The triangular area between the greater, lesser, and third occipital nerves and its possible clinical significance

Occipital Neuralgia (ON) is defined as a unilateral or bilateral pain in the posterior area of the scalp occurring in the distribution area or areas of the greater occipital nerve (GON), lesser occipital nerve (LON), and/or third occipital nerve (TON). In the present study, the purpose was to show the possible importance of the triangular area (TA) in nerve block applied in ON by measuring the TA between GON, TON, and LON.

A total of 24 cadavers (14 males, 10 females) were used in the present study. The suboccipital region was dissected, revealing the points where the GON and TON pierced the trapezius muscle and superficial area, and the point where the LON left the sternocleidomastoid muscle from its posterior edge and was photographed. The area of the triangle between the superficial points of these three nerves and the center of gravity of the triangle (CGT) were determined by using the Image J Software and the results were analyzed statistically.

The mean TA values were 952.82 ± 313.36 mm² and 667.55 ± 273.82 mm², respectively in male and female cadavers. Although no statistically significant differences were detected between the sides (p > 0.05), a statistically significant difference was detected between the genders (p < 0.05). The mean CGT value was located approximately 5 cm below and 3-3.5 cm laterally from the external occipital protuberance in both genders and sides.

In ON that has more than one occipital nerve involvement, all occipital nerves can be blocked by targeting TA with a single occipital nerve block, and thus, the side effects that may arise from additional blocks can be reduced. The fact that there was a statistically significant difference according to the genders in the TA suggests that different block amounts can be applied according to gender.