Rhomboid muscle variations: notes on their naming and classification principles

Abstract

In this report we present two cases of rhomboid muscle variations observed during routine anatomical dissections. In the first case, on the left side of an adult male cadaver, a long and slender aberrant muscle was identified starting from the lateral part of the superior nuchal line and inserting to the scapula between the rhomboid minor and levator scapulae. The muscle was identified as the rare rhomboid capitis. In the second case, in an adult female cadaver, a bilateral variation in the origin of the rhomboid major fibers was described. On the left side, the rhomboid major fibers started from spinous processes of C1-C6, while on the right side it was narrower and originating from spinous processes of C1-C3. Reviewing the literature about the rhomboid muscles variations, we conclude that one and the same aberrant structure might be named differently. We also discuss the presentation of the known variations of the rhomboids in a common scheme instead of classification.

A Cadaveric Study of a Safe and Accurate Electromyographic Needle Approach to the Rhomboid Major

“…Interestingly, in one cadaver, the distal origin of the RM muscle had different levels of thoracic vertebrae on both sides. Similar asymmetrical rhomboids were presented in a case report 9 . A narrow origin of the RM muscle may contribute to the relatively small distal insertion angle of the RM muscle with the medial border of the scapula.…”

“…Similar asymmetrical rhomboids were presented in a case report. 9 A narrow origin of the RM muscle may contribute to the relatively small distal insertion angle of the RM muscle with the medial border of the scapula. It should be noted that when the DI angle is small, the needle can be inserted below the lower margin of the RM muscle, resulting in an increased risk of pleural penetration.…”