The jugular foramen -- a morphometric study.

The jugular foramen (JF) varies in shape and size from side to side in the same cranium, and in different crania, racial groups and sexes. Side dominance is also said to be common. The foramen's irregular shape, its formation by two bones and the numerous nerves and venous channels that pass through it further compound its anatomy. A morphometric study of 20 (40 JF) adult male Nigerian dry skulls was carried out. A bony bridge completely partitioned the JF in 3 (7.5%) of the JF. There was no tripartite JF. The JF mean length on the right and left were 13.90 mm (11.6-17.0 mm) and 14.11 mm (9.2-20.2 mm), while their widths measured 10.22 mm (6.8 -14.4 mm) and 9.57 mm (7.4-12.8 mm) on the right and left respectively. The mean JF area on the right was 437.49 mm (265.35-669.54 mm) and that on the left was 419.48 mm (276.46-634.60 mm). Side predominance of one of the JF appeared in 80% of cases. When present, the predominance of the right side was 55%, with 25% on the left. There was a difference in the length and width on each side but no significant difference in the length, width and area of the JF between the two sides. There was a positive correlation between skull width/ length and height/length ratio and JF area and length on each side. In conclusion, complete bony subdivision of the JF was not common among our study population and although the JF was generally larger on the right in our population, this is not statistically significant. A higher skull width/length and height/length ratio is associated with a greater JF length and area.