BICEPS BRACHII MYOLOGY



OVERVIEW

The Biceps Brachii muscle is a strong biarticular muscle bridging the shoulder and elbow joint. Located on the anterior aspect of the upper arm, it is a long fusiform muscle composed of two heads, a laterally located long head and a medially located short head. The short head of the biceps originates from the apex of the coracoid process of the scapula via a flat tendon while the long head originates from the supraglenoid tubercle of the scapula via a long cylindrical tendon. The bellies and fibers of the two heads travel down the arm, crossing over the elbow, and converging into a single tendon the inserts on the radial tuberosity of the radius. Because of these attachment sites, direction of the fibers, and the joints involved, the biceps are responsible for shoulder flexion, elbow flexion, and forearm supination. The long head can also participate in shoulder abduction.


LOCATION:

  • Anterior, superficial aspect of the humerus.

ORIGIN:

  • Short head - The short head of the biceps originates from the apex of the coracoid process of the scapula via a flat tendon.

  • Long head - originates from the supraglenoid tubercle of the scapula via a long cylindrical tendon.

INSERTION:

  • The fibers of the biceps brachii run inferiorly from its sites of origin and converge into single tendon that inserts on the radial tuberosity of the radius.

FUNCTION:

  • Shoulder Flexion

  • Elbow Flexion

  • Forearm Supination

  • Shoulder Abduction (long head)


SHORT AND LONG POSITION

Because the two heads have different origination sites, the short and long position of this muscle will vary slightly depending on which muscle belly one is attempting to target. The short position of this muscle can be found when the insertion site is closest to one of its origination sites. In general, the short position for the biceps brachii will be when the elbow and shoulder are in flexion and the hand has been supinated. Depending on the target belly, the elbow in this position may be further from or closer to the body. The long position of this muscle can be found when the insertion site is furthest away from one of its origination sites. In general, the long position for the biceps brachii will be when the elbow and shoulder are in extension and the hand is pronated.



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