What are Proximal Phalanges?

Proximal phalanges are the bones in the fingers and toes that connect to the metacarpal and metatarsal bones, respectively, the long bones of the hands and feet. There are three phalanges in the finger and two in the thumb. The four smaller toes likewise contain three phalanges while the big toe has two. The proximal phalanges are distinguished from the middle and distal phalanges in that they are nearest the body, while the distal phalanges are the farthest from the body in the tips of the fingers and toes.

As an anatomical term of relative location, proximal is often used to refer to the near end of a limb or extremity. Distal, by contrast, refers to the far end of a bodily structure. This holds true for joints, as well, so the articulation between the proximal phalanges and middle phalanges in the four smaller fingers and toes is known as the proximal interphalangeal joint, whereas the articulation between the middle phalanges and distal phalanges is known as the distal interphalangeal joint. The articulations between the proximal and distal phalanges in the thumb and big toe are known simply as interphalangeal joints.

Identifiable as the bone between the two largest knuckles of each finger, the proximal phalanx, as it is known in the singular, is longer and thicker than the middle and distal phalanges. When making a fist, the proximal phalanges form the flattened aspect of the hand that would make contact when throwing a punch. Considered to be long bones, they are longer than they are wide, with the shaft of each bone slightly narrower than its ends.

In the foot, the proximal phalanges feature slightly different dimensions. While the proximal and middle phalanges in the fingers are similar in length, the proximal phalanges in the toes are significantly longer that the middle and distal bones. Additionally, those in the toes are narrower along their shafts relative to their ends than are the phalanges of the fingers.

Though the proximal phalanges in the fingers and toes are not named individually, they can be identified by a number that corresponds to the finger or toe in which they are found. The proximal phalanx in the thumb, for instance, is known as the first proximal phalange, while that in the little finger is known as the fifth. In the foot, the bone in the big toe is the first phalange while the pinky toe is the fifth.