THE FOSSA OVALIS, AND RELATED BLOOD VESSELS SIXTEEN FICL'EES The descriptions of tlie fossa ovalis puxented herein a r e based upon permailerit records obtained consecutively from dissections of 200 thighs. Eight specimens xmre females, 192 males; sixteen were from one side of as many snbjects, 184 from both thighs of ninety-two subjects. The illustmtioris (figs. 1 to 16) represent the arialomy of selected fossae, from male bodies, arranged in the order of increasing size of the fossa. I n 100 cases tlie relationship of femoral and vein to the fossa was recorded. FOSSA OVALIS ?'he fossa o w l i s (O.T. saphenous opening) is regularly described as possessing a sharp lateral edge of falciform contour, a n ill-defined medial edge, and concave, proximal and distal margins or comua. Its clirrierisions a r e said to be variable, although the degree of variability is not recorded. In the present study the occurrence of the typical form predominates (figs. 10 t o 13). But not infreqaeiitly, in small fossae, tho medial edge is well-defined, the inlcrior coriiu coiitiiiued proximally t o closely approach, or actually reach, the superior cornu (figs. 1 to 8 ) , thus forming a complete oval ; rarely the opening resembles an enlarged hiatus rather tliaii a trine fossa (fig. 1). When thus reduced in size, the Contribution no. 276 from the Anatomical J,nlioratoriPs of Nortlirvestern University Medical School. 399 400 B. J . A 9 8 0 N AKD C. B. McVAP niedial and lateral margins arc not situated at different dorsoventral levels ; the medial crus, spreading toward the lateral one, covers eornpletely the cleclivitj7 between the subjacent iliopsoas and pectineus muscles, the margins of the fascia clasping the confluens of saphenous and femoi-al veins. I n outliiie, the fossa is occasionally almost circular (figs. 2 and 7). Usnally, Iiowevei*,it is oval (figs. 1,4, 8 t o 13) ; wheii thus compressed laterally, the long axis may be placed vertically (figs. 8, 10 and 12), or obliquely (figs. 4, 11 and 1 5 ) ; the narromncss may be strikingly displayed (figs. 8 aiid 10) or poorly (ligs. 13 arid 15). Occasionally the fossa is dartshaped, with the pointed end directed downward (figs. 14 and 16). The rclalioriship of thc superior crus t o the inguinal ligament is inconstant. It is conveiitioiially described as being attached above to the medial half of the inguinal ligament. When the fossa is proximally placed in the thigh, the eornii appears as a derivative of the inguinal ligament (figs. 5, 6 and lo), the ligament itself seeming to scrve as one boundary of the f ossa. Its independence in other instances is equally striking, an appreciablc distance often intervening between the ligament and the cornu (fig.2, 2 c i n ; fig. 3 and 15, 3.5 em.; figs. 14 and 16, 0.5 em.). Within the space of the fossa proper accessory hiatuses not infrequently occur, traiismittjng musculai~tributaries t o the larger veins (see under Vessels hereinafter). These appear in siniple form (figs. 9, 1 2 and 14) or as multiple orifices (fig. 13). Auxiliary fossae occur near the major one (figs. 10 and 13). I n size the greatest variability is expressed (table 1). The smnllmt fossa in the 200 is 1.6 em. in length, 1.7 em. in width (fig.2 ) ; the narro~-estmeasures 1.0 em. (fig.I), the shortest 1.6 cui. (fig. 2). The largest fossa in the group is 8.5 em. in length, 3.5 em. in width (fig. 1 6 ) ; the widest measures 6.4 em., the longest 8.5 cm. (fig. 16). Ninety per c m t of the specimens (i.e., 180 fossae) measure between 3.0 em. (fig. 5 ) aiid 6.4 em. iii lcngth (fig. 15) : 53.5% (I07 fossae) measure between 3.5 em. (fig. 6 ) and 5.4 em. (fig. 11). The average T H K F'OSSa OVALIS 401 length is 4.6 cm. In width, 87% (174 fossac) a r e between 1.5 em. and 3.9 em.; i0.576 (141 fossae) a r e between 2.0 em. (fig. 10) and 3.9 cm. The average width is 2.8 em. Figs. 1t o 9 Fossa ovalis, with related blood vessels one-half natural size. Abbreviations : V.s.m., r e n a saplicna ningna j V.e.s., rena epigastrica superficialis; V.c.i.s., vena circunnflex ilium superficialis ; V.p.c., v m a pudenda externa. Asterisk indicates acressnry saphenous tributary. 