While riding her bicycle on campus without a helmet a student is hit by a car and falls, hitting her head on the pavement. She is brought to the Emergency Room in an unconscious state with signs of a closed head injury. Tests reveal blood in her cerebrospinal fluid taken from a spinal tap. Diagnosis is of torn cerebral veins as they pass from the brain to the superior sagittal sinus. From which of the following was the bloody fluid taken?