THE CARPUS AND METACARPUS. 339 
THE CARPUS (KNEE) AND METACARPUS (CANNON). 
Tue KNEE of the horse corresponds with the wrist of man, and though 
tl2 name so well known to horsemen will probably always be maintained, 
yet scientifically each of the bones receives the cor- 
‘responding names, and the whole group is called the 
carpus. 
The anterior surface of the carpus is convex ; 
the posterior, concave and irregular, and marked by 
bony prominences. 
It consists of eight bones, disposed in two rows, 
one above the other, as follows :— 
The first, or top row, beginning to enumerate 
from within outwards, consists of the scaphoid, 
lunar, cuneiform, and pisiform bones. 
The second, or lower row, consists of the ossa 
trapezoid, magnum, and unciforme, and sometimes 
of a small floating bone situated behind the trapezoid. 
The superior row may be described as follows :— 
Os ScaPHOoIDES (cxady, a cradle), the largest of 
this row, articulates superiorly with the inferior 
and inner extremity of the radius, internally by 
means of two distinct facettes with the os lunare, 
and inferiorly with the os trapezoides and os 
magnum. 
Os Lunarz (luna, the moon) articulates superiorly 
with the radius, internally as before mentioned with 
the os scaphoides, and externally through the me- 
dium of two facettes with the os cuneiforme. 
Os CuNEIFORME (cuneus, a wedge) articulates su- 
‘ periorly with the inferior and outer extremity of 
the radius, inferiorly with the os unciforme, and 
posteriorly with the os pisiforme. 
Os PisIFoRME (pisum, @ pea) is situated at the 
postero-external side of the top row, and presents for 
description two surfaces and four borders. The ex- 
ternal surface is unevenly convex, and elevated for 
ligamentous attachment. The internal surface is 
concave and porous, and also roughened for lga- 
mentous attachment. The anterior border presents 
two smooth ovoid surfaces: the superior one arti- 
culates with the radius; the inferior with a corre- 
sponding surface, mentioned as occurring on the pos- 
terior surface of the os cuneiforme. The three other 
borders, namely, the superior, posterior, and inferior, 
are unevenly convex, and roughened for the attach- 
ment of ligaments. 
_ The bones of the inferior row, viz. the Os TRAPE- 
ZOIDES (tpamela, a table), OS Macnum (the large bone), 
‘and Os UncirorME (uncus, a hook), articulate laterally 
one with the other, superiorly with the top row of 
Fic. 27.—Forr View or 
THE CARPAL BONES, COM- 
MONLY CALLED THE KNEE. 
2. Lower extremity of 
radius. 
3. Ulna, lower extremity 
of. 
. Os pisiforme. 
— cuneiforme. 
. — lunare. 
— scaphoides. 
— unciforme. 
9. — magnum. 
). Large metacarpal bone. 
11. Small metacarpal bone. 
QI oe 
w 
Fia. 28.—Os PisirorMe. 
1. Body of os pisiforme. 
2. Surface articulating 
with inferior ex- 
tremity of the ra- 
dius. 
3. Surface articulating 
with the cuneiform 
bone. 
bones, and inferiorly with the three metacarpal bones. 
THe MeracarpaL Bones, answering to the bones in the palm of tha 
hand of man, are three. One (metacarpus magnus) 
Z2 
is much larger than 
