. Cunningham's Text-book of anatomy. Anatomy. 150 OSTEOLOGY. developed, lies close below the infra-orbital groove, and it is not till later that they become separated by the growth of the maxillary sinus, which first makes its appearance as a shallow fossa to the medial side of the orbito-nasal element about the fourth month. In the adult bone the course of the infra-orbital canal and foramen indicates the line of fusion of the orbito-nasal and zygomatic elements, whilst the position of the anterior palatine canal serves to determine the line of union of the incisive with the palatine elements
. Cunningham's Text-book of anatomy. Anatomy. 150 OSTEOLOGY. developed, lies close below the infra-orbital groove, and it is not till later that they become separated by the growth of the maxillary sinus, which first makes its appearance as a shallow fossa to the medial side of the orbito-nasal element about the fourth month. In the adult bone the course of the infra-orbital canal and foramen indicates the line of fusion of the orbito-nasal and zygomatic elements, whilst the position of the anterior palatine canal serves to determine the line of union of the incisive with the palatine elements. In addition to the foregoing centres, Rambaud and Renault describe another, infra-vomerine, which, together with its fellow, is wedged in between the incisive and the palatine elements beneath the vomer, thus explaining the Y-shaped arrangement of the foramina of Stensen, which open into the anterior palatine canal. The premaxillse, which in most vertebrates are in- dependent bones lying in front of the maxillae, constitute in man and apes the portions of the maxilla which lie in front of the anterior palatine foramen, and support the superior incisor teeth. Each premaxilla is developed from two centres: a facial, which ultimately contains the incisor and canine teeth, and forms the front*part of the hard palate, as well as the anterior half of the frontal process of the complete maxilla (Fawcett); and a palatine centre (supra vomerine of Rambaud and Renault) which forms the medial wall of the correspond- ing canal of Stensen. The former develops very early, either before or after the maxilla (Mall), and fuses almost at once with the maxilla along the alveolar margin; the latter appears about the twelfth week, and soon fuses with the facial centre. The line of fusion of the pre- maxillee with the maxillae proper can be readily seen in young skulls, and occasionally also in the adult. It corresponds to a suture which passes on the palate obliquely laterally and forwards, from
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectanatomy, bookyear1914
