. Journal of anatomy . ochondrally, as will, to a large extent, be seen in the photograph of asection of an 80 mm. embrj^o (fig. 14). In the same model (30 mm.) theprocessus alaris sends backwards a pointed process which comes intocontact with the auditory capsule (Jacoby). This condition is even visibleat the 110 mm. stage (fig. 15). Notes on the Development of the Human Sphenoid 217 It may be mentioned here that the foramen ovale and foramen spinosumare generally regarded as being formed in the cartilage of the great I doubt. It certainly is not the case in the 80 mm. embryo, and a
. Journal of anatomy . ochondrally, as will, to a large extent, be seen in the photograph of asection of an 80 mm. embrj^o (fig. 14). In the same model (30 mm.) theprocessus alaris sends backwards a pointed process which comes intocontact with the auditory capsule (Jacoby). This condition is even visibleat the 110 mm. stage (fig. 15). Notes on the Development of the Human Sphenoid 217 It may be mentioned here that the foramen ovale and foramen spinosumare generally regarded as being formed in the cartilage of the great I doubt. It certainly is not the case in the 80 mm. embryo, and allthe ajDpearances suggest that they are formed in ectochondral bone. Since this was sent to print I have been able to show that the superiormaxillary nerve does not either groove or pierce the cartilage of the greatwing, but that both the foramen ovale and the foramen spinosum aredeveloped in membrane bone. This is seen at the 100 mm. stage. Tlie Ossification of the Sphenoid.—This has been to a certain extent Us- AT. -Rfe Fig. 13. dealt with by me in a short note in the Anatoviischer Anzeiger, vol. 80, in which I pointed out that the internal pterygoid plate was the firstpart of the sphenoid to ossify. Fig. 12 is from a coronal section of the head of a 37 mm. embryo(Harvard) collection. It shows us that the external pterygoid plate ()is composed of connective tissue. is the exteinal pterygoid muscle; is the bony (ectochondral) internal pterygoid plate; the tensorpalati; M. mandible; Meckels cartilage; Meckels ganglion; nasal septum; N. nasal cavity; O. the mouth; internal pterygoidmuscle ; P. the ununited palate. At this stage the hamulus is ossifying in cartilage, which cartilage canbe seen in the 30 mm. model. 218 Professor Fawcett Ossification next commences in the temporal or greater wing justexternal to the foramen rotundura (fig. 13) () at about the 42 mm. stage. Fig. 13, from the 42 mm. embryo, shows ossification in
Size: 1663px × 1502px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1860, booksubjectanatomy, bookyear1867
