood from the lower limb. Therefore, the Great Cerebral Vein is the most appropriate answer as it is indeed located within the brain's systemic veins.