. An introduction to the osteology of the mammalia . fforded by the cervicalvertebrae of the Monotremata, where the greater part of eachtransverse process ossifies separately from the rest of the ver-tebra, and remains for a long time only suturally connectedwith it (Fig. 5). They thus closely correspond to the cervical 26 THE VERTEBRAL COLUMN. [CHAP. ribs of reptiles, which are unquestionably homologous seriallywith the thoracic ribs. The anterior, or more properly inferior, bar of the trans-verse process of the seventh, and occasionally of some of theother cervical vertebras in Man, is autog
. An introduction to the osteology of the mammalia . fforded by the cervicalvertebrae of the Monotremata, where the greater part of eachtransverse process ossifies separately from the rest of the ver-tebra, and remains for a long time only suturally connectedwith it (Fig. 5). They thus closely correspond to the cervical 26 THE VERTEBRAL COLUMN. [CHAP. ribs of reptiles, which are unquestionably homologous seriallywith the thoracic ribs. The anterior, or more properly inferior, bar of the trans-verse process of the seventh, and occasionally of some of theother cervical vertebras in Man, is autogenously developed,and has some characters by which it may be placed in thecategory of rudimentary ribs. The transverse processes of the anterior lumbar vertebraeof certain Mammals, as the Pig, are originally autogenouselements, though coalescing very early with the rest of thevertebrae. In the sacral region, the separate lateral ossifications whichconnect the vertebral column with the ilium present manycharacters allying them to ribs. (See Fig. 6.). FIG. 6.—Anterior surface of first sacral vertebra (human) showing mode of develop-ment, no. neural arch ; c centrum ; / distinct (pleurapophysial) ossification forattachment of ilium. Finally, the transverse processes of the caudal vertebrae ofsome animals (as the Manatee and Beaver) are separatelydeveloped, though it is doubtful whether this circumstancealone is sufficient to entitle them to be considered as costalelements. Division of the Vertebral Column into Regions.—For con-venience of description the whole vertebral column has in.] DIVISION INTO REGIONS. 27 been divided into five regions, the cervical, thoracic? lumbar,sacral, and caudal. This divison is useful, especially as it is not entirelyarbitrary, and in most cases is capable of ready definition,at least in the Mammalia; but at the contiguous extre-mities of the regions, the characters of the vertebrae of oneare apt to blend into those of another region, either nor-
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectbones, bookyear1885
