. Kirkes' handbook of physiology . the individual sarcous elements has collected more at the extremity than in the center; hence thislatter is more transparent. The optical effect is that the contractile disc appears to possess amedian disc (Disc of Hensen). Several nuclei, C and D, are shown, and in them a minute net-work. X 300. (Klein and Noble Smith.) of those muscles which are under the control of the will and hence termedvoluntary; also the muscle of the heart. SKELETAL MUSCLE 59 For the sake of description, striated muscular tissue may be dividedinto two classes, (a) skeletal, which com
. Kirkes' handbook of physiology . the individual sarcous elements has collected more at the extremity than in the center; hence thislatter is more transparent. The optical effect is that the contractile disc appears to possess amedian disc (Disc of Hensen). Several nuclei, C and D, are shown, and in them a minute net-work. X 300. (Klein and Noble Smith.) of those muscles which are under the control of the will and hence termedvoluntary; also the muscle of the heart. SKELETAL MUSCLE 59 For the sake of description, striated muscular tissue may be dividedinto two classes, (a) skeletal, which comprises the whole of the striated mus-cles of the body except (b) the heart. Skeletal Muscle. The muscle fibers of the skeletal muscles areusually grouped in small parallel bundles, fasciculi. The fasciculi extendthrough the muscle, converging to their tendinous insertions. Connective-tissue sheaths, endomysium, surround the fasciculi and support the blood-vessels, while a stronger sheath, the perimysium, encases the entire * SB fk| ] I (ja5? ! !m f5J3 ! * bs iH I • ?e] H ! I mi fe2 Lty n^C? * F5 tea f/ifi^fBffl »V 3. VSss £|* bS \ Fig. 73.—.4, Portion of a Medium-sized Human Muscle Fiber. B, Separated bundles of fibrilequally magnified; a, a, larger, and b. b, smaller collections; c, still smaller; d, d, the smallest whichcould be detached, possibly representing a single series of sarcous element. X 800. (Sharpey.) The unit of muscular structure is the fiber. Each muscle fiber is a longcylinder with fusiform ends. The fibers vary in diameter from 10 to ioo ix,while the length may reach as much as 40 mm. Each fiber is enclosed ina distinct sheath, the sarcolemma. The sarcolemma is a transparent structure-less sheath of great resistance which surrounds each fiber, figure 71. The substance of the fiber enclosed by the sarcolemma, the contractilesubstance, contains a number of oval nuclei distributed along the length ofthe fiber and lying just under or through the sa
Size: 1189px × 2102px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectphysiology, bookyear1
