Atlas of Human Anatomy by Netter

Boundaries:

Superiorly-pelvic inlet and inferior abdominal cavity

Inferiorly-pelvic diaphragm

Anterior wall-bodies and rami of pubic bone and pubic symphysis

Posterior wall-sacrum and coccyx, adjacent ilia and overlying piriformis muscle

Lateral walls-hip bones, obturator foramen and membrane, and overlying obturator internus muscle

Pelvic inlet, outlet, and brim

Inlet defined by an oblique plane

Extends from promontory to the superior aspect of the pubic symphysis

Lies at an angle approximately 55 degrees from horizontal

Rim of pelvic inlet = pelvic brim, composed of a bony line running through

Sacral promontory

Arcuate line of the ilium

Pectineal line of the pubis (pecten pubis)

Pubic crest

Superior edge of pubic symphysis

Pelvic outlet is bounded by

Tip of coccyx

Sacrotuberous ligaments

Inferior ischiopubic rami and ischial tuberosities

Inferior edge of pubic symphysis

Pelvic inlet divides pelvis into two parts

True pelvis or lesser pelvis or pelvis minor, which

lies between pelvic inlet and outlet

contains the pelvic viscera

False pelvis or greater pelvis or pelvis major, which

lies above pelvic brim

between the iliac fossae

contains part of the ileum and sigmoid colon

The birth canal includes the pelvic inlet, true pelvis, cervix, vagina, and pelvic outlet

Joints of the Pelvis

Lumbosacral joints

Composed of

Intervertebral joint via intervertebral disc between L4 and S1

Two posterior zygapophysial joints

Reinforced by iliolumbar ligaments

Sacroiliac joint

Articulation between ear-shaped surfaces of the sacrum and ilium

Atypical synovial joint formed with fibrocartilage rather than hyaline cartilage

Movement is very limited

Stabilized by interosseous and anterior and posterior sacroiliac ligaments

Pubic symphysis
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Union of bodies of right and left pubic bones

Secondary cartilaginous joint

Fibrocartilaginous interpubic disc in the joint

Stabilized by superior and inferior pubic ligaments

Affected by the hormone relaxin during pregnancy to permit freer movement between vertebral column and to increase pelvic diameter

during childbirth

Sacrococcygeal joint

Articulation between sacrum and coccyx

Secondary cartilaginous joint

Stabilized by anterior and posterior sacrococcygeal ligaments

Ligaments of the Pelvis

The weight of the body acting through the spine will tend to rotate the sacrum, tipping the lower part backwards.

This movement is prevented by the sacrospinous and sacrotuberous ligaments.

Sacrospinous ligament: extends from lateral border sacrum to ischial spine

Sacrotuberous ligament: larger and extends from dorsum and lateral border sacrum and posterior surface ilium to ischial tuberosity

Attachments of sacrospinous and sacrotuberous ligaments enclose the lesser and greater sciatic notches, respectively, forming the greater

and lesser foramina