Incidence of pyramidalis muscle

Abstract

Pyramidalis is a triangular muscle that lies in front of the lower part of rectus abdominis muscle within the rectus sheath. This muscle is known to vary considerably in size and present either unilaterally or bilaterally. A large number of studies supports the racial variation in its occurrence. This preliminary study was carried out to investigate the incidence of pyramidalis muscle and also to establish its anatomical dimensions in a sample group of Sri Lankans. A total of forty two cadavers were studied during the routine gross anatomy dissections. The presence or absence of the muscle either bilaterally or unilaterally was noted on visual inspection. The maximum length and width of the pyramidalis was measured using a sliding caliper capable of measuring to the nearest 0.01mm. Pyramidalis was present bilaterally in 85.71% and absent in 14.28% of the subjects. The maximum length of the muscle was 6.24 ± 0.12 cm on right side and 7.09 ± 0.20 cm on left side. The maximum width was 1.32 ± 0.14 cm on right side and 1.52 ± 0.18 cm on left side. Bilateral variation in the dimensions of the muscle was statiscally significant. The occurrence of pyramidalis muscle was established for a group of adult Sri Lankan population. Our results reveal there is a racial trend in the incidence of pyramidalis muscle between Sri Lankan and other races such as black and white populations.