Which action is shared by the trapezius and rhomboid muscles?

Which action is shared by the trapezius and rhomboid muscles?

• A. Depression of the scapula
• B. Protraction of the scapula
• C. Retraction of the scapula
• D. Elevation of the scapula

Answer: (C)

Retraction of the scapula is the shared action. Retraction pulls the shoulder blades toward the spine. The middle fibers of the trapezius are responsible for drawing the scapula inward, and the rhomboid major and minor lie beneath the trapezius and also pull the medial borders of the scapula toward the spine (while contributing to a bit of elevation). Other movements don’t fit both muscles as consistently: protraction is mainly done by serratus anterior, and while the trapezius and rhomboids can influence elevation, the common action they share most clearly is retraction.

Retraction of the scapula is the shared action. Retraction pulls the shoulder blades toward the spine. The middle fibers of the trapezius are responsible for drawing the scapula inward, and the rhomboid major and minor lie beneath the trapezius and also pull the medial borders of the scapula toward the spine (while contributing to a bit of elevation). Other movements don’t fit both muscles as consistently: protraction is mainly done by serratus anterior, and while the trapezius and rhomboids can influence elevation, the common action they share most clearly is retraction.