Final answer:
The singular of phalanges is phalanx. This term refers to each of the bones forming the fingers and toes. The thumb and big toe contain two phalanges, while the other digits have three each.
Step-by-step explanation:
The singular of phalanges is phalanx. The word phalanx is derived from the Greek term used to describe a military formation, reflecting how these bones are arranged in rows in our hands and feet. Each phalanx bone forms part of a finger or a toe. In the thumb and big toe, there are two such bones, the proximal and distal phalanges, while the other digits have three each: the proximal, middle, and distal phalanges. An articulation between two phalanges is known as an interphalangeal joint.
The phalanx bones are critical for the mobility and function of our fingers and toes, serving as lever arms that permit fine motor control. The understanding of these bones is important not only in human biology and medicine but also within evolutionary biology, as variations in the phalanges reflect adaptations to different activities and environments among species.