Overview
- Obturator foramen covered by the Obturator Membrane (a felted mass of fibrous tissue)
- A gap above converts the Obturator Notch into a canal for the Obturator Nerve and Vessels
- Obturator internus arises from the whole membrane and from the bony margins of the foramen
- Origin extends posteriorly as high as the Pelvic Brim and across the flat surface of the Ischium to the margin of the Greater Sciatic Notch
- Origin extends down to the Falciform Ridge on the Ischial Tuberosity
Course
- Muscle fibres converge towards the Lesser Sciatic Notch
- Tendon takes a right-angled turn to pass into the buttock
- Bone here lined by Hyaline cartilage
- Separated from the tendon by a bursa
- As the muscle emerges into the buttock, it is reinforced by the additional muscle fibres of the Superior and Inferior Gemelli muscles, arising from the margins of the Lesser Sciatic Notch
- Tendon inserts into the medial surface of the Greater Trochanter above the Trochanteric Fossa
Nerve Supply
- Own nerve (L5, S1, S2)