A STUDY OF MORPHOLOGY, MORPHOMETRY, SYMMETRY AND DEVELOPMENT OF EXTERNAL OPENING OF CAROTID CANAL WITH COMPARISON IN MALE, FEMALE AND FOETUS

Introduction: The Carotid Canal is an important structure at the base of skull as it conveys the internal carotid artery, along with a sympathetic nerve plexus and a venous plexus. Previous researches done on carotid canal suggest that abnormalities to this canal, such as fractures of carotid canal and carotid sympathetic plexus schwannoma have their effect on the internal carotid artery and the structures passing through it. Cases of absence of carotid canal have also been reported, which causes variations of the internal carotid artery. Attempt has been made in this study to give a detailed view of the ‘external opening of carotid canal’ (EOCC) which is the gateway of the carotid canal at the skull base. This study shall be useful for Surgeons, Radiologists, Anatomists, Forensic Experts, Anthropologists, etc. Aim: This study aims at measuring the various dimensions of the external openings of the carotid canal pair present at the base of skull, and to observe the age changes, sexual dimorphism, and symmetry of the external opening of the carotid canal from the analysis of these measurements. Materials and methods: Total 235 dry skulls that included 181 adolescent to adult skulls of known age and sex (age ranging from 13 years up to old age skulls of 60 years or above) and 54 foetal skulls were studied for this purpose. The longest & shortest diameter of each carotid canal, was measured using a screw adjusted compass and a Vernier Calliper. Their distance from pharyngeal tubercle and from the X axis and Y axis was measured. Observations and Results: In the present study, it was observed that external opening of each carotid canal was unique in its morphology and morphometry. The dimensions of external opening of carotid canal progressively increased from foetal age to 25 years of age, however after 25 years of age, it did not show any age change within same sex, but it showed age changes when adolescent female skulls of age less than 25 years were compared with adult male skulls of age above 25 years. It was also observed that the external opening of carotid canal showed sexual dimorphism when compared within same age group (that is, between adolescent male and female skulls below 25 years age, and between adult male and female skulls above 25 years age. Further it was also observed that EOCC did not show any asymmetry in foetal age, however it showed asymmetry in female skulls below age 25 years (adolescent).