ABSTRACT
Ansa cervicalis is a nerve loop that is embedded in the anterior wall of carotid sheath of the neck. It is formed bydescendent hypoglossi and descendens cervicalis. It supplies the infrahyoid muscles. During routine dissection,a rare variant in the morphology of Ansa cervicalis was observed in adult male cadaver. The variant ansacervicalis exhibited two loops, and was present bilaterally. The formation, course and relations of the nerve loopis complex. During literature search, we came across studies which propose different classifications. Hence wehave added a note on the different classifications.Ansa cervicalis is important since it can be used in nerve-nerve anastomosis, nerve-muscle pedicle implantationin relation to reconstructive surgeries of larynx. Hence, the knowledge of variations in the formation, anddistribution is relevant. It can affect the outcome during reinnervation surgeries following recurrent laryngealparalysis and surgeries around this area of neck.
ABSTRACT
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: The knowledge of the possible variations of ansa in relation to the great vessels of the neck prevents the inadvertent injury to those vessels. Any injury can result to phonation disability in professional voice users. In case of infrahyoid muscles palsy, patients have no serious voice problems in their normal speech but the pitch of their voice and also prosody in their singing are lost dramatically. Conclusion: These variations are of clinical importance for the reconstructive surgeries which involve the infrahyoid muscles.
ABSTRACT
OBJECTIVE: The omohyoid muscle is a long, thin muscle consisting of superior and inferior bellies and an intermediate tendon, which runs obliquely in the lateral cervical region. The omohyoid is important in neck dissections because it is the surgical landmark for level III and IV lymph node metastases. METHODS: In the present study, the anterior and posterior triangle of the neck was dissected in 35 male cadavers and observed for variations in the omohyoid bilaterally. Observations were focused on variations in number, attachments, and position of omohyoid. RESULTS: Among the 35 cadavers studied, double omohyoid was present in one cadaver, inferior belly originated from the clavicle in three cadavers, superior belly merged with the sternohyoid in two cadavers, and the omohyoid received additional slips from the sternum in one cadaver. Standard attachment and position of the omohyoid was observed in the remaining cadavers. CONCLUSION: Variations of this muscle are important because of its close relation to the large vessels and brachial plexus. Because of the direct adhesion of the intermediate tendon to the anterior wall of the internal jugular vein and its connection with it through a thin lamina of the pretracheal layer of the cervical fascia, the contraction of the omohyoid muscle has a direct effect on the lumen of this vessel.