Medial rotation is a term describing a specific anatomical motion. The term medial in anatomy refers to moving closer to the median plane, or central vertical divider, of the body. Thus, a medial rotation is the movement of a limb or muscle group toward the center of the body. Medial rotation is a type of movement that is considered in job design and in ergonomic evaluations in order to ensure that repetitive stress of rotation on a body part, or muscle group, does not pose a significant injury risk. Medial rotation is sometimes referred to as internal rotation.
Anatomical terms are used to divide the body into distinct sectors and identify motions about these sectors. Beginning with an assumption of a fixed anatomical position, movements are described with reference to set sectors or locations. Medial rotation refers to a rotational movement toward the median plane.
This plane is a theoretical dividing line that splits the body into equal left and right parts from top to bottom. This movement is sometimes referred to as internal rotation because the motion is inward toward the body's central vertical axis.
An example of medial rotation is turning the legs at the hip so that the toes point toward one another. Reaching the arm across the waist toward the opposite side of the body is also an example of medial rotation.
These types of motion are common in the workplace, specifically with workers who move a lot of items daily and can result in musculoskeletal injuries without good ergonomic design and company safety procedures to mitigate risk.