Osseous variations of the hypoglossal canal area

The hypoglossal canal is a paired bone passage running from the posterior cranial fossa to the nasopharyngeal carotid space. Hyperostotic variations of this structure have been described.

One hundred sixteen adult cadaveric dried skull specimens were analyzed. Several canal features, dimensions, and distances relative to constant and reliable landmarks were recorded.

One osseous spur in the inner or outer orifice of the canal was present in 18.10% of specimens (42/232). Two or more osseous spurs were evident in 0.86% of specimens (2/232). However, complete osseous bridging, in the outer or inner part of the canal, was evident in 19.83% of specimens (46/232). Osseous bridging extending through the entire course of the canal was visible in 1.72% of the specimens (4/232). The mean lateral length of the canal was 10.22 mm, the mean medial length was 8.93 mm, the mean transverse and vertical diameters of the internal orifice were 7.44 mm and 4.42 mm, respectively, and the mean transverse and vertical diameters of the external orifice were 6.15 mm and 3.91 mm, respectively. The mean inclination of single hypoglossal canals was 42.3 degrees and 32.4 degrees on the right and left side, respectively.

A detailed and accurate evaluation of the hypoglossal canal topographic anatomy with regard to specific, standard osseous landmarks was performed. Additional data with respect to several morphologic features of the hypoglossal canal area also was obtained. Results of this study provide important information that will enable effective and reliable surgical intervention in the area of the hypoglossal canal.