5.21 Pelvic Jts and Ligaments


Joints of pelvis: sacroiliac, sacrococcygeal, pubic symphysis

Ligaments: vertebro-pelvic ie sacrotuberous, sacrospinous and iliolumbar.

Sacroiliac joint

Synovial joint but cartilage is fibrocartilage (not hyaline),

Surfaces are jagged, very little movement. 

Capsule attaches around articular margin

Anterior sacroiliac ligament: joins above and below pelvic brim; stronger in females

-           strong interosseous and superficial posterior parts

Stability of jt depends on its ligaments: body weight through L5 pushes vertebral downwards to symphysis

-           opposing gliding are interosseous and iliolumbar ligaments of ant sacroiliac.

-           sacrotuberous and sacrospinous prevent forward rotation

Sacrotuberous ligament  (331)

Very strong.

Posterior border of ilium, sacrum & upper coccyx ischial tuberosity. 

-           falciform process extension below pudendal canal helps proximal attachment

-           gives origin to glut max

-           pierced by perforating cutaneous nerve, branches of inferior gluteal vessels and coccygeal nerves.

Sacrospinous ligament

Lies on pelvic aspect of S-T ligament.

From lower sacrum & coccyx spine of ischium.

-           coccygeus muscle lies on pelvic surface

ST and SS ligaments enclose lesser sciatic foramen.

-           lateral part occupied by emerging obturator internus muscle

-           medial part leads forwards into pudendal canal above falciform process of sacrotuberous ligament.


V sideways, from transverse process of L5 vertebrae iliac crest

-           gives origin to quadratus lumborum, becomes continuous with anterior lumbar fascia.

Sacrococcygeal Ligament

Symphysis apex of sacrum base of coccyx.

-           intervening fibrocartilage disc.

-           - anterior, posterior and lateral sacrococcygeal ligaments support it and create a foramen for anterior ramus of fifth sacral nerve

Some flexion / extension possible.

Pubic symphysis

Secondary cartilaginous jt

Thin plate of hyaline, centrally a tissue space may develop.

-           superior and arcuate pubic ligaments support it

-           no movement, but slightly separation in childbirth.