. Kirkes' handbook of physiology . ll parts of the skin and its inversions, the stomo-deum and proctodeum. The nerves of sensation are contained in the same .508 THE SENSES trunks with other sensory nerves. They are found in the posterior or sen-sory roots of the spinal nerves and in the sensory divisions of the cranialnerves, especially the fifth, seventh, ninth, and tenth. All parts of the epidermis supplied with sensory nerves are thus, in somedegree, organs of touch, yet the sense is exercised in greatest perfection incertain parts, the sensibility of which is extremely delicate, , the
. Kirkes' handbook of physiology . ll parts of the skin and its inversions, the stomo-deum and proctodeum. The nerves of sensation are contained in the same .508 THE SENSES trunks with other sensory nerves. They are found in the posterior or sen-sory roots of the spinal nerves and in the sensory divisions of the cranialnerves, especially the fifth, seventh, ninth, and tenth. All parts of the epidermis supplied with sensory nerves are thus, in somedegree, organs of touch, yet the sense is exercised in greatest perfection incertain parts, the sensibility of which is extremely delicate, , the skin ofthe hands, the tongue, and the lips, which are provided with abundant touchpapilla?. A peculiar and very acute sense of touch is exercised through themedium of the nails and teeth, and, to a less extent, the hair may be consid-ered an organ of touch, as in the case of the eyelashes. The sense of touch renders us conscious of the presence of a contactstimulus, from the slightest to the most intense degree of its action. The. modifications of this sense often depend on the extent of the parts sensation of pricking, for example, is produced when the sensitive fibersare intensely affected in a small extent; the sensation of pressure indicatesa slighter affection of the parts over a greater extent and depth. It is by thedepth to which the parts are affected that the feeling of pressure is dis-tinguished from that of mere contact. In almost all parts of the body which have delicate tactile sensibility theepidermis, immediately over the dermal papillae, is moderately thin. Whenits thickness is much increased, as over the heel, the sense of touch is verymuch dulled. On the other hand, when it is altogether removed, and thecutis laid bare, the sensation of contact is replaced by one of pain. Further,in all highly sensitive parts, the papillae are numerous and highly vascular,and the sensory nerves are connected with special end-organs which havebeen described on pag
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