Definition

By: Gregory R. Waryasz, MD

The biceps brachii muscle of the musculoskeletal system is characterized by being an anterior compartment muscle of the arm that has no attachment to the humerus. The biceps brachii works at the glenohumeral, elbow, and radioulnar joints.

It is part of the arm.  It consists of skeletal muscle fibers.

Its unique structural features include its two heads; long and short.  About 10% of the population has a third head, but no matter the anatomy, there is a common tendon for insertion.  The third head can be located from the superomedial part of the brachialis and lying posterior to the brachial artery.  The long head of the biceps tendon travels in the intertubercle groove of the humerus and is held in place by the transverse humeral ligament.  The insertion into the arm fascia is through the bicipital aponeurosis.  The biciptal aponeurosis is a triangular membranous band that runs from the biceps tendon

The origin of the short head is the tip of the coracoid process of the scapula.  The origin of the long head is the supraglenoid tubercle of the scapula.

The insertion is the tuberosity of the radius and the fascia of the arm through the bicipital aponeurosis.

The blood supply is from the brachial artery and venous drainage is from the accompanying veins.

The innervation is from the musculocutaneous nerve.

The biceps brachii muscle as well as all other bones, muscles, and ligaments of the body are derived of mesodermal origin in the embryo.

The function of the biceps brachii muscle is to supinate the forearm, flex the forearm when supine, and the short head of the biceps plays a role in resisting shoulder dislocation.  The synergists are brachilais, brachioradialis, and the supinator.

Common diseases include Erb’s Palsy, tendinitis, tendinopathy, tears, rupture, and dislocation.

Erb’s palsy is a condition of persistent lack of biceps muscle function from birth trauma.

Tendinitis is inflammation of the tendon usually due to overuse.

Tears can occur at any point in the tendons or muscle belly.

Tendon rupture can occur proximally or distally.  When the rupture occurs proximally, it can form a Popeye Deformity. The Popeye deformity refers to the detached muscle belly forming a ball near the center of the distal part of the anterior arm.  Ruptures occur from repetitive overload motions usually.

Dislocation of the long head of the biceps tendon occurs usually at the intertubercular groove.

Commonly used diagnostic procedures include clinical history, physical exam, and MRI.

It is usually treated with physical therapy and NSAIDs tendinitis.  Biceps tendon tears, dislocation, and rupture may or may not require surgery.  Erb’s palsy may be permanent or resolve in infancy.

References

Lieberman J (ed), AAOS Comprehensive Orthopaedic Review, American Academy of Orthopaedic Surgeons, 2008.

Moore K, Dalley A (eds), Clinically Oriented Anatomy (5th edition), Lippincott Williams & Wilkins, Philadelphia, PA, 2006.

Wheeless’ Textbook of Orthopaedics: Biceps Brachii (http://www.wheelessonline.com/ortho/biceps_brachii)