The sphenoidal spine and the sphenoidal tubercle

An accurate knowledge of the human anatomy must rely on an adequate use of the anatomical terminology. Unfortunately, the modern anatomical nomenclature excluded an important amount of terms of the ‘ancient’ anatomy.

A recent paper presents a study on dried human skulls . In the paper’s abstract is a sentence referring to a ‘ sphenoidal process ’ related to the pterygomaxillary fissure (PMF). We searched within the paper in order to understand what may be that process, due to the fact that it was the first time we encountered that term. Surprisingly, when searching the document with the key words ‘ sphenoidal process ’, the term was not found within all the document but, instead, we found several times the ‘ sphenoidal spine ’. The discussion there points to that spine significance for the maxillary nerve block: ‘ the width of the pterygomaxillary fissure and the existence of the enlarged sphenoidal spine (Fig. 3) are of great clinical significance ’ and ‘ an enlarged sphenoidal spine obstructs the entrance to the pterygomaxillary fissure ’. We observed Fig. 3 where a needle is intended to point that ‘ sphenoidal spine ’ (anyway, none can agree that a bony spine may have a ‘ lateral wall ’ as mentions the legend) and we were surprised to find that the respective spine was misdiagnosed. Due to the fact that the structure misdiagnosed there as ‘ sphenoidal spine ’ was defined to be highly relevant for the maxillary nerve block we considered opportune to address this letter to the editor in order to correct the terms and so to avoid confusion.

The description of the sphenoidal spine can be found in usual anatomical textbooks dealing with the anatomy of the sphenoid bone. Gray’s anatomy, for example, describes the greater sphenoidal wing as presenting at its posterior part the spina angularis, attaching the sphenomandibular ligament and the Tensor veli palatini . The angular spine of sphenoid ( spina ossis sphenoidalis ) appears as a sharp, bony spur that extends downwards from the greater wing . Moreover, the spine of the sphenoid belongs to the trans-spinosum corridor that may be used to reach the internal carotid artery and does not interfere so much with the lateral approaches of the pterygopalatine fossa .

The confusion is probably due to the lack within modern anatomical textbooks of the description of the sphenoidal tubercle that is a prominence located at the anterior end of the infratemporal crest of the greater sphenoidal wing, as described in the ‘ancient’ French anatomical literature . The respective infratemporal crest is the bony ridge between the vertical temporal surface and the horizontally-oriented inferior surface of the greater wing of the sphenoid . As so, the so-called ‘ sphenoidal spine ’ in the paper discussed here is in fact the sphenoidal tubercle of the infratemporal crest of the greater wing. Nevertheless, the term ‘ sphenoidal process ’ has no correspondent within the anatomical literature.

The topographic difference of the sphenoidal spine and sphenoidal tubercle is major, as we present in Fig. 1 . The sphenoidal spine, located medially to the articular tubercle of the temporal bone, can be identified by the presence within its base of foramen spinosum while the sphenoidal tubercle, individually variable as morphology, projects supero-laterally to the PMF. As so, if one will attempt to enter the pterygopalatine fossa using the sphenoidal spine as landmark will not reach that fossa and may penetrate some important arteries, as are the middle meningeal artery, within the foramen spinosum , or the internal carotid artery.

Feb 8, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on The sphenoidal spine and the sphenoidal tubercle
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