ANATOMICAL VARIATIONS IN THE ANSA CERVICALIS AND INNERVATION OF INFRAHYOID MUSCLES

Background ? Infrahyoid muscles are supplied by the ansa cervicalis. The present study aimed to study the variations in the ansa cervicalis and the innervation of infrahyoid muscles. Methods ? The study was conducted on 40 cadaveric hemi-necks. Results ? Out of the 40 hemi-necks, high level of ansa cervicalis was observed in 2 hemi-necks, intermediate level of ansa was observed in 35 hemi-necks and low level of ansa was observed in 3 hemi-necks. Additionally, dual ansa with absence of inferior root was seen in 4 hemi-necks, dual ansa with absence of inferior root and inter-communication between C2 and C3 was seen in 2 hemi-necks, common trunk supplying all infrahyoid muscles including superior belly of omohyoid was seen in 2 hemi-necks, nerve to inferior belly of omohyoid from inferior root was seen on 1 side. In one specimen unilaterally, superior belly of omohyoid was innervated by a branch from hypoglossal nerve, two superior roots arising from hypoglossal nerve and the inferior root formed only by C3 was seen in the same specimen. Discussion: Conclusion ? These variations are of clinical importance for the reconstructive surgeries which involve the infrahyoid muscles.