Bony Pelvis and Pelvic Wall Flashcards
What are the components of the pelvic girdle?
sacrum
coccyx
Os coxae (R and L)
What bones make up the os coxae?
ilium, ischium, pubis
What are the anterior and posterior articulations of the pones of the ox coxae?
anteriorly; pubic symphysis
posteriorly: S1-S3 @ SI joints
What are the hip bones?
ox coxae
Where do the bones of the os coxae fuse?
at the acetabulum by age 17
What is the subpubic angle?
between ischial tuberosities
What is the female subpubic angle?
greater than 80 degrees
What is the male subpubic angle?
less than 70 degrees
When is sacral fusion complete by?
25
Where do the coccyx and sacrum articulate?
sacrococcygeal symphisis
–>fibrocartilage disc
How many fused vertebrae make up the coccyx?
3-5 fused
What connects the ilium, ischium and pubis in children?
tri-radiate cartilage @ acetabulum
—>Will fuse after puberty
What is the concavity b/t ischial spine and tuberosity?
lesser sciatic notch
What concavity is superior to the ischial spine and formed by part of the ilium?
greater sciatic notch
What is the pubic arch formed by?
R and L ischiopubic rami –>meet at pubic symphysis
What is the oblique ridge of the lateral part of the superior pubic ramus?
pectineal line or pectin pubis
What is the thickening on the anterior part of the body of the pubis?
pubic crest–>ends laterally as pubic tubercle
The superior ramus of the pubis helps form the _________
acetabulum
The inferior ramus of the pubis helps form_____
bony borders of the obturator foramen
What is the dividing line separating the false and true pelvis?
pelvic brim
–>AKA pelvic inlet or superior pelvic aperture
What comprises the pelvic brim?
- sacral promontory @ base
- anterior border of ala
- iliopectineal line
- pubic crest
- superior surface of pubic symphysis
**imaginary circle around “hole” the hip bones make with the sacrum and coccyx
What is the false pelvis?
pelvis major
–>above pelvic brim/inlet
What is the true pelvis?
pelvis minor
–>below pelvic brim/inlet
What are the bony boundaries of the pelvis minor?
- sacrum
- coccyx
- inner surface of ischium
- inner surface of pubis
- small part of ilium
What are the boundaries of the pelvic outlet/inferior pelvic aperture?
anteriorly: pubic arch (inferior to pubic symphysis)
laterally: ischial tuberosities
posterolaterally: sacrotuberous L
posteriorly: tip of coccyx
Describe lumbosacral joints
- IV disc b/t L5 and sacrum
- zygapophyseal joints b/t L5 and S1
–>allows for greater movement and contributes to the lumbar curve of the spine
What ligament stabilizes L5 vertebra on the sacrum by anchoring its TP to the iliac crest?
iliolumbar L
–>goes across the top of the ileum from the sacrum/L5
What ligament limits forward motion of L5 vertebra?
iliolumbar L
What is an atypical IV joint that occurs b/t S5 and the coccyx?
sacrococcygeal joint
What makes up the sacrococcygeal joint?
IV disc–>posterior movement of coccyx during defecation and childbirth
A and P sacrococcygeal Ls–>stabilize
What do the inferior pubic (arcuate) and superior pubic ligaments reinforce?
pubic symphysis
What type of joint is the sacroiliac joint?
synovial
What ligaments stabilize the sacroiliac joint?
- interosseous sacroiliac L
- posterior sacroiliac L
- iliolumbar L
- sacrotuberous L
- sacrospinous L
Where is the sacroiliac joint located?
between lateral sacrum (S1-3) and internal surface of ileum
–>posterior to iliac fossa
What lie in the same vertical plane in terms of the pelvic girdle in anatomical position?
R and L ASIS
anterior aspect of pubic symphysis
What forms the anteroinferior wall of the pelvic cavity?
