An anatomical investigation of the carotid canal.

BACKGROUND The carotid canal (CC) located in the petrous temporal bone transmits the internal carotid artery, internal carotid venous plexus and sympathetic nerve plexus from the neck into the cranial cavity. It is an accessible passage into the cranial cavity and is considered an important anatomical landmark for neurosurgeons. The aim of this study was to investigate the topographical, morphometric and morphological parameters of the CC. MATERIALS AND METHODS An examination of the CC and related adjacent structures in 81 dry skull specimens was performed. Distribution of sample by sex was 34 females and 47 males, and by race 77 African and 4 Caucasian. The mean age was 50 years (range: 14-100 years). RESULTS The external opening of the CC was found to be round-shaped, oval-shaped and tear-drop-shaped in 28.4%, 49.4% and 22.2% of the specimens, respectively. (1) Mean diameters [mm]: (a) medio-lateral 7.52 mm and (b) antero-posterior 5.41mm. Statistically significant difference in the vertical diameter was recorded in the race groups and laterality of the samples. (2) Mean distances [mm] between: (a) medial margins of external opening of CC was 50.03 mm, (b) lateral margins of external opening of CC was 62.73 mm and (c) external openings of CC and foramen lacerum was 15.6 mm. There was a statistically significant correlation between race and location of the opening of external CC in relation to foramen lacerum (viz. postero-lateral, lateral and diagonal, and lateral). CONCLUSIONS The present study corroborated previous reports on the CC; however, the tear-drop shaped external CC opening was a unique finding. The knowledge of the reference measurements pertaining to the CC and its relationship to adjacent structures may postulate a suitable surgical "safe-zone" range within the CC area.