144 MORPHOLOGY OF THE BONES OF THE LIMBS. 



as composed of the radiale and the centrale. Traces of the central e are often to be recognized 

 in the adult scaphoid, and it may in rare cases be developed as a separate bone. In the 

 proximal series of the tarsus the course of development is somewhat different. The astragalus 

 results from the union of the tibiale and intermedium, although the latter occasionally 

 remains distinct as the os trigonum (p. 133) : at the back of the posterior articular surface on 

 the under aspect of the astragalus there is often to be seen a slight groove, indicative of this 

 separation (fig. 146). The fibulare forms the greater part of the os calcis, and the centrale of 

 the navicular bone. The pisiform bone has been considered a sesamoid bone (ulnare sesamoi- 

 dewn) developed in the tendon of the flexor carpi ulnaris, but recent investigations tend to 

 show that it is a vestige of a suppressed ray (digitus postminimus) : the corresponding 

 structure of the tarsus enters into tuberosity of the os calcis. On the outer margin of the 

 carpus there is in some animals another bone (radiale sesamoideum), which, if represented in 

 man, seems most nearly to correspond to the tuberosity of the scaphoid ; and the tuberosity of 

 the navicular bone of the tarsus may be the representative of a similar element (tibiale 

 sesamoideuni) in the foot. These so-called " sesamoid " ossifications are also regarded by 

 Bardeleben as vestiges of a suppressed digit (prepollex or prehallux). 1 



The following tables present a synoptical view of the probable corresponding or homolo- 

 gous bones and their parts in the thoracic and pelvic limbs : 



I. TABLE OP THE HOMOLOGOUS BONES IN THE THORACIC AND PELVIC LIMBS. 



THORACIC LIMB. PELVIC LIMB. 



Scapula Ilium. 



Precoracoid . . . . . . Pubis. 



Coracoid Ischium. 



Glenoid cavity . Cotyloid cavity. 



Clavicle . . . . ' . . Absent. 



Humerus ' . Femur. 



Great tuberosity . . . . . . Small trochanter. 



Small tuberosity . . . . . Great trochanter. 



External condyle and capitellum . . . Internal condyle. 



Internal condyle and trochlea ... . External condyle. 



Absent ... ... Patella. 



Radius Tibia. 



Ulna . . . . . . ... Fibula. 



Carpus '. Tarsus. 



Metacarpus Metatarsus. 



Pollex Hallux. 



Digital phalanges Digital phalanges. 



II. TABLE OF THE HOMOLOGOUS BONES OF THE CARPUS AND TARSUS. 

 CARPUS. Typical names. TARSUS. 



Pyramidal . . Ulnare. . . Fibulare < Os calcis 



Pisiform . . . Ulnare sesamoideum (?) Fibulare sesamoideum (.') . . ) 



Lunar . . . Intermedium Intermedium . . . . ) Astraffalus 



(Radiale Tibiale J A 



Scapho . . < Radiale sesamoideum (?) Tibiale sesamoideum (.') ^ Navicular 



( Centrale Centrale . . . . ) * 



Trapezium . . " Carpale I. Tarsale I Int. Cuneiform. 



Trapezoid . . II. II Mid - Cuneiform. 



Magnum . . HI. HI Ext. Cuneiform. 



Uncif orm . j ~ * V> ^ \ Cuboid. 



1 According to another view, which is supported by Baur and Leboucq, the " tibial sesamoid " is the 

 tibiale, and the astragalus the intermedium only. 



