Pkoc. Eot. Soc. Victoria, 23 (N.S.). Pt. II., 1911.] 



Art. XXIX. — Some Observations on the Coni^jarative 

 Anatomy of the Fibula. ^ 



By WILLIAM MACKENZIE, M.D., F.R.S. (Edin.). 

 (With Plates LXXVI.— LXXVIII.). 



[Read lOtli November, 1910]. 



Bone serves vai'ious uses in the animal economy. Of its sub- 

 sei^nence to muscle there are numerous instances scattered 

 throughout the comparative world. Thus, muscle dominance 

 produces a broadening of the bone surface where muscle attach- 

 ment is required, and a narrowing or rotundity where such attach- 

 ment is diminished or absent, compactness or lightness of bone 

 "where strength or otherwise is requisite, and bony ridges, and 

 projections to afford leverage, as, for example, in the case of the 

 attachment of the two thigh flexors in the leg of the Koala 

 Phascolarctus. As obviously the erect position adopted by man 

 and consequent mode of progression have impaired the func- 

 tion of numerous muscles throughout the body, i-ecognition of 

 acconitpanying bony changes becomes a matter not only of com- 

 parative, but also of surgical interest. 



If we regard the extremities, one would naturally expect such 

 changes to be more marked in the lower than the upper limb, 

 and indeed that is so. Man's hand not distinguishable much 

 from that of the tree climber, and having independent thumb 

 action is capable of numerous possibilities of adajDtion, though 

 Koala with his two thumbs is to be envied ; but in the lower 

 limb which we use solely for ambulation no longer have we 

 the approximating Hallux of the Koala or Lemur — we simply 

 require a broadened surface for support ; the intermediat-e 

 position between the Hallux of man and of the Lemur or Koala 

 being seen in the Baboon. Associated with this alteration of 



1 The work in connection with this paper was done in the Anatomical Department, 

 Veterinary School, Melbourne University. 



