Keter surrounds the head as a circle, and its name “Keter” derives from the words “circle” (Igul) and circumference (Sivuv). Keter includes all 613 parts (desires) of the Partzuf (soul): 248 organs (GE) and 365 ligaments (AHP). Their correction is called a “commandment.” Altogether there are 613 commandments (corrections).
Also, there are seven commandments “de Rabanan,” from the word “big”—the upper degree. Since 613 commandments represent organs (parts) of the Partzuf and all their elements that are needed to achieve correction and revelation of the worlds, whereas seven commandments are the crowns hidden in the Torah.
Overall, there are 620 desires, 620 letters of ten sayings (major commandments) that correspond to 620 commandments (that explain ten major commandments) inherited by Israel at Mount Sinai.
– I. Chaver, Pitchei Shearim, Chapter “Netiv Gadlut de ZA,” Item 3