Falanger

Falanger, or phalanges in English, are the bones that form the digits of the hands and feet in many vertebrates, including humans. In humans, each hand contains 14 phalanges: three in each of the four fingers and two in the thumb. Similarly, each foot carries 14 phalanges: three in each of the four toes and two in the big toe. The phalanges are organized into proximal, middle, and distal groups, with the exception that the thumb and the big toe lack a middle phalanx.

Anatomy and joints: Phalanges articulate with the metacarpal or metatarsal bones at the metacarpophalangeal joints (the knuckles) and with adjacent phalanges at the interphalangeal joints. The fingers have proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints, while the big toe typically has a single interphalangeal joint. Each phalanx has a proximal base and a distal head, forming the articular surfaces for its neighbors.

Development and variation: Phalanges form by endochondral ossification, with ossification progressing from the shafts to the ends. Congenital and acquired variations occur, including polydactyly (extra digits) and brachydactyly (short digits), which affect the length and number of phalanges.

Clinical relevance and function: Phalanges are essential for fine motor skills, grip, and tactile manipulation. They are common sites of injury, such as fractures or dislocations, particularly in the fingers, and fractures may influence nail growth and sensation if near the distal phalanges.