Nothing matches your deltoids (shoulder), wide or large, toned or tight they are eye catcher. Importantly the integrity of deep shoulder joint muscle called rotator cuff. Then comes the trapezius and it contributes alot in shoulder stability. Let’s start with superficial deltoid.
The deltoid muscle is segmented in distinct fiber portions. Anterior one originates from lateral 3rd of clavicle, posterior from spine of scapula and middle deltoid from acromion process. All 3 portions insert on deltoid tuberosity of humerus and as each pass over a different part of glenohumeral joints (shoulder), they have a separate action;
Anterior fibers flex and medially rotate arm
Middle fibers abduct arm, and
Posterior fibers extend and crossways rotate arm.
Rotator Cuff Muscles: Infraspinatus, Supraspinatus, Subscapularis, and Teres Minor
Rotator cuff assists to stabilize shoulder joint as holds the head of humerus inside glenoid fossa of scapula. It consists of 4 muscles and all helps in deltoid movements. 3 of them originate posteriorly, while remaining 1 originating anteriorly.
Posterior Muscles- Infraspinatus, Supraspinatus and Teres Minor
The supraspinatus is superior one and originates from supraspinous fossa of scapula and acts alone to help shoulder abduction, Infraspinatus from infraspinous fossa of scapula and the teres minor from lateral border of scapula and act together with insfrapinatus as lateral rotators of arms. All 3 insert on greater tubercle of humerus.
Teres major originates near teres minor; its role is closely paired with the latissimus dorsi because of its insertion. It originates from inferior angle of scapula and inserts on medial lips of intertubercular groove of humerus.
It assists latissimus dorsi in adduction, extension and medial rotation of arm, however merely when there is some resistance against such movements, like in weight training.
Anterior Muscles (Subscapularis)
The author and the creator of Old School New Body Review says, Rotator Cuff’s anterior muscle is the only subscapularis which originates from subscapular fossa of scapula which inserts on lesser tubercle of humerus.
2 Important Workouts Shoulders
Barbell Shrug 5 by 4-6
Military Press 5 by 4-6
Alternate with same number and rest 1 to 2 minutes between each. Increase the weight on barbell and military press
Military Press is best for deltoid because it hits anterior deltoid very hard. How extreme you take bar (chin, nose or all the way to upper chest) down depend on your comfort and preference.
Barbell shrugs are best for trap development growth. Remember load shouldn’t be very heavy. Try to touch your traps with ears to high up your strive.