A Variant Origin of the Carotid Sinus Nerve.

Cureus. 2018 Jun 26;10(6):e2883. doi: 10.7759/cureus.2883.

Andrew K, Iwanaga J, Loukas M, Oskouian RJ, Tubbs RS.

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Abstract

The carotid sinus nerve is known to convey baroreceptive fibers from the carotid sinus. Despite studies on the baroreflex pathway and the course and communications of the carotid sinus nerve with the surrounding nervous and vascular structures, there have been scant reports on variations in the origin of the carotid sinus nerve (CSN). We identified an unusual origin of the CSN. On the right side of a cadaveric specimen, the CSN was found to arise from two small rami extending from the external laryngeal nerve. Such a case can help better understand various pathways used to monitor the carotid sinus. Additionally, surgeries that manipulate the superior laryngeal nerve could possibly injure a variant carotid sinus nerve, as seen in the present case.

KEYWORDS:

cranial nerve ix; glossopharyngeal nerve; intercarotid plexus; vagus nerve

Figure 1

Medial view of the specimen reported here. Note the superior laryngeal nerve (vertical yellow arrow), internal laryngeal nerve (elevated with hemostats), and internal laryngeal nerve (white arrowhead).

Observe that the CSN (horizontal yellow arrow) is arising from the external laryngeal nerve to then descend onto the carotid sinus noted here as a swelling at the origin of the internal carotid artery.

CSN: carotid sinus nerve

Figure 2

Zoomed-in view of Figure ​Figure11.

Note the two rami (upper two arrows) contributing to the formation of the CSN (lower four arrows). The region of the carotid sinus is outlined by the yellow dotted circle.

CSN: carotid sinus nerve