Pelvis & Perineum Flashcards
What is the hip bone a fusion of?
Iliu, Ishium, Pubis
What are the ilium, ischium, and pubis held together by prior to puberty?
Cartilage at the acetabulum
What are the 6 landmarks of the ilium?
Ala Iliac crest Anterior/Posterior Iliac Spine Iliac Fossa Body Auricular Surface
What are the 6 landmarks of the ischium?
Body Ramus Ischial Tuberosity Ischial Spine Lesser Sciatic Notch Greater Sciatic Notch
What are the 5 landmarks of the pubis?
Superior ramus Inferior ramus Pubic crest Pubic tubercle Pectin Pubis
What forms the obturator foramen?
The ramus of the ischium forms the inferior margin, while the inferior ramus of the ischium forms the anteromedial portion
What kind of cartilage is the pubic symphysis?
Fibrocartilage
What is special about the subpubic angle?
It is gender different
In anatomical position how is the ASIS positioned?
In the same vertical plane as the pubis symphysis
What is included in the pelvic inlet?
- Bounded by pelvic brim consisting of: Sacral promontory and ala Ilial arcuate line Superior pubic ramus Pubic symphysis
What is included in the pelvic outlet?
- Bounded by: Pubic Arch Ischial Tuberosities Sacrotuberous ligament Tip of coccyx
What closes the inferior pelvic aperature of the pelvic outlet?
Closed by the muscular pelvic diaphragm
What are the other terms for the Greater Pelvis and where is it located?
False Pelvis or Pelvis Major
- located superior to pelvic inlet
What are the other terms for Lesser Pelvis and where is it located?
True Pelvis or Pelvis Minor
- located between pelvic inlet and pelvic outlet
What are the main differences between male & female pelvus’?
Male= heavier & thicker with more prominent bony markings for muscle attachments
- Narrow & deep lesser pelvis
Subpubic angle= 60
Female= wider & shallower with large pelvic inlet & outlet
Subpubic angle = 90
An anteroposterior compression of the pelvis will result in a fracture where?
Lateral compression?
Anteroposterior= Pubic rami Lateral= acetabula and ilia
Where is the syndesmosis portion of the SI joint?
posteriorly between tuberosities of both bones
Where is the synovial portion of the SI joint?
anteriorly between auricular surfaces of both bones
unusual synovial joint in that little mobility is possible
What are the 5 ligaments that support the SI joint?
Anterior SI Ligament Interosseus SI Ligament Posterior SI Ligament Sacrotuberous Ligament Sacrospinous Ligament
Which of the 5 SI ligaments is primarily responsible for weight transfer?
Interosseus SI Ligament
Which of the 5 SI ligaments allows the axial weight to draw the ilia inward (medially)?
Posterior SI Ligament
Which of the 5 SI ligaments limits upward movement of the inferior part of the sacrum?
Sacrospinous Ligament and Sacrotuberous Ligament together
Which of the 5 SI ligaments resists sacral rotation during periods of sudden weight gain (landing a high jump) and contributes to the formation of the Greater & Lesser Sciatic Foramina?
Sacrospinous Ligament
In the Lumbosacral joint what prevents L5 from sliding anteriorly?
S1 facets face posteromedially
What ligament supports the Lumbosacral joint?
Iliolumbar Ligament (spans from L5 TPs to medial surface of ilial ala)
What does the Sacrococcygeal joint consist of?
Fibrocartilage disc between apex of sacrum & coccyx
Anterior/posterior Sacrococcygeal Ligament (strengthens this joint)
What ligaments thicken the pubis symphysis?
Superior Pubic Ligament- laterally to pubic tubercles
Inferior Pubic Ligament- rounds the subpubic angle to form the pubic arch
What happens to the pelvic joint/ligament during pregnancy?
Increased levels of sex hormones & RELAXIN= freer movements
SI joint loosens= greater pelvic rotation
Increased distance between pubic bones
Overall pelvic diameter increases 10-15%
Distance between sacral promontory & pubic symphysis does NOT change
therefore most increase is in transverse axis
How is the anterior pelvic wall formed?
by bodies and rami of pubic bones & pubic symphysis
How is the lateral pelvic wall formed?
hip bones with obturator foramen
What is the obturator foramen closed by?
obturator membrane
What are the attachments of the Obturator Internus muscle?
Internal surface of obturator membrane & ilium/ischium (O) then turns sharply to attach to Greater Trochanter (I)
What is the tendinous arch of obturator fascia an attachment for?
Levator Ani muscle
What is the innervation of obturator internus?
