211 



Nachdruck verboten. 



An Os centrale (Rosenberg) partially united to the Scaphoid. 



By William Wright. 

 With one Figure. 



The above anomalous condition of an accessory carpal bone was 

 met with in the left hand of a male subject during its dissection in 

 the anatomical rooms of the Birmingham University. 



The Os centrale had the shape of a rounded pyramid, the apex 

 pointing outwards and backwards the base forwards and inwards: its 

 height and maximum breadth each measured 9 mm. The base of the 

 pyramid articulated with the Os magnum, the inferior surface with the 

 trapezoid, the other articulating surfaces which were rounded and 

 convex with the scaphoid, the bone being received into a hollow on 

 its infero-internal aspect. Dorsally it was united with the scaphoid 

 but on levering it out of its bed it readily detached itself from that 

 bone in a way incompatible with a strong osseous union. It did not 

 appear on the dorsal aspect of the carpus owing to its being covered 

 by a thin lamina of bone which projected inwards from the scaphoid ; 

 so thin was the lamina that its origin — in part at least — from an 

 adventitious ossification of a dorsal ligament was suggested. 



The articulating surfaces were cartilaginous and smooth, the 

 synovial cavity between it and the scaphoid being disposed as is seen 

 in the sketch of the bones taken from the antero-internal aspect. In 

 looking through the English literature on the subject I have only 

 been able to discover one undoubted case of this 

 variety of Os centrale whilst none of the other 

 three varieties of ossa centralia to which Pfitzner 

 and Thilenius have directed attention have so far 

 as I know been reported. The case above mentioned 

 was described by Sir William Turner in 1883 

 and closely resembles the one here noted although 

 the os centrale was quite free and appeared on 

 the dorsal aspect of the carpus, the dorsal surface 

 of it and the scaphoid being connected by a liga- Scaphoid and Os centrale 

 mentous band. 



The specimen here figured has a further interest in that it 

 throws light upon the causation of the two forms which the scaphoid 



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