- bodies and rami of pubic bones
- pubic symphysis
What is the fxn of the anterioinferior wall?
bears weight of urinary bladder
What forms the lateral walls of the pelvic cavity?
2 hip bones
What muscles cover the lateral pelvic walls?
obturator internus M
–>tendons pass through lesser sciatic foramen to attach to greater trochanter
What is the fxn of the medial surfaces of obturator internus M?
covered by obturator fascia which provides attachment for the pelvic diaphragm
What forms the posterior wall of the pelvic cavity?
sacrum and coccyx
–>form bony wall and roof in midline
What forms the posterolateral walls of the pelvic cavity?
- ligaments associated with the SI joints
- piriformis Ms
What forms the pelvic floor/ floor of the pelvic cavity?
pelvic diaphragm
–>coccygeus and levator ani Ms and associated fascia
What is the fxn of the pelvic diaphragm?
separates true pelvis from perineum
What is the O/I of piriformis?
lateral masses S2-4 and sacrotuberous L–> greater trochanter of femur
What is the action of piriformis M?
exits pelvis via greater sciatic foramen
–>LATERAL rotation of thigh
What innervates piriformis M?
N to piriformis (S1-2)
What is the O/I of obturator internus M?
anterolateral wall of pelvic minor and obturator membrane–>greater trochanter of femur
What is the action of obturator internus M?
exits pelvis via lesser sciatic foramen
–>LATERAL rotation of thigh
What innervates obturator internus M?
nerve to obturator internus (L5-S1)
What perforates the pelvic diaphragm?
-urethra and anal canal
–>also vagina in females
What is the largest and most important part of the pelvic diaphragm?
levator ani M
–>pubic bone to coccyx, joints other M midline @ perineal body
What M is funnel shaped and separates the pelvic cavity from the perineum?
levator ani
What makes up the levator ani M?
1: pubococcygeus
- ->pubis to coccyx and anococcygeal L
2: puborectalis
- ->pubis, posterior to encircle anorectal jxn
- -> U shaped sling
3: iliococcygeus
- ->tendinous arch and ischial spine to coccyx and anococcygeal L
What forms a U shaped sling of muscle that is medial and inferior to pubococcygeus?
puborectalis M of levator ani
–>increases angle b/t rectum and anal canal to maintain continence
What is the dual innervation of levator ani M?
superior surface: S3-4
inferior surface: inferior rectal N (S2-4)
What are the actions of levator ani M?
- support pelvic viscera
- resists inferior thrust
- raises pelvic floor in forced exhalation, coughing, vomiting, urination, lifting heavy objects
- maintains bowel continence and prevents defecation through angle of puborectalis M (increases angle b/t rectum and anal canal)
What M forms the posterior portion of the pelvic diaphragm?
coccygeus M
ischial spines and sacrospinous L–> lateral anterior sacrum and coccyx
What is the action of coccygeus M?
support coccyx, pull it forward after defecation or childbirth
What innervates the coccygeus M?
S4-5
What potential space is between the rectum and sacrum?
retrorectal space
–>rectum surrounded by loose CT so can expand before defecation
What space and fascia separate urinary bladder from rectum in males?
rectovesical space
What space is between the pubic bones and anterior surface of bladder?
retropubic space
–>subserous fat allows expansion of bladder
The pelvic fascia is continuous with ______-
abdominal fascia where two fascias are anchored to pelvic brim
The 3 layers of pelvic fascia are in contact with _________
pelvic diaphragm -->diaphragmatic hollow pelvic organs -->visceral pelvic wall and floor -->parietal
Injury to the pelvic floor is frequently observed when?
during vaginal delivery
What muscles are most commonly injured in chidlbirth?
pubococcygeus M
puborectalis M
–>support urethra, vagina and anal canal
What are clinical conditions arising from injury to pelvic floor during childbirth?
- urinary stress incontinence
- prolapse of pelvic organs
- fecal incontinence
What can cause urinary stress incontinence in men?
prostate gland removed
chronic cough
