Wrist bones

Wrist bones. General information

Bones of a wrist are formed by set of 8 small spongy bones which are located in two ranks, in each of which is on 4 stones.

The first or proximal row located closer to a forearm consists of the following bones presented one after another since a thumb:

• carinate or os scaphoideum;
• semi-lunar or os lunatum;
• trihedral or os triquetrum;
• pea-shaped or os pisiforme.

Connection of the first three stones forms an elliptic joint surface which joints a wrist and the distal end of a beam bone. The pea-shaped bone of a wrist which can be carried to a sesamoid stone, in turn, is attached to a trihedral bone.

The second row of bones of a wrist – distal – is formed by the following stones:

• trapeze or os trapezium;
• trapezoid or os trapezoideum;
• capitate or os capitation;
• ankyroid or os hamatum.

The surface of each bone is supplied with special joint facets which help stones to connect to the next bones. Also on palmar surfaces of a number of bones of a wrist hillocks to which sheaves and muscles fasten are located. Treat such bones: carinate, trapeze, ankyroid.

The habit view of bones of a wrist has the form of the arch which convex part is located on the palm back, bent – on palmar.

Nearly all 8 bones of a wrist have six surfaces (except pea-shaped). At the same time all bones without exception belong to joint: their lower surface creates sockets, and upper – articular heads. Between the side surfaces of bones there are also joints tying wrist bones among themselves.

Injuries of bones of a wrist

Among the most widespread injuries of a wrist there are dislocations and fractures:

• Dislocations of bones of a wrist. Dislocations happen different options, depending on the bones involved in an injury. Most often dislocations of a semi-lunar bone meet, is slightly more rare – carinate, is rare – pea-shaped. To distinguish dislocation of a semi-lunar bone rather difficult even by means of X-ray inspection. Nevertheless, the main symptoms is the following: existence of a ledge in the center of the palmar side of a wrist and retraction on back, feeling of pain when straightening fingers which are often not mobile or takes the form of halfbent. Besides, the radiocarpal joint swells up a little from a palm, the movements are painful. Dislocation by a reverse thrust, drafts or pushings through by Beler's method is set. Navicular dislocation often is followed by a change. It is possible to diagnose it only by means of radiological inspection. Such dislocation under anesthetic or a local anesthesia by draft then the bandage is applied is set, the special gymnastics, physical therapy is appointed. Dislocation of a pea-shaped bone of a wrist, as a rule, does not exert a negative impact on functioning of a brush and a wrist. Operational treatment at which the bone is hemmed on the place is appointed, and on the copular device stitches are put;
• Fractures of bones of a wrist – the phenomenon rather rare, however the navicular is most subject to changes. In more exceptional cases (as well as at dislocations) fractures of semi-lunar and pea-shaped bones are possible. Fractures of other bones of a wrist – exceptional cases. The change of a navicular is possible in the situations connected with falling on the bent hand, punch on a firm surface or at direct stroke to a palm. In most cases at a change the navicular breaks on two parts. Change symptoms the are as follows: morbidity of a radiocarpal joint amplifying at load of I or II fingers, impossibility of compression of a brush in a fist because of pain. Diagnosis is carried out by means of X-ray inspection, treatment includes an immobilization from 1 to 6 months. If the wrist bone fracture at the same time is not followed by shift, then it is recommended to apply a plaster bandage approximately for 3 months. In the presence of shift carry out an osteosynthesis of bone fragments by screws. At the same time the term of an immobilization increases up to 2 months. The fracture of a semi-lunar bone arises when falling on a brush or as a result of direct stroke. After damage puffiness of a joint, the pain amplifying at extension of a brush in the back is noted. Treatment means imposing of a plaster splint which term of carrying makes from 1,5 to 2 months. As a rule, complications at accretion of a bone are not noted. The most rare species of fractures of bones of a wrist – a fracture of a pea-shaped bone which reason of an injury are blows in the field of damage or blow by a brush edge on a firm surface. Symptoms are pain around a radiocarpal joint from a little finger which amplifies at compression of a brush in a fist or attempt to bend a little finger. Treatment assumes the immobilization lasting not less than 1 month.