MUSCLES CONNECTED WITH THE SHOULDER-JolNT. 621 



as is seen by fig. 3, this muscle receives a head from a surface of the scapula as com- 

 pletely turned viscerad as the iliacal surface of the ilium ever is. The origin of the 



slender epicoraco-humeral of the Channeleon is limited to the external surface of it 

 coracoid and prcecora cold ; but its twpraqpmatu*, if we may so style the muscle which 



comes next in order from below upwards after the deltoid, does receive just such a 

 factor from the visceral surface of the scapula as do s the ejAcora co-humeral of the 



Crocodile. This muscular belly having the item of the scapula placed exteriorly to it 

 reminds one forcibly of the relation held by the os ilii to the iliac** ; but the lesson w hich 



it teaches does not depend up 



upon the retentioi 



some extent by the Chamteleon of the primitive rod-like character of the scapula, which 

 makes it easier for us to see how it may rotate anyone of its surfaces, when developed lik 

 the fluting on a column, into several different bearings in dilferent animals. It i- easier 



for us to understand how a muscle can wrap its origin round and about the various 

 aspects of a cylindriform, than it is for us to conceive of similar i n dill'crentism in the 

 various surfaces of a many-facetted bone; and upon the conquering of this difficulty 

 depends our power of homologizing the spinali with the i/iarus*. 



A second argument in the same direction presents itself from another quarter, that 

 of innervation. The homologies of the nerves of the two limbs are much masked by the 

 iliopsoas having carried with it in front of the pubic arch the anterior crural nerve — as 

 also by the separation from this nerve of the peroneal trunk, which is seen, by its distri- 

 bution, to correspond mainly with those elements of the niusculo-spiral nerve which are 

 distributed in the distal segments of the upper limb. But if we place side by side, with 

 diagrams of the nerves of the two limbs, such as those given in plates iii. and iv. of 

 Mr. Flower's "Diagrams," tables which give the spinal nerves to which the nerves of tin- 

 limbs are ultimately traceable, we see that the suprascapular nerves correspond with the 

 nerves to the iliacus, and the nerve to the subclarius with the obturator's branch to tin 

 inner head of the pectineus. The branch from the anterior crural, or from itl internal 

 cutaneous division, to the outer head of the pectineus answers to the circumflex, v hilsl 

 the muscle, by having these two sources of nerve-supply, corresponds, even curiously, 

 with the two levatores humeri of the Fowl, and the glutei-wcvxQs and muscles an- then 

 left as homologues of the subscapular, teres major, and kUMmm dorsi. 



Thirdly, there can be little doubt that the coraco-brachiales , superior and inferior, of 

 Meckel (no. xvi. and xvii. of Schoepss), in the bird correspond, not only to the addmctore* 

 in the lower limb, but also to the obturator iutcrnus and extern**, arising as they do, the 

 former from the visceral, and the latter from the external surface of the parts homoL 

 with the points of origin of the two obtura tores. Now, close as is the relation between 

 the tendons of the smaller glutei and the obturatores at the external or larger trochanter 

 of the human femur, it is not at all more intimate than that which subsists between th. 

 tendons of the coraco-brachiales and those of the subscapular}* and teres major on the 

 lesser tuberosity, as represented by the crateriform rim of the pneumatic foramen. I f t he 



* The so-called "third or deep head'' of the Iliopsoas (see Henle, Handbuch Anat. Mensch. i. 3. 12), the mits- 

 culus iliacus internm minor of Luschka (Anat. Mensch. ii. 2. 131) is described by the latter anatomist as lying quit- 

 exteriorly to the pelvic cavity. It comes thus to correspond most instructively with a t> res minor. Similarly helpful 

 is the lar^e size of the facet of origin of the teres major in such an animal as Ursus m*ritimus. 





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