Anatomical Structure And Location Of The Lesser Sciatic Notch Of The Hip Bone

Description

Lesser sciatic notch (incisura ischiadica minor) is identified on the posterior border of the os coxae, lying inferior to the ischial spine and superior to the ischial tuberosity on the ischium. The concavity is framed proximally by the pointed ischial spine and distally by the thickened, roughened ischial tuberosity, a relationship that helps orient the posteroinferior pelvis when the ilium and pubis are also in frame. From a typical lateral or posterolateral presentation of the hip bone, the notch reads as a shallow semicircular indentation that will be converted into the lesser sciatic foramen once the sacrospinous and sacrotuberous ligaments are considered. A small but reliable landmark. Clinically, the lesser sciatic notch matters because it defines the bony boundary for structures that turn around the ischium to reach the perineum and gluteal region, including the tendon of obturator internus as it exits the pelvis and courses to the greater trochanter. It also sits in close topographic relationship to the pudendal nerve and internal pudendal vessels after they pass around the ischial spine, a corridor implicated in pudendal neuralgia and in surgical procedures that place sutures near the sacrospinous ligament (for example, sacrospinous colpopexy). The fixed bony contour in this illustration supports teaching of pelvic exit anatomy by separating what is osseous (spine, notch, tuberosity) from what becomes a foramen only when ligamentous attachments are added. Use this illustration in pelvic anatomy and perineum modules, in orthopaedic and urogynecologic references that discuss the lesser sciatic foramen, or in exam preparation materials that distinguish the greater versus lesser sciatic notches and their transmitted structures. It also suits surgical education diagrams that pair the ischial spine and notch as palpation landmarks for pudendal nerve block orientation. Anatomical accuracy verified by SciePro's Medical Advisory Board.