An unreported anatomical finding: unusual insertions of the stylohyoid and digastric muscles

Abstract

The presence of a unusual appearance of the stylohyoid and digastric muscles may lead to a confusion in some pathological cases, during the radiological examination and aesthetic facial surgery. These differences may cause pharyngeal pain and foreign body sensation in the throat. During the dissection, unusual insertions, origin, insertion, shape and bilaterality were investigated in 28 cadavers' heads. In a total of 56, the presence of unusual insertions which belong to the stylohyoid muscle were observed in 22 sides (39.3%), and atypical fibers which belong to the digastric muscle were observed in 39 sides (69.6%). Bilaterality of the presence of atypical appearance was observed for stylohyoid and digastric muscles, in 10 (35.7%) and 19 (67.8%) specimens, respectively. In 12 heads (42.9%), atypical fibers, the stylohyoid and the digastric coexisted. These fibers which were shaped like a circular spiral were realized to have the shape of an arch or circle in front of the hyoid bone. The posterior bellies of the digastric muscle, the mylohyoid and the remaining suprahyoid muscles of both sides were normal. The unusual insertion of the stylohyoid muscles which cover the hyoid bone as a collar was not described in the classification of the previous studies. These fibers may give an variant mobility to the hyoid and they occur depending on the differences in the stylohyoid chains. Although the styloid process was in normal size, unusual insertions of the stylohyoid muscle that cover the hyoid as a belt or collar may give symptoms similar to those of the stylohyoid syndrome.