This is a great editorial in the S&C journal on the above-mentioned topic.
Published: Aug 2017
I was surprised to find out that the largest muscle in the upper body by VOLUME was the deltoid muscle, followed closely by the triceps. Both Lats and Pecs have lower volumes.
Basically the article proposes that we should refer to exercises according to whether it is a single or multi-joint exercise. This is because some have referred to the knee extension exercise as a small muscle exercise however according to muscle volume, the quads are by far the largest muscle in the whole body.
Please click here to read the full article.