The phalanges are among the most delicate structures of the human skeleton. As a freely movable part of the bony foot, they belong to the lower extremity. With the exception of the two-limbed big toe, the toes each consist of three individual bony members.
What are the bones of the toes?
The toes are located at the distal end of the foot and, as its end members, form the final termination of the lower extremity. Analogous to the hand, the structure of the foot can be distinguished between the tarsal bones, the metatarsals, and the phalanges. In total, the foot skeleton is composed of 26 individual bones, including 14 phalanges. These connect distally to the metatarsal bones. In all five toes, they are made up of several, individual bone links, the so-called phalanges. These are called proximal, medial or distal phalanges, or also proximal phalanges, medial phalanges and distal phalanges, depending on their position in relation to the trunk of the body. The phalanges are held together by articular connections as well as muscles, ligaments, and tendons and, accordingly, are flexibly movable.
Anatomy and structure
The individual toes have two bony links, or phalanges, in the big toe and three in all other toes. The medial phalanx is absent in the big toe. According to their structure, the phalanges can be divided into a proximal base, a body located in the middle, and a distal head. The phalanges are among the elongate tubular bones with two cartilaginous articular endings and an intervening shaft. The proximal phalanges, which are directly attached to the tarsals, are longer than the middle and distal phalanges and have a biconcave shape. The squat-looking medial phalanges connect the proximal and distal phalanges as the middle phalanx. Size-wise, the medial phalanx also lies in the middle, with the shaft slightly wider than that of the proximal phalanges. The relatively stunted and flattened terminal phalanges are comparatively the shortest of the phalanges. Based on toe length, different foot shapes are distinguished. The most common is the so-called Egyptian foot, in which the big toe is the longest.
Function and tasks
The connection of the individual phalanges is based on small joints. The articular surfaces of the metatarsophalangeal joints, also called metatarsophalangeal joints, are formed from the bones of the metatarsus and the associated phalanges. The joints located between the proximal and middle phalanx and between the middle and distal phalanx are described as toe middle joints and toe end joints, respectively, and proximal and distal interphalangeal joints. Thus, all toes except the big toe each have three joints: the proximal joint and the two interphalangeal joints. The metatarsophalangeal joints are functionally classified as the egg joints, which allow movement in two axes, namely abduction and adduction, i.e. movements to the side, and flexion and extension, i.e. movements forward and backward. The interphalangeal joints are hinge joints that allow only one direction of motion with flexion and extension only. The big toe has only one interphalangeal joint because of the lack of a medial phalanx. In summary, the following movements can be performed with the toes: flexion in the direction of the sole of the foot, extension in the direction of the dorsum of the foot, and spreading apart and drawing together of the toes. The foot with its anatomically differentiated, freely movable phalanges is the part of the human locomotor system on which the various fine motor processes of locomotion are based. The stabilization function of the toes is not only a prerequisite for running or walking, but also for certain sports or movement sequences such as hopping or dancing. The big toe is essential for all the fine motor functions. This serves both to roll and cushion the foot and to push it off the ground, i.e. to accelerate the walking motion.
Diseases
Malformed toe bones or toes with limited weight-bearing capacity due to disease have a limiting effect on the mobility of those affected. Different clinical pictures such as arthrosis and gout, but also malformations or fractures are possible causes for this impairment.The clinical picture of osteoarthritis describes degenerative signs of wear and tear on joints, which is usually due to progressive destruction of the protective cartilage layer on the joint surfaces. Symptomatically, swelling and limited mobility occur in the area of the joint as well as load-dependent pain at the beginning and rest pain in the further course. As the disease progresses, malpositions are observed, causing contractures and ultimately stiffening of the joint. The wear-related stiffening of the metatarsophalangeal joint of the big toe as a consequence of osteoarthritis is called hallux rigidus. The deformity most frequently noted in the foot is hallux valgus or bunion. In this case, the metatarsophalangeal joint of the big toe is angled laterally outward and the first metatarsal bone shows an inward deviation. Externally, this is represented by a strongly protruding ball of the toe. The deformities in the area of the small toes, i.e. toes 2-4, include the hammer toe and the claw toe. Hammer toe is characterized by a hammer-like bent toe with simultaneous hyperextension in the metatarsophalangeal joint. Depending on whether the deformity can be repositioned or not, a distinction is made between a flexible and a fixed hammer toe. A clawed toe with simultaneous subluxation or dislocation of the metatarsophalangeal joint to the dorsal side is typical of a clawed toe. The tip of the toe usually no longer touches the ground. In a fracture of the toes, the distal phalanx is usually affected. Most commonly, such a fracture is caused by direct, external force on the bone.
