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NERVE ENDINGS
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See also:NERVE ENDINGS .—Sensory nerves end by breaking up into fibrillae or by various tactile See also:organs. In the former See also:case the See also:minute fibrils, of which it has been shown that the axons or nerve See also:fibres consist, See also:separate and end among See also:epithelial cells of the mucous membrane or skin. In the latter case the nerve fibres lose their coating of myelin and end in one of the seven following organs: I. End bulbs of See also:Krause (fig. 3, A), See also:oval bulbs composed of elongated cells among which the nerve fibrils end in knobs or coils; each is surrounded by a sheath of neurilemma, and the organs are found in the lips, See also:tongue, conjunctiva, epineurium of nerves, synovial membranes of See also:joints, and in the glans penis et clitoridis, where they have a mulberry-like See also:appearance. 2. Pacinian corpuscles (fig.. 3, B) are large enough to be seen by the naked See also:eye, and are oval bodies made up of a See also:series of concentric capsules of connective See also:tissue rather resembling the structure of an See also:onion; in the centre of this is a structureless core, at the distal extremity of which the nerve fibre ends in one or more knobs. These See also:Cunningham's See also:Text-See also:Book of See also:Anatomy. bodies are found in the See also:palm and See also:sole, in the mesentery, the genital organs and in joints. 3. Tactile corpuscles of Meissner and See also:Wagner (fig. 3, C) aregval bodies found in certain of the skin papillae and mucous membrane, especially of very sensitive parts like the See also:hand and See also:foot, lips, tongue and nipple. They are oval and made of a connective tissue See also:capsule from which septa enter the interior. The nerve fibre generally takes a See also:spiral course through them, loses its myelin sheath, and ends by breaking up into its fibrils, which eventually become bulbous. 4. Tactile corpuscles of Grandry are found in the skin of those parts devoid of See also:hair, and consist of a capsule containing two or more A B From See also:Robert Howden, in Cunningham's Text-Book of Anatomy. of Pacini; C, Corpuscle of Meissner. (B, C, after Ranvier.) largish cells, between which the nerve fibre ends in the so-called tactile discs. 5. Kuffini's endings are flattened oval bodies with a thick connective tissue capsule, in which the nerve fibre divides into many See also:common to the whole See also:system, or for which a See also:place does not 6. Organs of Golgi are found in tendons. Nerve fibres penetrate the tendon bundles and See also:divide in a See also:tree-like manner to end in little disks and varicosities. 7. Neuro-See also:muscular spindles are small fusiform bundles of embryonic muscle fibres among which the nerve fibres end by en-circling them and forming flattened disks. These are sensory endings, and must not be confused with the motor end plates. They are found in most of the striped muscles of the See also:body. Motor nerves end in striped muscle by motor end plates. These are formed by a nerve fibre approaching a muscle fibre and suddenly losing its myelin sheath while its neurilemma becomes continuous with the sarcolemma of the muscle fibre. The See also:axis See also:cylinder divides, and its ramifications are surrounded by a disk of granular See also:matter containing many clear nuclei. In very See also:long muscle fibres more than one of these end plates are sometimes found. Involuntary motor endings are usually found in sympathetic nerves going to unstriped muscle. The fibres See also:form minute plexuses, at the points of See also:union of which small triangular ganglion cells are found. After this the separate fibrils of the nerve divide, and each ends opposite the See also:nucleus of an unstriped muscle See also:cell. Additional information and CommentsThere are no comments yet for this article.
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