What Is a Proximal Phalanx?

Definition and Pathologies of the Proximal Phalanges

Foot with the proximal phalanges outlined and labeled. Credit: Photo © Terence Vanderheiden, D.P.M.

In the human foot, a proximal phalanx is the bone in each toe closest to the metatarsal bone that connects to the intermediate phalanx bone. 

What Are Phalanges?

"Phalanges" is the plural form of phalanx. In anatomy it refers collectively to the digital bones in the hands and feet. There are 56 phalanx bones in the human body. The big toe (known as the hallux) and the thumb each have two phalanges, while the other fingers and toes each have three.

The phalanx bones of the toe are more shorter than those in the hand. This is particularly true of the proximal phalanx.

Shape of the Proximal Phalanx

The proximal phalanx shape is concave beneath, meaning it is curved inward, like the inside of a bowl. The top of the proximal phalanx is convex, having the opposite shape with an outward curve like the outside of a ball. The sides of the bone are compressed, making the bone narrower at the middle than at the ends.

The base end of the proximal phalanx is concave in shape where it connects to the metatarsal bone. The head of the proximal phalanx connects to the intermediate phalanx in a trochlear fashion that allows for articulation.

Foot Pathologies Involving the Proximal Phalanx

The human foot is a very complex part of the body that bears the brunt of significant forces as we move about in our lives. As such, it can be prone to injury.

Here are a few common problems that can be related to or affect the proximal phalanx.

Fractured Toe Bones
Broken toes are common, usually caused by something heavy hitting them or stubbing a toe against an object. They are quite painful and can make walking difficult. If untreated, serious fractures can heal incorrectly and cause other foot problems down the line.

Hammer Toes
Hammer toes are a common foot problem, especially among women, that can affect one or more toes, though it is uncommon in the big toe.

They are characterized by an elevated bend at the middles of the toes at the metatarsophalangeal join where the proximal phalanx meets the metatarsal bones. Weak muscles in the toes allow tendons to shorten and thus pull the toe back toward the foot, causing the elevated joint and the "hammered" appearance of the toe. One of the causes of hammer toes can be shoes that are too short.

Metatarsalgia
Metatarsalgia is pain that occurs in the foot between the arch and the toes, often in the metatarsophalangeal joint of the big toe. It is usually associated with problems with foot biomechanics or deformities. Tenderness and pain when walking are common symptoms.

Osteoarthritis
Osteoarthritis is a degenerative disease of joints where cartilage, which acts is the cushion between bones in a joint, deteriorates. It can develop as a result of the normal wear-and-tear on the joint. Sprains and injuries to the foot, abnormal foot biomechanics and deformities can also cause osteoarthritis to develop.

Osteophytes (Bone Spurs)
Bone spurs are bony growths or projections that can develop along joints.

They are often associated with osteoarthritis. They can cause pain and result in limitations to the movement of the joints they affect.

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