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Introduction The hypoglossal canal is a constant feature of the human skull and presents variations in its morphology. These variations include duplication and bridging of the canal. There have been number of studies earlier which merely defined presence and absence of the bridging of the canal however none gave a detailed classification. Hence the aim of present study was to provide a detailed classification of the bridging pattern based on the observations on a large number of sample size. Methods The 625 skulls were procured from Department of Anatomy of GSVM Medical College, Kanpur, Santosh Medical College, Ghaziabad and School of Medical Sciences and Research, Greater Noida. The hypoglossal canal of each skull was examined and the bridging pattern was observed and classified. The skulls with no bridging were classified as Type 1; incomplete bridging was classified as Type 2; complete endocranial bridging as Type 3; exocranial bridging as Type 4 and complete bridging throughout the canal as Type 5. These categories were further subdivided according to unilateral or bilateral bridging of the canal. Results The results obtained show that the hypoglossal canal is the constant feature of occipital bone of the skull and invariably presents with morphological variations. Type 1 category was seen in 84% of skulls, Type 2 was observed in 4.32% with left side dominance. Type 3a category was seen in 7.68% and Type 3b in 4.16%. There was no skull with Type 4 and Type 5 category. Discussion The bridging pattern of hypoglossal canal is governed by molecular, environmental and racial factors. The detailed classification of bridging pattern is of great significance to the anthropologists, forensic experts, radiologists and neurosurgeons. |
