The mendosal suture of the occipital bone: occurrence in Indian population, embryology and clinical significance.

The occipital bone is ontogenetically and functionally unique when compared to the other bones of the skull in humans and other mammalian cousins. The occipital bone develops from six ossification centers; any defect in the ossification process will give rise to mendosal suture (accessory suture) and conditions like posterior plagiocephaly. There is a paucity of literature regarding the mendosal suture and further more, its report in Indian population is not known. The present study was conducted to find out the occurrence of mendosal suture in the Indian dry skulls. Fifteen specimens (3%) were found to have these sutures out of five hundred (500) skulls examined. Nine (3.1%) samples are of male skulls out of two hundred ninety (290) and six (2.85%) samples are that of female skulls out of two hundred ten (210). The mendosal suture ran close to the superior nuchal line in all specimens and traveled medially from the lambdoidal suture. The length of the sutures ranged from 0.8 cm to 2.6 cm (1.88 cm) on the right side and 1.4 cm to 2.9 cm (1.94 cm) on the left side respectively in male skulls; and 0.7 cm to 2.8 cm (1.55 cm) on the right side and 1 cm to 2.4 cm (1.42 cm) on the left side, respectively, in female skulls. The origin of mendosal suture from the lambdoidal suture was 5.7 cm to -6.3 cm (5.98 cm) from the tip of the mastoid process on the right side and 5.6 to -6.3 cm (6 cm) on the left side, respectively, in male skulls; and 5.4 cm to -5.8 cm (5.58 cm) on the right side and 5.4 cm to -5.6 cm on the left side respectively in female skulls. The occurrence and clinical significance of the present study is discussed.