Licence: Public Domain Mark
Credit: On the muscles of the back / by Holmes Coote. Source: Wellcome Collection.
Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.
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![terior articulating process, corresponding with tlie transverse process” (Cuvier): in other words, with the diapopliysial element of Owen. It is composed of tendinous and fleshy fibres, extending between these ])oiuts of bone along the whole length of tlie vertebral column. 3. The sacro lumbalis is composed of tendinous and fleshy slips, passing from the posterior border of the upper third of the ribs, (somewhat corresponding with the angle of the ribs in human anatomy) along the whole length of the vertebral column. What, then, would be a summary of the preceding remarks? Jhe posterior aspect of the vertebral column presents three promineitt points of leverage arranged in longitudinal linear series on either side of the trunk. Tlie central points are the apices of the spinous processes, which, as we know, are often bifid. External to these are the diapo- physes. External to the diapophyses are the angles of the ribs. From between these points of bone muscular and tendinous bands pass, constituting three longitudinal com- pound muscles — the spinalis dorsi (which comprises the interspinalis), the longissimus dorsi, and the sacro-lum- balis. They are all extensors of»the spine, where the muscles act together upon both sides of the trunk. Where only one set acts, the spinal column is inclined to the corresponding side. Under the preceding lies a layer of oblique muscular and tendinous fibres, passing from the transverse processes (diapophyses) to the spinous processes, the semi-spinalis or trausverso-spinalis (Cuviei*). Their action is to rotate the vertebrae upon one another. Were I to state that in the human subject the muscles of the back might be dismissed in as summary a manner, there are many who, remembering the list of hard names with v;hich that dej)artment of human anatomy is en- riched, would feel disposed to withhold their belief. It can be readily proved, however, if one point bo conceded; namely, that we adopt an accurate and scientific nomenclature of tlie elements of the vertebrae, instead of the faulty one now in use. Let it be borne in mind that eveiy vertebra is composed of a body or cen- tre, around which, in its perfect form, are four canals ; one, the vertebral groove for the spinal chord; a second. represented by the ribs and the sternum, for the heart and great vessels; and two lateral canals for the vertebral arteries; any of the surfaces of hone, bounding these canals, may constitute a lever for muscular attachment. Con- fining our attention to the posterior surface of the vertobral column, we notice (1) the spinous processes; (2) the diapophyses (or transverse processes), but faintly marked in the cervical re- gion ; long and prominent in the dorsal region; known as the tubercles, or the apophysary elements (Cmveilhier) in the lumbar region, still more faintly mai-ked in the sacral region; (3) the ribs, short and stunted in the cervical region, where they are hollowed or grooved to support the cervical nerves, as they emerge from the intervertebral foramina; long and moveable in the chest, where they form an osseous cavity, capable of rising and falling in respira- tion ; short and fixed in the abdominal region, where (under the unhappy name of transverse processes, which confounds them with the dorsal diapophyses) they give origin to the transversalis muscle by well-marked fibrous ribg. The mobility of the vertebrae, the ft/ inclination of the articulating processes, the length and direction of the bony levers, must all be remembered in the examination of the muscles of the back. Where five vertebras coalesce to form a solid piece, the sacrum, a base of support to the column above it, the muscles attached to these bones, no longer needed, become blended together, and are regarded as constituting the oritrin of the muscular and tendinous slips, which, proceeding thence, ])ass upwards to the moveable vertebrae of the dorsal or cervical region. This is why we talk of the longissimus clorri and the sacro-lumbalis arising from the sacrum and pelvis, and extending u])- wards to their respective inseriions. Cuvier, iu his description of the same muscles in the common snake (Coluber natrix), makes them arise at the head (the only part of the vertebral column where the vertebrae are coalesced) and extend dowuwai'ds to the tail. The more moveable the vertebrae one upon another, the thicker and more powerful are the muscles attached to them. Hence, in the lumbar region, the extensor muscles are strongest; iu the neck the rotator muscles arc strong- est. In the dorsal region, where (from](https://iiif.wellcomecollection.org/image/b22424702_0004.jp2/full/800%2C/0/default.jpg)
