The biceps muscle has two tendons in the shoulder - the long head of biceps tendon (LHB) and short head tendon (see image).
The LHB is approximately 9cm long and has to travel through a narrow groove at the front of the shoulder. It then has to bend through 90° to enter the shoulder joint and then attach to the labrum at the top of the glenoid. This has arisen through the process of evolution, as the human shoulder blade has moved in position from the side of our body to the back. This development has allowed us to throw but has had a few unforeseen consequences. One of these is the strain placed upon our LHB tendon.
This rather tortuous course places the tendon at a risk of inflammation. When the LHB becomes inflamed this can lead to pain at the front of the shoulder known as biceps tendonitis. Biceps tendonitis can occur on its own or be associated with rotator cuff problems both impingement and tears.
Sometimes the LHB tendon in the shoulder may rupture and result in a bunching of the biceps in the upper arm, known as a 'popeye biceps' appearance.
Ruptured right LHB with Popeye sign biceps (arrow)
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