Pelvis and pelvic joints

Question 1

What are the pelvic bones

Answer 1

Ilium
Pubis
Ischium
Triradiate cartilage
Sacru
Coccyx

Question 2

Name the pelvic joints

Answer 2

Sacroiliac joint (b/w ilium and sacrum)
Sacrococcygeal symphysis (b/w sacrum and coccyx)
Pubic symphysis (between pubic bodies or 2 hip bones)
Lumbosacral joint (b/w Lx and sacrum--> it is not an articulation within the pelvis)
Hip joint (b/w acetabulum and head of femus--> not part of pelvis)

Question 3

How many articulations are there within the pelvis

Answer 3

4 articulations:
2 sacroiliac
Sacrococcygeal symphysis
Pubis symphysis

Question 4

What is a symphysis

Answer 4

a fibrocartilaginous fusion; hence not a joint

Question 5

What is the function of the pelvis

Answer 5

Transfer weight from upper axial body to lower appendicular body (especially during movements)
Provides an attachment for the muscles and ligaments used in locomotion
Contains and protects the abdominopelvic viscera

Question 6

What is the greater pelvis

Answer 6

Known as the ‘falsa pelvis’
Located superiorly
Provides support of the lower abdominal viscera (such as ileum and sigmoid colon)
Has little obstetric relevance

Question 7

What in the lesser pelvis

Answer 7

Also known as the ‘true pelvis’
Located inferiorly
Within the lesser pelvis lies the pelvic cavity anf pelvic viscera

Question 8

What is the pelvic brim

Answer 8

the outer edges of the pelvic inlet

Question 9

What is the pelvic inlet

Answer 9

the junction between the greater and lesser pelvis

Question 10

What are the borders of the pelvic inlet

Answer 10

Posterior–> superior portion of sacrum and sacral wings (ala)
Lateral–> arcuate line of the inner surface of ilium and the pectineal line on superior pubic ramus
Anterior–> pubic symphysis

Question 11

What are the borders of the pelvic outlet

Answer 11

Anteriorly–> pubic symphysis
Posteriorly–> coccyx
anterolaterally–> ischiopubic ramus
Posterolaterally–> sacrotuberous ligament

Question 12

Where is the birth canal

Answer 12

between the pelvic inlet and outlet

Question 13

What is the anatomical or true conjugate

Answer 13

From middle of sacral prominence to posterior superior edge of pubic symphysis
Should be 11cm or more

Question 14

What is the obstetric conjugate

Answer 14

The shortest of the 3 diameters
Determined from the sacral promontory to the thickest part pf pubic bone
Narrowest fixed distance
should be 10cm or more

Question 15

What is the diagonal conjugate

Answer 15

From sacral promontory to posterior inferior edge of pubic symphysis
Should be 11.5cm or more

Question 16

When is the inlet assumed contracted

Answer 16

When any one of the pelvic diameters are less than normal

Question 17

Where is the iliolumbar ligament

Answer 17

From tip of L5 to posterior aspect of inner lip of iliac crest

Question 18

What is the function of iliolumbar ligament

Answer 18

Strengthens the lumbosacral joint

Question 19

Where is the sacrotuberous ligament

Answer 19

From sacrum to tuberosity of the ischium

Posterior surface of sacrum and coccyx and PSIS & PIIS to ischial tuberosity

Question 20

Where is the sacrospinous ligament

Answer 20

From ischial spine to lateral margins of sacrum, lower sacrum and coccyx to ischial spine

Question 21

What is the function of the sacrotuberous and sacrospinous ligament

Answer 21

Stabilise SIJ
Sacrotuberous and sacrospinous prevent anterior rotation of sacrum within pelvis
Limit rotation of pelvis and adds attachments for glute max
Rotation of the superior sacrum is counterbalanced by the strong sacrotuberous and sacrospinous ligaments that anchor the inferior end of the sacrum to the ischium, preventing its superior and posterior rotation