402 B. J . AXSON AND C. B. McVtzP Without exception fossne are capacious for the vessels which they transmit: in only one case does tlie circumference of the sapheiious vein approach that of the fossa through which it passes (fig. 1): regularly a very considerable space, unoccupied by vessels, is included between the cornua of the fossa (eg., figs. 10 to 16), tlie size of contents in no way affecting the proportions of the orifice. So aniple, in fact, is the space of the fossa, that the contained femoral vein is almost invariably exposed throughout its width. Moreover, in 83% of 100 consecutive cases the femoral artery, also, is TABJJE 1 Di?nerrsions of fossu ovalis Length in cp.ntim eters specimens centmeters Number of specimens 1.6 2.0-2.4 3.5-2.9 3 .O-3.4 3.5-3.9 1 4 6 19 21 38 33 34 21 12 4 3 1 1 1.0-1.4 1.5-1.9 11 19 5.0-2.4 48 47 4.0-4.4 4.54.9 5.0-5.4 5.5-5.9 6.04.4 G.5-G.9 7.0-7.4 7.5 8.5 Z'umber of Width i n 2.5-2.9 3.0-3.4 3.6-3.9 4.0-4.4 4.5-4.9 5.0-5.4 5.5-5.9 6.0-G.4 46 14 7 3 3 0 2 I 200 200 wholly o r partially exposed. More specificially, in 3670, three-fourths t o all of its breadth i s in view (figs. 7 and 16) : in SO%, one-half to one-fourth; in 1770, not only is tlie artery entirely in view, hut space occurs laterally, unoccupied by vessel (fig. 5). There is apparently no constant relationship betwwn the size of the body and the caliber of the fossa. I n specimens of the same height the fossae may be of widely different proportions, fossae of great size (fig. 16) and small (fig. 1) occurring in specimens of the same height (69 inches), others THE FOSSA OT’ALIS 403 Q S Figs. 10 to 16 Fossa ovalis and vessels, continued. Onc-half natural size. Figure 10 is of t h e right side (as :ire figs. 1, 4, 7 t o 9 ) ; all others are from thc l e f t side. 404 B. J. ANSOX AND C. B. McVAY of similar proportions (figs. 9 and 10) appearing in cadavers of differing heights (64 and 70 inches, respectively). BLOOD VESSELS The veins of the scrotal, inguinal, and anterior femoral regions are usually received by the great saphenous tributary of the femoral vein, in the immediate neighborhood of the fossa ovalis. I n many of the cases, the superficial epigastric and superficial iliac circumflex veins enter the saphenous vein as independent channels (figs. 10, 14). Any of the three major vessels may be doubled (figs. 4 and 5, Vv.p.e.; fig. 6, Vv.e.s.) ; two adjacent tributaries may be confluent (figs. 2, 9, 3 1 and 12, V.e.s. and V.c.i.s.; fig. 3, TT.e.s. and V.p.e.). Not infrequently veins are received from the femoral muscles through accessory hiatuses in the deep fascia (figs.12 to 14), and from lymphatic glands lodged in the superficial fascia (figs. 2 and 7 ) . I n some instances the arrangement of superficial veins from the area proximal to the fossa ovaljs is excessively simple (figs. 1 and 7), while, in other cases the venous pattern is compl~s. I n one instance (fig. 3) seven channels, in two groups (medial and lateral) converge upon a,short vessel tributary t o the femoral vein: a saphcnous vein joins a superficial external pudendal to form the common medial channel, the latter receiving, sup.eriorly, one of three superficial epigastric veins ; the most laterally placed of the superficial epigastric veins, joining the superficial iliac circumflex, forms the lateral venous channel, which near the confluens vvitli the medial channel, receives a third superficial epigastric vein superiorly, a second saphenous vejn inferiorly. ,4 vein may be bifid throngh part of its course (fig. 12) ; accessory saphenous veins are common (figs. 3, 4, 6, 12 to 16), occasionally as many as three occurring within the territory of the femoral triangle (fig. 7 ) . Only those cases which are illustrated will br ronsidcred here. A detailed study of the vessels of the lower abdominal wall and of the thigh is now in progress; the results of this study nil1 he reported in a suhsequeiit paper.