The biceps is a great muscle with some intricacies that has provided decades of confusion for orthopedic surgeons. We finally think we have figured it out, but then again that’s what they said about VHS videotapes.
First the anatomy of the biceps muscle. It is made up of two tendons that attach to the scapula in two different places. The short head of the biceps starts at the part of the scapula called the coracoid. This is a pressure point and is right in front of the shoulder more towards the chest. It is bony and easily felt on thin arms. The long head of the biceps gets it name because it has to travel farther to get down the arm. Its tendon is felt right in front of the ball of the humerus. It travels in a little groove that is covered by a ligament and then travels underneath the pectoralis major tendon as it heads to the elbow and attaches to the radius of the forearm.
Now here’s where it gets fun. Roll up your sleeve and keep your elbow flexed at 90 degrees like it is resting on a chair. Point your thumb up in the air and check out your biceps. Now rotate your forearm so you are looking at your palm. What happened to your biceps? It contracted because that is called supination and the biceps is the strongest supinator in the body. So it not only flexes your elbow as it does when we do strict pull ups, but also supinates. This is important because if it tears it gives weakness with supination activities like using a screwdriver or opening a door.
The long head of the biceps is usually the culprit for pain in the shoulder. It can be irritated in its tunnel or in the shoulder itself with a tendonitis which is inflammation of the tendon. It can be seen as a red infiltration into the tendon.
Mild injuries can also result in microscopic tearing of individual tendon fibers. As the severity of an injury increases, larger tears can occur to the point where the tendon is partially torn or even completely ruptured. If a rupture occurs, the long head will usually fall distally toward the elbow causing what is called a Popeye deformity.
Age, inactivity, or over-activity can weaken a tendon which may lead to injury due to the decreased ability to endure repetitive motions and sudden loads. The important part of this is that pain usually precedes anything bad and is our body’s warning signal to us encouraging us to back off or else. Some individuals develop bone spurs at the acromion which can lead to wear and tear of their tendons. This is called Impingement Syndrome (topic to be discussed later). The biceps tendon can also be injured at its attachment site on top of the glenoid. This usually involves an avulsion, where the tendon is pulled off the bone and rendered unstable. This is called a SLAP tear or Superior Labrum Anterior Posterior tear. Stay tuned to learn about SLAP tears and how we can try to avoid them as a CrossFit community.