Pectinate line is an impoant landmark because ?

The pectinate line (anorectal junction) is an impoant landmark in that it divides the anal canal into upper and lower poions. Developmentally, the pectinate line is the junction between the development of the hindgut (gut tube) and the proctodeum (body wall). The pectineal line is an impoant anatomic landmark in that it distinguishes the vascular, nerve, and lymphatic supplies. Superior to the pectinate line:The vascular supply is from the superior and middle rectal aeries and veins. Visceral motor and sensory innervation is the inferior hypogastric plexus. Lymph drainage is to the internal iliac, inferior mesenteric, and pararectal lymph nodes. The epithelium is simple columnar, as is the remainder of the small and large intestines, which reflects the endodermal origin of this pa of the anal canal.Inferior to the pectineal line. The vascular supply is from the inferior rectal aeries and veins. Somatic motor and sensory innervation is the inferior rectal nerves. Lymph drainage is to the superficial inguinal lymph nodes. The epithelium is stratified squamous keratinized epithelium, similar to the skin, which reflects the ectodermal origin of this pa of the anal canal.