Interphalangeal joints of the hand

The primary function of the interphalangeal joints is to facilitate the dexterous movements of the fingers. These joints allow fingers to bend and straighten, which is crucial for a wide range of daily activities such as typing, playing musical instruments, and performing delicate tasks requiring fine motor skills. The flexion at these joints enables the fingertips to come close to the palm, providing a powerful grip. The hinge structure of these joints allows for movement primarily in one direction, making them vital for actions such as clenching a fist or gripping tools, which require a specific range of motion. Additionally, the interphalangeal joints contribute to hand stability and function by working in conjunction with the other joints and structures in the hand, thus ensuring strong and precise movements.

Interphalangeal joints are located in each of the fingers, with the proximal interphalangeal joints situated between the first (proximal) and second (middle) phalanges, while the distal interphalangeal joints connect the second (middle) phalanx to the third (distal) phalanx. The PIP joints can be found roughly at the midpoint of the fingers, whereas the DIP joints reside closer to the fingertips. Given that each finger has a unique arrangement of three phalanges (except for the thumb, which has two), the thumb possesses only one interphalangeal joint, linking its two phalanges. This anatomical arrangement contributes significantly to the hand's versatility and functional capacity.

• The thumb's singular interphalangeal joint allows for greater opposition, making it essential for grasping and pinching functionalities.
• The amount of movement within the interphalangeal joints can vary among individuals, often influenced by factors such as age and activity level.
• Injuries to the interphalangeal joints are common in sports and can lead to conditions such as 'mallet finger', where the tendon that straightens the fingertip ruptures.