VESSELS AND NERVES OF MUSCLE. 



iir 



penetrating the smallest fasciculi, they end in capillary vessels, ■which 

 run between the fibres. The vessels are supported in their progress 

 by the subdivisions of the sheath of the muscle, to which also they 

 supply capillaries. The capillaries destined for the proper tissue of the 

 muscle are extremely small ; they form among the fibres a fine net- 

 work, with narrow oblong meshes (fig. 75)^ which are stretched out in 

 the direction of the fibres : in 



other words, they consist of Fig. 75. 



longitudinal and transverse 

 vessels, the former running 

 ]iarallel with the muscular 

 fibres, and lying in the angu- 

 lar intervals between them, 

 — the latter, which are much 

 shorter, crossing between the 



longitudinal ones, and pass- „. ^_ „ „ ,, 



° 1 .1 • i Fm. lb. ■ — -Capillary Vkssels of Muscle, 



mgover or under the mter- %^^^ ^^^ Lvjection by Likbekkuun, seex 

 vennig fibres. witu a low magnifying power. 



None of the capillary vessels enter the sarcolemma or proper sheath of the fibre, 

 and the nutritious fluid which they convey must therefore reach the finer 

 elements of the muscle by imbibition. Moreover, as the capillaries do not 

 penetrate the fibres, but lie between them, their nmnber in a given space, or 

 their degree of closeness, will in some measiu'e be regulated by the number 

 and consequently by the size of the fibres ; and accordingly in the muscles of 

 different animals it is found that, when the fibres are small, the vessels are 

 numerous and fonn a close network, and rice versa : in other words, the 

 BinaUer the fibres, the gxeater is the quantity of blood supplied to the same bulk 

 of muscle. In confonnity with this, we see that in birds and mammalia, in 

 which the process of nutrition is active, and where the rapid change requires a 

 copious sujjply of material, the muscular fibres are much smaller and the vessels 

 more nmnerous than in cold-blooded animals, in which the opi)osit e conditions 

 prevail. 



Lymphatics. — Of lymphatic vessels in the muscular tissue nothing 

 certain is known. The rich supply of these vessels in the sheaths oi 

 muscles and of their tendons would seem, as pointed out by Ludwig 

 and Schweigger-Seidel, to serve the purpose of collecting and convey- 

 ing away the lymph from those organs, but how the fluid reaches the 

 lymphatic vessels of the sheath is not certainly known : probably l)y the 

 medium of the intercommunicating cell-spaces of the connective tissue 

 which, as before remarked, penetrates between the fasciculi and fibres 

 of the muscle. 



Nerves. — The nerves of a voluntary muscle are of considerable size. 

 Their branches pass between the fasciculi, and repeatedly unite with 

 cacii other in form of a plexus, which is for the most part confined to 

 a small part of the length of the muscle, or muscular division in which 

 it lies. From one or more of such primary plexuses, nervous twigs 

 proceed, and form finer plexuses composed of slender bundles, each con 

 taining not more than two or three dark-bordered nerve-fibres, whence 

 single fibres pass off between the muscular fibres and divide into 

 branches which are finally distributed to the tissue. The mode of 

 final distribution will be described with the general anatomy of the 

 nerves. 



