The costo-uterine muscle of the guinea-pig: a smooth muscle attaching the uterus to the last rib.

A conspicuous smooth muscle (of transverse sectional area comparable to that of the taenia coli) situated in the suspensorium ovarii and in the ligamentum ovarii proprium of the guinea-pig is described. The muscle is attached to the last rib, it reaches the medial side of the ovary, to which it is loosely attached; it passes beyond the caudal pole of the ovary (from which it receives additional muscle bundles), it approaches the oviduct, passing ventral to it, then it spreads around it and eventually reaches the distal end of the uterus; this muscle (which is here indicated as costo-uterine muscle) is in direct continuation with, or transforms itself into, the longitudinal outer coat of the uterus.