it is unique in that it also functions to flex the great toe and helps supinate the ankle. Injury and treatment Common injuries associated with the FHL tendon are tenosynovitis, tendinopathies, and muscle strains. Because the FHL muscle is small, injuries associated with this muscle and its tendon are often overlooked. An MRI can be used to evaluate the cause and condition of the FHL tendon. Tears and areas of impingement can be found using this method. A diagnostic ultrasound can also be used to diagnose FHL injuries, as it shows the muscle in movement and potential areas of impingement. Conservatively, an FHL injury can be evaluated by determining if movements caused by the FHL muscle cause pain along the inner ankle or under the big toe. After passing through the tarsal tunnel, the flexor hallucis longus tendon must curve around a bony landmark called the sustentaculum tali. Friction at this site is likely to cause pain on the posteromedial aspect of the ankle. While commonly referred to as "dancer's tendinitis," FHL tendinitis occurs commonly in ballet dancers, gymnasts, and runners. Due to their excessive use of toe flexion, which results in ten times their body weight being applied to this small muscle and tendon, inflammation and irritation is common at the site of the sustentaculum tali. Hallux saltans is a condition that develops as a result of overusing the FHL muscle. With this condition, a nodule develops along the FHL tendon which may produce a popping effect during contraction because it drags along surrounding tissues. If left untreated and continually irritated, stenosis of the tendon may occur, resulting in the big toe becoming stiff and relatively immobile. This condition is known as Hallux Rigidus. Most FHL injuries can be managed through conservative treatment. Rest is usually the first indicated intervention for minor FHL injuries. Ice and ultrasound therapy can also help with the inflammation and pain. Physical therapy exercises and stretches can help rehabilitate the muscle and tendon and potentially address biomechanical errors that cause the inflammation and microtears in the tendon. Some FHL injuries can be treated through rest, physical therapy, splints, and anti-inflammatory medication. However, more serious or chronic injuries may require surgery. If surgery is indicated, tears in the FHL will be repaired, and debris will be removed from the area. It is worth noting that an os trigonum may cause similar symptoms to the ones