Joints of pelvis: sacroiliac, sacrococcygeal, pubic symphysis
Ligaments: vertebro-pelvic ie sacrotuberous, sacrospinous and iliolumbar.
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
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.
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.
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.
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.