External obturator muscle

<h2 id="structure">Structure</h2>
<p>It arises from the margin of bone immediately around the medial side of the <a href="/facts/Obturator_membrane/yNDH5yk9">obturator membrane</a> and surrounding bone, viz., from the <a href="/facts/Inferior_pubic_ramus/4gU0dgIy">inferior pubic ramus</a>, and the ramus of the <a href="/facts/Ischium/hfj1UDwx">ischium</a>; it also arises from the medial two-thirds of the outer surface of the <a href="/facts/Obturator_membrane/yNDH5yk9">obturator membrane</a>, and from the tendinous arch which completes the canal for the passage of the obturator vessels and nerves.
</p><p>The fibers springing from the pubic arch extend on to the inner surface of the bone, where they obtain a narrow origin between the margin of the foramen and the attachment of the obturator membrane.
</p><p>The fibers converge and pass posterolateral and upward, and end in a tendon which runs across the back of the neck of the femur and lower part of the capsule of the hip joint and is inserted into the <a href="/facts/Trochanteric_fossa/jfQDyXCj">trochanteric fossa</a> of the femur.
</p>
<h3>Relations</h3>
<p>The obturator vessels lie between the muscle and the obturator membrane; the <a href="/facts/Anterior_branch_of_the_obturator_nerve/mU37TrgI">anterior branch of the obturator nerve</a> reaches the thigh by passing in front of the muscle, and the <a href="/facts/Posterior_branch_of_obturator_nerve/jAec0TpL">posterior branch</a> by piercing it.
</p>
<h3>Variation</h3>
<p>In 33% of people, a <a href="/facts/Supernumerary_body_part/cqHM8DWA">supernumerary</a> muscle is found between the <a href="/facts/Adductor_brevis_muscle/LSFeWrQy">adductor brevis</a> and <a href="/facts/Adductor_minimus_muscle/BIsB2FEL">minimus</a>.  While this muscle, when present, is similar to its neighbouring adductors, it is formed by separation from the superficial layer of the external obturator, and is thus not <a href="/facts/Ontogeny/ckqaQlL7">ontogenetically</a> related to the <a href="/facts/Adductor_muscles_of_the_hip/gANruvYX">adductor muscles of the hip</a>.  This muscle originates from the upper part of the <a href="/facts/Inferior_pubic_ramus/4gU0dgIy">inferior pubic ramus</a> from where it runs downwards and laterally. In half of cases, it inserts into the anterior surface of the insertion <a href="/facts/Aponeurosis/Uhq7UcN4">aponeurosis</a> of the adductor minimus. In the remaining cases, it is either inserted into the upper part of the <a href="/facts/Pectineal_line_(pubis)/5UpCmtGw">pectineal line</a> or the posterior part of the <a href="/facts/Lesser_trochanter/7z2upaP8">lesser trochanter</a>.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a>
</p><p>It has been demonstrated by the course of the <a href="/facts/Posterior_branch_of_obturator_nerve/jAec0TpL">posterior branch of obturator nerve</a> that the obturator externus is divided into a superior <a href="/facts/Muscle_fascicle/9m3dVs38">muscle fascicle</a> and a main belly.  The supernumerary muscle described above originates from the superior fascicle, while an anomalous fascicle — also derived from the external obturator  — originates from the main belly.  The "original" external obturator, i.e. without these supernumerary muscular parts, actually occurs in only 20% of cases, and apparently the external obturator readily undergoes <a href="/facts/Ontogeny/ckqaQlL7">ontogenetic</a> variations.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a>
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<h2 id="function">Function</h2>
<p>The external obturator muscle acts as a lateral rotator of the hip joint. As a short muscle around the hip joint, it stabilizes the hip joint as a postural muscle.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a> It also helps to abduct the hip joint when in flexion.<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a> And it helps to stabilise the head of the femur in the socket during flexion and internal rotation as it's posterior fibers reinforce the posterior capsule of hip joint.<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a>
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<h2 id="additional-images">Additional images</h2>

<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/Obturator_externus_groove/yy7jU48S">Obturator externus groove</a></li></ul>
<p class="note">This article uses <a href="/facts/Anatomical_terminology/n3IASQlr">anatomical terminology</a>.</p>

