The term CRANIAL BONE is composed of seven crossword solutions: SINUS (5 letters), ITER (4 letters), BASIAL (6 letters), OPTIC (5 letters), IDEA (4 letters), DURA (4 letters), and SPHENOID (8 letters). The SINUS is a hollow cavity in the skull, which is connected to the nasal cavity. The iter is a small opening in the skull that connects the brain to the spinal cord. The basial is a bone located at the base of the skull. The OPTIC is a bone that houses the eye socket. The IDEA is a bone located at the top of the skull. The dura is a tough membrane that covers the brain and spinal cord. The sphenoid is a butterfly-shaped bone located at the base of the skull.