Carpal bones
A – H = carpal bones
2 ulna ( ulna )
3 metacarpal bones ( ossa metacarpalia )
The carpal bones ( carpal bones , ossa carpi , Latin os , plural ossa , 'bones' and old Greek καρπός karpos 'carpal') belong to the short bones ( ossa brevia ) of the skeleton . In humans, each carpal ( carpus ) consists of eight carpal bones, which are divided into two rows of four bones each.
Carpal bones of man
- The next to the body ( proximal ) row consists of (described from the thumb to the little finger)
- A scaphoid bone ( os scaphoideum or os carpi radiale , formerly also os naviculare ),
- B moon bone ( os lunatum or os carpi intermedium ),
- C Triangular bone ( Os triquetrum or Os carpi ulnare , in French also Os pyramidal ), to which the
- The pea bone ( os pisiforme or os carpi accessorium ) rests on it.
- The distal ( distal ) series ( Ossa carpal bones, carpal bones ) is (from the thumb to little finger described) from
- E Large polygonal bone ( Os trapezium or Os carpale primum , formerly also Multangulum maius ),
- F Small polygonal bone ( Os trapezoideum or Os carpale secundum , formerly also multangulum minus ),
- G headbone ( Os capitatum or Os carpale tertium ) and
- H Hook bone ( Os hamatum or Os carpale quartum ).
The arrangement of the bones can be imprinted with the following slogans :
- Body-hugging row: a boat that drove in the moonlight in a triangle around the pea leg.
- Row distant from the body: large polygon, small polygon, the head must be on the hook.
Some Lovers Try Positions - That They Can't Handle or So Long To Pinky , Here Comes The Thumb (lined up in an arc) is used as a learning aid in English , whereby the first letters of the words correspond to those of the Latin short names of the carpal bones .
The scaphoid bone is the main joint connection to the spoke (radius), on the finger side to the large polygonal bone ( os trapezium ), small polygonal bone ( os trapezoideum ) and to the head bone ( os capitatum ). The navicular ( scaphoid ), in clinical practice often referred to the outdated notion as "navicular" is at the wrist of the most commonly fractured bones. The fracture is often overlooked on standard x-rays and is better represented in the so-called "scaphoid quartet". However, the gold standard of diagnostics is the CT cross- sectional examination. While in the past often conservative treatment measures, i.e. a plaster treatment over 12 weeks, were used, today there is a tendency towards surgical therapy. A special screw is typically inserted into the bone via a minimally invasive approach that ideally only perforates the skin. In the event of non-treatment or incorrect treatment, there is a risk that the bony will not heal, a so-called " pseudarthrosis ". As a result of the pseudarthrosis, in turn, there is an imbalance in the statics of the carpal bones and changes in force transmission in the wrist. In extreme cases, the wrist collapses (SNAC wrist; SNAC: scaphoid nonunion advanced collaps). If left untreated, these changes lead to increased wear and tear on the joints, known as osteoarthritis.
The lunar bone represents the joint connection both to the spoke and to the ulna (ulna), on the finger side also to the head bone ( os capitatum ) and to the hook bone ( os hamatum ). The lunar bone fractures much less often than the scaphoid bone, but can be forced out of the carpal connection (lat. Luxate ) with appropriate force . In fact, dislocations of the remaining carpal bones around the lunar bone that has remained in place are even more common (“de Quervain's dislocation fracture”). Occasionally there is a so-called Lunatum- malacia . This is a gradual loss of bones caused by recurring microtraumas. An example of this is the construction worker who has been handling a jackhammer for a long time. Treatment of lunate malacia is difficult. In addition to bone removal and replacement with tendons, the relocation of another carpal bone, the pisiform bone, or the very complex revascularization operation, in which an attempt is made to reconnect the bone to the blood vessel system, are used.
The triangular and pea bones are only responsible for the connection to the ulna, on the finger side to the hook bone ( os hamatum ).
On the finger side, the carpal bones remote from the body establish a connection to the metacarpal bones of the following fingers: the large polygonal bone to the thumb and index finger , the small polygonal bone to the index finger and middle finger , the head bone to the middle and ring finger and the hooked bone to the ring finger and little finger .
Comparative anatomy
In the other mammals, some carpal bones are species-specific (or specific to other taxa ) receded or fused. The os carpale secundum is often missing in horses . When predators are radial carpal bone and carpal intermedium for intermedio radial carpal bone grown. In ruminants , the os carpale primum is missing and the os carpale secundum and os carpale tertium are fused together.
literature
- Franz-Viktor Salomon: musculoskeletal system . In: Franz-Viktor Salomon et al. (Hrsg.): Anatomie für die Tiermedizin . Enke-Verlag, Stuttgart 2004, pp. 22-234. ISBN 3-8304-1007-7
- W. Platzer: Pocket Atlas of Anatomy, Volume 1 - Musculoskeletal System . Thieme Verlag, Stuttgart 2005, p. 124. ISBN 3-13-492009-3
