Blood drainage from the head and neck is facilitated by the jugular veins, which run along the left and right sides of the cervical region. There are three pairs of jugular veins:
1. Internal jugular vein: The largest and the primary vessel responsible for draining blood from the cranial cavity.
2. External jugular vein: This vein is smaller in diameter and collects blood from the superficial structures of the head, face, and neck.
3. Vertebral vein: Drains blood from the upper part of the spinal cord, brainstem, cerebellum, and the posterior part of the brain.