The Role of the Biceps Muscle

The biceps muscle is one of the most frequently exercised muscles, often targeted to enhance arm aesthetics. However, despite its reputation as a primary flexor of the elbow, its main function is actually to rotate the forearm (supination), such as when turning the palm upward to hold an object.

What is a Tendon?

Tendons are strong, flexible connective tissues that attach muscles to bones. These fibrous cords enable movement by transmitting force from muscles to bones while also absorbing impact to reduce the risk of injury. The biceps tendon has three key attachment points:

• Two proximal attachments at the shoulder
• One distal attachment at the elbow

Proximal Biceps Tendon: The “Good Twin” and “Bad Twin”

At the shoulder, the biceps tendon has two distinct attachment sites:

• Short head (Good Twin): Attaches in front of the shoulder and remains intact even if the other tendon ruptures.
• Long head (Bad Twin): Located within the shoulder joint, it is more prone to injury and often a source of pain. If it ruptures, a visible deformity called the Popeye Deformity may appear, characterized by a bulging biceps muscle lower on the arm. Surgery is usually unnecessary if the short head remains intact.

Distal Biceps Tendon: A Critical Attachment

The single distal attachment at the elbow is crucial for forearm rotation and elbow flexion. If this tendon ruptures, symptoms may include bruising and a Reverse Popeye Deformity, where the biceps muscle retracts upward toward the shoulder. Unlike proximal tears, distal biceps ruptures often require urgent surgical repair within a few weeks to prevent long-term strength loss.

Identifying Biceps Tendon Injuries

• Proximal Biceps Tear (Bad Twin): Bruising near the shoulder, a noticeable bulge lower in the arm (Popeye Deformity)
• Distal Biceps Tear: Bruising near the elbow, reduced ability to turn the palm upward, and a Reverse Popeye Deformity

Reducing the Risk of Biceps Tendon Rupture

To minimize the risk of tendon injuries:

• Avoid smoking: Smoking restricts blood flow, and tendons already receive limited circulation, making healing more difficult.
• Practice controlled weightlifting: Use slow, steady movements when flexing the elbow and avoid excessive weights.

By understanding the function and vulnerabilities of the biceps tendon, individuals can take preventive measures and seek timely medical attention when necessary.