An Anatomical Study of the Lesser Occipital Nerve and Its Potential Compression Points

Abstract

This study maps the course of the lesser occipital nerve and its potential compression sites in the posterior scalp. Twenty sides of 10 fresh cadaveric heads were dissected. Two fixed anatomical landmarks were used: the y axis was the vertical midline in the posterior scalp through the midline of the cervical spine. The x axis was a horizontal line drawn between the most anterosuperior points of the external auditory meatus. A topographic map of the lesser occipital nerve and its potential compression points was created. The lesser occipital nerve emerged from the posterior border of the sternocleidomastoid muscle at an average of 6.4 ± 1.4 cm lateral to the y axis and 7.5 ± 0.9 cm caudal to the x axis. Branches of the occipital artery were found to interact with the lesser occipital nerve in 11 of the 20 hemiheads (55 percent). The mean location of the artery-nerve interaction was 5.1 ± 0.9 cm lateral to the y axis and 2 ± 1.45 cm caudal to the x axis. Two patterns of artery-nerve interaction were seen: a single site of artery crossing over the nerve in nine of 20 hemiheads (45 percent) and a helical intertwining relationship in two of 20 of hemiheads (10 percent). A fascial band was identified to compress the lesser occipital nerve in four of 20 hemiheads (20 percent). This anatomical study traced the lesser occipital nerve as it courses through the posterior scalp and mapped its potential decompression sites.