104 



KELIQULE AQUITANKLE. 



fragment, 45 millims. at the middle, and 31 below: the three corresponding transverse diameters are, 

 respectively, 37, 27, and 27 millims. The length of the fragment, comprising nearly all of the shaft, is 

 323 millims. ; and adding the probable length of the ends wanting here, but present on another and smaller 

 tibia, I make the total length of the tibia under notice to have been 41 centims. (16-142 inches) at least. 

 These measurements abundantly show that the bone is much thicker (in a fore-and-aft direction) with 

 respect to its length, and much narrower with respect to its thickness, than are the tibias of existing men. 



d. Platycnemic Bones. We may here offer some remarks on the nature of the structural differences 

 between the flattened or compressed tibias, described above, and modern tibias. The latter have a triangular 

 and prismatic shaft, thus presenting three faces and three edges. The anterior edge, or " crest of the tibia," 

 is just covered by the skin ; the other two edges are behind ; one of them facing inward, just beneath the 

 skin ; the other facing outward, covered by flesh, and giving insertion along its length to the interosseous 

 aponeurosis extending between it and the fibula. The three faces of the bones, bordered by the three edges, 



are : the internal and subcutaneous face ; the external face, giving insertion in its upper two-thirds to the 



tibialis anticus ; and the posterior, with backward aspect, and giving insertion to several muscles. It is this 



posterior face which chiefly interests us now. 



The two limiting edges 1 1', E E' (fig. 44), are almost parallel in the lower three-fifths of the bone ; but in 



the upper two-fifths they gradually separate from below upwards, terminating respectively on the margins of 



the two condyles of the tibia. This widened portion, forming the upper 



two-fifths of the posterior face, is obliquely traversed, from above down- 

 wards, and from the outside inwards, by a rough line (pp' p"), termed the 



" popliteal line," commencing above the fibular articulation, and descending 



thence very obliquely until it touches the inner edge of the tibia. From 



the middle, almost, of this line another (jj'), which we call the " tibial 



line," goes off very obliquely ; but it is much less prominent, sometimes 



indeed scarcely marked. It descends along the posterior face, gradually 



approaching the outer edge, in which it ends at about the middle of the 



length of the bone. These two lines divide tho upper portion of the 



posterior face of the tibia into three surfaces, which give insertion to 



three muscles. The popliteal muscle occupies the great triangular space 



between the " popliteal line " and the inner edge (pp 1 ' p", I); the space 



between the " tibial line," the " popliteal line," and the outer edge (pp', 



jj', E E') is occupied by the tibialis postims ; and lastly there is the space 



in the sharp angle which, intercepted by the " popliteal " and the " tibial 



line " (p" p', jj 1 ), is occupied by the flexor longus digitorwn pedis. These 



three muscles are inserted equally by their respective margins on the 



" popliteal line," which moreover gives throughout its length insertion to the soleiis muscle. The " tibial 



line" gives insertion only to the intermuscular aponeurosis separating the tibialis posticus from \heflexor 



longus. Lastly, towards the point of union of these two lines, at the edge of the tibialis posticus, and at 



about the middle of the bone's width, there is a nutritive foramen (N), well known as the largest of the 



kind in the skeleton. 



These descriptive details are necessary to show clearly the conformation of the platycnemic tibias. 



Their characteristic compression occurs in only the upper two-fifths of the shaft, which is triangular 



in its lower moiety. The two diagrammatic sections here given (fig. 45, i, 2), transverse to the 



bone at the nutritive foramen (N, fig. 44), enable us to compare the triangular with the flat tibias. 



