| Internal obturator muscle | |
|---|---|
 The obturator internus and nearby muscles (posterior view) | |
 Coronal section of anterior part ofpelvis, through the pubic arch. Seen from in front. (Obturator internus labeled at right.) | |
| Details | |
| Origin | Ischiopubic ramus andobturator membrane |
| Insertion | Medial aspect of thegreater trochanter |
| Artery | Inferior gluteal artery |
| Nerve | Nerve to obturator internus (L5, S1, S2) |
| Actions | Abducts andlaterally rotates the extended hip and abducts the flexed thigh at the hip, and stabilizes thehip during walking |
| Identifiers | |
| Latin | musculus obturatorius internus |
| TA98 | A04.7.02.012 |
| TA2 | 2605 |
| FMA | 22298 |
| Anatomical terms of muscle | |
Theinternal obturator muscle orobturator internus muscle originates on the medial surface of theobturator membrane, theischium near the membrane, and the rim of thepubis.
It exits thepelvic cavity through thelesser sciatic foramen.
The internal obturator is situated partly within thelesser pelvis, and partly at the back of thehip-joint.
It functions to help laterally rotate femur with hip extension and abduct femur with hip flexion, as well as to steady the femoral head in the acetabulum.
The internal obturator muscle arises from the inner surface of the antero-lateral wall of thepelvis.[1] It surrounds theobturator foramen.[1][2] It is attached to theinferior pubic ramus andischium, and at the side to the inner surface of thehip bone below and behind thepelvic brim.[1] It reaches from the upper part of thegreater sciatic foramen above and behind to theobturator foramen below and in front.[1]
It also arises from the pelvic surface of theobturator membrane.[1] This is except in the posterior part, from thetendinous arch which completes the canal for the passage of the obturator vessels and nerve, and to a slight extent from theobturator fascia, which covers the muscle.
The fibers converge through thelesser sciatic foramen.[1] These end in four or five tendinous bands, which are found on the deep surface of the muscle. These bands are reflected at a right angle over the grooved surface of the ischium between its spine and tuberosity.
Theobturator nerve passes on the superficial surface of the internal obturator muscle.[3] Thepudendal nerve passes on the lateral surface of the internal obturator muscle and thecoccygeus muscle.[4] Thesciatic nerve passes superficial to the internal obturator muscle on the posterior surface.[5][6]
The tendon inserts on thegreater trochanter of the proximalfemur.[1]
The internal obturator muscle is supplied by theobturator internus nerve (L5,S1, andS2).[1]
This bony surface is covered by smooth cartilage, which is separated from the tendon by abursa, and presents one or more ridges corresponding with the furrows between the tendinous bands.
These bands leave the pelvis through the lesser sciatic foramen and unite into a single flattened tendon, which passes horizontally across the capsule of the hip-joint, and, after receiving the attachments of thesuperior andinferior gemellus muscles, is inserted into the forepart of the medial surface of the greater trochanter above thetrochanteric fossa.
A bursa, narrow and elongated in form, is usually found between the tendon and the capsule of the hip-joint. It occasionally communicates with the bursa between the tendon and the ischium.
The internal obturator muscle helps to support theurinary bladder as part of thepelvic floor.[7]
This article incorporates text in thepublic domain frompage 477 of the 20th edition ofGray's Anatomy(1918)
