Pelvis & Perineurium Flashcards
What are the 3 parts of the pelvic bone(os coxa)?
- Ilium
- ischium
- pubis
What do pelvic bones do in puberty?
Fuses together at the acetubulum during adolescence
-articulation site for the femoral head
Describe the pelvic girdle
- two pelvic bones and sacrum
- left and right ilia articulate with sacrum posteriorly
- left and right pubis articulates anteriorly with pubic symphysis
What are the pelvic openings?
Sublinguinal canal- Abdomen/ abdominopelvis and anterior thigh
Obturator canal- pelvis and medial thigh
Greater sciatic foramen- pelvis and gluteal region
Lesser sciatic foramen- gluteal region and perineum
Contrast the true and false pelvis
The iliac blades contribute to the abdominal cavity = false pelvis
Below the pelvic inlet is the pelvic cavity= true pelvis
Contrast the pelvic inlet and pelvic outlet
Pelvic inlet- sacral promontory, sacral ala, arcuate line, pectineal line, pubic crest
Pelvic outlet- Anterior: pubic symphysis, ischiopubic ramus; posterior is hail tuberosities, sacrotuberous ligaments and sacrum
What are the sacroiliac joints?
Iliac and sacral ala
Two components:
-synovial- mobile
-syndesmosis- immobile
Sacrotuberous and sacrospinous…
Ligaments oppose posterior sacral rotation
Sacraspinous ligaament- from sacrum to ischial spine
Sacrotuberous ligament- from sacrum to ischial tuberosity
Describe pelvic measurements
A variety of obstetric measurements can be done
- conjugate (AP)
- conjugate diagonal
- transverse
- oblique
- interspinous diameter(narrowest)
- anterior posterior (AP) diameter of pelvic inlet
These measurements are used to determine the fixed size of the birth canal and the likelihood of a safe vaginal delivery
Contrast the male and female pelvis
Female:
- flared ala
- oval pelvic inlet(brim)
- wide pelvic outlet
- wide subpubic angle
- J-shaped sacrum
Male:
- upright ala
- heart shaped pelvic inlet(brim)
- narrow pelvic outlet
- narrow subpubic angle
- C-shaped sacrum
What are the muscles of the pelvic walls?
Wall
- piriformis
- obturator internus
What are the muscles of the pelvic floor?
Floor (pelvic diaphragm)
- Coccygeus
- levator ani-(assists in maintaining fecal and urinary continence)
- iliococcygeus
- pubococcygeus
- puborectalis-forms a “U” shaped sling around the anorectal junction that helps maintain fecal continence
What is the function of obturator internus?
- Lateral rotation
- abduction
What is the innervation and blood supply of the obturator canal?
Obturator nerve
Obturator artery
What is the function of the piriformis?
- Lateral rotation
- abduction
What is the pelvic diaphragm?
Funnel shaped muscle that reinforces the pelvic organs
Anterior defect= urogenital hiatus
Consists of:
- levator ani muscle
- iliococcygeus
- pubococcygeus
-coccygeus
What is an episiotomy?
The pelvic and perineal muscles may tear during childbirth
- Tearing of the perineal body may result in severe post partum complications
- To prevent excessive damage specifically to the external anal sphincter the muscles are cut
- Typically the cut is made obliquely through the muscles
Describe pudendal nerve block
The ischial spine can be palpated via the vaginal canal
The spine is used as a landmark for administering a pudendal nerve block
What is a pudendal canal?
Passage within the obturator fascia (lateral wall of ischioanal fossa) - internal pudendal vessels & pidendal nerve run from the lesser sciatic notch to the perineum
Pudendal nerve and internal pudendal artery pass out the greater and in the lesser sciatic notch
What is the pelvic blood supply?
The abdominal aorta bifurcates at L4 into the common iliac arteries
Common iliac arteries divide into internal and external iliac arteries
Explain the effect of the external and internal iliac artery
Internal iliac artery supplies the pelvis and gluteal region- umbilical (partially oblitered), superior vesicle, middle rectal, superior gluteal, inferior gluteal, internal pudendal, lateral sacral, obturator, iliolumbar
External iliac gives two branches before it reaches the inguinal ligament
-The deep circumflex iliac artery and inferior epigastric artery
It becomes the femoral artery as it passes deep to the inguinal ligament and supplies the lower limb
Pelvic arteries are highly variable particularly in terms of…
Size and origin. Name arteries according to their distribution , not origin!(course not source)
With the exception of the ovaries, all pelvic viscera are supplied by branches of the internal iliac arteries
What is the function of the obturator artery?
Passes anterior-inferiorly on the lateral wall of the pelvi, to the upper part of the obturator foramen, and escaping from the pelvic cavity through the obturator canal with the obturator nerve
What is the function of the iliolumbar artery?
Passes superiorly between psoas major & vertebral column upwards
