Bones and joints of the pelvis

Question 1

What type of joint is the sacroiliac joint?

Answer 1

Synovial

Question 2

What type of joint is the pubic symphysis?

Answer 2

Secondary cartilaginous

Question 3

What lies above and below thse obturator foramen?

Answer 3

Above: superior pubic ramus

Below: inferior pubic ramus

Question 4

How do the pubic crest and pubic tubercle relate to the pubic body?

Answer 4

Pubic tubercle is lateral edge of pubic crest

Pubic crest is superior margin of pubic body

Question 5

What does the pectineal line lie on?

Answer 5

Superior pubic ramus

Question 6

Which bony landmark dermarcates the greater and lesser sciatic notches?

Answer 6

Ischial spine

Question 7

Describe the bony features of the sacrum?

Answer 7

Question 8

What are the lateral masses of the sacrum formed by?

Answer 8

Transverse processes fusing on each side

Question 9

Describe the line of demarcation of the true and false pelvis?

Answer 9

Pubic crest, pectineal line, arcuate line of ilium, anterior margin of ala, sacral promontroy

Iliopectineal lie

Question 10

List the pelvic types?

Which are most common in males and females?

Answer 10

Gynaecoid typical in women (val, wider transversely)

Android most common in males, followed by anthropoid (wider AP)

Question 11

Describe the difference in pelvic inlet and outlet between males and females?

Answer 11

Inlet: wider transversely in females

Outlet: diamon shaped in both

Question 12

Describe the borders of the pelvic outlet?

Answer 12

Inferior margin of pubic symphysis anteriorly

Tip of coccyx posteriorly

Ischial tuberosities either side

Question 13

Describe the plane of least dimensions in the pelvis?

Answer 13

Through ischial spine, S4 and base of pubis

One of the points where baby rotates during birth

Question 14

Describe the ligaments of the sacroiliac joint?

Answer 14

Anterior and posterior sacroiliac ligaments

Interosseous sacroiliac ligament: strongest, locks in rotation

Accessory: iliolumbar, sacrotuberous and sacrospinous

Question 15

Describe the sacrotuberous and sacrospinous ligaments?

Answer 15

Sacrotuberous: sacrum to ischial tuberosity
Sacrospinous: sacrum to ischial spine

Accessory ligaments of SIJ

Form greater and lesser sciatic foraminae

Question 16

Describe nutation and counter-nutation?

How are these movements limited?

Answer 16

Nutation: top of sacrum moves forwards, closes inlet and opens oultet
Counter-nutation: top of sacrum moves backwards, opens inlet and closes outlet

Limited by all ligaments in pelvis

Question 17

Describe the ligaments of the pubic symphysis?

Answer 17

Superior pubic ligament
Inferior arcuate ligament

Prevent separation and resist compressive forces

Question 18

How are the ligaments of the pubic symphysis reinforced?

Answer 18

Criss-crossing fibres from :

oblique abdominal muscles

rectus sheath

adductor longus