Question

Explain how the pectoralis major can have concentric actions of both abduction and adduction of the glenohumeral joint. Provide an example movement to demonstrate your understanding.

Answer 1

Ans ;

Pectoralis major :

The pectoralis major has four actions which are primarily responsible for movement of the shoulder joint.The first action is flexion of the humerus, as in throwing a ball underhand, and in lifting a child. Secondly, it adducts the humerus, as when flapping the arms. Thirdly, it rotates the humerus medially, as occurs when arm-wrestling. Fourthly the pectoralis major is also responsible for keeping the arm attached to the trunk of the body. It has two different parts which are responsible for different actions. The clavicular part is close to the deltoid muscle and contributes to flexion, horizontal adduction, and inward rotation of the humerus

Hypertrophy of the pectoralis major increases functionality. Maximal activation of the pectoralis major occurs in the transverse plane through pressing motions. Both multi-joint and single-joint exercises induce pectoralis major hypertrophy. A combination of both single-joint and multi-joint exercises will result in a maximum hypertrophic response. [Aesthetic contours of regions in the muscle may be specifically-addressed (“targeted”) by specific exercises; for instance, “plating” or “stitching” of the pectoralis major —towards the center of the sternum —-may be targeted by a wider hand position.] The pectoralis major can be targeted from numerous training angles along the sternum and clavicle.

Exercises that include horizontal adduction and elbow extensions such as the barbell bench press, dumbbell bench press, and machine bench press induce high activation of the pectoralis major in the sternocostal region. Heavy loads are strongly correlated with pectoralis major activation

The normal range of motion is 90 degrees. Primarily infraspinatus and teres minor are responsible for the motion. Adduction – Defined as bringing the upper limb towards the midline in the coronal plane. Pectoralis major, latissimus dorsi, and teres major are the muscles primarily responsible for shoulder adduction