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The Pectoralis major is a muscle of the pectoral region. This muscle along with the Pectoralis minor, Subclavius and Serratus anterior forms the pectoral region. It is the largest muscle in this region. Morphologically it is thin and fan-shaped. It is characterized by 2 heads, the large Sternocostal head, and the small Clavicular head. ORIGIN The Sternocostal head arises from- Medial parts of 2nd-6th costal cartilages and aponeurosis of the external oblique muscle of the abdomen. Lateral half of the anterior surface of the sternum up to 6th costal cartilage. The Clavicular head arises from the medial half of the anterior aspect of the clavicle. INSERTION Pectoralis major is inserted by a bilaminar tendon on the lateral lip of the bicipital groove of the humerus. This tendon has an anterior lamina and a posterior lamina. Anterior lamina is thick, short and is formed by clavicular fibers. Posterior lamina is thin, long and is formed by sternocostal and aponeurotic fi

The coracobrachialis is the smallest of the three muscles that attach to the coracoid process of the scapula.  coracobrachialis ORIGIN: The coracobrachialis is Originates from the coracoid process of the scapula. coracobrachialis INSERTION: The coracobrachialis is inserted on the medial surface of the humerus shaft. coracobrachialisACTION: The coracobrachialis is majorly working for flexion & adduction of the humerus. The coracobrachialis is a synergist of the  pectoralis major . coracobrachialis NERVE SUPPLY: The coracobrachialis is supplied by the Musculocutaneous nerve.

            The teres major is a thick, rounded muscle of the shoulder joint. It is a thick but somewhat flattened muscle. Supraspinatus , Infraspinatus , Subscapularis , and Teres Minor together This Four Muscle work as rotatory to the Humerus. So, also known as Rotator Cuff. teres major ORIGIN: teres major Originates from the posterior surface of the scapula at the inferior angle. teres major INSERTION: teres major inserted at the intertubercular groove of the humerus, tendon fused with the tendon of latissimus dorsi. teres major ACTION: teres major posteromedially extends, medially rotates, & adducts arm. teres major synergist of latissimus dorsi . teres major NERVE SUPPLY: The lower scapular nerve.

                      The teres minor is a narrow, elongated muscle of the rotator cuff.                     Supraspinatus ,  Infraspinatus ,  Subscapularis , and  Teres Minor  together This Four Muscle work as rotatory to the Humerus. So, also known as  Rotator Cuff. teres minor ORIGIN: Teres minor originates from the lateral border of a dorsal scapular surface. teres minor INSERTION: Teres minor is inserted at greater tubercle of humerus, inferior to the infraspinatus teres minor ACTION: helps to hold the head of the humerus in glenoid cavity. stabilizes the shoulder joint. rotates humerus laterally. Same as Infraspinatus muscle. teres minor NERVE SUPPLY: Teres minor is Supplied by the Axillary nerve.

              The subscapularis is a large triangular muscle.  Supraspinatus ,  Infraspinatus ,  Subscapularis , and  Teres Minor  together This Four Muscle work as rotatory to the Humerus. So, also known as  Rotator Cuff. ORIGIN: The subscapularis is originated from subscapular fossa of the scapula. INSERTION: The subscapularis is inserted at lesser tubercle of the humerus. ACTION: The subscapularis is chief medial rotator of the humerus, assisted by pectoralis major . The subscapularis is helped to hold the head of a humerus in glenoid cavity, stabilizes the shoulder. NERVE SUPPLY: The subscapularis is supplied by the Subcapular nerve.

                              the infraspinatus muscle is a thick triangular muscle, which occupies the chief part of the infraspinatous fossa. As one of the four muscles of the rotator cuff. Supraspinatus, Infraspinatus, Subscapularis, and Teres Minor together This Four Muscle work as rotatory to the Humerus. so also known as Rotator Cuff . Infraspinatus ORIGIN: the infraspinatus originates from infraspinous fossa of the scapula. Infraspinatus INSERTION: the infraspinatus is inserted at greater tubercle of humerus, posterior to supraspinatus. Infraspinatus ACTION: helps to hold the head of the humerus in glenoid cavity. stabilizes the shoulder joint. rotates humerus laterally. Infraspinatus NERVE SUPPLY: the infraspinatus muscle is supplied by the Suprascapular nerve.

                           The supraspinatus (plural supraspinati) is a relatively small muscle of the upper back. Supraspinatus,Infraspinatus, Subscapularis and Teres Minor together This Four Muscle work as rotatory to the Humerus. so also known as  Rotator Cuff . Supraspinatus ORIGIN: Supraspinatus originates from supraspinous fossa of the scapula. Supraspinatus INSERTION: Supraspinatus is inserted at the superior part of greater tubercle of the humerus. Supraspinatus ACTION: Supraspinatus stabilizes the shoulder joint. Supraspinatus helps prevent downward dislocation of the humerus. Supraspinatus NERVE SUPPLY: Supraspinatus is innervated by Suprascapular nerve.

The deltoid muscle is a rounded, triangular muscle located on the uppermost part of the arm and the top of the shoulder. which is shaped like an equilateral triangle . It comprises 3 distinct portions each of which produces a different movement of the glenohumeral joint, The deltoid muscle is the muscle forming the rounded contour of the human shoulder. It is also known as the 'common shoulder muscle'. we can see Muscles as anterior deltoid and posterior deltoid as it covers the whole shoulder from above. lateral deltoid is the lateral view of the shoulder. Like many other muscles, the deltoid can be sore for a variety of reasons, including overuse and tendon injuries. the common word for that is deltoid muscle pain. DELTOID ORIGIN: The deltoid has three origins : the lateral end of the clavicle,  the acromion of the scapula at the top of the shoulder, and  the spine of the scapula. DELTOID INSERTION: deltoid tuberosity of humerus. DELTOID Mu

The latissimus dorsi is a large, flat muscle on the back that stretches to the sides, behind the arm, and is partly covered by the trapezius on the back near the midline. ORIGIN: The latissimus dorsi originates via lumbodorsal fascia into spines of T7-L5, lower 4 ribs & iliac crest. INSERTION: The latissimus dorsi is inserted at the floor of the intertubercular groove of the humerus. ACTION: the agonist of arm extension. powerful arm adductor. medially rotates arm & shoulder. depresses scapula. pulls the body upward & forward with arms fixed overhead. NERVE SUPPLY: The latissimus dorsi is innervated by the sixth, seventh, and eighth cervical nerves through the thoracodorsal (long scapular) nerve.