{{Not to be confused with|Lunate surface of acetabulum}}{{Short description|Ring of cartilage that surrounds the acetabulum of the hip}} {{Infobox anatomy | Name = Acetabular labrum | Latin = labrum acetabuli | Image = Gray342.png | Caption = Hip-joint, front view. The capsular ligament has been largely removed. (Cotyloid lig. visible at center.) | Image2 = | Caption2 = | Precursor = | System = | Artery = | Vein = | Nerve = | Lymph = }} The '''acetabular labrum''' ('''glenoidal labrum of the hip joint''' or '''cotyloid ligament''' in older texts) is a fibrocartilaginous ring<ref name=":1">{{Cite book |last1=Moore |first1=Keith L. |title=Clinically Oriented Anatomy |last2=Dalley |first2=Arthur F. |last3=Agur |first3=Anne M. R. |publisher=Wolters Kluwer |year=2018 |isbn=978-1-4963-4721-3 |edition=8th |location=}}</ref><ref name=":224" /><ref name=":0" /> which surrounds the circumference of the acetabulum of the hip, deepening the acetabulum. The labrum is attached onto the bony rim and transverse acetabular ligament. It is triangular in cross-section (with the apex represented by the free margin).<ref name=":224">{{Cite book |last=Standring |first=Susan |title=Gray's Anatomy: The Anatomical Basis of Clinical Practice |year=2020 |isbn=978-0-7020-7707-4 |edition=42nd |location=New York |pages=1368 |oclc=1201341621}}</ref><ref name=":0">{{Cite book |last1=Palastanga |first1=Nigel |title=Anatomy and Human Movement: Structure and Function |last2=Soames |first2=Roger |publisher=Churchill Livingstone/Elsevier |year=2012 |isbn=978-0-7020-3553-1 |edition=6th |series=Physiotherapy Essentials |location=Edinburgh |pages=290}}</ref>

The labrum contributes to the articular surface of the joint<ref name=":224" /><ref name=":1" /> (increasing it by almost 10%<ref name=":1" />). It embraces the femoral head,<ref name=":224" /> holding it firmly in the joint socket<ref name=":0" /> to stabilise the joint. It thus also seals the joint cavity, facilitating even distribution of synovial fluid so that friction is reduced and dissolved nutrients are better distributed.<ref name=":224" />

The labrum is about 2 to 3&nbsp;mm thick but is wider and thinner in the anterior portion. The anterior portion of the labrum is most susceptible to an acetabular labrum tear.<ref name=Lewis>Lewis, Cara L. & Sahrmann, Shirley A. (2006). "Acetabular Labral Tears". ''Journal of the American Physical Therapy Association''. 86, 110–121.</ref>

==See also== *Glenoid labrum

==References== {{Reflist|2}}

{{Joints of lower limbs}} {{Authority control}}

{{DEFAULTSORT:Acetabular Labrum}} Category:Ligaments of the lower limb