CARPUS SCAPHOID AND SEMILUNAR BONES. 109 



year, and the superior about the seventh. The bone is perfected at 

 twenty. 



.Articulations. With four bones; humerus, ulna, scaphoid, and semi- 

 lunar. 



Attachment of Muscles. To nine; by the tuberosity to the biceps ; by 

 the oblique ridge to the supinator brevis, pronator radii teres, flexor sub- 

 limis digitorum and pronator quadratus ; by the anterior surface, to the 

 flexor longus pollicis and pronator quadratus ; by the posterior surface, to 

 the extensor ossis metacarpi pollicis, and extensor primi internodii ; and 

 by the styloid process, to the supinator longus. 



CARPUS. The bones of the carpus are eight in number ; they are ar- 

 ranged in two rows. In the first row, commencing from the radial side, 

 are the os scaphoides, semilunare, cuneiforme, pisiforme ; and in the se- 

 cond row, in the same order, the os trapezium, trapezoides, os magnum, 

 and unciforme. 



The SCAPHOID bone is named from bearing some resemblance to the 

 shape of a boat, being broad at one end, and narrowed like a prow at the 

 opposite, concave on one side, and convex upon the other. It is, how- 

 ever, more similar in form to a cashew nut, flattened and concave upon 

 one side. If carefully examined, it will be found to present a convex and 

 a concave surface, a convex and a concave border, a broad end, and a nar- 

 row and pointed extremity, the tuberosity. 



To ascertain to which .hand thie~1>one belongs, let the student hold il 

 horizontally, so that the convex surface may look backwards (i. e. towards 

 himself), and the convex border upwards: the broad extremity will indi- 

 cate its appropriate hand ; if it be directed to the right, the bone belongs 

 to the right ; and if to the left, to the left carpus. 



Articulations. With five bones ; by its con- Fi - 53 -* 



vex surface with the radius; by its concave 

 surface, with the os magnum and semilunare ; 

 and by the extremity of its upper or dorsal 

 border, with the trapezium and trapezoides. 



Attachments. By its tuberosity to the ab- 

 ductor pollicis, and anterior annular ligament. 



The SEMILUNAR bone may be known by 

 having 1 a crescentic concavity, and a some- 

 what crescentic outline. It presents for exami- 

 nation four articular surfaces and two extremi- 

 ties ; the articular surfaces are, one concave^ 

 one convex, and two lateral, one lateral surface 

 being crescentic, the other nearly circular, and 

 divided generally into two facets. The extre- 

 mities are, one dorsal, which is quadrilateral, flat, and indented, for th 



* A diagram showing the dorsal surface of the bones of the carpus, with their articu 

 lations. The right hand. 2. The lower end of the radius. 1. The lower extremity 

 of the ulna. 3. The inter-articular fibro-cartilage attached to the styloid process of tho 

 ulna, and to the margin of the articular surface of the radius. S. The scaphoid bone. 

 L. The semilunare articulating with five bones. C. The cuneiforme, articulating with 

 three bones. P. The pisiforme, articulating with the cuneiforme only. T. The first 

 bone of the second row, the trapezium, articulating with four bones. T. The second 

 bone, the trapezoides, articulating also with four bones. M. The os magnum articu 

 latir.g with seven. U. The unciforrne, articulating with five. 



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