Anatomy
The metatarsals are also called Metatarsalia or Ossa metatarsi I-V, because on each foot the human has five metatarsals, which are numbered from the inside to the outside with the numbers I to V. Each of these consists of:
- The base
- The corpus (middle piece) and
- The caput (head)
In the area of the base, the metatarsal bones together with certain tarsal bones (3 Ossa cuneiforme = 3 sphenoid bones, Os cuboideum = cuboid bone) form the so-called tarsal metatarsophalangeal joints. In this joint, however, hardly any movement is possible, since tight ligaments prevent this; it is called amphiarthrosis. The joint space is known as the Lisfranc amputation line, since the metatarsus can be severed (amputated) here.
The head of the metatarsal bones together with the base of the toe bones form the metatarsophalangeal joints. In this joint, the toes can be stretched upwards by about 50° and bent downwards by about 40°. In addition, a slight movement of the toes outwards and inwards is possible.
The metatarsals are involved in the formation of the arch of the foot, which is formed between the tarsal and metatarsal bones. The metatarsal bones are arranged in an arch. The arch of the foot is secured by muscles and ligaments and serves the stability of the foot.
A distinction is made between a longitudinal and a transverse arch. If this arch is insufficiently developed, so-called foot deformities occur, such as flat foot, hollow foot, splayfoot, etc. In the case of the splayfoot, for example, the metatarsal bones are no longer arranged in an arch, but lie in a row next to each other, which leads to a widening of the forefoot.
Bone fractures (metatarsal fractures)
If a blow or similar directly hits the forefoot, one or more metatarsal bones may be broken. Often, however, such a bone fracture also occurs as a fatigue fracture (= marching fracture). If such an injury is present, pain, swelling and hematoma formation occur.
X-rays should definitely be taken. Often these fractures can be healed without surgery by wearing a lower leg cast for 6 weeks. In more complicated fractures, however, surgical treatment is necessary to ensure the correct position of the metatarsal bones.