Karl Pearson and Adelaide G. Daven 
161 
appears if we loosely speak of the fabella as lying in the tendon of i/. gastrocnemius 
and the cycDiiella as in the tendon of M. popliteus. 
We have already prepared the reader by citing Cheselden and Humphry (see 
our pp. 150, 153) for such not being the case; both cyainella and fabella are or 
n)ay be the node, " Knotenpunkt," or junction of a whole network of fibrous 
structures, tendons and ligaments. Thus Gruber himself tells us (p. 69) that the 
lateral fabella is at the junction of M. gastrocnemius externus and the Ligamentum 
popliteum at the point before it/, gastrocnemius is free of the knee-capsule and 
where the short lateral ligament takes its departure. For this reason Gruber 
asserts that the external fabella serves (i) to strengthen this junction, (ii) to keep 
the " Knotenpunkt " on the articular surfiice of the condyle, and (iii) to prevent 
M. ga^strocnemius externus slipping on to the lateral face of the external condyle. 
This explanation does not seem to us of great validity for if the fabella were of such 
great service, how would nine-tenths of the human population get on without it ? 
But this conception of the fabella as a node to which there are many muscular 
attachments not only accounts largely for its variety of form, but also leads us to 
seek for its origin in something to which such muscular attachments were peculiar. 
Another most suggestive point here is that Gruber noticed occasionally a 
supernumerary head* of M. popliteus (see our p. 154 and our Fig. 9, Plate IV) 
springing directly from the fabella. Thus the two heads of popliteus are brought 
into touch with the two lateral sesamoids and this division of the head is not 
inconsistent with the division of an original structure. Gruber's confusion of 
lateral fabella and cyamella has in itself a slight contributory significance. 
More than once Gruber speaks of the controlling power of the fabella. whether 
orthosesamoidal or hemisesamoidal over the ligaments and tendons. Thus on p. 72 
he notes that in man its movements control : M. gastrocnemius externus, M. plantaris, 
M. semimembranosus, and M. popliteus biceps by means of its supernumerary head 
supposing this abnormal muscle presentf. Whenever both M. plantaris and the- 
fabella lateralis exist in man, a jDortion of the former, or the whole of it, originates 
in this sesamoid (p. 45). In short in the case of man in the extended position of 
* On seven occasions this supernumerary head sprang from the fdhella ; on four occasions without 
a seFanioid this anomalous head originated from tlie head of the oblique popliteal ligament, or and also 
from the knee-capsule, pp. 45 — 6. We think, but it is not quite clear, that Macalister (see our p. 154) 
also had associated the supernumerary head of M. popliteus with a sesamoid. See also J. F. Knott, Proc. 
R. Irish Academy, Second Series, Vol. iii, p. 639, 1882. 
t Again p. 48 we read : " Da nun das Ossiculum und die Cartilago geiade im Knotenpunkte der 
Vereinigung der Kniekapsel, der Sehne des Gastrocnemius externus, des Lig. popliteum und des Lig. 
laterale externum breve genu sitzen, da von denselben der Gastrocnemius externus mit Fleischbtindeln 
abgehen kann, immer der Plantaris davon entspringt, oder falls er fehit, durch von da kommende 
Fleischbiindel des Gastrocnemius externus ersetzt wird, bisweilen von denselben der Popliteus mit einem 
supernumeraren Kopfe entspringt; so werden audi diese Muskeln die Versoliiebuiig des Ossieulum. und 
der Cartilago dirigiren, und es werden durch denselben Apparat, durch den die im Bereiche des Gondylus 
externus laxere Kniekapsel vor Einklemmung geschiitzt wird, auch das Ossiculum, und die Cartilago vor 
Einklenimung bewahrt. Beide werden bei diesem Manover, und bevor es zur grossten Spannung kommt, 
schrag ein — und aufwarts an dem Condylus externus, wenn auch nur eine massige Strecke, gleiten 
miissen, um der Einklemmung zu entgehen, und bei der Streckung des Kniegelenkes wieder auf ihren 
Platz auf demselben Wage zuruckkebren," 
