BONES OF THE HAND. 49 



Scaphoid, 5. Semilunar, 5. Cuneiform, 3. Pisiform, I. 

 Trapezium, 4. Trapezoid, 4. Os-magnum, 7. Unciform, 5. 



What peculiarities have the Carpal bones ? The first three enter into the 



formation of the wrist-joint ; the pisiform does not, but is wholly without it, 

 and may be considered a mere appendage of the carpus. When the hand is 

 in pronation 



The Scaphoid, or boat-shaped bone, has a tuberosity on its outer side, its 



largest auricular facet is uppermost, and a transverse groove crosses its 



posterior surface. 

 J^he Semilunar Bone has a crescentic facet externally, and a convex facet 



superiorly. 

 The Cuneiform Bone is wedge-shaped, its convex surface above, and has an 



isolated facet for the pisiform articulation. 



The Pisiform Bone is the smallest, and has but one facet, which lies poste- 

 riorly when the bone is in position. 

 The Trapezium has a deep groove for the tendon of the flexor carpi radialis, 



and a saddle-shaped facet, inferiorly. 

 The Trapezoid is small and quadrilateral, bent on itself, with a saddle-shaped 



facet looking downwards. 

 The Os-magnum has a head looking upwards, a neck, and a body ; is the 



largest bone of the carpus, and has a tubercle on the inner side of the base. 

 The Unciform Bone is triangular, with a concavity which lies to the outer 



side; and the unciform process, long and curved, projecting from its palmar 



surface. 



Describe the Metacarpus. The 5 metacarpal bones are placed between the 

 carpus and the phalanges, are long bones, and each has a head, shaft, and 

 base. Their heads articulate with the respective phalanges. 



ist Metacarpal Bone,d articulates with the trapezium, is shorter than the 

 others by one-third, and its base has but I articular facet. This bone is 

 classed among the phalanges by Professor W. H. Pancoast. 



2d Metacarpal Bonef articulates with 3 bones of the carpus, the trape- 

 zium, trapezoid, and os-magnum ; its base is large, and has 4 articular facets. 



$d Metacarpal Bonef articulates with I bone of the carpus, the os-mag- 

 num ; its base has a projecting process on the radial side, and 2 small 

 facets on the opposite side. 



^th Metacarpal Boneg articulates with 2 bones of the carpus and with the 

 adjacent metacarpal bones; its base is small, and has 2 circular facets, I 

 on each side. 



th Metacarpal Bonefi articulates with I carpal bone, the unciform; its 

 base has I lateral articular facet. 

 5 D 



