458 



JacksorCs Anatomical Description 



prevented by two thin, semilunar valves on the inside of 

 the auricle, the inner one extending about three fourths 

 the length of the cavity, the outer one being considerably 

 shorter, and the two terminating in a muscular band which 

 would tend completely to close them ; muscular structure 

 of this cavity well developed, except on septum and to- 

 wards the opening into ventricle, the bands running very 

 irregularly. The left auricle receives two small, very 

 delicate, pulmonary veins, which unite just as they 

 enter ; the line of entrance is sufficiently marked, but 

 there are no valves as on the right side ; Dr. Grant also 



, (Pro- 

 March 



(A 



iv, 218), they are found here as well as in the right 

 ■ auricle- This cavity is moderately thick and muscular, 

 the fibres running nearly in a straight line from the ven- 

 tricular opening, some of them being nearly an inch in 

 .length and easily raised. The opening into the ventricle 

 is considerably smaller than on the right side. The 

 ventricle is a oroad, flattened, crescentic, kidney-shaped 

 organ, not connected by a tendinous ligament to the peri- 

 cardium, as stated by Carus (Comp. Anat. li, 285). It 

 measures transversely at the base three and two thirds 

 inches, and from the base to the part corresponding to 

 the apex two inches. Parietes generally about half an 

 inch thick, but on the right side, just below the giving off 

 of the vessels, they are much thinner ; on the outside 

 they are firm, but tow^ards the inner surface spongy, and 

 on the left side very much more so than on the right, the 

 muscular fibres being of considerable size and forming 

 distinct meshes with some small columnae carneae ; be- 

 ^eath the auricular septum they form a complete lace- 



