Anatomical Variation in Morphometry and Morphology of the Foramen Magnum and Occipital Condyle in Dried Adult Skulls

BACKGROUND: The foramen magnum (FM) is the largest opening and is outlet through which medulla oblongata and spinal cord along with meninges, vertebral arteries, anterior and posterior spinal arteries, tectorial membrane, alar ligaments, and spinal branch of the accessory nerve. Occipital condyle (OC) is an important part of craniovertebral or craniocervical junction located anterolaterally on either side of the FM. The objective of the study was to assess variations of FM and OC in Ethiopian dried adult skulls. METHODS: Observation-based descriptive study design was employed. The study was undertaken in 54 FM and 108 OC of 54 adult Ethiopian skulls. The morphometry of FM and OC were determined using a sliding vernier caliper. RESULTS: The mean values of anteroposterior and transverse diameters of the FM were 35.19 and 30.17 mm, respectively, and the mean area of the FM was 853.36 mm. The shapes of FM were determined as round in 22.2%, oval in 18.5%, egg like in 20.4%, triangular in 3.7%, pentagonal in 11.1%, hexagonal in 7.4%, irregular in 13%, and rectangular in 3.7% of the cases. The mean length of right and left OC was 25.69 and 26.96 mm, respectively, and the mean widths of the right and left OC were 12.76 and 13.04 mm, respectively. CONCLUSION: Our study identified various shapes of FM and diameter. The anteroposterior diameter is greater than the transverse diameter. The morphometric study of OC confirmed the length of left side is significantly greater than the right side.