Obturator internus muscle

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Internal obturator muscle
Posterior Hip Muscles 1.PNG
The obturator internus and nearby muscles (posterior view)
Gray407.png
Coronal section of anterior part of pelvis, through the pubic arch. Seen from in front. (Obturator internus labeled at right.)
Details
Origin Ischiopubic ramus and obturator membrane
Insertion Medial aspect of the greater trochanter
Artery Inferior gluteal artery
Nerve Nerve to obturator internus (L5, S1, S2)
Actions Abducts and laterally rotates the extended hip and abducts the flexed thigh at the hip, and stabilizes the hip during walking
Identifiers
Latin musculus obturatorius internus
TA98 A04.7.02.012
TA2 2605
FMA 22298
Anatomical terms of muscle

The internal obturator muscle or obturator internus muscle originates on the medial surface of the obturator membrane, the ischium near the membrane, and the rim of the pubis.

Contents

It exits the pelvic cavity through the lesser sciatic foramen.

The internal obturator is situated partly within the lesser pelvis, and partly at the back of the hip-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.

Structure

Origin

The internal obturator muscle arises from the inner surface of the antero-lateral wall of the pelvis. [1] It surrounds the obturator foramen. [1] [2] It is attached to the inferior pubic ramus and ischium, and at the side to the inner surface of the hip bone below and behind the pelvic brim. [1] It reaches from the upper part of the greater sciatic foramen above and behind to the obturator foramen below and in front. [1]

It also arises from the pelvic surface of the obturator membrane. [1] This is except in the posterior part, from the tendinous arch which completes the canal for the passage of the obturator vessels and nerve, and to a slight extent from the obturator fascia, which covers the muscle.

Passage

The fibers converge through the lesser 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.

The obturator nerve passes on the superficial surface of the internal obturator muscle. [3] The pudendal nerve passes on the lateral surface of the internal obturator muscle and the coccygeus muscle. [4] The sciatic nerve passes superficial to the internal obturator muscle on the posterior surface. [5] [6]

Insertion

The tendon inserts on the greater trochanter of the proximal femur. [1]

Nerve supply

The internal obturator muscle is supplied by the obturator internus nerve (L5, S1, and S2). [1]

Muscles of the gluteal and posterior femoral regions. Obturator internus muscle.png
Muscles of the gluteal and posterior femoral regions.

Bursa/bands

This bony surface is covered by smooth cartilage, which is separated from the tendon by a bursa, 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 the superior and inferior gemellus muscles, is inserted into the forepart of the medial surface of the greater trochanter above the trochanteric 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.

Function

The internal obturator muscle helps to support the urinary bladder as part of the pelvic floor. [7]

Additional images

Related Research Articles

<span class="mw-page-title-main">Human leg</span> Lower extremity or limb of the human body (foot, lower leg, thigh and hip)

The leg is the entire lower limb of the human body, including the foot, thigh or sometimes even the hip or buttock region. The major bones of the leg are the femur, tibia, and adjacent fibula. The thigh is between the hip and knee, while the calf (rear) and shin (front) are between the knee and foot.

<span class="mw-page-title-main">Greater trochanter</span> Quadrilateral part of the thigh bone

The greater trochanter of the femur is a large, irregular, quadrilateral eminence and a part of the skeletal system.

<span class="mw-page-title-main">Piriformis muscle</span> Hip muscle in the lateral rotator group

The piriformis muscle is a flat, pyramidally-shaped muscle in the gluteal region of the lower limbs. It is one of the six muscles in the lateral rotator group.

<span class="mw-page-title-main">Coccygeus muscle</span> Muscle of the lower back arising by its apex from the spine of the ischium

The coccygeus muscle or ischiococcygeus is a muscle of the pelvic floor located posterior to levator ani and anterior to the sacrospinous ligament.

<span class="mw-page-title-main">External obturator muscle</span> One of six small hip muscles in the lateral rotator group

The external obturator muscle or obturator externus muscle is a flat, triangular muscle, which covers the outer surface of the anterior wall of the pelvis.

The semimembranosus muscle is the most medial of the three hamstring muscles in the thigh. It is so named because it has a flat tendon of origin. It lies posteromedially in the thigh, deep to the semitendinosus muscle. It extends the hip joint and flexes the knee joint.

<span class="mw-page-title-main">Obturator foramen</span> Opening in the pelvis

The obturator foramen is the large, bilaterally paired opening of the bony pelvis. It is formed by the pubis and ischium. It is mostly closed by the obturator membrane except for a small opening, the obturator canal, through which the obturator nerve and vessels pass.

<span class="mw-page-title-main">Obturator nerve</span>

The obturator nerve in human anatomy arises from the ventral divisions of the second, third, and fourth lumbar nerves in the lumbar plexus; the branch from the third is the largest, while that from the second is often very small.

<span class="mw-page-title-main">Ischium</span> Lower and back region of the hip bone

The ischium forms the lower and back region of the hip bone.

<span class="mw-page-title-main">Pubis (bone)</span> Most forward-facing of the three main regions making up the os coxa

In vertebrates, the pubis or pubic bone forms the lower and anterior part of each side of the hip bone. The pubis is the most forward-facing of the three bones that make up the hip bone. The left and right pubic bones are each made up of three sections; a superior ramus, an inferior ramus, and a body.

<span class="mw-page-title-main">Superior gluteal artery</span>

The superior gluteal artery is the terminal branch of the posterior division of the internal iliac artery. It exits the pelvis through the greater sciatic foramen before splitting into a superficial branch and a deep branch.

