Variations in the pattern of mental spines and spinous mental foramina in dry adult human mandibles.

The frequency and morphology of mental spines and spinous mental foramina was studied in 1200 adult human mandibles of Indian origin. The mental spines were present in 1178 mandibles (98.2%). The usual textbook description of four spines, arranged in two pairs one above the other was found only in 231 mandibles (19.6%). Mandibles with only two superior mental spines were seen in 842 cases (71.4%) which were associated with either a median vertical ridge below them (47.7%) or with a rough impression in place of the median ridge (23.7%). Spinous mental foramina (one to three) close to the midline and in between the spines were found in 1165 mandibles (97.57%). The presence of these foramina has not been mentioned in most textbooks of anatomy.