86 SPECIAL ANATOMY. 



1. Os [Trapezium] multangulum majus, for opponens, abductor brevis polr 

 lids, below the navicular, above the first metacarpal bone ; with a groove in 

 its palmar surface, for the tendon of the flexor, carp. rad. 



2. Os [Trapezoides], multangulum minus, s. pyramidale, for flex, pollids 

 brevis, below the navicular, above the second Os Metacarpi. Ossa multangula 

 form a concave, articular surface, for os naviculare. 



3. Os [magnum], capitatum, for adductor, and flex, brevis pollids, below the 

 scaphoid and semilunar bones, above the third metacarpal bones ; with Capi- 

 tulum. The largest bone of the second row. 



4. Os [unciforme'], hamatum, hooked bone, below the cuneiform, above the 

 oss. metacarp. iv. and v. Its hook, proc. uncinatus, for m. flex, brevis et op- 

 ponens digiti 5, lies close to the pisiform bone. 



Os capitatum et hamatum form an articular head, for the articular fossa of 

 the first row. The Middle bones have four, the external only three articular 

 surfaces. 



Structure. The carpal bones consist of a spongy, bony mass, covered ex- 

 ternally with compact tissue. Ossification commences after birth ; at the end 

 of the first year in the magnum and the unciform bone between the third and 

 fourth years in the cuneiform; between the fourth and fifth in the trapezium 

 and semilunar; between the eighth and ninth in os naviculare and trapezoid; 

 between the twelfth and fifteenth in os pisiforme, which is generally the latest 

 perfected of all the bones. 



100. 2. Metacarpus, Middle hand, 



consists of five parallel, columnar bones, which, united together 

 like a grating, are connected with the carpal bones and phalanges 

 of the fingers. 



a. Superior carpal end, Basis; enlarged, rather hollowed out, for the recep- 

 tion of the carpal bones; tri- or quadrangular, with two small lateral surfaces 

 to receive the lateral metacarpal bones. 



Basis, oss. Metacarp. 



I. For abduct, poll, long., unites with os trapezium. 



II. For flex, et extern, carp. rad. longior., with os [Trapezium], Trapezoid, and 

 [Magnum]. 



III. For extens. carp. rad. brev., with os magnum. 



IV. With os [magnum] and unciforme. 



V. For extens. carpi ulnaris., with os unciforme. 



b. Central part, for m. interossei, roundish, triangular, rather concave on the 

 palmar aspect. 



c. Inferior, digital end, capitulum, with two tubercula and one sinus on either 

 side. 



Capitul. oss. metacarpi : I. for m. opponens, abduct, brev. pottic. 



V. for m. opp. minimi digit. 



I., The metacarpal bone of the thumb, is shortw and thicker than the rest ; 

 has no lateral articular surfaces, and is moveable in a free joint, Jlrthrodia. 



II. is the longest, has on its base only one lateral articular surface. A little 

 shorter, but thicker, is 



III., with two lateral articular surfaces. 



IV. is shorter, and V. shorter still. The last has only one articular surface, 

 but a tubercle on the base, for m. extens. carp, ulnaris. 



