The back part of the head.
Oligodendroglia: Non-nerve cells (see glia) forming part of the supporting structure of the central nervous system.
Oligodendroglioma: A growth of new cells derived from the oligodendroglia.
Orbital: Related to the bony eye socket and surrounding area.
Osteoma: A benign tumor of bone.
Osteomyelitis: Inflammation of bone due to infection, which may be localized or generalized.
Osteophytectomy: Surgical removal of osteophytes (bony outgrowths). Osteophytes may develop on the upper and/or lower edges of the vertebral bodies, often causing pressure on the spinal cord.