332 



THE SENSES 



THE AFFERENT ENDINGS IN THE JOINTS, ETC. Less is known 

 about these than about the end-organs of the muscles and tendons. 

 Kolliker has described the sensory nerves of bone. In the periosteum 

 nerves are also found, but they are smaller and less numerous. There 

 are in the joints the so-called articular end-bulbs which are in connec- 



FIG. 186 



A muscle-spindle from a cross-striated muscle of a dog: a and 6 are coils of the nerve fiber 

 making up the "spindle," while sy.n., is a sympathetic vasomotor fiber. (This may be the 

 organ through which cross-striated muscle is actively and delicately controlled.) (Gluber 

 and DeWitt.) 



tion with the Pacinian corpuscles already described. The four articular 

 regions (bone, periosteum, synovial membrane, and skin over the joints) 

 probably combine to send to the brain important knowledge of the 

 movements of the limb at a joint. 



Kinesthetic Function. Such are the most important of the known 

 afferent organs serving the kinesthetic sense. The general purpose of all 



FIG. 187 



A neurotendinous end-organ from the tendo-Achillis of man: sR and gH, two nerve fibers; 

 fpt, a primitive fibrillary bundle of the tendon; rfnc, the ultimate ribbon-shaped branches of the 

 nerve-fibers. (Ciacio via Barker.) 



these afferent impulses is to furnish the person information as to the 

 postures and relative activity of his limbs and other bodily muscular 

 parts. More essential than these ideas of posture ordinarily are the 

 impressions We receive from these end-organs concerning the movements 

 of our limbs and muscles, active or passive, of which the active are the 



