Trans-obliquus inferior capitis course of the greater occipital nerve: A potential cause of occipital neuralgia?

Occipital neuralgia can be due to multiple etiologies. One of these is potential compression of the greater occipital nerve (GON). In this regard, one relationship of the GON, its course through the obliquus inferior capitis muscle (OIC), has yet to be well studied. Therefore, the current anatomical study was performed to elucidate this relationship better. In the prone position, the suboccipital triangle was exposed, and the relationship between the GON and OIC was documented in 72 adult cadavers (144 sides). The GON was found to pierce the OIC on four sides (2.8%), unilaterally in two cadavers and bilaterally in one cadaver. Two cadavers were male, and one was female. Histological samples were taken from GONs with a normal course around the OIC, and nerves were found to pierce the OIC. The GON of all four sides identified histological changes consistent with nerve potential compression (e.g., epineurial and perineurial thickening). This is also the first histological analysis of the trans-OIC course of the GON, demonstrating signs of chronic nerve potential compression. Although uncommon, entrapment of the GON by the OIC may be an underrecognized etiology of occipital neuralgia.