Muscular Variation In The Neck Region With Narrowing Of The Minor And Major Supraclavicular Fossa

Abstract

Background: The sternocleidomastoideus muscle is the most prominent landmarks of the surface anatomy of the neck, separates the anterior part of the neck (anterior triangle) from the posterior part of the neck (posterior triangle). An accessory head of sternocleidomastoideus muscle may cause complications while trying to access vital neurovascular structures that are located in the minor and major supraclavicular fossa. The purpose of this study is to describe an anatomical variation of the sternocleidomastoideus muscle and clinical impact.
 Methods and Findings: The anatomical variations described were found during routine dissection conducted in the laboratory of Morphology of the University of Pamplona in two male cadavers of 47 and 75 years respectively. Measurements were taken using a Vernier caliper. Topographic details of the variations were examined, recorded and photographed. The morphological variations in the number of heads (three and four) of origin of sternocleidomastoideus muscle was found in two male subjects in right and left neck, bilaterally. The posterior cervical triangle was diminished. The bilateral narrowing of the minor and major supraclavicular fossa minimizing space needed for potential surgical access. The branching patterns of the spinal accessory nerve and arterial patterns were normal.
 Conclusions: The Knowledge of the presence of additional heads of sternocleidomastoideus muscle it might cause difficulties in subclavian or external jugular vein catheterization, and in surgical interventions involving structures lying under the sternocleidomastoideus muscle. These variations must be kept in mind while approaching the region to avoid complications as the classical anatomical landmarks might be misinterpreted and confuse.

Classification of Sternocleidomastoid Muscle Variations and Comparison of Its Incidence among Populations

“…Variations in SCM origin must thus be addressed to avoid complications during surgery. As summarized in Table IV, SCM abnormalities have been reported in many countries around the world including Greece, Brazil, India, Australia, Turkey, Columbia, Pakistan, the US, and Korea (Natsis et al, 2009;Amorim Júnior et al, 2010;Mehta et al, 2012;Raikos et al, 2012;Saxena et al, 2013;Saha et al, 2014;Kim, 2015;Anil et al, 2016;Arquez, 2017;Dupont et al, 2018;Mansoor & Rathore, 2018;Oh et al, 2019). However, most were case reports observed during lessons on gross anatomy for medical or paramedical students, and few systematic studies have been published.…”

“…However, most were case reports observed during lessons on gross anatomy for medical or paramedical students, and few systematic studies have been published. SCM variation has been documented in India (27.8 %) and Columbia (11.7 %) (Saha et al, 2014;Arquez, 2017).…”

“…An incidence of anatomical variations is greater than 10 % in an individual population and demands clinical consideration. Previous studies in West Bengal and Columbia have shown the rates of 27.8 % 11.7 %, respectively (Saha et al, 2014;Arquez, 2017). As that in the Thai population has yet to be documented, we systemically investigated the types and incidence of SCM abnormality in cadavers from Northeast Thailand.…”

“…It is possible that variations or abnormalities in SCM origin and insertion may cause abnormal neck and head movements and complications during central venous catheterization. Abnormality of the SCM -especially in terms of its originhas been reported in numerous populations including those in Brazil, Greek, India, Australia, Soult Korea, Turkey, Colombia, Pakistan, and the US (Natsis et al, 2009;Amorim Júnior et al, 2010;Mehta et al, 2012;Raikos et al, 2012;Saxena et al, 2013;Goswami et al, 2014;Saha et al, 2014;Kim, 2015;Anil et al, 2016;Arquez, 2017;Mansoor & Rathore, 2018;Dupont et al, 2018;Oh et al, 2019). Most of these previous studies were case reports using human embalmed cadavers.…”

Unilateral Duplication Of Parotid Duct. A Rare Anatomical Variation

“…These parapharyngeal tumors can grow into "dumbbell-shaped" tumors, because their growth is directed through the stylomandibular tunnel [14]. Sternocleidomastoideus can be used in several ways by the surgeons who harvest these muscle flaps for reconstructions such as during parotid surgery (parotidectomy), where the Sternocleidomastoideus muscle could serve as an excellent candidate for myocutaneous flap, may cover the surgical defects and possibly preventing Frey's sindrome [15,16] Aktan et al reported a case of double PD in the right side of the face of a 63-year-old male cadaver that merged with each other at a distance of 7 mm before perforating the buccinator muscle. They stated that these ducts were intra-parotid ascending and descending ducts, which did not merge inside the PG as it occurs normally [7].…”