Articles from "The reference handbook of the medical sciences" (William Wood & Co., New York, third edition, 1914) / by C. Judson Herrick.

  • Herrick, C. Judson (Charles Judson), 1868-1960
Date:
[1914?]
Catalogue details

Licence: In copyright

Credit: Articles from "The reference handbook of the medical sciences" (William Wood & Co., New York, third edition, 1914) / by C. Judson Herrick. Source: Wellcome Collection.

    37/44 (page 23)
    End-Organs von Frey to be sensitive to pain and cold only. The free nerve endings found here he assumes to be pain receptors and the end-bulbs of Krause (Fig. 2041) to be cold receptors. By an analogous argument he assumes that the “genital corpuscles of Dogiel Fig. 2042,—Genital Corpuscle from the Gians Penis of Man. (After Dogiel from Bohm-Davidoff-Huber’s Histology.) (Fig. 2042) and some similar endings widely distributed in the skin are warmth receptors. By some other physiologists these two types of end-organs are re- garded as belonging to the tactile system. 4. End-organs for pain. Some physiologists be- lieve that there are separate nerve endings for pain; / Fig. 2043.—Vertical Section Through the Cornea. (After Cohn- heim from Barker’s Nervous System.) The corneal corpuscles and the cells of Descemet’s membrane are left out of the drawing; the anterior epithelium has been drawn only in part, a, Descemet’s membrane: b, nerves from the plexuses; c, branches going to the epithelium, here ascending by accident very obliquely; d, fibers of the subepithelial layer; e, vertical out threads with horizontal out- runners; end nodules can be seen; /, an undoubted precorneal horizontal fiber. others regard pain as a qualit}’ which may be present in any sense, and not as itself a true sensation. The free intraepithelial nerve endings are regarded by von Frey as the pain receptors, because these endings alone are present in some parts of the body where susceptibility to pain is the only sense quality present, such as the dentine and pulp of the teeth and the cornea (Fig. 2043). Similar endings are found through- out the epidermis (Fig. 2044) and in many deep structures. 5. End-organs of general chemical sensibility. In man this is found only on moist epithelial surfaces, such as the mouth cavity; but in fishes it may be present over the entire bodily surface (Sheldon). The sense organ is probably the free nerve terminals among the cells of the epithelium, never special sense organs like taste buds, for these when present in the skin belong to a quite different system. 6. Organs of hearing. The stimulus is material vibrations whose frequency ranges between 16 and 40,000 per second. The receptor is the organ of Corti in the cochlea, perhaps also the sensory spots in the saccule and utricle. There are two forms, (1) noise, stimulated by sound concussions or irregular mixtures of aerial vibrations; (2) tone, stimulated by sound waves or periodical aerial vibrations. Fig. 2044.—Transverse Section Through the Skin of the Ear of a White Mouse Three Days Old. (After Van Gehuchten.) a, horizontal fibers; b, bifurcation; Jn, nerve fibers. 7. End-organs of vision. The stimulus is ethereal vibrations ranging between 392 billions and 757 billions per second. Here also there are two forms: (1) brightness, stimulated by mixed ethereal vibrations; (2) color, stimulated by simple ethereal vibrations. 8. End-organs of smell. This sense has both ex- teroceptive and interoceptive qualities, the latter being apparently the more primitive. See the fuller discussion beyond under the Interoceptors (Visceral Senses) and in the article Olfactory Nerve. B. Proprioceptors.—These sense organs are con- tained within the skeletal muscles, joints, etc., and are stimulated by the normal functioning of these organs, thus reporting back to the central nervous system the exact state of contraction of the muscle, flexion of the joint, tension on the tendon, etc. These reactions are generally unconsciously performed. 9. End-organs of muscular sensibility. The organ is a series of nerve endings among special groups of muscle fibers known as muscle spindles. These endings are usually spirally wound around their muscle fibers and are stimulated by the contraction of the muscle (Fig. 2045). 10. End-organs of tendon sensibility. Similar nerve endings are spread out over the surfaces of tendons and are stimulated by stretching the tendon during muscular contraction (Fig. 2046). 11. End-organs of joint sensibility. Nerve end- ings found in the joints and the surrounding tissues are stimulated by bending the joint and report back to the central nervous system the degree of flexion