Pelvic Osteology

Question 1

What are the 3 main areas of the pelvic bone?

Answer 1

1. Ilium
2. Pubis
3. Ischium

Question 2

What are the 5 lines which form the pelvic inlet?

Answer 2

1. Sacral promontory
2. Sacral ala
3. Arcuate line
4. Pectineal line
5. Pubic crest

Question 3

What joins separate the 3 main parts of the pelvic bone?

Answer 3

Primary cartilaginous joints to allow for growth

Question 4

What are the 2 ligaments found in the hip bone?

Answer 4

1. Sacrospinous ligament

2. Sacrotuberous ligament

Question 5

Where does the sacrospinous ligament run?

Answer 5

Apex attached to ischial spine and base attached to lateral margins of sacrum and coccyx

Question 6

What does the sacrotuberous ligament run?

Answer 6

Sacrum to the ischial tuberosity

Question 7

Where is the sacrotuberous ligament situated with regards to the sacrospinous ligament?

Answer 7

Posterior

Question 8

What is a function of the sacrotuberous and sacrospinous ligaments?

Answer 8

Convert two sciatic notches into two sciatic foramina

Question 9

What is the sacrum?

Answer 9

Fusion of five sacral vertebrae

Question 10

What is the coccyx?

Answer 10

Fusion of four coccygeal vertebrae

Question 11

What is the function of the large facet on the lateral surfaces of the sacrum?

Answer 11

Articulation with ilium to form sacroiliac joint

Question 12

What is the function of the sacral tuberosity?

Answer 12

Attachments for ligaments of the sacroiliac joint

Question 13

Where is the sacral tuberosity found in relation to the large facet on the sacrum?

Answer 13

Posterior

Question 14

What is the function of sacral foramina?

Answer 14

Allow for passage of anterior and posterior rami of sacral nerves

Question 15

What are 4 main differences between male and female pelvises bones?

Answer 15

1. Male bones are bigger
2. Males have heart shaped inlet - Females have oval shaped inlet
3. Males have smaller outlet
4. Males have more curved sacrum

Question 16

What causes male pelvises to be heart shaped?

Answer 16

More distinct promontory

Question 17

Why is the pelvic outlet larger in females than males?

Answer 17

Allow more room for delivery

Question 18

What 2 muscles form the pelvic diaphragm?

Answer 18

1. Levator ani

2. Coccygeus muscles

Question 19

What forms the anterior fibres of the levator ani?

Answer 19

Levator prostatae (male) or sphincter vaginae (female) sling around prostate or vagina into perineal body

Question 20

What is perineal body?

Answer 20

Mass of fibrous tissue in front of anal canal

Question 21

What is the function of the sphincter vaginae?

Answer 21

Constrict vagina

Question 22

What 2 fibres form the intermediate fibres of the levator ani?

Answer 22

1. Puborectalis

2. Pubococcygeus

Question 23

What is the puborectalis?

Answer 23

Forms a sling around the junction of the rectum and anal canal

Question 24

What is the pubococcygeus?

Answer 24

Passes posteriorly to insert into anococcygeal body

Question 25

Where is the anococcygeal body located?

Answer 25

Between tip of coccyx and anal canal

Question 26

What forms the posterior fibres of the levator ani?

Answer 26

Iliococcygeus inserted into anococcygeal body and coccyx

Question 27

What are 4 functions of the levator ani?

Answer 27

1. Muscular sling to support pelvic viscera
2. Resist rise in intrapelvic pressure
3. Sphincter action on anorectal junction
4. Maintain anorectal angle

Question 28

What is the nerve supply of the levator ani?

Answer 28

Perineal branches of the fourth sacral nerve and pudenal nerve (branch of sacral plexus)

Question 29

Where does the puborectalis originate?

Answer 29

Pubis

Question 30

Where does the pubococcygeus originate?

Answer 30

Body of pubis

Question 31

What is the descending order of muscles from the top of the lateral edge of the pelvic floor?

Answer 31

1. Coccygeus
2. Levator ani
   a) Iliococcygeus
   b) Pubococcygeus
   c) Puborectalis