Pelvic Osteology Flashcards
What are the 3 main areas of the pelvic bone?
- Ilium
- Pubis
- Ischium
What are the 5 lines which form the pelvic inlet?
- Sacral promontory
- Sacral ala
- Arcuate line
- Pectineal line
- Pubic crest
What joins separate the 3 main parts of the pelvic bone?
Primary cartilaginous joints to allow for growth
What are the 2 ligaments found in the hip bone?
- Sacrospinous ligament
2. Sacrotuberous ligament
Where does the sacrospinous ligament run?
Apex attached to ischial spine and base attached to lateral margins of sacrum and coccyx
What does the sacrotuberous ligament run?
Sacrum to the ischial tuberosity
Where is the sacrotuberous ligament situated with regards to the sacrospinous ligament?
Posterior
What is a function of the sacrotuberous and sacrospinous ligaments?
Convert two sciatic notches into two sciatic foramina
What is the sacrum?
Fusion of five sacral vertebrae
What is the coccyx?
Fusion of four coccygeal vertebrae
What is the function of the large facet on the lateral surfaces of the sacrum?
Articulation with ilium to form sacroiliac joint
What is the function of the sacral tuberosity?
Attachments for ligaments of the sacroiliac joint
Where is the sacral tuberosity found in relation to the large facet on the sacrum?
Posterior
What is the function of sacral foramina?
Allow for passage of anterior and posterior rami of sacral nerves
What are 4 main differences between male and female pelvises bones?
- Male bones are bigger
- Males have heart shaped inlet - Females have oval shaped inlet
- Males have smaller outlet
- Males have more curved sacrum
What causes male pelvises to be heart shaped?
More distinct promontory
Why is the pelvic outlet larger in females than males?
Allow more room for delivery
What 2 muscles form the pelvic diaphragm?
- Levator ani
2. Coccygeus muscles
What forms the anterior fibres of the levator ani?
Levator prostatae (male) or sphincter vaginae (female) sling around prostate or vagina into perineal body
What is perineal body?
Mass of fibrous tissue in front of anal canal
What is the function of the sphincter vaginae?
Constrict vagina
What 2 fibres form the intermediate fibres of the levator ani?
- Puborectalis
2. Pubococcygeus
What is the puborectalis?
Forms a sling around the junction of the rectum and anal canal
What is the pubococcygeus?
Passes posteriorly to insert into anococcygeal body
Where is the anococcygeal body located?
Between tip of coccyx and anal canal
What forms the posterior fibres of the levator ani?
Iliococcygeus inserted into anococcygeal body and coccyx
What are 4 functions of the levator ani?
- Muscular sling to support pelvic viscera
- Resist rise in intrapelvic pressure
- Sphincter action on anorectal junction
- Maintain anorectal angle
What is the nerve supply of the levator ani?
Perineal branches of the fourth sacral nerve and pudenal nerve (branch of sacral plexus)
Where does the puborectalis originate?
Pubis
Where does the pubococcygeus originate?
Body of pubis
What is the descending order of muscles from the top of the lateral edge of the pelvic floor?
- Coccygeus
- Levator ani
a) Iliococcygeus
b) Pubococcygeus
c) Puborectalis
