True about pectinate line ?

Blood supply above pectinate line is through superior rectal aeryPa of anal canal above pectinate line develops from dorsal pa of endodermal cloaca (primitive rectum) and pa of anal canal below pectinate line develops from ectodermal proctodeum.Mucous membrane above pectinate line is supplied by autonomic nerves (sympathetic L1 L2 and parasympathetic: S2 S3 S4) and therefore is insensitive to pain. Pa below the pectinate line is supplied by somatic nerves (inferior rectal nerve a branch of pudendal nerve) and therefore is sensitive to pain. Thus pain sensations are carried by pudendal nerve.Pectinate line forms the water-shed line of anal canal. Area above pectinate line drains into internal iliac nodes and area below it drains into superficial inguinal nodes.Aerial supply of the area is above pectinate line is through superior rectal aery (continuation of inferior mesenteric aery) and area below pectinate line is supplied by inferior rectal aery.