Surgical anatomy of hypoglossal canal for various skull base surgeries.

PURPOSE: Anatomical knowledge of the hypoglossal canal is very important in relation to drilling of occipital condyle, jugular tubercle etc. So, this study was conducted to identify various morphometric and morphological features of the hypoglossal canal and its distance from adjacent structures relative to stable and reliable anatomic landmarks.

METHODS: The study was performed on 142 hypoglossal canals of 71 adult human dry skulls. The parameters measured were the transverse, vertical diameter, depth of the hypoglossal canal. The distances from the hypoglossal canal to the foramen magnum, occipital condyle and jugular foramen were also noted. In addition, the different locations of the hypoglossal canal orifices in relation to the occipital condyle were assessed. The different shapes and types of the hypoglossal canal were also noted.

RESULTS: There was significant difference (p < 0.05) in measurements taken on the right and left sides in males and females. The intracranial orifice of hypoglossal canal was present in middle 1/3rd in 100% of occipital condyle for both genders. The extracranial orifice of the hypoglossal canal was found to be in the anterior 1/3rd in 99% and 93.7% for male and female, respectively. Simple hypoglossal canal with no traces of partition was found to be more in males and females. The most common shape noted was oval both in males and females (71.8% and 68.7% respectively).

CONCLUSION: The results of the dimensions of the hypoglossal canal and its distance from other bony landmarks will be helpful for neurosurgeons to plan which surgical approaches should be undertaken while doing various surgeries in posterior cranial fossa.