OCR Text |
Show 1885.] OF THE HUMAN SPHENOID BONE. 581 in S t f o n t l l h 1 1 6 °f.sification o f t h e P^phenoid, or that portion in relation with the optic nerves, may be summarized as follows:- Fig. 3. PS. L.S O.F. O.F. OS. F. F. A series of figures to show the disposition of the various nuclei of the human sphenoid bone. The upper figure shows the relation of the centres to the cartilage; the latter in all cases is represented by dots. In the middle figure the basisphenoidal nuclei have coalesced, the orbito-sphenoids have joined the presphenoids, and the internal pterygoids have joined the alisphenoids. In the lowest figure the sphenoid bone is represented as at the eighth month of foetal life. ^.#, Alisphenoid ; 2?.$, basisphenoid ; L, lingular; .F, pterygoids; O.S, orbito-sphenoids ; P.S, presphenoid ; O.F, optic foramen ; F\ R, foramen rotun-duin ; F. 0, foramen ovale ; C, cranio-pharyngeal canal. The dorsum sella? at this date is cartilaginous, and therefore it is not represented in the f'gurc-s. The foramen ovale, until some time after birth, is only a notch in the alisphenoid. Ossific matter is deposited immediately external to the optic foramen, and extends rapidly outwards to form the orbitosphenoid. This occurs about the commencement of the third month. PROC. ZOOL. Soc-1835, No. XXXVIII. 38 |