464 



HUMAN ANATOMY. 



Fig. 485. 



^^^ \ 



The blood-vessels of striped muscle are very numerous to insure adequate 

 nutrition to a tissue of great functional activity. The larger arteries and accompany- 

 ing veins penetrate the muscle along the septal extensions of the epimysium and 

 divide into smaller branches which run between the fasciculi. These vessels undergo 



further subdivision into twigs which pass between 

 the finer bundles of muscle-fibres and ultimately 

 break up into the capillaries enclosing the indi- 

 vidual fibres. 



The capillary vessels of voluntary muscle 

 form a characteristic net-work consisting of nar- 

 row rectangular meshes (Fig. 485), the longer 

 sides of which correspond to the direction of 

 the muscle-fibres between which they run ; the 

 shorter sides of the meshes are formed by the 

 capillaries which extend across or may encircle 

 the individual fibres. The capillaries supplying 

 muscles subjected to prolonged and powerful 

 contractions often exhibit local dilatations, which 

 may serve for temporary reservoirs for the blood 

 during contraction. The closeness of the capil- 

 lary net-work is determined by the size of the 

 muscle-fibres, muscles composed of fine fibres 

 possessing the smallest vascular meshes. 



The relation of the blood-vessels to cardiac 

 muscle is unusually intimate, the capillaries not 

 only enclosing the muscle- fibres with a rich net- 

 work, but lying within depressions on the surface 

 of the fibres, or even in channels surrounded by 

 the muscular tissue (Meigs). 

 The lymphatics of striated muscular tissue are represented by the interfascicular 

 clefts, which extend within the connective tissue between the muscle-fibres, and the 

 more definite channels within the septa. The larger lymph-vessels formed by the 

 confluence of those lying between the fasciculi pass to the sheath of the muscle and 

 tendon and carry of? the lymph from the muscular tissue. 



The nerves supplying striped muscle include both motor and sensory fibres. 

 The former terminate in specialized arborizations, the motor 7ierve- endings which 



4 



Longiludiiial 



Transverse 



Injected voluntary muscle, showing arrange- 

 ment of interfascicular vessels and capillaries. 

 X 50- 



Fig. 486. 



Neural canal 



Ectoblast, 



Lateral plate of myotome 

 Medial plate of myotome- 

 Wolffian body 



Parietal mesoblast 

 somatopleura 



Wolffian body 

 Parietal mesoblast 



Umbilical vein 



Body-cavity Aorta Body-cavity 



Transverse section of rabbit embryo, showing differentiation of myotomes. X 90. 



are usually regarded as lying beneath the sarcolemma upon the sarcous substance. 

 The sensory fibres are connected with the neuro-muscular end organs or muscle- 

 spindles, from which the afferent nerves proceed centrally. The detailed description 



