Anatomy Bones and Muscles · MU Pleven

19. Connections of the pelvis . Form and dimensions of the pelvis

Covers the joints that connect the pelvic bones, including the lumbosacral, sacroiliac, pubic symphysis and sacrococcygeal joints, with their types and ligaments, and the sacrotuberous and sacrospinous ligaments that convert the sciatic notches into foramina. It then describes the overall form of the pelvis, its greater and lesser parts, and the boundaries of the inlet and outlet. The dimensions of both apertures are listed in centimetres, and the note closes with a comparison of male and female pelvic features such as subpubic angle.

Inside: 5 sections · 5 labelled pictures · 12 flashcards · 3 min

Topic 19 of 236 in the MU Pleven syllabus for Anatomy Bones and Muscles (Medicine, Year 2). The free AceMed note covers it in 5 sections, about 355 words (3 min of reading), with 12 flashcards.

In this note

  1. Connections of the pelvis bones. Form and dimensions of the pelvis.
  2. Connections of the Pelvis Bones
  3. Form of the Pelvis
  4. Dimensions of the Pelvis
  5. Sexual Differences in Pelvis

Connections of the Pelvis Bones

1. Bones forming the pelvis

  • Two hip bones (os coxae: ilium, ischium, pubis – fused in adult).
  • Sacrum.
  • Coccyx.

2. Joints of the pelvis

1. Lumbosacral joint

  • Between L5 vertebra and sacrum.
  • Type: secondary cartilaginous (symphysis) + synovial (zygapophyseal joints).
  • Ligaments: iliolumbar, lumbosacral.

2. Sacroiliac joints

  • Between auricular surfaces of sacrum & ilium.
  • Type: synovial plane joint.
  • Ligaments: anterior, interosseous, posterior sacroiliac ligaments.

3. Pubic symphysis

  • Between bodies of right and left pubic bones.
  • Type: secondary cartilaginous (fibrocartilage disc).
  • Ligaments: superior & inferior pubic ligaments.

4. Sacrococcygeal joint

  • Between sacrum and coccyx.
  • Type: secondary cartilaginous.
  • Ligaments: anterior, posterior sacrococcygeal.

3. Ligaments strengthening the pelvis

  • Sacrotuberous ligament (sacrum → ischial tuberosity).
  • Sacrospinous ligament (sacrum → ischial spine).
  • These convert the greater and lesser sciatic notches → greater and lesser sciatic foramina.

Form of the Pelvis

1. General shape

  • Pelvis = basin-like ring formed by sacrum + 2 hip bones.
  • Divided into:
  • Greater (false) pelvis: above pelvic brim, part of abdomen.
  • Lesser (true) pelvis: below pelvic brim, contains pelvic organs.

2. Pelvic inlet (superior pelvic aperture)

  • Bounded by:
  • Sacral promontory,
  • Ala of sacrum,
  • Arcuate line of ilium,
  • Pectineal line & pubic crest,
  • Pubic symphysis (upper border).

3. Pelvic outlet (inferior pelvic aperture)

  • Bounded by:
  • Tip of coccyx,
  • Sacrotuberous ligament,
  • Ischial tuberosities,
  • Ischiopubic rami,
  • Pubic symphysis (lower border).

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