First lines of physiology, being an introduction to the science of life; written in popular language . tends from the lowerpart of the loins to the head, along the back of the body,w^here it may be plainly felt throughout its entire is composed of twenty-four pieces of bone calledvertehrcB. It forms a column somewhat, but not quiteregularly conical; and instead of being perpendicular, ithas several curvatures, giving it somewhat the form ofthe letter S, inverted; as you see in fig. 44, page 185,which represents it detached and in profile. When youregard it in front or rear, it appear
First lines of physiology, being an introduction to the science of life; written in popular language . tends from the lowerpart of the loins to the head, along the back of the body,w^here it may be plainly felt throughout its entire is composed of twenty-four pieces of bone calledvertehrcB. It forms a column somewhat, but not quiteregularly conical; and instead of being perpendicular, ithas several curvatures, giving it somewhat the form ofthe letter S, inverted; as you see in fig. 44, page 185,which represents it detached and in profile. When youregard it in front or rear, it appears straight. 458. Of the twenty-four vertebrae, seven belong to theneck, and are called the cervical vertehrce,—twelve tothe back, called the dorsal vertebrcB,—and five to theloins, called the lumbar vertehrcc. The cervical part ofthe spine curves gently forw^ard, to bring it more nearlyunder the centre of gravity of the head, which it sup-ports. The dorsal portion sweeps widely backward, toenlarge the cavity of the chest: and the lumbar portionagain projects anteriorly, to restore the STRUCTURE OF THE SPINAL COLUMN. 207 459. The conical form of the spinal column is princi-pally owing to the shape of the bodies of the vertebrae(431), which constitute by far the largest portion of eachof these bones, except the atlas, which has no body,(429, 431). 460. Fig. 48 represents oneof the cervical vertebra, andwill serve us to explain theirgeneral form and their severalparts. At a, you see the spongybody of the bone, with its up-per surface slightly excavated, but nearly flat. The under sur- ^^^^KIBJS^Pcface is also flattened. From y/^ ^^^ffr ^^ ^the sides of the body you see a cc bridge of bone encircling an A Cervical Vertebra. nnpn «mpp marlrpri ir Thi<a «• The body. h. The forked spi- Open space, maiKea ^^. illS j^^^gp^^P^gg c. c. Transverse pro- is a portion of the lont?- canal cesses, a. a Holes for the cervical. , 7 111 c- arteries—also grooves for the spi-
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Keywords: ., bookcentury1800, bookdecade1840, bookidfirstlinesof, bookyear1846
