Biceps Brachii Muscle – Origins & Actions – Human Anatomy | Kenhub


Hey, everyone. This is Matt from Kenhub! And
in this tutorial, we will discuss the origin, insertion, innervation, and function of the
biceps brachii. The biceps brachii muscle, commonly called
biceps or bice for all you weight-lifters out there, is a large, thick muscle of the
upper arm. The surface anatomy of the anterior side of the upper arm is essentially formed
by the biceps. While both its origin tendons are covered
by the deltoid, its insertion tendon can be easily seen and palpated in the crook of the
arm. The biceps brachii consists of two heads,
the long head and the short head. The long head originates at the supraglenoid tubercle
above the socket of the scapula. It lies within the intrascapular space but is extrasynovial
or outside of the actual joint. The long biceps tendon makes a sharp turn
at the humeral head and continues its course in the bicepital groove also known as the
intertubercular sulcus. This turning point is secured by ligaments at the capsular area
and is known as the biceps pulley. The short head arises at the coracoid process
of the scapula where it partly blends with the origin tendon of the coracobrachialis. Both heads unite to form one large muscle
at the anterior side of the humerus and attach to the radial tuberosity. A fibrous membrane
emerging from the distal part of the muscle known as the bicepital aponeurosis or lacertus
fibrosus inserts at the deep fascia of forearm. The biceps brachii muscle is supplied by the
musculocutaneous nerve, a branch of the brachial plexus. The biceps is a two-joint muscle. In the shoulder
joint, both muscle heads partially enforce opposite movements. The long head pulls the
arm away from the trunk, known as abduction, and turns it inwards, or what we call internal
rotation, whereas the short head pulls the arm back towards the trunk, also known as
adduction. When both head contract simultaneously, it
leads to an arm bend also known as flexion. In the elbow joint, the muscle bends the forearm
and rotates it outwards which is known as supination. The supination is most powerful
in a flexed elbow. In addition to the movement functions, the
biceps has the important task to support the humeral head within the shoulder joint. This video is more fun than reading a text
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