2. The next Instance shall be in one or two Things, wherein the Skeletons of Sexes differ. Thus the Pelvis made in the Belly by the Ilium, Ossa Coxendicis and Pubis, is larger in a Female than Male Skeleton, that there may be more room for the lying of the Viscera and Fœtus. So the Cartilage bracing together the two Ossa Pubis, or Sharebones, Bartholine saith, is twice thicker and laxer in Women than Men: As also is the Cartilage that tieth the Os Sacrum to its Vertebra; and all to give way to the Passage of the Fœtus.
Another considerable Difference is in the cartilaginous Production of the seven long Ribs, whereby they are braced to the Breast-Bone. These are harder and firmer in Women than in Men; the better to support the Weight of the Breasts, the sucking Infant, &c.
[d] It is remarkable in the Joynts, and a manifest Act of Caution and Design, 1. That altho’ the Motion of the Limbs be circular, yet the Center of that Motion is not in a Point, but an ample Superficies. In a Point, the Bones would wear and penetrate one another; the Joynts would be exceedingly weak, &c. but the Joynts consisting of two large Superficies, Concave and Convex, some furrowed and ridged, some like a Ball and Socket, and all lubricated with an oily Substance, they are incomparably prepared both for Motion and Strength. 2. That the Bones next the Joynt are not spungy, as their Extremities commonly are, nor hard and brittle, but capped with a strong, tough, smooth, cartilaginous Substance, serving both to Strength and Motion.
But let us here take notice of what Galen mentions on this Subject. Articulorum unusquisque Eminentiam Cavitati immissam habet: Veruntamen hoc fortasse non adeò mirabile est: Sed si, consideratâ omnium totius corporis ossium mutuâ connexione, Eminentias cavitatibus suscipientibus æquales semper inveneris; Hoc mirabile. Si enim justo amplior esset Cavitas, laxus sanè & infirmus fieret Articulus; si strictior, motus difficulter fieret, ut qui nullam versionem haberet; ac periculum esset non parvum, eminintias ossium arctatas frangi: sed horum neutrum factum est.——Sed quoniam ex tam securâ constructione periculum erat, nè motiones difficiliùs fierent, & eminentiæ ossium extererentur, duplex rursus auxilium in id Natura molita est. 1. Cartilagine os utrumque subungens, atque oblinens: alterum, ipsis Cartilaginibus humorem unctuosum, velut oleum, superfundens; per quem facilè mobilis, & attritu contumax omnis articulatio Ossium facta est.——Ut undique diligenter Articulus omnis custodiretur, Ligamenta quædam ex utroque osse produxit Natura. Galen de Us. Part. l. 1. c. 15.
[e] For the affording this oily or mucilaginous Matter, there are Glandules very commodiously placed near the Joynts, so as not to suffer too great Compression by the Motion of the neighbouring Bones, and yet to receive a due Pressure, so as to cause a sufficient Emission of the Mucilage into the Joynts. Also another Thing considerable is, that the excretory Ducts of the mucilaginous Glands have some Length in their Passage from the Glands to their Mouths; which is a good Contrivance, to prevent their Mouths being oppressed by the Mucilage, as also to hinder the too plentiful Effusion thereof, but yet to afford a due Expressure of it at all Times, and on all Occasions, as particularly in violent and long-continued Motions of the Joynts, when there is a greater than ordinary Expence of it. See Cowper’s Anat. Tab. 79.
[f] There is no doubt to be made, but that the Muscles receive their Motion from the Nerves. For if a Nerve be cut, or straightly bound, that goes to any Muscle, that Muscle shall immediately lose its Motion. Which is doubtless the case of Paralyticks; whose Nerves are some of them by Obstructions, or such like Means, reduced to the same State as if cut or bound.
And this also is the cause of that Numness or Sleepiness we find oftentimes, by long sitting or lying on any Part.
Neither is this a modern Notion only: For Galen saith, Principium Nervorum omnium Cerebrum est, & spinalis Medulla.——Et Nervi à Cerebro animalem virtutem accipiunt——Nervorum utilitas est facultatem Sensûs & Motûs à principio in partes diducere. And this he intimates to have been the Opinion of Hippocrates and Plato. De Us. Part. l. 1. c. 16. & passim.
[g] Dr. Willis thinks, that in the Brain the Spirits are elaborated that minister to voluntary Motion; but in the Cerebellum, such as effect involuntary, or natural Motions; such as that of the Heart, the Lungs, &c. Cerebri Anat. c. 15.