International Journal of Research in Medical Sciences | August 2017 | Vol 5 | Issue 8 Page 3534 International Journal of Research in Medical Sciences Singh K et al. Int J Res Med Sci. 2017 Aug;5(8):3534-3539 www.msjonline.org pISSN 2320-6071 | eISSN 2320-6012 Original Research Article Sexual dimorphism in stapes by discriminant functional analysis Kamal Singh*, Aarti Rohilla INTRODUCTION Our knowledge about these ossicles goes back to the 15 th century, when Alessandro Achillini (1463-1513) for the first time noted the presence of the malleus and incus. 2 Giovanni Filippo Ingrassia, one of the leading Italian Physicians of the 16 th century revisited and redefined some of Galeno’s reports. The most important discovery in Ingrassia’s study about the hearing organ was the first description of the third bone of the ossicular chain that he called “stapes”. 3 The stapes is the stirrup like bone which lacks periosteum, having a head (articulating with the incus), a constricted neck, two diverging limbs from neck (processes or crura) and a flattened base (footplate). The footplate is attached to the margin of the fenestra vestibuli by a ring of fibres (the annular ligament). It articulated with incus to form incudostapedial joint which is a ball and socket articulation. The articular surfaces are covered with articular cartilage, and each joint is enveloped by capsule rich in elastic tissue and lined by synovial membrane. The handle of the malleus faithfully follows all movements of the tympanic membrane moving the incus which pushes the stapedial footplate towards the labyrinth and the perilymph contained within the labyrinth. The three bones together act as a bent lever so that the stapedial footplate does not move in the fenestra vestibuli like a piston, but rocks on a fulcrum at its anteroinferior border, where the annular ligament is thick. The rocking movement around a vertical axis, which is like a swinging door, is said to happen only at moderate intensities of sound. With loud, low-pitched sounds, the axis becomes horizontal, and the upper and lower margins of the stapedial footplate oscillate in opposite directions around this central axis, thus preventing excessive displacement of the perilymph. 4 Department of Anatomy, Pandit Bhagwat Dayal Sharma, PGIMS, Rohtak-124001, Haryana, India Received: 15 June 2017 Accepted: 08 July 2017 *Correspondence: Dr. Kamal Singh, E-mail: drkamalanatomy@gmail.com Copyright: © the author(s), publisher and licensee Medip Academy. This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License, which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. ABSTRACT Background: Sexing of human skeleton is highly contested subject and is usually done by using morphological and metrical traits of big intact bones like skull, mandible, pelvis and long bones etc. 1 The stapes remains well protected by being housed in the middle ear, even in the mutilated bodies. Methods: The morphometric study of the 120 human stapes bones from 60 unidentified cadavers was aimed to know the presence of sexual dimorphism. Results: The weight and measurements of footplate could be a good criterion for determining percentage accuracy as male and female respectively and could be used as a potential tool for determination of sex. Conclusions: The study of normal dimensions and indices of stapes will provide insight to the forensic experts for deciding the sex of an individual in the disputed cases. Our findings are the results for guidance and future manipulation in the forensic and legal medicine. Keywords: Indices, Ossicles, Stapes, Sexing DOI: http://dx.doi.org/10.18203/2320-6012.ijrms20173557