464 



NERVOUS SYSTEM 



ing to the different properties connected with sensation with which 

 the parts are endowed. In addition it is probable that sensory nerves 

 are connected with the hair-follicles, so largely distributed throughout 

 the cutaneous surface. There are, also, terminal filaments not con- 

 nected with special organs, some of them, perhaps, ending simply in 

 free extremities and some connected with epithelium. 



Corpuscles of Vater or of Pacini. These bodies were called cor- 

 puscles of Pacini until it was shown that they had been seen about a 

 century and a half ago by Vater. In man they are oval or egg-shaped 

 and measure ^5 to \ of an inch (i to 4 millimeters) in length. They 

 are found in the subcutaneous layer on the palms of the hands and the 



soles of the feet, and are most 

 abundant on the palmar sur- 

 faces of the fingers and toes, 

 particularly the third phalanges. 

 In the entire hand there are 

 about six hundred and about 

 the same number in the feet. 



^ *, ^^ They are sometimes, but not 



yT$ constantly, found in the follow- 

 W ing situations: the dorsal sur- 



vSfc jj& faces of the hands and feet, 



on the cutaneous nerves of the 

 arm, the forearm and the neck, 

 the internal pudic nerve, the 

 intercostal nerves, the articular 

 nerves of the extremities, the 

 nerves beneath the mammary 

 glands, the nerves of the nipples 

 and in the substance of the 

 muscles of the hands and feet. They are always found in the great 

 sympathetic plexuses, in front of and by the sides of the abdominal 

 aorta, and behind the peritoneum, in the vicinity of the pancreas. They 

 have been observed in the mesentery and near the coccygeal gland. 



The corpuscles consist of several layers of connective tissue enclos- 

 ing one, two or three central bulbs in which are found the ends of the 

 nerve. These bulbs are finely granular and nucleated and are regarded 

 by most anatomists as composed of connective tissue. At the base of 

 the corpuscle is a pedicle formed of connective tissue surrounding a 

 medullated nerve-fibre which penetrates the corpuscle. Within the 

 corpuscle the medullary substance of the nerve-fibre is lost and only 

 the axis-cylinder remains. 



Fig. 102. Transverse section of a corpuscle of Vater, 

 X 30 (Author's collection). 



The corpuscle lies in the pancreas, portions of 

 which are shown in the section, which is deeply stained 

 with alum-carmin. 



