These are differentiated by their position with respect to the pectinate line. Internal hemorrhoids originate above the pectinate line. External hemorrhoids occur below the dentate (or pectinate) line. The leaves are somewhat comb-like or nearly pectinate in arrangement. The anal canal below the pectinate line drains into the superficial inguinal nodes. The pectinate line divides the two regions. The crista terminalis provides the origin for the pectinate muscles. Cutaneous innervation below the pectinate line and external anal sphincter. The pectinate line only roughly marks this transition. The pectinate muscles originate from the crista terminalis. The valves and sinuses form the pectinate line. Like the right atrium, the left atrium is lined by pectinate muscles. They also have a pectinate nail on their longest toe. Because the suture line is above the pectinate line, post-operative pain is minimized for patients. Hemorrhoids above the pectinate line are considered "internal" and those below it "external".