Corpus: Carpal bones
from ancient Greek: καρπός ("karpos") - root of the hand
Synonym: wrist bones
1. Definition
2. Anatomy
The carpal bones are arranged in two rows, known as the proximal and distal carpal rows. These bones are connected via cartilaginous articular surfaces and stabilized by strong ligaments.
2.1. Proximal row
The proximal row includes:
2.2. Distal row
The distal row consists of:
There is limited mobility between the proximal and distal rows of carpal bones due to tight ligament connections.
3. Varieties
Accessory carpal bones, such as the os pisiforme secundarium, os centrale, os trapezoideum secundarium, or os styloideum, occasionally occur. These variants may form due to additional ossification centers or trauma.
4. Function
The carpal bones are crucial for hand mobility. Together with the radius, the proximal carpal row forms the wrist joint, while distally, they connect with the metacarpal bones. This configuration enables movements such as thumb opposition via the saddle joint.
5. Development
All endochondral bone nuclei in the carpal bones develop after birth. The ossification process begins within the first year of life, with the capitate and hamate bones typically developing as early as the 3rd month. The triquetral bone ossifies later, between the 2nd and 3rd year, with gender differences noted: in girls, the nucleus appears at the beginning of the 2nd year, while in boys, it appears after 2.5 years.
The lunate bone ossifies between the 3rd and 6th years of life, and the scaphoid bone follows, developing between the 4th and 6th years. The trapezium and trapezoid bones also ossify during this same period. The pisiform bone is the last to ossify, with its nucleus appearing between the ages of 8 and 12.
6. Mnemonic Aids
- S'he l'ooks t'oo p'retty, t'ry t'o c'atch h'er!
- S'ome l'overs t'ry p'ositions t'hat t'hey c'an't h'andle!