Does your friendly neighborhood snake prefer to go straight or take the scenic route?From Da Vinci to MRI

Why study whether male erection is' straight 'or' curved '? It all starts with a human sketch by Leonardo da Vinci from 1493. This sketch is unique in medical history as it depicts the moment of intercourse. In it, the erect male penis appears almost straight, from the external part to the internal root. This anatomical hypothesis was seen as a perfect example of human mechanics during the Renaissance. However, modern science has turned this sketch into a "Rashomon" of sexual medicine.



A team led by Willibrord Weijmar Schultz from the University Medical Center Groningen in the Netherlands used MRI to solve this century-old puzzle. Researchers carefully selected eight couples with normal sexual function. Before the experiment, the men took 50 mg of Viagra to ensure a full erection. Forty - five minutes after the medication took effect, the scanning began. Each couple was asked to simulate intercourse in the "missionary position" - just as depicted in da Vinci's sketch. The MRI scanner, with a bore diameter of only 60 cm, became the special "stage" for this scientific experiment. The volunteers had to perform precise movements amid the noise of the machine. When they heard the "click" command, they had to freeze so the scanner could capture the key moment.



These volunteers had to endure the loud noise of the MRI machine and perform coordinated movements within the confines of the 60 - cm - diameter scanner. What's more, they had to do this with a group of scientists watching intently. When instructed to stop, they had to freeze immediately - a true testament to their dedication to science.



The results were surprising. The external part of the penis accounts for only two - thirds of the total length, while the internal root makes up the remaining one - third. The angle between them is between 110° and 120°, forming a distinct "C" curve, similar to an Australian Aboriginal boomerang. Subsequent experiments at the University of Montpellier in France confirmed this finding. High - definition images clearly showed the true shape of the penis inside the body: during intercourse, the penis forms an elegant arc along the front wall of the vagina. This physiological structure perfectly matches the anatomy of the female reproductive system.



Looking more closely at other parts of da Vinci's sketch, other interesting details emerge. For example, the tube from the female breasts to the uterus reflects the then - prevailing belief that menstrual blood turned into milk during pregnancy. The channel connecting the male penis to the brain illustrates a popular theory of the time—that semen originated in the brain. Although these details were based on incorrect anatomy, the sketch still shows da Vinci's remarkable insight into human structure. He was the first to accurately depict the triangular muscle group in the perineal region, laying the foundation for modern urological surgery. Such a detailed and precise drawing in that era is truly admirable.



These scientific discoveries have not only corrected a five - century - old anatomical misunderstanding but also opened new avenues for research in sexual medicine. Modern sexual health experts note that the natural curvature of the penis significantly impacts sexual quality of life. The application of MRI technology has allowed us to see this hidden yet crucial physiological phenomenon for the first time. As da Vinci once said, "Simplicity is the ultimate sophistication." As the spotlight of science illuminates the intimate corners of sexuality, we are left in awe of the intricate designs of biological evolution. The complex anatomical structures and mechanisms, honed by natural selection, reveal a beauty and power that surpasses even the wildest artistic imagination.