Nerve to obturator internus (L5-S2)
What is the action of obturator internus?
laterally rotate thigh, hold head of femur in acetabulum
How is the posterior pelvic wall formed?
by sacrum/coccyx, SI joints, & associated ligaments
What are the attachments of the Piriformis muscle?
2nd-4th sacral segments and sacrotuberous ligament (O) then it exits through greater sciatic foramen to attach to greater trochanter of femur (I)
What nerves cross the internal surface of the piriformis?
Sacral Plexus
What is the innervation of the piriformis?
S1-S2 ventral rami
What is the action of the piriformis?
Laterally rotates and abducts thigh, holds femur head in acetabulum
How is the pelvic floor formed and what does it consist of?
Formed by Pelvic Diaphgram
Consists of Levator Ani M and Coccygeus M
(Separates pelvic cavity from perineum)
What is the importance of the Levator Ani Muscle?
Forms a muscular sling for supporting abdominopelvic viscera
Resists increases in intra-abdominal pressure
- Important during forced expiration, coughing, sneezing, vomiting, urinating, defecating, and lifting heavy objects
- role in voluntary control of urinating and defecating
What is the innervation of the levator ani muscle?
S4 ventral rami & Inferior Rectal nerve (from pudendal)
What is the action of levator ani muscle?
raises pelvic floor and compress abdominopelvic contents
What is the puborectalis muscle? (4)
The narrow medial part of levator ani muscle
- Forms U-shaped sling from R/L pubic bodies to anorectal junction
- surrounds the urogenital hiatus
- creates the puborectal sling at anorectal junction forming the anorectal flexure (= important for maintaining fecal continence)
What is the pubococcygeus muscle?
the main intermediate part of levator ani muscle
spans from pubis to coccyx
attached to anterior part of tendonous arch of obturator fascia
What is the iliococcygeus muscle?
Posterolateral part of levator ani muscle
spans from posterior part of tendinous arch to coccyx
Where is the coccygeus muscle located?
spans from ischial spine to inferior sacrum and coccyx
What is the innervation of the coccygeus muscle?
S4-S5 ventral rami
What is the action of coccygeus muscle?
Contributes to levator ani in forming the pelvic diaphragm
What is pelvic fascia continuous with?
Endoabdominal fascia in abdomen
What does parietal pelvic fascia cover?
Obturator internus, piriformis, coccygeus, levator ani
What does visceral pelvic fascia cover?
urinary bladder, prostate, vagina, uterus, rectum
What is the visceral pelvic fascia continuous with and wehre?
With the parietal pelvic fascia at point pelvic organ penetrates pelvic floor
What is the tendinous arch of pelvic fascia?
Continuous bilateral fibrous sling that spans from pubis to sacrum along pelvic floor
What are the ligaments of the tendinous arch in males?
Puboprostatic L- anteriorly from prostate to pubis
Sarogenital L- posteriorly from sacrum to prostate
What are the ligaments of tendinous arch in females?
Pubovesical L- anteriorly from urinary bladder to pubis
Uterosacral L- posteriorly from sacrum to vagina
What and where is the perineum?
Inferior to pelvic outlet and separated from pelvic cavity by the pelvic diaphgram
= both external surface & shallow compartment of body
What are the general borders of the perineum?
Mons pubis anteriorly
Medial surfaces of proximal thigh laterally
Gluteal fold & intergluteal cleft posteriorly
What are the osseofibrous borders of the perineum? (5)
Pubic symphysis Ischiopubic rami Ischial tuberosities Sacrotuberous Ls Inferior sacrum & coccyx
What subdivides the perineum and what are the subdivisions?
An imaginary transverse line connecting the ischial tuberosities.
- Anal Triangle
- Urogenital Triangle
- Perineal Body (central point of perineum)
Where is the anal triangle and what does it contain?
- Posterior to transverse line
- Contains anus
Where is the urogenital triangle and what does it contain?
- Anterior to transver line
- contains external genitalia
What is the urogenital triangle covered by?
Perineal membrane spanning pubic arch
attachment point for erectile bodies & is perforated by urethra (both sexes) and vagina
What is the perineal body and where is it located?
Irregular shaped fibromuscular tissue
- midpoint of transverse line
- posterior to vestibule of vagina or bulb of penis
- anterior to anus & anal canal
What attaches to the perineal body?
- Superficial Transerse Perineal M
- Deep Transverse Perineal M
- External Anal Sphincter
- Bulbospongiosus
- very important support system for pelvic viscera in females
What innervates Superficial Transverse Perineal M & Deep Transverse Perineal M and what do they do?
Deep Perineal N (from pudendal n)
- supports & anchors perineal body- provides support to pelvic floor
