136 
On the Sesamoids of the Knee- Joint 
likeness to sesame" non est necessarium, hoc opere pertractare*. If only Galen had 
told us which sesamoids he knew, what sesame wasf, and how and why they were 
like the seeds of it, our task would have been simplified ! The comparison may 
have been obvious to the Greek anatomists because the sesame seed that they were 
referring to was familiar to their readers and because they had special sesamoid 
bones in mind, it is far less obvious nineteen centuries later. 
But we are not exact in stating that sesamoids have as a rule been dismissed 
in the language of Galen in the text-books. The opinion that it was unneedful to 
discuss them has been frequently accompanied by the dogma that sesamoids are 
the product of intensive stress acting upon cartilage. This dogma appeared to 
receive confirmation from the undoubted existence of hemisesamoids in regions 
where orthosesamoids are usually or on occasion discoverable. A hemisesamoid was 
an orthosesamoid in the making. This dogma appealed to that tendency in anatomy 
— largely the product of pathological study — which attributes innumerable charac- 
ters of individual bones to specific use. The bone was not adapted by evolution to 
its use, but use was the source of its characters, and indeed if these were observed 
in the foetus or at birth, they were in themselves evidence of the inheritance of 
acquired characters. The fossa hi/potrochanterica and the crural trough were the 
product of muscular action on the bone, even if they were to be found more 
frequently in female than male femora and were discoveiable iu infants and non- 
robust or even diseased bones. The "intensive stress" origin of sesamoids had indeed 
been questioned by Dr Robert Nesbit before the middle of the 18th century. He 
wrote as follows in his Human Osteogeny, London, 1736, p. 136 : 
" The only parts of a foetal skeleton, which remain to be taken notice of, are the 
ossa sesamoidea which all the writers, I have met with on this subject, have wholly 
passed over unobserved. The number of them in foetuses are, as in adults, very 
different in different subjects. Those, which are the most constantly found, are two 
in the bottom of the foot, fixt in the ligament of the articulation of the fii'st bone 
of each great toe, with its os metatarsi. In all foetuses, from three months after 
conception to birth, the places of these ossa sesamoidea are always filled with 
cartilages of nearly the same shape those sesavwide bones usually have, when they 
arc arrived at perfect maturity, Plate IV [actually Plate Vl] 18 a. a. fig. 19 a. a. 
In one subject at birth I found, in each of the sesamoide bones of one foot, a very 
small point of ossification. 
" In like manner those ossa sesamoidea which are sometimes found at the 
beginning of the rii usculi gastrocnemii, are to be seen in foetuses. 
"By the desci-iptions I have now given of all the different parts of foetal skeletons, 
it manifestly appears, that there is not one single bone, except the teeth, or one 
epiphysis in an adult skeleton, which is not to be found in a full grown foetus, or in 
its place a cartilage of nearly the same shape : consequently, the account cannot be 
right, which the ingenious professor Monro gives of the ossa sesamoidea being 
* Liber de ossibus Galcni Libroruiii Pars Qiiinta, Biisileae, 1538, p. 727. 
t See, however, below, p. 141. 
