l62 THE TISSUES. 



nerve-fibers of the funiculi ; consequently, the lamellae are covered 

 by a layer of endothelial cells. In the larger funiculi, septa of 

 fibrous connective tissue pass from the perineurial sheath into the 

 funiculi, dividing them into compartments varying in shape and size ; 

 these are spoken of as compound funiculi. The funiculi of a nerve- 

 trunk are bound together by an investing sheath of loose fibro-elastic 

 tissue, continuous with the perineurial sheaths, which penetrates 

 between the funiculi, and which contains fat-cells, blood-vessels, and 

 lymph-vessels ; the latter are in communication with the lymph- 

 spaces of the perineurial sheaths. 



When a nerve-trunk divides, the connective-tissue sheaths above 

 mentioned are continued on to the branches, and this even to the 

 smallest offshoots. Thus, single fibers even possess a connective- 

 tissue sheath, Henle's sheath, which consists of a few connective- 

 tissue fibers and of flattened cells. 



PERIPHERAL NERVE TERMINATIONS. 



According to the character of the peripheral organs in which 

 the telodendria of nerve-fibers (neuraxes of type I cells and dendrites 

 of spinal ganglion cells) occur, the nerve-fibers are known as motor 

 and sensory nerve-fibers, the terminations as motor and sensory 

 nerve-endings. 



Motor Nerve-endings (the Telodendria of Nerve-fibers Ending 

 in Muscle Tissue). The motor nerve -endings in striated, voluntary 

 muscle tissue will first be considered. The motor nerve-endings 

 in voluntary muscle tissue are the endings of neurones (peripheral 

 motor neurones), the cell-bodies of which are situated in the ventral 

 horns of the spinal cord and in the medulla. The neuraxes of these 

 cells leave the cerebrospinal axis as medullated nerve -fibers (motor 

 fibers) which, after branching, end in the muscle-fibers in the so-called 

 motor endings. In figure 124 is represented, by way of diagram, 

 a complete peripheral motor neurone. Each motor nerve - fiber 

 branches repeatedly before terminating, although this branching 

 does not often take place until near the termination of the nerve- 

 fiber. Kolliker estimates that in the sternoradialis of the frog, each 

 motor fiber innervates about twenty muscle-fibers ; but whether this 

 number may be regarded as the average number of muscle-fibers 

 receiving their motor nerve-supply from one motor neurone can not 

 be stated with any degree of certainty at the present time. 



Each motor ending represents the termination of one of the ter- 

 minal medullated branches of a motor nerve-fiber. The neuraxis of 

 this fiber passes under the sarcolemma and terminates in a teloden- 

 drion (end-brush) in an accumulation of sarcoplasm, in which are 

 found numerous muscle nuclei, forming a more or less distinct ele- 

 vation on the side of the muscle-fiber, Doyercs elation. The 

 medullary sheath accompanies the nerve-fiber until it passes under 

 the sarcolemma, when it stops abruptly. The neurilemma of the 



