Sim's ( Simm’s) position:

named after J. Marion Sims is usually used for rectal examination, treatments and enemas. It is performed by having a patient lie on on their left side, left leg extended and right leg flexed.

In the 1840s the American physician Marion Sims successfully repaired damage to the walls of the vagina, bladder and rectum of some American slaves he had bought for this purpose. Such damaged tissue often prevented women from enjoying social life as the leaking of feces and urine caused constant soiling and repellent odor. The slaves, of course, occupied the lowest status and had little choice but to let Sims attempt, again and again over years, to surgically fix the terrible wounds caused by childbirth - using no anesthesia. But once Sims had repaired the tears and mastered the procedure he opened probably the first hospital for women, in New York, and traveled the world helping similarly afflicted women, including European royalty. It was a huge breakthrough in gynecology and demonstrated the power of actually looking at the genitals of a patient in order to help her. The so-called Sims posture, or position, below, used by Sims to access the woman's perineum, became useful to other doctors in examinations because the woman could not see the physician, thus maintaining the emotional distance achieved by "sightless" examination procedures that were now becoming obsolete.

1. Patient lies on their left side
2. Patient's left arm is extended behind their back
3. The patient's right arm is brought forward and right leg flexed.

an exaggerated Sim's position

1. lying on left side

2. two pillows under right knee, which is jack-knifed*
3. left leg straight out and toward the back.

¹jack·knife Function: noun :a large strong pocketknife

^*2jackknife Function: verb

intransitive verb: to double up like a jackknife <jackknifed into a seat beside me, folding up his six feet eight -- Lady Bird Johnson>