202 



ANATOMY FOB NUKSES. [CHAP. XVIII. 



or nerve, the whole nerve being covered by a dense fibrous 

 sheath of connective tissue. 



Besides connecting the funiculi, the connective tissue serves 

 to convey the blood-vessels and lymphatics distributed to the 

 nerve-fibres. 



The nerves that conduct nervous impulses towards the nerve- 

 centres are called afferent or sensory nerves, while those that 



FIG. 117. SECTION OF THE INTERNAL SAPHENOTJS NERVE. Stained in osmic 

 acid and subsequently hardened in alcohol. Drawn as seen under a very low magni- 

 fying power. (G. A. S.) ep, epineurium, or general sheath of the nerve, consisting 

 of connective tissue separated by cleft-like areolae, which appear as a network of 

 clear lines, with here and there fat-cells,/,/, and blood-vessels, v. ; per, perineurium, 

 or particular sheath of funiculus; end, endoneurium, or connective tissue within 

 f uniculus, embedded in which are seen the cut ends of the medullated nerve-fibres. 

 The fat-cells and the nerve-fibres are darkly stained by the osmic acid. 



transmit nervous impulses from the nerve-centres towards the 

 periphery are termed efferent or motor nerves. Both afferent 

 and efferent fibres may run in the same sheath. 



The nervous system. The great nerve-centre of the body is 

 the cerebro-spinal centre or axis, consisting of the brain and 

 spinal cord. The nerves arising from this centre extend from 

 thence through the body to the muscles, sensible parts, and 



