‘Man is not truly one, but truly two’ – Robert Louis Stevenson’s Strange Case of Dr Jekyll and Mr Hyde

When I was studying the anatomy, I used to improve my memory combining the information I wanted to remember with a visual image, a sentence, or a word. The posterior  interosseous nerve is the continuation of the deep branch of the radial nerve; he passes beneath the Frohse’s arcade, a fibrous arch between the two heads of the supinator muscle. The deep branch of the radial nerve and his continuation… two sides of the same coin… In the same period I was reading the Stevenson’s novel, so easy for me to combine the duplicity of the nerve with the main character of the book.

A compressive entrapment of the posterior interosseous nerve is called Radial Tunnel Syndrome and the arcade of Frohse is the most common site of compression.

Axial Ultrasound and T2w Mri scan (0.3 Tesla) of the Frohse’s arcade normal anatomy.

The early diagnosis of this pathological condition can be easily done with dynamic ultrasound examination; repeating all the clinical manouvres is possible to directly appreciate the nerve compression syndrome. First of all you need to know where the posterior  interosseous nerve is located and how it appears under normal conditions; I suggest you to perform the axial scan. Take a look at the video below and enjoy your study.