<p> <i>This article incorporates text in the <a href="/facts/Public_domain/YWKMDKw4">public domain</a> from <a href="https://archive.org/stream/anatomyofhumanbo1918gray#page/477/mode/2up">page 477</a> of the 20th edition of</i> <a href="/facts/Gray%2527s_Anatomy/dLMyjr2p">Gray's Anatomy</a> <i>(1918)</i>
</p>

<h2 id="external-links">External links</h2>
<ul><li><a href="https://www.meduniwien.ac.at/plastination/pelvis/pelvis-e12-15-text.html">Cross section image: pelvis/pelvis-e12-15</a>—Plastination Laboratory at the Medical University of Vienna</li>
<li><a href="http://www.wesnorman.com/lljoints.htm">lljoints</a> at The Anatomy Lesson by Wesley Norman (Georgetown University) (<i><a href="http://www.wesnorman.com/Images/hipjointanterior.jpg">hipjointanterior</a></i>)</li>
<li><a href="https://web.archive.org/web/20100715211225/http://www.ptcentral.com/muscles/musclelegs.html#obturator%20externus">PTCentral</a></li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>Sauerland, Eberhardt K.; Patrick W. Tank; Tank, Patrick W. (2005). Grant's dissector. Hagerstown, MD: Lippincott Williams & Wilkins. p. 129. ISBN 0-7817-5484-4. <a href="0-7817-5484-4" target="_blank">0-7817-5484-4</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>"Summary of Lower Limb". Archived from the original on 2008-01-23. Retrieved 2008-01-27. <a href="https://web.archive.org/web/20080123061508/http://mywebpages.comcast.net/WNOR/summarylistll.htm" target="_blank">https://web.archive.org/web/20080123061508/http://mywebpages.comcast.net/WNOR/summarylistll.htm</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
<li id="fn:3"><p>Larson, Maddy R.; Ryan, Weston (2024), "Anatomy, Abdomen and Pelvis, Obturator Muscles", StatPearls, Treasure Island (FL): StatPearls Publishing, PMID 36943954, retrieved 2024-05-07 <a href="http://www.ncbi.nlm.nih.gov/books/NBK589636/" target="_blank">http://www.ncbi.nlm.nih.gov/books/NBK589636/</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li>
<li id="fn:4"><p>Nakamura, E; Masumi, S; Miura, M; Kato, S; Miyauchi, R (1992). "A supernumerary muscle between the adductors brevis and minimus in humans". Okajimas Folia Anatomica Japonica. 69 (2–3): 89–98. doi:10.2535/ofaj1936.69.2-3_89. PMID 1436954. <a href="https://doi.org/10.2535%2Fofaj1936.69.2-3_89" target="_blank">https://doi.org/10.2535%2Fofaj1936.69.2-3_89</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li>
<li id="fn:5"><p>Yatsunami, M; Tai, T; Irie, Y; Ogawa, K; Miyauchi, R (2004). "A morphological study on the human obturator externus muscle with reference to anomalous muscle and anomalous fasciculus originating from the obturator externus muscle". Okajimas Folia Anatomica Japonica. 80 (5–6): 103–14. doi:10.2535/ofaj.80.103. PMID 15134328. <a href="https://doi.org/10.2535%2Fofaj.80.103" target="_blank">https://doi.org/10.2535%2Fofaj.80.103</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li>
<li id="fn:6"><p>A>K datta-inf extremity <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li>
<li id="fn:7"><p>"Obturator externus muscle". Kenhub. Retrieved 2021-01-22. <a href="https://www.kenhub.com/en/library/anatomy/obturator-externus-muscle" target="_blank">https://www.kenhub.com/en/library/anatomy/obturator-externus-muscle</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li>
<li id="fn:8"><p>"Obturator Externus". Physiopedia. Retrieved 2025-02-16. <a href="https://www.physio-pedia.com/Obturator_Externus" target="_blank">https://www.physio-pedia.com/Obturator_Externus</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li>
</ol>

External obturator muscle open-in-new

External obturator muscle