Variations in the anatomy of ansa cervicalis

With the emerging utilisation of ansa cervicalis in nerve reconstructive surgery, it is important for surgeons to be conversant with the anatomy of these nerves. This descriptive cross sectional study aimed at describing the morphology and topographic anatomy of ansa cervicalis. We examined 38 adult human formalin-fixed cadavers. The superior root was present in 38 (100%) cases and 37 (97%) cases, on the right and left sides, respectively. More than half (56%) of these roots were located superior to the posterior belly of the digastric muscle. The inferior root, on the other hand, was present in 34 (89.5%) cases on the right side and 31 (81.6%) cases on the left side. Of all the inferior roots, 81.5% were located lateral to the internal jugular vein. The loop was seen in all the cases that had the inferior root, and was mostly (64.6%) located above the superior belly of the omohyoid muscle. Knowledge of the anatomy of ansa cervicalis is not only important for nerve reconstruction surgeries, but also for operations in the neck, so as to avoid injuring the great vessels that are closely related to it. (Folia Morphol 2010; 69, 3: 160-163