Elbow Anatomy Update

Most malls in America offer at least one arcade to entertain those who aren't shopping. There's an arcade in your body, too, but it's not for fun. It's a canal that gives the ulnar nerve safe passage along the inside edge of the elbow. It's called the Arcade of Struthers, named after Sir John Struthers, a whale anatomist from Scotland.

Until recently doctors and anatomists thought the Arcade of Struthers was a thin band of tissue near the elbow. Two doctors from the University of Toronto Hand Program have shown it's not what we'd always thought. They dissected 11 arms and mapped out the arcade one layer at a time. They measured, sketched, and photographed every section above and beside the arcade.

They found the same anatomy in all 11 specimens. The ulnar nerve was followed from the armpit down past the elbow, into the inside edge of the forearm. Instead of a thin band, the arcade is actually a canal with muscle, fascia, and ligament on all sides. The ulnar nerve actually takes a turn and changes direction at the opening of the canal.

The ulnar nerve slid easily through the canal in ten of the 11 cadavers. Even so, the shape of the canal wasn't the same in all 11 arms. The length varied as much as two centimeters (just under an inch). In two cases there were extra bands of tissue crossing over the ulnar nerve at the end of the canal.

The authors report exact details of the anatomy for the Arcade of Struthers. They say this will help other doctors when doing surgery on the ulnar nerve in this area. The canal is one place where pressure on the nerve can occur.

Knowing where the nerve changes direction helps when tracing the nerve through the arm. Seeing the arcade as a canal instead of a thin band will guide the surgeon. Knowing there can be extra bands of tissue also helps the surgeon look for the cause of nerve compression. Treating ulnar nerve problems will be easier with this new detailed description of the Arcade of Struthers.

References: Herbert P. von Schroeder, MD, and Luis R. Scheker, MD. Redefining the "Arcade of Struthers." In The Journal of Hand Surgery. November 2003. Vol. 28A. No. 6. Pp. 1018-1021.