Reconciling the Rashbam's understanding for leaning left with the anatomy of the throat

Question

The Gemara (Pesachim 108a) rules:

פרקדן לא שמיה הסיבה הסיבת ימין לא שמה הסיבה ולא עוד אלא שמא יקדים קנה לוושט ויבא לידי סכנה

Lying prone is not called leaning. Leaning right is not called leaning. Furthermore, the trachea might come before the esophagus and he will come to a danger.

Rashbam ad. loc. first proposes that the issue of danger is when one is lying prone, but he then proposes a second understanding (followed l'halacha by the Mishnah Berurah 472:10 with a practical difference for lefties at the Seder) in which this last line refers to the second clause, regarding leaning right:

דושט הוי על (דרך) ימין ונפתח הכובע שעל פי הקנה מאיליו כשהוא מטה כלפי ימין ואם יכנס בו המאכל הרי סכנה שאין אוכלין ומשקין נכנסין אלא דרך הושט

The esophagus is to the right, and when one leans to the right the epiglottis will open from the windpipe. If food enters [the windpipe], there will be a danger, for food and drink only pass through the esophagus.

How can Rashbam say that the trachea is to the left and the esophagus to the right, when the trachea is to the front, and the esophagus is to the back? Wikipedia has a nice diagram, but you can tell for yourself by pressing gently on the front of your throat: the hard rings you'll feel are the outer lining of your trachea.

How can Rashbam posit that this line refers specifically to leaning to the right, when it contradicts very obvious anatomical facts?

Answer 1

I'm not sure this quite answers your question, but Radvaz (3:584 (1012)) does seem to question Rashbam's anatomical facts, and says something that might be considered an answer:

ועוד ראיתי כי הסימנים שוכבין זה על זה ולא ידעתי אם סימני אדם נשתנה

Depending on how you read this, he could be entertaining the possibility that the anatomical facts had changed over time. What might have been anatomically true in the times of Rashbam (or Chazal) may have no longer been true.