Rounded shoulders are an unnatural posture characterized by an exaggerated curvature of the upper back, often a forward positioning of the head where the shoulder girdle is protracted, and a thoracic kyphosis.
Most people round their shoulders and slump forward when sitting at a desk, in the car, on the couch, etc. This position turns on the pec minor to help support the shoulder.
Poor posture involving the pec minor can contribute to the following dysfunctions:
The pectorals minor is a thin, triangular muscle, situated at the upper part of the chest, beneath the pectorals major.
It arises from the upper margins and outer surfaces of the third, fourth, and fifth ribs, near their cartilages and from the aponeuroses covering the intercostalis.
The pectoralis minor depresses the point of the shoulder, drawing the scapula inferior, towards the thorax, and throwing its inferior angle posteriorly.