Question 22

Where is the sacrococcygeal ligament

Answer 22

Anterior–> from anterior surface of sacrum to front of coccyx (continuation of the anterior longitudinal ligament)
Lateral portion–> inferior lateral angle of sacrum to transverse process of 1st coccygeal vertebrae
Also has dorsal portions

Question 23

What and where are the ligaments around the pubic symphysis

Answer 23

Superior pubic ligament-> runs between pubic tubercles
Inferior (arcuate) pubic ligament–> between inferior pubic rami and blends with fibrocartilaginous disc of pubic symphysis
Anterior pubic ligament–> across front of symphysis
Posterior pubic ligament–> membranous structure whihc blends with periosteum

Question 24

What is the difference between male and female pelvis in terms of primary function

Answer 24

Female pelvis: locomotion and childbirth (adaption by mainly lesser pelvis)
Male pelvis: locomotion

Question 25

What is the difference between male and female pelvis in terms of pelvic build

Answer 25

Males have greater muscle, heavier build therefore muscles and ligament markings are more pronouced
Heavier build is also present above the pelvis in males hence there are differences in the lumbosacral and hip joints too

Question 26

What is the difference between male and female pelvis in terms of iliac crests

Answer 26

Female: smoother and a little medial curve at the anterior end for more room for the growing fetus
Male: rougher and greater medial curve at the anterior end

Question 27

What is the difference between male and female pelvis in terms of acetabulum

Answer 27

Female: smaller
Male: larger due to greater upper body bulk

Question 28

What is the difference between male and female pelvis in terms of acetabular diameter

Answer 28

Female: less than distance from anterior rim to pubic symphysis
Male: approximately equal to distance from anterior rime to pubic symphysis

Question 29

What is the difference between male and female pelvis in terms of anterolateral wall

Answer 29

Female: longer length
Male: shorter length

Question 30

What is the difference between male and female pelvis in terms of symphysis pubis

Answer 30

Female: shorter length, therefore the shape of obturator foramen is more triangular
Male: Longer length, therefore the shape of obturator foramen is more ovoid

Question 31

What is the difference between male and female pelvis in terms of pubic tubercle

Answer 31

Female: tubercles are wider apart
Male: tubercles are shorter distance apart

Question 32

What is the difference between male and female pelvis in terms of subpubic arch or angle

Answer 32

Female: pistol angle = 80-85 degrees
Male: ‘V’ angle = 50-60 degrees

Question 33

What is the difference between male and female pelvis in terms of ischiopubic rami

Answer 33

Female: lighter build and narrows at pubic symphysis
Clitoral attachment is less developed
Male: heavier build, roughly 1cm width along length
Rough and elevated for crus penis attachment

Question 34

What is the difference between male and female pelvis in terms of ischial spines

Answer 34

Female: angle out or back (for childbirth)
Male: angle in and therefore closer together

Question 35

What is the difference between male and female pelvis in terms of obturator foramen

Answer 35

Female: triangular shape
Male: ovoid shape

Question 36

What is the difference between male and female pelvis in terms of greater sciatic notch

Answer 36

Female: Inverted ‘L’ shape–> more horizontal sacrum therefore angle roughly equals 75 degrees
Male: Inverted ‘J’ shape–> more vertical sacrum therefore angle roughly equals 50 degrees

Question 37

What is the difference between male and female pelvis in terms of auricular surface

Answer 37

Female: smaller and more obiquely set; greater concavity of dorsal border of auricular surface (this increases the space to hold foetus)
Male: Larger and more vertical, flatter dorsal border or auricular surface

Question 38

What is the difference between male and female pelvis in terms of sacrum

Answer 38

Female: flatter, shorter, broader–> more horizontal (for childbirth) therefore there is a greater sacro vertebral angle (sacral prominence) and L-shaped sciatic notch
Male: greater curve, longer, narrower, and 5 segments (more vertical therefore J-shaped sciatic notch)

Question 39

What is the difference between male and female pelvis in terms of pelvic cavity

Answer 39

Female: shorter and more cylindrical for WB’ing, ambulation and childbirth
Male: longer and more conical for weight bearing and ambulation