occipital protuberance

noun

: either of two prominences on the occipital bone:

a

: a prominence on the outer surface of the occipital bone midway between the upper border and the foramen magnum that with the external occipital crest gives attachment to the ligamentum nuchae

called also external occipital protuberance, inion

b

: a prominence similarly situated on the inner surface of the occipital bone

called also internal occipital protuberance