The shoulder is a “ball-and-socket” joint between the humerus bone ofthe upper arm and the scapula bone (shoulder blade). Six main movements occur at the shoulder: flexion, extension, abduction, adduction, internal rotation, and external rotation. During shoulder flexion, the upper arm is elevated forward toward the face. During shoulder extension, the arm moves Side Deltoid backward behind the plane of the body. During abduction, the arm moves up and out to the side of the body. During adduction, the arm is pulled in toward the side of the body. Horizontal abduction and adduction occur when the arm moves Rear Deltoid in a horizontal plane at shoulder level, such as during chest flys or rear deltoid flys. The deltoid muscle of the shoulder consists of three separate sections, or heads, each capable of moving the arm in different directions. a broad tendon attachment above the shoulder joint, the deltoid’s three heads merge into a single tendon that attaches to the humerus bone of the upper arm. The anterior deltoid (in front) attaches to the clavicle and raises the arm forward (shoulder flexion). The lateral deltoid (at the side) attaches to the acromion and lifts the arm outward to the side (abduction). The posterior deltoid (behind) attaches to the scapula and moves the arm backward (shoulder extension).
The rotator cuff is a group of four musdes that form a protective sleeve around the shoulder joint. Despite being a barely visible muscle group, the rotator cuff is essential for shoulder stability and strength. All four muscles originate from the scapula (shoulder blade) and pass across the shoulder joint to attach onto the humerus bone of the upper arm. The supraspinatus lies above the joint and raises (abducts) the arm up and outward-as when hailing a taxi. Infraspinatus and teres minor are located behind and act to rotate the arm out-as when hitchhiking. Subscapularis is situated in front and rotates the arm inward-as when folding your arms across the chest.
Most used shoulder exercise for shoulder building: Barbell Shoulder Press
1. Seated on a bench, take a shoulder-width grip on the bar with your palms facing forward.
2. Lower the weight slowly (in front) until it touches your upper chest.
3. Push vertically upward until your elbows lock out
Primary: Anterior deltoid.
Secondary: lateral deltoid, triceps, trapezius, and upper pectoralis.
Hand spacing: A shoulder-width grip is preferred to target the anterior deltoid. Wider grips on the bar minimize triceps contribution, but as the grip gets wider the risk of shoulder injury increases.
Range of motion: A shorter rep terminating the press Just before lockout keeps tension on the deltoid.
Positioning: Performing the exercise while seated upright Is a stricter version than standing and prevents cheating the weight upward using momentum generated by the legs.