114 MUSCULAR TISSUE 



have a central nucleus and peripheral fibrillae; but the fibers of the 

 cardiac muscle are more or less polygonal in outline and more constant 

 in size, excepting occasional branches, while the smooth cells are circular 

 in outline and of very diverse diameters, depending upon the different 

 levels at which the section passes through adjacent fusiform cells. In 

 longitudinal sections the cardiac muscle can be easily recognized by its 

 branching character and the presence of intercalated disks ; smooth mus- 

 cle by the fusiform character of its associated celjs. Smooth muscle is 

 frequently difficult to distinguish from compact, white fibrous connective 

 tissue. When both are present in the same section, stained with the 

 routine hematoxylin-eosin technic, the two exhibit a slight difference in 

 staining reaction. The smooth muscle commonly stains a deeper red; 

 the collagenous fibers have a lighter orange tinge. Moreover, from a 

 morphological standpoint, while portions of the white fibrous connective 

 tissue may appear spindle-shaped, thus simulating the unit of smooth 

 muscle structure, the associated nuclei of enveloping connective tissue 

 cells are peripheral to the bundle, whereas the nucleus of smooth muscle 

 is of course in the center of the analogous structure, the muscle cell. 



BLOOD SUPPLY 



The blood-vessels of voluntary striped muscle distribute their larger 

 trunks within the connective tissue of the epimysium. The smaller 

 branches penetrate the endomysium and supply a rich capillary plexus 

 with long rectangular meshes. This network of capillaries surrounds 

 the muscle fibers so completely that each fiber is placed in relation with 

 four or five capillary vessels which run parallel with the long axis of the 

 fiber. The blood supply of cardiac muscles is in general similar, but 

 even more abundant and intimate, with respect to its terminal meshes. 

 The blood supply of smooth muscle is relatively meager. 



Numerous lymphatics occur in the perivascular connective tissue. 

 These lymphatic vessels are especially abundant in cardiac muscle. 



NERVE SUPPLY 



Skeletal muscle is innervated both by cerebrospinal and sympathetic 

 nerves, supported in the connective tissue envelopes and septa. The 

 former include both sensory and motor fibers ending in muscle spindles 



