SPIXAL NERVES. PACINIAN BODIES. 



443 



Fig. 287. 



found, also, in the sympathetic plexus in front of, and close to, 

 the abdominal aorta, behind the peritoneum, especially near the 

 pancreas ; frequently in the mesen- 

 tery close to the intestine; and 

 occasionally on the internal pudic 

 nerve, on the glans penis, the bulb 

 of the urethra, the intercostal nerves, 

 sacral plexus, cutaneous nerves of 

 the arm and forearm, the dorsum 

 of the hand and foot, and the cuta- 

 neous nerves of the neck. 



The Pacinian bodies consist of 

 twenty to sixty concentric layers 

 of connective (areolar) tissue; the 

 external being separated by wider, 

 and the internal by narrower inter- 

 spaces, containing a clear serous 

 moisture, and which is collected in 

 larger quantity in an elongated 

 central cavity bounded by the in- 

 nermost lamella (Fig. 287). A 

 rounded peduncle formed from the 

 continuation of its lamellae, and 

 connected with a nervous twig, in- 

 closes a dark nerve-fibre, 2 oVs of 

 an inch or more in diameter, and 



Pacinian corpuscle, from the mesentery of 

 a cat; showing the general construction of 

 these bodies. The stalk and body, the outer 

 x and inner system of capsules, with the cen- 



conducts it into the central cavity tral cavityj are see n. . Arterial twig end- 



Of the Pacmian body. * Here it be- ing in capillaries which form loops in some of 



. . the intercapsular spaces, and one penetrates 



COmeS 2GVT5 Of an inch Wide, and to the central capsule, b. The fibrous tissue 



1 "of an inch thick, pale, non- of the stalk prolonged from the perineurium. 



u u u ' n. Nerve-tube advancing to the central cap- 



medtlllated, almost like an axis- sule, there losing its medulla, and stretching 



fibre, and terminates in the distal ^s^^xis to the opposite end where it is 



fixed by a tubercular enlargement. 



part of the cavity in a free, slightly 



granular tubercle, frequently with a bifid or a frifid extremity. 



The function of these bodies is still entirely unknown. 



5. The anastomoses of the branches of the spinal nerves, consti- 

 tuting the several plexuses, present no histological peculiarities, 

 and may be studied in the works on descriptive anatomy. 



