HOMOLOGY OF THE BONES OF THE LIMBS 



209 



In the tarsus, the tibiale and intermedium coalesce to form the talus, and the fibulare 

 becomes the calcaneus. It is interesting to note that although in the human subject there are 

 three bones in the first row of the carpus and two in the first row of the tarsus, in carnivores the 

 navicular and lunate are united to form a naviculo-lunate bone^-the homologue of the talus. 

 In the human tarsus the intermedium occasionally remains distinct as the os trigonum. 



Tarsale I forms the first cuneiform, tarsale II the second cuneiform, tarsale III the third 

 cuneiform, and tarsale IV and V are joined to form the cuboid. The os centrale forms the 

 navicular. 



In addition to the carpal and tarsal elements enumerated above, brief mention must now 

 be made of the sesamoid bones of the two segments, which are regarded by many anatomists 

 as vestiges of suppressed digits. In the hand are the ulnar and radial sesamoids, the ulnar 

 being represented by the pisiform and the radial probably by the tuberosity of the navicular. 

 (In the mole and other allied species with fossorial habits, the radial sesamoid is greatly de- 

 veloped to form a sickle-shaped bone which has received the name of os falciforme.) 



The corresponding structures in the foot are the tibial and fibular sesamoids, the tibial 

 being most nearly represented by the tuberosity of the navicular and the fibular by the tuber 

 of the calcaneus. 



Table Showing the Homologous Bones of the Carpus and Tarsus. 



in Quain's Anatomy.) 



Carpus Primitpve Names 



{After G. D. Thane 



Tarsus 



References. — For the development of the skeleton, consult the bibliography 

 in Bardeen's article in Keibel and Mall's ' Human Embryology/ Vol. 1. For 

 further references concerning the adult structure and morphology of the skeleton, 

 the sections on osteology in the larger works on human anatomy by Quain, von 

 Bardeleben, Rauber-Kopsch. Poirier-Charpy, etc., should be consulted. Refer- 

 ences to the most recent literature may be found in Schwalbe's Jahresbericht, 

 the Index Medicus, and in the various anatomical journals. 



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