nuchal line
nounMedical Definition of nuchal line
: any of several ridges on the outside of the skull: as
a
: one on each side that extends laterally in a curve from the external occipital protuberance to the mastoid process of the temporal bone
— called also superior nuchal line
c
: one on each side that extends laterally from the middle of the external occipital crest below and roughly parallel to the superior nuchal line
— called also inferior nuchal line