Constellation of variations in the superficial veins of the posterior triangle of neck: an uncommon presentation with clinical applications.

Background: Anatomical variations of the external jugular vein (EJV) are significant due to their notable implications in flap design and diagnostic evaluations (EJV cannulation).

Case report: The present case report details a unique venous anomaly observed during the dissection of right posterior cervical triangle in an adult male donated human body. Notably, the EJV atypically terminated by forming a venous loop with the transverse cervical vein. This loop comprised three segments: the proximal segment formed by the EJV, distal by the transverse cervical vein, and an intervening midsegment. From the convexity of the loop, two veins originated, running parallel for approximately 2.5 cm before piercing the investing layer of the deep cervical fascia to drain into the subclavian vein (SCV) separately.

Results: The first vein (V1) entered the SCV 1.77 cm distal to the clavicular head of the sternocleidomastoid muscle (SCM), while the second (V2) did so at 2.57 cm distal to the same landmark. Additionally, posterior external jugular vein (PEJV), an infrequent finding, was observed running along the anterior border of the trapezius muscle, draining into the transverse cervical vein instead of the EJV. The suprascapular vein, instead of opening into the EJV, drained directly into the SCV.

Conclusions: These findings underscore the significance of acknowledging such rare venous variations to avoid potential complications during surgical procedures involving the neck region.