On the cervical vertebrae and their articulations in fin-whales / by John Struthers.

  • John Struthers
Date:
[1872]
Catalogue details

Licence: Public Domain Mark

Credit: On the cervical vertebrae and their articulations in fin-whales / by John Struthers. Source: Wellcome Collection.

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    in great Fin-Whales has satisfied me that both upper and lower transverse processes, in their various degrees of develop¬ ment, may be interpreted by dividing them into three stages. (See Fig. 4, also Figs. 1, 2 and 3.) Lower transverse processes, (a) First or root stage, short, directed outwards and down¬ wards, alone present in some. Thick, smooth before and behind. Portions of rete mirabile lie here, (b) Second or tubercular stage. Directed outwards, extensive, being opposite the inner half or more of the ring; begins by an internal angular pro¬ tuberance or process, and terminates by an external protuber¬ ance ; thinner at the upper edge where it bounds the ring, thick and rough below. Besides muscles, this stage attaches a series of strong intertransverse ligaments. (c) Third, or nerve-groove stage, corresponding to the space left for the pas¬ sage of the inferior division of the spinal nerve, accompanied by communication of rete mirabile. Process at this stage turns upwards and outwards; groove is on anterior surface, directed obliquely downwards and outwards, broad enough to receive the hand laid flat. The very different thickness of these two stages at their lower part gives, especially where they meet, the twisted appearance which the processes present on their anterior surface. Upper Transverse Processes, (a) First, or nerve- groove stage, corresponding to the space for the passage of the upper division of the spinal nerve, accompanied by dorsal communication of rete mirabile. Is opposite the inner third of the ring, reaching from the articular process for three or four inches outwards, broad enough to receive the hand flat. Groove most marked on the posterior surface of the anterior vertebrae and on the anterior surface of the posterior vertebrae, (b) Second or tubercular stage, opposite the outer two-thirds of the ring; beginning by a marked rough projection on the superior edge, and continuing rough outwards. It attaches a series of superior intertransverse ligaments, (c) Third, or terminal stage; situ¬ ated to the outer side of the ring, and curving downwards and inwards a little to unite with the inferior process. It forms the extreme part of the transverse process, is scarcely broader than the processes in adolescence, but in maturity forms a tabular expansion beyond the foramen.