HUMAN ANATOMY. 



NERVE-TERMINATIONS. 



The terminations of the fibres composing the peripheral nerves the axones of 

 certain mot. ,r neurones situated within the crrcbro-spmal axis and the sympatt 



: the neurones of the sensory ganglia supply the means 



bv which the various structures < ,i the body are brought into intimate relation 

 with the nen -"in. Some of these terminations transfer impulses resulting in 



muscular contractions; others convey impressions that produce various sensations 



(pain, pressure, muscle-sense, 

 Kic;. 863. . temperature). The nerve- 



Nerve A terminations, therefore, may 



be grouped according to func- 

 tion into motor and sensory 

 endings. 



MOTOR NERVE-ENDINGS. 



The motor endings in- 

 clude (a) terminations of the 

 axones of neurones situated 

 within the motor nuclei of 

 the spinal cord and brain- 

 stem that pass to voluntary 

 muscle ; () terminations of 

 sympathetic neurones that 

 end in involuntary muscle and 



in cardiac muscle. 



Endings in Voluntary 

 Muscle. On approaching 

 their peripheral destination 

 --l-^Eiid- the medullated nerve-fibres 

 branch repeatedly, each fibre 

 in this manner coming into 

 relation with a number of mus- 



Motor nerve-endings in voluntary muscle; bundle of nerve-fibres is , H!, ,.,..- Wk, fl,^ A 



en separating to supply th< cle-nbres. When the med- 



ullated nerve-fibre reaches the 



muscle-fibre which it supplies, its medullary sheath abruptly ends and the neurilemma 

 becomes insepara! ly fused \\ ith the sarcoh inina, whilst the a xis-cy lin'der passes beneath 

 this sheath to terminate in an cnd-platf. The latter appears as an oval area, from 

 .O4o-.o6omm. in it ' diameter, which is applied 



to the inns. le-Mibstance ; in profile it shows a slight FIG. 864. 



projection beyond the contour of the muscle-fibre, 

 although this i> often wanting. Embedded within 

 ral mi. leated sheet of granular protoplasm, the 

 sotc-f>/iift\ lie the brush-like terminal arbori/atioiis of the 



vlinder formed of irregular varirosites and club- 

 shaped ends. I-'roin the details of the development of 



the motor end plates, as d. -scribed by I'.ardeen, it is *-y ^ 



probable that the granular sole-plate and its nuclei are 



differentiated from the sarcoplasm and the nuclei of the ''\.*f r ^ 



muse le hbi . iv^.rciively. The much discnsscd relation 

 of tin- end plate to the sarn >lrmma whether mtsideor 



h serins to be derided in favor of a subs., 



lemmal position, sinci- the musrlr-sheath appears sub- ,^ 



srqnentlv to the formation of the motor ending, a fact 



, ' . . Motor nerve-ending iti voluntary 



that explains the apparent piercing ot the san olemma muscle; a, axone u-rnimatm K in i-nd- 



bvthraxi, rylind.-r. Fsnallv earh musdr -fibre is pro- '.''^ " n< ll< -'"" : >' lale - 



videil u ith a single motor end- jilate, which may lie at an 



J or um-(|ual distance from the ends of the fibre. Exci-ptionally two end-plates 

 louinl on one muscle-fibre. \\\ uhich case the endings lie near each other. 



