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The dimensions and shape of the human vagina are of great importance in medicine and surgery;〔 there appears to be no one way, however, to characterize the vagina's size and shape.〔 In addition to variations in size and shape from individual to individual, a single woman's vagina can vary substantially in size and shape during sexual arousal and sexual intercourse.〔 Parity is associated with a significant increase in the length of the vaginal fornix.〔 The potential effect of parity may be via stretching and elongation of the birth canal at the time of vaginal birth.〔 Although the dimensions of the human vagina have not been the subject of intensive research to the same extent as research into human penis size,〔 a number of research studies have been made of the dimensions of the human vagina. == Dimensions in the baseline state == A 1996 study by Pendergrass et al. using vinyl polysiloxane castings taken from the vaginas of 39 Caucasian women, found the following ranges of dimensions: * lengths (measured using rods): 6.86 to 14.81 cm (2.7 to 5.84 inches); * widths: 4.8 to 6.3 cm (1.88 to 2.48 inches); * introital diameters: 2.39 to 6.45 cm (0.94 to 2.53 inches) A second study by the same group showed significant variations in size and shape between the vaginas of women of different ethnic groups. Both studies showed a wide range of vaginal shapes, described by the researchers as "Parallel sided, conical, heart, () slug"〔 and "pumpkin seed"〔 shapes. Barnhart et al., however, were unable to characterize the shape of the vagina as a "heart, slug, pumpkin seed or parallel sides" as suggested by the previous studies.〔 A 2003 study by the group of Pendergrass et al. also using castings as a measurement method, measured vaginal surface areas ranging from 65.73 to 107.07 cm2 (10.19 to 16.60 sq. inches) with a mean of 87.46 cm2 (13.56 sq. inches) and a standard deviation of 7.80 cm2 (1.21 sq inches) Research published in 2006 by Barnhart et al., gave the following mean dimensions, based on MRI scans of 28 women: * Mean length from cervix to introitus: 6.27 cm (2.46"). * Mean width: * * at the proximal vagina: 3.25 cm (1.27"); * * at the pelvic diaphragm: 2.78 cm (1.09"); * * at the introitus: 2.62 cm (1.03") 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Human vaginal size」の詳細全文を読む スポンサード リンク
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