GAXGLIA 119 



nerve fibres with needles this fibrous endoneurium remains adher- 

 ent to the surface of the nerve fibre and gives the appearance of 

 an outermost fibrous sheath, the so-called connective tissue sheath 

 of Henle. 



Nerve trunks frequently branch, the branches being formed 

 either by an individual funiculus or by groups of funiculi. In 

 the smaller nerve trunks the funiculi are further subdivided. It 

 is by anastomosis of the funiculi that most of the nerve plexuses 

 are formed. Individual nerve fibres of the medullated type do 

 not branch except in those portions which are naked axis cylin- 

 ders, viz., at the cytoproximal portion of the neuraxis by means 

 of collaterals, and at the cytodistal portion by means of end 

 arborizations. Occasionally also the nerve fibre divides at a node 

 of Ranvier. 



Vascular Supply. The nerve trunks are well supplied with 

 Uood vessels. The larger of these are found in the epineurium, 

 and from them branches of considerable size enter the septa to be 

 distributed through the perineurium to the funiculi. The coarser 

 septa of the endoneurium contain minute arteries and veins. A 

 capillary network with elongated meshes occupies the finer di- 

 visions of the endoneurium, its vessels being thus brought into 

 contact with the nerve fibres. 



Perivascular lymphatic vessels abound in the epineurium and 

 its septa, and lymphatic tissue spaces are found throughout 

 the connective tissue of the nerve trunk. Where the cerebro- 

 spinal nerve trunks penetrate the meninges these lymphatic 

 vessels are said to be continuous with the similar vessels of the 

 dura mater. 



Minute nerve fibre bundles, nervi nervorum, are also found in 

 the epineurium ; their fibres are mostly, if not entirely, distributed 

 to the blood vessels. 



GANGLIA. A ganglion may be described as a group of nerve 

 cells occurring in the course of a peripheral nerve trunk. The 

 largest of the ganglia form fusiform swellings in the course of the 

 nerve, which are visible to the naked eye. The smallest, on the 

 other hand, contain not more than half a dozen nerve cells, and 

 these must be sought with the aid of the microscope and can only 

 be found by the most careful observation. 



Whatever may be their size, all ganglia appear to have a simi- 

 lar structure, except for those differences which characterize the 

 sympathetic as distinguished from the cerebro-spinal type. The 



