480 



THOMAS DWIGHT ON THE 



DIAGRAM OF THE DORSAL ASPECT OF THE WRIST. 



surface of which is uncommonly large. Between them is a bone Avhich evidently is 

 the result of the fusion of two semilu- 

 nars. Its upper border is slightly 

 notched. The pisiforms in the tendons 

 of the ulnar flexors are displaced above 

 the wrist on to the ulnae. Extension of 

 the hand would have brought them on 

 to the cuneiform bones. At each end 

 of the second row there is an unciform 

 bearing the little and ring fingers. Each 

 rests on the corresponding cuneiform 

 and touches the semilunar. Next come 

 tlie two ossa magna, ver\^ symmet- 

 rically disposed, each bearing the 

 metacarpal bone of the middle finger. 

 Their anterior halves diverge so as 

 to leave an interval between them, 

 behind which they touch each other. 



their heads resting side by side in the nuddle bone of the first row. In the notch 

 between these bones is the trapezoid (os midtangulum minus) bearing the left index 

 finger. Each middle finger touches it. the extra one by a Ijroader surface than the 

 normal one of the left hand. Still it is very symmetrically placed, so that from a 

 view of the carpus alone it would be very hard to say to which side it belongs, 

 bTit a glance at the specimen or at the cast is enough to show that the index 

 finger l^elongs to the left hand. The metacarpal bones and phalanges require no 

 special description. Those of the extra hand are somewhat smaller than the normal 



one. 



The Muscles. In this account Dr. Jackson's description is followed as closely 

 as possible. "The tendons of the latissimus dorsi, teres major and iniaor, sub- 

 scapuhiris, mfrasjnnatiis, pecforalis major and minor are shown in the prepar- 

 ation." No mention is made of the supraspinatus. It has been stated that its fossa 

 is rudimentary, if present at all it must have been very small. Dr. Jackson says 

 that the delto'ul lind Ijeen i-emo\ed. The absence of the roughness for its insertion 

 and the lightness of the spine of the scapula and the acromion have been noted. 

 These facts imply that it was small ; an interesting point to be returned to later. 

 •'Coraco-brachiaHs small." The biceps is obscure. There seems to l)e a small long 

 head with probably a sliort liead from the coracoid joining it low down. The long 

 head is tendinous in the middle of the arm. This muscle is inserted into the extra 



