Flexor tendons are strong, cord-like connectors between muscles and bones. They translate muscle contractions into joint movement, allowing for actions like bending or curling. These tendons are important components of the musculoskeletal system, enabling a wide range of daily activities.
Key Locations of Flexor Tendons
Flexor tendons are found in areas requiring fine motor control and bending, such as the hands, wrists, and feet. In the hand, these tendons originate from muscles in the forearm and extend through the wrist into the fingers and thumb. Two main flexor tendons, the flexor digitorum superficialis (FDS) and the flexor digitorum profundus (FDP), run into the fingers, while the flexor pollicis longus (FPL) controls the thumb.
These tendons pass through tunnels in the wrist, such as the carpal tunnel, and continue along the palm side of the hand and fingers. Within the fingers, they are held close to the bones by a system of fibrous rings called pulleys, which ensure efficient movement and prevent “bowstringing” of the tendons. Flexor tendons are also in the feet and toes, connecting lower leg muscles to foot and toe bones, facilitating actions like pointing or curling them.
Essential Role in Body Movement
Flexor tendons primarily enable the bending, or “flexion,” of joints. When attached muscles contract, tendons pull on bones, causing the joint to bend. For instance, in the fingers, the FDS flexes the middle joint, while the FDP flexes the fingertip joint. The FPL allows for the bending of the thumb’s joints.
This coordinated action is important for activities like grasping objects, making a fist, or performing intricate tasks. In the feet, flexor tendons allow the toes to curl and the foot to point downward, contributing to balance and propulsion during walking or running. Without healthy flexor tendons, these everyday movements would be significantly compromised.
Common Conditions Affecting Flexor Tendons
Flexor tendons can be affected by conditions that impair their function and cause discomfort. One common issue is tendinitis, which involves inflammation or irritation of the tendon, often due to overuse or repetitive strain. This can lead to pain, stiffness, and sometimes a “clicking” or “catching” sensation, as seen in conditions like trigger finger, where a nodule forms on the tendon.
Tears or ruptures of flexor tendons can occur, ranging from partial to complete. These injuries often result from deep cuts on the palm side of the hand or wrist, or from a sudden, forceful pulling of a finger or thumb. Conditions like rheumatoid arthritis can weaken tendons, making them more prone to tears even without direct trauma. An injured flexor tendon can result in an inability to bend the affected finger or thumb.