ZOOLOGY FOR MEDICAL STUDENTS 



CHAP. 



ankle -in other words to the type of jointing actually characteristic of 

 tin 1 tetrapod hind-limb. We may take it that the hind-limb was the 

 more important in pushing the body forward and it is probably in 

 ronvlation with this that the fore-limb shows a simpler jointing the 

 flexure in the wrist region being less marked than that in the ankle. 



The limb of the tetrapod is supported by a well-developed bony 

 skeleton which, while showing endless differences in detail, correlated 

 with variations in function, is arranged on a common general plan 



I ORE I.IMU. /-^ HIND-LIMB. 



Scapula 



Phalanges 

 Pre-axial. 



T ,' A v 



Phalanges 

 Post-axial. 



" m 



FIG. 179. 

 Diagram of limb-skeleton of a Tetrapod. 



throughout the Tetrapoda. This common plan is shown diagrammatically 



. 179. There is a general correspondence between the elements 



) to build up the skeleton of the pectoral and the pelvic limb 



respectively although different sets of names have been allocated to 



tin- individual elements as is indicated in Fig. 179. 



It .should be mentioned that in describing the details of the tetrapod 



limb it is customary to suppose the limb to be placed in a position 



ending to that of the human arm when extended at right angles 



the Ion;, axis of the body, with the palm of the hand facing forwards. 



' line passing outwards along the centre of the limb to the 



