MUSCLES. 371 



mities of the muscular fasciculi, and combine with the fibrous filaments 

 originating there to form the tendinous connexion of the muscle. 



The close union that exists between the muscle and its tendon for- 

 merly gave occasion to the belief, that the latter is only the former con- 

 densed. An examination of some of the physical and vital properties 

 of the two will show, that they differ as essentially as any two of the 

 constituents of the body that could be selected. The tendon consists 

 chiefly of gelatin, and does not exhibit the same irritability ; whilst the 

 muscle is formed essentially of fibrin ; and contracts under the will, 

 as well as on the application of certain mechanical and chemical irri- 

 tants. The differences, in short, that exist between the two, are such 

 as distinguish the primary fibrous and areolar tissues ; yet the opinion 

 of their identity prevailed in antiquity ; was embraced by Boerhaave 

 and his school, and, as Dr. Bostock 1 observes, was so generally admitted 

 even in the middle of the last century, that Haller 2 and Sabatier 3 

 scarcely ventured to give a decided opposition to it. 



Similar remarks are applicable to the notion of Dr. Cullen, 4 that 

 muscles are only the moving extremities of nerves. The fibres of the 

 muscle were supposed by him to be continuous with those of the nerve ; 

 to be, indeed, the same substance, but 

 changed in structure; so that when the Fig. 157. 



nerve is converted into muscle, it loses the 

 power of communicating feeling, and ac- 

 quires that of producing motion. 



Every muscle and every fibre of a muscle 

 is probably supplied with bloodvessels, lym- 

 phatics, and nerves. These cannot be 

 traced into the ultimate filament ; but, as 

 this must be possessed of life and be con- 

 tractile under the will, it must receive Capillary Net- work of Muscle. 

 through the bloodvessels and nerves the 



appropriate influences. MM. Dumas and Prevost, 5 and Mr. Bow- 

 man, as has been remarked, affirm, that the microscope shows, that 

 neither the one nor the other terminates in the muscle. The vessels 

 merely traverse the organs ; the arteries terminating in corresponding 

 veins ; so that the nutrition of muscles is effected by the transudation 

 of plastic materials through the parietes of the artery, in the same man- 

 ner probably as various other parts, teeth, hair, cartilages, for exam- 

 ple, are nourished. A similar distribution is assigned by them to the 

 nerves. All the branches, they assert, enter the muscle in a direction 

 perpendicular to that of the fibres composing it ; and their final ramifi- 

 cations, instead of terminating in the muscular fibres, surround them 

 loopwise, and return to the trunk that furnished them, or anastomose 

 with some neighbouring trunk. In their view, each nervous filament, 

 distributed to the muscles, sets out from the anterior column of the 



1 An Elementary System of Physiology, 3d edit., p. 84, London, 1836. 



2 Elem. Physiol., ii. 1, 18. 3 Traite complet d'Anatomie, i. 242, Paris, 1791. 

 * Institutions of Medicine, 29, 94 ; or Works of William Cullen, M.D., by John Thorn 



son, M.D., i. pp. 15, 68, Edinb. and Lond., 1827. 

 6 Magendie's Journal de Physiologic, torn. iii. 



