PACINIAN BODIES. 373 



with the spinal cord than it would have if it proceeded to its 

 destination without such communication with other nerves. 

 Thus, each nerve by the wideness of its connections, is less de- 

 pendent on the integrity of any single portion, whether of 

 nerve-centre or of nerve-trunk, from which it may spring. By 

 this means, also, each part supplied from a plexus has wider 

 relations with the nerve-centres, and more extensive sympa- 

 thies; and, by means of the same arrangement, as Dr. Gull 

 suggests, groups of muscles may be associated for combined 

 actions; every member of the group receiving motor filaments 

 from the same parts of the nerve-centre. 



The terminations of nerve-fibres are their modes of distribu- 

 tion and connection in the nerve-centres, and in the parts 

 which they supply: the former are called their central, the 

 latter their peripheral terminations. 



The peripheral termination of nerve-fibres has been always 

 the subject of considerable discussion and doubt. The follow- 

 ing appear to be the chief modes of ending of nerve fibres in 

 the parts they supply : 



1. In fine networks or plexuses ; examples of this are found 

 in the distribution of nerves in muscles, and in mucous and 

 serous membranes. 2. In special terminal organs, called 

 touch-corpuscles (Fig. 113), end-bulbs (Fig. 114), and Pacinian 

 bodies (Figs. 136, 137). 3. In cells ; as in the eye and inter- 

 nal ear, and some other parts. 4. In free ends ; as from the 

 fine plexuses in muscles, according to Kolliker. 5. In mus- 

 cles, a peculiar termination of nerves in small bodies called 

 motorial end-plates, has been described by Rouget and others. 

 These small bodies, varying from ^'g^ to ^-5-^ of an inch in 

 diameter, and placed by different observers outside and inside 

 the sarcolemma, are fixed to the muscular fibres, one for each, 

 and to them the extremity of a minute branch of nerve-fibre 

 is attached. These little plates appear to be formed of an 

 expansion of the end of a nerve-fibre with a small quantity of 

 connective tissue. 



The Pacinian bodies or corpuscles (Figs. 136 and 137), to 

 which reference has been just made, are little elongated oval 

 bodies, situated on some of the cerebro-spinal and sympathetic 

 nerves, especially the cutaneous nerves of the hands and feet ; 

 and on branches of the large sympathetic plexus about the 

 abdominal aorta (Kolliker). They often occur also on the 

 nerves of the mesentery, and are especially well seen in the 

 mesentery of the cat. They are named Pacinian, after their 

 discoverer Pacini. Each corpuscle is attached by a narrow 

 pedicle to the nerve on which it is situated ; it is formed of 

 several concentric layers of fine membrane, with intervening 



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