What does it mean that there is a bone bulge in the back of the head?

Protruding bones are anatomically the position of occipital tuberosity, which is common in normal people.

Occipital protuberance, congenital, everyone has it, but some people are more prominent. It's not a brain tumor. You don't need surgery. Located below the middle part of the back of the head, there is a small bone protrusion like a bag.

Occipital foramen hernia is a particularly critical type of cerebral hernia, which easily leads to dysfunction and death of patients' life center. Occipital foramen hernia is a pathological process in which the cerebellar tonsil is pressed downward to press the medulla oblongata, which in turn causes disorder of vital signs, disturbance of consciousness and pupil changes. Most common in infratentorial lesions.

Occipital foramen hernia is a clinical emergency. Once it happens or is suspected, it must be treated urgently. If breathing stops, it is feasible to puncture and drain the ventricles, give stimulants to the respiratory center, and deal with the cause while artificially assisting breathing.