<span class="mw-page-title-main">Inferior gluteal artery</span>

The inferior gluteal artery is a terminal branch of the anterior trunk of the internal iliac artery. It exits the pelvis through the greater sciatic foramen. It is distributed chiefly to the buttock and the back of the thigh.

<span class="mw-page-title-main">Obturator artery</span>

The obturator artery is a branch of the internal iliac artery that passes antero-inferiorly on the lateral wall of the pelvis, to the upper part of the obturator foramen, and, escaping from the pelvic cavity through the obturator canal, it divides into an anterior branch and a posterior branch.

<span class="mw-page-title-main">Lesser sciatic foramen</span> Opening between pelvis and thigh in human anatomy

The lesser sciatic foramen is an opening between the pelvis and the back of the thigh. The foramen is formed by the sacrotuberous ligament which runs between the sacrum and the ischial tuberosity and the sacrospinous ligament which runs between the sacrum and the ischial spine.

<span class="mw-page-title-main">Nerve to obturator internus</span> Human nerve

The nerve to obturator internus is a mixed nerve providing motor innervation to the obturator internus muscle and gemellus superior muscle, and sensory innervation to the hip joint. It is a branch of the sacral plexus. It is one of the group of deep gluteal nerves.

<span class="mw-page-title-main">Nerve to quadratus femoris</span>

The nerve to quadratus femoris is a nerve of the sacral plexus that provides motor innervation to the quadratus femoris muscle and gemellus inferior muscle, and an articular branch to the hip joint. The nerve leaves the pelvis through the greater sciatic foramen.

<span class="mw-page-title-main">Lesser sciatic notch</span>

Below the ischial spine is a small notch, the lesser sciatic notch; it is smooth, coated in the recent state with cartilage, the surface of which presents two or three ridges corresponding to the subdivisions of the tendon of the obturator internus, which winds over it.

<span class="mw-page-title-main">Pelvic fascia</span>

The pelvic fasciae are the fascia of the pelvis and can be divided into:

<span class="mw-page-title-main">Outline of human anatomy</span> Overview of and topical guide to human anatomy

The following outline is provided as an overview of and topical guide to human anatomy:

<span class="mw-page-title-main">Hip bone</span> Bone of the pelvis

The hip bone is a large flat bone, constricted in the center and expanded above and below. In some vertebrates it is composed of three parts: the ilium, ischium, and the pubis.

References

PD-icon.svgThis article incorporates text in the public domain from page 477 of the 20th edition of Gray's Anatomy (1918)

  1. 1 2 3 4 5 6 7 8 Chiva, Luis M.; Magrina, Javier (2018-01-01), Ramirez, Pedro T.; Frumovitz, Michael; Abu-Rustum, Nadeem R. (eds.), "Chapter 2 - Abdominal and Pelvic Anatomy", Principles of Gynecologic Oncology Surgery, Elsevier, pp. 3–49, doi:10.1016/b978-0-323-42878-1.00002-x, ISBN   978-0-323-42878-1 , retrieved 2021-03-04
  2. ↑ Jacob, S. (2008-01-01), Jacob, S. (ed.), "Chapter 4 - Abdomen", Human Anatomy, Churchill Livingstone, pp. 71–123, doi:10.1016/b978-0-443-10373-5.50007-5, ISBN   978-0-443-10373-5 , retrieved 2021-03-04
  3. ↑ Ahmadian, Amir; Abel, Naomi; Dakwar, Elias (2015-01-01), Tubbs, R. Shane; Rizk, Elias; Shoja, Mohammadali M.; Loukas, Marios (eds.), "Chapter 35 - Injuries to the Nerves of the Abdominopelvic Region", Nerves and Nerve Injuries, San Diego: Academic Press, pp. 545–555, ISBN   978-0-12-802653-3 , retrieved 2021-02-27
  4. ↑ de Groat, William C.; Yoshimura, Naoki (2015-01-01), Vodušek, David B.; Boller, François (eds.), "Chapter 5 - Anatomy and physiology of the lower urinary tract", Handbook of Clinical Neurology, Neurology of Sexual and Bladder Disorders, 130, Elsevier: 61–108, doi:10.1016/b978-0-444-63247-0.00005-5, ISBN   9780444632470, PMID   26003239 , retrieved 2021-02-27
  5. ↑ Midha, Rajiv (2008-01-01), Kim, Daniel H.; Midha, Rajiv; Murovic, Judith A.; Spinner, Robert J. (eds.), "2 - Mechanisms and pathology of injury", Kline and Hudson's Nerve Injuries (Second Edition), Edinburgh: W.B. Saunders, pp. 23–42, doi:10.1016/b978-0-7216-9537-2.50010-4, ISBN   978-0-7216-9537-2 , retrieved 2021-03-04
  6. ↑ Bouche, P. (2013-01-01), Said, Gérard; Krarup, Christian (eds.), "Chapter 19 - Compression and entrapment neuropathies", Handbook of Clinical Neurology, Peripheral Nerve Disorders, 115, Elsevier: 311–366, doi:10.1016/b978-0-444-52902-2.00019-9, ISBN   9780444529022, PMID   23931789 , retrieved 2021-03-04
  7. ↑ Richenberg, Jonathan L. (2011-01-01), Allan, Paul L.; Baxter, Grant M.; Weston, Michael J. (eds.), "CHAPTER 29 - Ultrasound of the bladder", Clinical Ultrasound (Third Edition), Edinburgh: Churchill Livingstone, pp. 550–571, doi:10.1016/b978-0-7020-3131-1.00029-8, ISBN   978-0-7020-3131-1 , retrieved 2021-03-04
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