Muscles of the Shoulder and Upper Limb (Arm)

Muscles That Move the Pectoral Girdle and Arm 
Deltoid is a large, fleshy, triangular muscle (deltoid in Greek means triangular) that covers the shoulder and causes the bulge of the upper arm. It runs from both the clavicle and the scapula to the humerus. This
muscle abducts the arm (raises the arm laterally) to the horizontal position. (The term ann is used in this section to refer to the entire upper limb.)
Pectoralis major is a large (major) anterior muscle of the upper chest. It originates from the clavicles of the pectoral girdle, but also from the sternum and ribs. It inserts on the hu merus. If you press your hands together forcefully, you can feel these muscles contract isometrically. The pectoralis major flexes the arm (raises it anteriorly) and adducts the arm, pulling it across the chest.
Latissimus dorsi (located both laterally and dorsally) is a wide, triangular muscle of the lower back. This muscle originates from the lower spine and sweeps
upward to insert on the humerus. The latissimus dorsi extends and adducts the arm (brings it down from a raised position). This muscle is very important for swimming, rowing, and climbing a rope.
Serratus anterior is located below the axilla (armpit) on the side of the chest. It runs between the upper ribs and the scapula. It pulls the scapula downward and forward, as when we push something. It also helps to raise the arm above the horizontal level.
The deltoid. pectoralis major, latissimus dorsi, and serratus anterior muscles all function to move the humerus and, therefore. the arm. in relation to the trunk.
Muscles That Move the Forearm
Biceps brachii is a muscle of the anterior upper arm that is familiar because it bulges when the forearm is flexed. It also supinates the hand when a doorknob is
turned or the cap of a jar is unscrewed. The name of the muscle refers to its two heads that attach to the scapula, where it originates. The biceps brachii inserts on the radius.
Triceps brachii is the only muscle of the posterior upper arm. It has three heads that attach to the scapula and humerus, and it inserts on the ulna. The triceps eA.'tends the foreaarm when something is pushed. It is sometimes called the boxer's muscle because it straightens the elbow when a punch is thrown.
The biceps and triceps brachii are antagonistica muscles because the biceps flexes the forearm. and the triceps extends it.
Muscles That Move the Hand 
Flexor carpi and extensor carpi muscles originate on the bones of the forearm and insert on the bones of the hand. They move the wrist and hand.
Flexor digitorum and extensor digitorum muscles also originate on the bones of the forearm and insert on the bones of the hand. They move the fingers.
The muscles that move the hand and fingers span the vvrist.