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Joints and Ligaments of the Pelvic Girdle

The joints of the pelvic girdle are:

1. Vertebral joints: the lumbosacral symphysis and sacrococcygeal joint , which are components of the vertebral column

2. Sacroiliac joints: which connect the sacrum to the two hip bones.

3. Public symphysis: the fibrocartilaginous joint that connects the hip bones anteriorly.

The structural stability of the pelvic ring relies primarily on the posterior sacroiliac complex. This complex includes the strong sacroiliac ligaments surrounding the sacroiliac joint, which together function like a suspension bridge1. This structure offsets the weight of the trunk onto the lower limbs and absorbs the strong shocks generated by body movement2.

  • 1 Tile M. Pelvic ring fractures: should they be fixed? J Bone Joint Surg Br. 1988 Jan;70(1):1-12.
  • 2 Agur AMR, Dallye A. Moore's essential clinical anatomy, 6th ed. 2008, Wolters Kluwer Health, Philadelphia
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    Bones and Joints of pelvis, anterolateral view Pelvic bones with the pelvic joint surfaces exposed
    The components of pelvic girdle in situ and ex situ.
    Click the image to view the articular surfaces of all pelvic joints. Note that the lumbosacral joint consists of components similar to other intervertebral joints: the L5 and S1 vertebrae are connected by an intervertebral disc and a zygapophyseal joint. The key difference from the lumbar vertebrae above it is a relatively dense network of ligaments connecting L5 (and partially L4) to the ilium. This additional ligamentous support results in more restricted lateral bending movement at this segment.
    The list of terms: Art. lumbosacralis – Lumbosacral joint, or lumbosacral symphysis
    Art. sacroiliaca – Sacroiliac joint
    Symphysis pubica – Pubic symphysis
    Promontorium – Promontory
    Facies auricularis ossis sacri – Auricular surface of sacrum
    Facies auricularis ossis ilii – Auricular surface of ilium
    Facies symphysialis ossis pubis – Symphysial surface of pubis
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    Pelvic ligaments, including lumbosacral ligaments, anterior sacroiliac and pubic ligaments Cleft and the interpubic disc of the pubic symphysis; The interosseous sacroiliac ligament
    Pelvis. Aspectus anterior.
    The iliolumbar ligaments connect the costal processes of L5 and L4 to the iliac wings and are continuous with the anterior sacroiliac ligaments. The pubic symphysis is encircled by ligaments, the thickest of which are located superiorly and inferiorly to the fibrocartilaginous disc1.
    Click the image to view the cleft within the fibrous cartilage (interpubic disc) of the pubic symphysis and the deepest and strongest2 fibers of the sacroiliac ligaments—the interosseous sacroiliac ligaments.
    The list of terms: Lig. iliolumbale – Iliolumbar ligament
    Lig. lumbosacrale – Lumbosacral ligament
    Lig. sacroiliacum anterius – Anterior sacroiliac ligament
    Lig. sacroiliacum interosseum – Interosseous sacroiliac ligament
    Promontorium – Promontory
    Lig. sacrospinale – Sacrospinous ligament
    Lig. sacrotuberale – Sacrotuberous ligament
    Lig. pubicum superius – Superior pubic ligament
    Lig. pubicum inferius – Inferior pubic ligament
    Discus interpubicus – Interpubic disc
  • 1 Becker I, Woodley S, Stringer M. The adult human pubic symphysis: a systematic review. Journal of Anatomy, 2010, 217:475-487.
  • 2 Vleeming A, et al. The sacroiliac joint: an overview of its anatomy, function and potential clinical implications. J Anat. 2012 Dec;221(6):537-67.
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    Posterolateral view to the pelvic ligaments, demonstrating greater and lesser sciatic foramina, sacrotuberal and sacrospinal ligaments Posterolaeral view to the male pelvis
    Pelvis. Aspectus posterolateralis.
    On the posterior aspect of the pelvis, a dense network of ligaments can be seen, almost completely covering the posterior surface of the sacrum. The most prominent is the sacrotuberous ligament, which is continuous with the posterior sacroiliac ligament. It connects the ischial tuberosity to the sacrum, ilium, and coccyx. Functioning as a kinematic chain, the sacrotuberous ligament helps transfer load from the spine and sacrum through the hamstring muscles to the lower limbs1, 2.
    Another important feature is that the sacrotuberous and sacrospinous ligaments, together with the hip bone, form two separate openings: the greater and lesser sciatic foramina. These foramina serve as passageways for a variety of muscles, nerves, and blood vessels.
    The list of terms: Foramen ischiadicum majus – Greater sciatic foramen
    Foramen ischiadicum minus – Lesser sciatic foramen
    Lig. sacrospinale – Sacrospinous ligament
    Lig. sacrotuberale – Sacrotuberous ligament
    Incisura ischiadica major – Greater sciatic notch
    Spina ischiadica – Ischial spine
    Incisura ischiadica minor – Lesser sciatic notch
    Tuber ischiadicum – Ischial tuberosity
  • 1 Vleeming A, et al. The sacroiliac joint: an overview of its anatomy, function and potential clinical implications. J Anat. 2012, 221(6):537-67.
  • 2 van der Made A, et al. The hamstring muscle complex. Knee Surg Sports Traumatol Arthrosc. 2015, 23(7):2115-22.
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    Posterior view of pelvic ligaments, showing iliolumbar, posterior sacroiliac ligaments and the sacrococcygeal ligaments Deep layer of the posterior sacroiliac ligament and posterior sacrococcygeal ligament
    Pelvis. Aspectus posterior.
    The posterior aspect reveals the layered structure of the posterior sacroiliac ligament. This ligament is continuous with the deeper interosseous sacroiliac ligament, as there is no strict border separating them1.
    Click the image to examine the layers of the sacrococcygeal ligaments:
  • The most superficial layer, the posterior superficial sacrococcygeal ligament, forms the roof of the lower sacral canal.
  • The lateral sacrococcygeal ligament is the homologue of the intertransverse ligaments.
  • The deepest layer, the posterior deep sacrococcygeal ligament, is the homologue of the posterior longitudinal ligament at the level of the sacrococcygeal joint2.
    • The list of terms: Lig. iliolumbale – Iliolumbar ligament
    Lig. sacroiliacum posterius – Posterior sacroiliac ligament
    Lig. sacrospinale – Sacrospinous ligament
    Lig. sacrotuberale – Sacrotuberous ligament
    Lig. sacrococcygeum posterius superficiale – Superficial posterior sacrococcygeal ligament
    Lig. sacrococcygeum posterius profundum – Deep posterior sacrococcygeal ligament
    Lig. sacrococcygeum laterale – Lateral sacrococcygeal ligament
    Hiatus sacralis – Sacral hiatus
  • 1 Ashby K, et al. Ligaments stabilizing the sacrum and sacroiliac joint: a comprehensive review. Neurosurg Rev. 2022, 45(1):357-364.
  • 2 Lee SH, Yang M, Won HS, Kim YD. Coccydynia: anatomic origin and considerations regarding the effectiveness of injections for pain management. Korean J Pain. 2023 Jul 1;36(3):272-280.
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    Published: 14/Oct/2025