An introduction to the study of the comparative anatomy of animals . thicker than the auricles, through thepresence of abundant muscular tissue in its walls. Its cavityis not smooth, but rather spongy in appearance, through thepresence of numerous muscular ridges which project into cavity does not extend far into the apex of the ventricle,is rather narrow dorso-ventrally^ but elongated from right toleft. The auriculo-ventricular aperture, by which the ventriclecommunicates with the auricles, is rather a wide opening,divided into two by the free edge of the auricular septum, anii Digitiz
An introduction to the study of the comparative anatomy of animals . thicker than the auricles, through thepresence of abundant muscular tissue in its walls. Its cavityis not smooth, but rather spongy in appearance, through thepresence of numerous muscular ridges which project into cavity does not extend far into the apex of the ventricle,is rather narrow dorso-ventrally^ but elongated from right toleft. The auriculo-ventricular aperture, by which the ventriclecommunicates with the auricles, is rather a wide opening,divided into two by the free edge of the auricular septum, anii Digitized by Microsoft® ANATOMY OF THE FROG 47 guarded, on its ventricular side, by a pair of valves which havethe form of flaps of membrane springing from the walls of theheart. One of these flaps is on the dorsal, the other on theventral side of the aperture, and each is connected with themuscular ridges of the ventricular wall by about a dozen veryfine fibrous cords the cordae tendinese. The length of thesecords is such that they allow the membranous flaps to rise up. Fig. 7- A, The frogs heart dissected from the ventral surface. B, an enlarged view ofthe truncus arteriosus. Ji A, right auricle ; LA, left auricle ; V, ventricle ;T, truncus arteriosus, divided into Py, pyiangium, and S^, synangium;^ V, opening of the sinus venosus into the right auricle ; Pv, opening of thepulmonary vein into the left auricle ; Aw, auriculo-ventricular valve ; s/v,semi-lunar valves guarding the passage from the ventricle to the pylangiiim;C, carotid arch ; S, systemic arch ; P, pulmo-cutaneous arch ; spv, spiralvalve in the pyiangium ; ^a, opening of the right pulmo-cutaneous arch ; co,opening of the carotid arches. and meet one another in the middle line so as to close theaperture, but they prevent their rising farther into the cavityof the auricles. The left-hand anterior corner of the ventricle is prolonged,on its ventral side, into a stout vessel, which passes forwardsand to the left across the
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Keywords: ., bookcentury1900, bookdecade1900, bookpublisherlondo, bookyear1900
