Fetal Development of the Incisive Canal, Especially of the Delayed Closure Due to the Nasopalatine Duct: A Study Using Serial Sections of Human Fetuses

Abstract

The incisive canal of the incisive bone or premaxilla is a narrow bony canal through which pass the nasopalatine nerve and its concomitant vessels. However, its fetal development remains obscure. To assess its development, serial frontal sections of the heads of 26 human fetuses, of gestational age 9-20 weeks (crown-rump length, 46-183 mm), were examined. The nerve initially passed through a wide loose tissue space, but after ossification of the upper part of the incisive bone at 12-15 weeks, the canal became narrow and filled with tight fibrous tissue. Canals in seven fetuses were dilated and open unilaterally or bilaterally. In two of these seven fetuses, a nasopalatine duct passed through the canal and connected the nasal cavity to a central lumen of the paramedian epithelial pearl in the incisive fossa (not to an oral cavity). Even if the canal was closed, the duct was likely to remain above and below the closed part. Paramedian pearls were present in all specimens larger than 110 mm (15 weeks), with or without association of midline pearls. These paramedian pearls usually protruded toward and/or extended into the dilated or open canal, suggesting that these pearls, not any primitive oronasal communication pathway, contributed to keeping the canal open. The dilated canal, located on the superomedial side of the second and third teeth buds, seemed to be usually closed by further ossification. Even in fetuses, the nasopalatine duct seemed to be a variant or unusual phase of development temporally occurring after normal palate fusion. Anat Rec, 300:1093-1103, 2017. © 2016 Wiley Periodicals, Inc.

Association between the developing sphenoid and adult morphology: A study using sagittal sections of the skull base from human embryos and fetuses

“…In contrast, the ossified posterior end of the ethmoid was fixed in the lower position by the nearby palatine bone, vomer, PTmed, and BS. In these anchors, the vomer was extremely bulky and developed early (Kim, Jin, et al, 2017; Kim, Oka, et al, 2017). Because of these anchors, the early ossified posterior part of the ethmoid seemed to be liable to separate from the major cartilaginous part depending on growth of the skull (see also above).…”

The Incisive Canal: A Comprehensive Review

“…Collectively, the fusion of these palatal shelves results in the formation of the secondary palate. The complete fusion of the primary and secondary palates occurs at the 12th embryonic week [ 4 - 7 ].…”

“…In another small observational study by Falci et al, using five fetuses between weeks eight and nine, the development of the incisive canal within the pre-maxillary bone was also confirmed [ 6 ]. Using a larger sample size of 26 human fetuses, Kim et al verified Radlanski’s argument of the incisive canal developing within the pre-maxillary bone by observing that the nerves and blood vessels grew within the mesenchyme, albeit anterior to where the definitive canal is positioned [ 7 ].…”

Sphenopalatine Foramen Localization: Radiological and Surgical Morphometric Analysis for Localization of Sphenopalatine Artery

“…The sphenopalatine foramen (SPF) represents an opening on the lateral nasal wall that is present at the articulation between the superior aspect of the vertical portion of the sphenopalatine bone and the inferior projection of the sphenoid bone. [10] The sphenopalatine foramen connects the nasal cavity to the pterygopalatine fossa of the skull and houses the sphenopalatine artery (SPA) and vein, the posterior superior lateral nerve and the nasopalatine nerves. [6] Difficulty in locating the SPA as it exits the SPF may be accompanied by active bleeding that obscures the operative field or oedematous and friable tissue caused by previous nasal packing.…”