Surgical anatomy of the internal carotid plexus branches to the abducens nerve in the cavernous sinus

•Sympathetic branches to the abducens nerve have been scantly described in the extant literature.•Fresh-frozen cadavers were used.•Branches from the sympathetic plexus to the abducens nerve were found.•Sympathetic connections between the ICA and the CX VI were found to be common. Sympathetic branches to the abducens nerve derived from the internal carotid artery sympathetic plexus, while in the cavernous sinus, have been scantly described in the extant literature. Therefore, the present cadaveric study was performed to better elucidate this anatomy. Eighteen cadaveric sides underwent dissection. The number of branches derived from the sympathetic plexus traveling with the internal carotid artery in the cavernous sinus was one on 11.1 %, two in 11.1 %, and three in 72.2 %. One side was found to have no branches (5.6 %). The mean diameter of the distance from the posterior border of the internal carotid artery, length, and diameter of the branches was 7.0 ± 4.1 mm, 2.9 ± 1.3 mm, and 0.4 ± 0.1 mm, respectively. Of 44 of 45 sympathetic branches, 97.8 % originated from the lateral wall of the cavernous part of the internal carotid artery with only one from the medial wall. Based on our cadaveric findings, sympathetic connections between the internal carotid artery and the abducens nerve are common. Therefore, surgeons who operate in or near the cavernous sinus should be aware of such connections in order not to place unwanted tension on the cavernous part of the internal carotid artery or abducens nerve during dissection.