The principal forms of the skeleton and the teeth : as the basis for a system of natural history and comparative anatomy / by Professor Owen.

  • Owen, Richard, Sir, 1804-1892.
Date:
1860
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Licence: Public Domain Mark

Credit: The principal forms of the skeleton and the teeth : as the basis for a system of natural history and comparative anatomy / by Professor Owen. Source: Wellcome Collection.

Provider: This material has been provided by The University of Leeds Library. The original may be consulted at The University of Leeds Library.

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    physcs, n, the neural spine, ns, the pleurapophyses, pi, the haemapophyses, h, and the haemal spine, hs. The exogenous parts are the diapophysis (Fig. 5), d, the parapophy- sis (ib.) p, the zygapophysis (Fig. 6), z (Gr. zugos, junction, and apophysis), the anapophysis (Fig. 2), a (Gr. ana, hackwards, and apophysis), the metapophysis (ib.), m (Gr. rneta, between, and apophysis), the hypapophysis (Fig. 5), y (Gr. hypo, below, and apophysis), and the epapophysis (Fig. 4), e (Gr. epi, above, and apophysis). Of the autogenous parts, the neural spine is most commonly exogenous; of the ex- ogenous parts, the parapophyses, diapophyses, and hypapophyses are sometimes autogenous. Vertebrae arc subject to many and great modifications—e. g., as to the number of the elements retained in their composition, as to the form and proportion of the elements, and even as to the relative position of the elements ; but the latter modification is never carried to such a degree as to obscure the general pattern or type of the segment. Fig. 6. TYPICAL VERTEBRA. Sometimes, as in the example (Fig. 4) of the third segment of the human skeleton, the neural arch, is much expanded, the haemal one, H, is contracted; and, in the expanded neural arch, the autogenous diapophyses, d d, are wedged between the neurapophyses, n. and the enormously expanded neural spine, ns. More commonly, as in the example from the raven's thorax (Fig. 5), the haemal arch, H, is much expanded, the neural one, N, contracted; and in the expanded haemal arch, the para- pophysis, p, here exogenous, is wedged between the centrum, C, and the pleurapophysis, pi. Sometimes, again, as is exemplified in the tail of the crocodile and of many other animals, both neural and haemal arches are alike contracted; the pleurapophyses, pi, being excluded from the latter, and standing out as continuations of the confluent diapophyses, d, and parapophyses, p. Such vertebrae deviate but little from the ideal type of the vertebra, under its less developed condition, as in Fig. 6. The segments are commonly simplified and made smaller as they approach the end of the vertebral column or axis, one element or process after another is removed, until the vertebra is reduced to its centrum, as in the subjoined diagram (Fig. 7), of the archetype verte- brate skeleton. In this scheme, which gives a side view of the series of segments or