Reference > Anatomy of the Human Body > Page 221
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Henry Gray (1825–1861).  Anatomy of the Human Body.  1918.
 
in the lower end; and at the fifth year, in the upper end. The upper epiphysis fuses with the body at the age of seventeen or eighteen years, the lower about the age of twenty. An additional center sometimes found in the radial tuberosity, appears about the fourteenth or fifteenth year.


FIG. 217– Plan of ossification of the radius. From three centers. (See enlarged image)



FIG. 218– Epiphysial lines of radius in a young adult. Anterior aspect. The line of attachment of the articular capsule of the wrist-joint is in blue. (See enlarged image)

 
6b. The Hand. 1. The Carpus
 
  The skeleton of the hand (Figs. 219, 220) is subdivided into three segments: the carpus or wrist bones; the metacarpus or bones of the palm; and the phalanges or bones of the digits.
  
The Carpus (Ossa Carpi)


The carpal bones, eight in number, are arranged in two rows. Those of the proximal row, from the radial to the ulnar side, are named the navicular, lunate, triangular, and pisiform; those of the distal row, in the same order, are named the greater multangular, lesser multangular, capitate, and hamate.

Common Characteristics of the Carpal Bones.—Each bone (excepting the pisiform) presents six surfaces. Of these the volar or anterior and the dorsal or posterior surfaces are rough, for ligamentous attachment; the dorsal surfaces being the broader, except in the navicular and lunate. The superior or proximal, and inferior or distal surfaces are articular, the superior generally convex, the inferior concave; the medial and lateral surfaces are also articular where they are in contact with contiguous bones, otherwise they are rough and tuberculated. The structure in all is similar, viz., cancellous tissue enclosed in a layer of compact bone.

Bones of the Proximal Row (upper row).—The Navicular Bone (os naviculare manus; scaphoid bone) (Fig. 221).—The navicular bone is the largest bone of the proximal row, and has received its name from its fancied resemblance to a boat. It is situated at the radial side of the carpus, its long axis being from above downward, lateralward, and forward. The superior surface is convex, smooth, of triangular shape, and articulates

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