Figure 1.
Bones and ligaments in a capuchin left hand.
A) surface of carpo-metacarpal joint. The black circle highlights the convex lateral joint surface of trapezium bone with metacarpal; the arrow indicates the central bone; 1) trapezium; 2) trapezoid; 3) capitate; 4) hamate; 5) pyramidal; 6) pisiform; 7) lunate; 8) scaphoid (bar = 4.0 cm). B) Lateral view of metacarpal I. The white arrow indicates the concave surface joint that connects with the trapezium bone (bar = 2.0 cm).
Figure 2.
Dissection shows (arrow) the tendon of insertion of digit I long flexor muscle, (1) opponent muscle, and adductor muscle’s (2a) oblique head and (2b) transverse head. (bar = 2.8 cm).
Figure 3.
Carpal bones in the right hand of a capuchin monkey.
A. Top view of the carpus: (1) scaphoid, (2) lunate, (3) pyramidal, (5) hamate, (6) capitate and (7) trapezoid bones. The arrow indicates the central bone. B. Bottomview of the carpus: (4) pisiform bone. The trapezium bone is not present in this piece (bar = 4 cm).
Figure 4.
Comparison of human and capuchin carpal bones.
A. Carpal bones in the human right hand (top view): (1) scaphoid, (2) lunate, (3) pyramidal, (4) hamate, (5) capitate, (6) trapezoid and (7) trapezium bones (bar = 2 cm). B. Carpal bones in the capuchin right hand (top view). The numbers indicate the corresponding bones of figure 14A. The arrow indicate the central bone and the asterisk * indicantes the metacarpal I (bar = 6 cm). The pisiform bone is not visible in either photographs.
Table 1.
Ratio (plus standard deviation) between carpal bones and carpus in capuchin and human († significant difference; Chi-square, p<0.05).
Figure 5.
Schematic representation of axis relations in capuchin and humans.
Note that the trapezium in humans is located lower relative to the horizontal axis in humans (A) than in capuchin (B). The angle between the carpal plane and the longest trapezium axis is approximately 80° in humans (Napier, 1955) and 110° in capuchins. * indicates the hamate’s hamulus and the arrow indicates the pisiform bone, which is proportionally larger in capuchin.
Table 2.
Ratio (plus standard deviation) between some axes in the capuchin and human wrists († significant difference; Chi-square, p<0.05).
Figure 6.
Nail-pulp and medial axes’ angle comparison.
(A) Photograph of a capuchin’s right hand, dissected (bar = 0.5 cm) and (B) human left hand (bar = 1.2 cm). Note that the angle formed by the crossing of the axes is of approximately 30° in capuchins and approximately 90° in humans.