A systeme of anatomy, treating of the body of man, beasts, birds, fish, insects, and plants illustrated with many schemes, consisting of variety of elegant figures, drawn from the life, and engraven in seventy four folio copper-plates. And after every part of man's body hath been anatomically described, its diseases, cases, and cures are concisely exhibited. The first volume containing the parts of the lowest apartiments of the body of man and other animals, etc. / by Samuel Collins ...

CHAP. XVI. Of the Auricles of the Heart.

THe right and left Ventricle of the Heart are adorned with an Auri∣cle, as with two Appendages, and in truth are two little Hearts, * 1.1 as having peculiar Fibres, if not Blood-vessels, and Nerves, and are Auxiliary Muscles subservient to the greater Machine of the Heart, and are like two Servants waiting at the doors of the Chambers, to convey the Blood more readily into the greater Cisterns or Lakes of this rare Engine of Motion.

The right Auricle is affixed to the right side of the Base of the Heart, and doth cover the termination of the Vena Cava (and not its Origens, as Great Vessalius conceiveth) which hath its length somewhat answering that of the right Auricle.

This Auricle is endued with somewhat of a Pyramidal Figure, * 1.2 as some will have it, because it hath an oblong Base ending into a more acute Cone, and is not far extended above the Base of the Heart.

The Base of this Auricle being distended with Blood, hath a Longitude far exceeding its Latitude, and its outward surface doth much vary according to its Repletion, by reason when the Auricle is distended, it is endued with an equal Convex Surface, and when it is rendred lank, as being emptied by the contraction of its Fibres, the Surface is full of roughness, as endued with many wrinkles, and its Surface is outwardly bedewed with watry Li∣quor, in which it is akin to the ambient parts of the Heart.

The inward surface of this Auricle, encircling its Cavity, holdeth great Analogy with that relating to the Ventricles of the Heart, and is smooth only where the Vena Cava doth terminate, and for the most part is rough and full of Furrows, as consisting of many implications of Carnous Fibres; So that it seemeth in some sort to outdo the Ventricles in eminent Asperities, and the dimensions of the Auricles are rendred greater or less, as distended or emptied of Blood.

And hath its Connexion after this manner, as I humbly conceive; * 1.3 The left side of its Base is conjoyned to the Confines and extreme parts of the substance of the Heart, where the anterior Region of the Vena Cava is lodg∣ed in the right Sinus, and the right side of the Base is connected to the body of the Vena Cava (according to the length of its insertion into the Heart) to which the Auricle is so united in its Anterior Region, as it seemeth to make one body with it, and in all other parts the Auricle seemeth to be free from all Connexion, and is lodged as well as the body of the Heart with∣in the Confines of the Pericardium, to which it is no where affixed by the interposition of any Membrane.

The left Auricle of the Heart is in conjunction with the termination of the Pulmonary Vein, and is adorned with a kind of Pyramidal, * 1.4 or rather Oval † 1.5 Figure, whose Cone is more acute than that of the right Auricle, and is not carried upward (as is the Cone of the other Auricle) but bendeth somewhat sidewise toward the left.

The left Auricle in persons of more mature years, or rather in old age, * 1.6 groweth much less in dimensions than the right Auricle and the Orifice

seated in the termination of the Pulmonary Vein (to which the left Auricle is conjoyned) which is more narrow than that of the Termination belonging to the Vena Cava, to which the right is affixed.

The outward Surface of the left, when rendered turgent with Blood, is like the right Auricle in its smooth Convex Figure, and the left doth very much resemble the other in its inward Surface as furnished with many Fur∣rows and Roughnesses.

The left Auricle also observeth much Analogy with the right in its Con∣nexion, * 1.7 by reason as the right is conjoyned to the termination of the Vena Cava in one side, and to its Body in the other, so the left Auricle in the right side of its Base is tied to the substance of the Heart near the egress of the Pulmonary Artery, and in the left side of the Base of the said Auricle to the body of the Pulmonary Vein.

The Auricles are accommodated with Arteries, * 1.8 Veins, and Nerves, of which the last are divaricated through the substance of those Muscles before they enter into the body of the Heart, and are derived from the Par Vagum.

The Auricles are furnished with many ranks of fleshy † 1.9 Fibres, from di∣vers Muscular Columns, * 1.10 very much resembling those in Figure, which are lodged in the Ventricles of the Heart: These intermedial Fibres are carried with an oblique course, and are inserted into the opposite Tendons, by reason they being seated in the Base of the Heart, are also imparted to the Auricles, and upon these Tendons the fleshy Fibres do rest as upon a Prop, or Fulci∣ment; And on the other side, the right Auricle, where it is concerned with the Vena Cava, is guarded with a hard Tendinous Circle, into which the fleshy Fibres are implanted.

Now I will discourse somewhat of the use of the Auricles, * 1.11 and respite the greatest part till I treat of the Motion of the Heart, and compare the Au∣ricles with the Ventricles; wherein it may be observed that the Auricles have not the same Analogy which passeth between the Ventricles, moving together with equal pace, by reason a greater proportion of Blood ought not to be impelled by the contraction of the right Ventricle into the Pulmonary Artery, than can be received out of the Pulmonary Vein into the left Cham∣ber of the Heart; So that an equal quantity of Blood must be entertained into both Cisterns of the Heart, and thence be distributed by a due measure through the Pulmonary Artery into the substance of the Lungs, and by the Aorta and its Branches and Ramulets, into all parts of the Body.

The motion of the Blood being so constant and orderly in the Ventricles, it may be worth our disquisition, why the Auricles do not observe the same Analogy with each other in dimensions, which Nature ordained (as I hum∣bly conceive upon this account) by reason the current of the Blood is more slow out of the Vena Cava into the right Ventricle; * 1.12 therefore it is is requi∣site that the Cavity of the right Auricle should be more enlarged, as recep∣tive of a larger proportion of Blood, thence to be injected into the right Ventricle, sufficient for its Repletion; by reason the Blood in Expiration is more speedily squeesed by the pressure of the Lungs out of the Pulmonary Vein into the left Ventricle; whereupon the motion of the Blood is more highly accelerated, and therefore a less Cavity will suffice in the left Auricle.

Notes

• * 1.1

  The Auricles of the Heart.
• * 1.2

  The right Au∣ricle of the Heart is en∣dued with a kind of Pyra∣midal Figure. The Auricles when filled with Blood, have an equal Convex Sur∣face, and when lank, have many Asperi∣ties or wrin∣kles.
• * 1.3

  The Connexi∣on of the right Auricle.
• * 1.4

  The Connexi∣on of the left Ventricle.
• † 1.5

  T. 15. F. 1. b b.
• * 1.6

  The lest Auri∣cle is lessened in persons of old age.
• * 1.7

  The left Au∣ricle is very like the right.
• * 1.8

  The Vessels of the Auri∣cles.
• † 1.9

  T. 15. F. 1. b b.
• * 1.10

  The fleshy Fi∣bres of the Auricles.
• * 1.11

  The use of the Auricles of the Heart.
• * 1.12

  The Cavity of the right Ven∣tricle is more large.