The muscles of the arm are divided into three layers by anatomists. The muscles that rotate the arm are known as the pronator teres. They attach to the middle part of the radius, the other long bone in the forearm. The other two layers of the arm consist of the flexor carpi radialis and flexor carpi ulnaris. These two muscles also adduct the wrist and the hand.
Overexertion or injury to the brachioradialis muscle can result in pain, swelling, and limited arm function. The brachioradialis is much different from tennis elbow, which is a completely separate muscle group. Treatment for this condition varies, but typically involves rest and ice therapy. In severe cases, it may require surgery. Pain in this muscle can be a sign of brachioradial tendinitis.
The teres major muscle is located on the lateral surface of the scapula, on the inferior angle of the scapula. It is related to the latissimus dorsi muscle, as the teres major tendon lies posterior to the latissimus dolorsi tendon. Both teres major and latissimus dorsi muscles act in the acceleration and follow through phases of the throwing motion.
There are three heads of the biceps brachii muscles in the human arm. The first two head formations are identical and originate from the same point in the arm. The third head originates from the point where the coracobrachialis muscle inserts on the biceps. In some cases, the presence of a third head may increase the strength of elbow flexion and supination, as well as the kinematics.
The coracobrachialis is a muscle that forms a large head that encircles the tendon of the short biceps brachii muscle. The musculocutaneous nerve passes through both heads. The superficial head is attached to most of the medial border of the tendon, while the deeper head attaches to the upper part of the lateral border. The musculocutaneous nerve runs between the superficial and deep heads.
Anconeus is a short muscle located in the posterior compartment of the forearm and elbow. It is innervated by a branch of the radial nerve, which divides into two parts at the radial groove of the humerus. Injuries to the anconeus muscle include elbow hyperextension, shoulder dislocation, and fractures of the upper humerus. Inflammation of the tendons can also occur.