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Accelerator Penis.
BEsides the former, the Virile Member hath two other Muscles allowed it called Urethram Trahentes, arising Fleshy from the Sphincter Ani, and joyning with its partner internally lateral, and marching by the fore part of the Penis, is inserted into the Ʋrethra, and is generally asserted that it was framed for the dilating of the Urethra; but the Use thus designed these Muscles is much rejected by Ren. de Graaf, the which he confuteth by these Reasons, That when all Muscles do work in their own proper method, their Venters do tumefie, and their ends do approach nearer each other; the which being granted, it cannot thus happen that the Penis should be extended, the Action of the Muscle being Contraction, and this being most contrary to Extention; neither can the Penis obtain Ere∣ction by the benefit or help of these Muscles, for it rather would appear depressed than erected these being contracted, and they being planted in the lower part, or under the Penis, taking their Origination from the Appendix of the Coxendix, and so implanted to the lower part of the Yard.
As to the two also which are assigned by other Authors to dilate the Urethra, they are in no ways capable to perform this, these Muscles running through the middle of it, are firmly united to each other by one extremity of Fibres, whilst the opposite to the former obliquely running over the Urethra, do send the same into the sides of its Nervous Bodies; but as to the Erection of the Penis two kinds of Vessels do seem chiefly to serve with the Muscles for the performance of this, as Nerves and Arteries; but of these you may plentifully satisfie your self in Regner. de Graaf, de Organ. Viror. Fol. 154. &c.
This you have at R. R. Tab. 13. Fig. 1. Fig. 2. at S. S. you have the same, ead. Tab. F. F. Shews the same, Tab. 12.