Bony Pelvis and Pelvic Wall Flashcards
What are pelvic girdle ligaments?
Sacroiliac Ligaments (Anterior and Posterior) Sacrotuberous Ligament (STL) Sacrospinous Ligament (SSL)
What are the major functions of STL and SSL?
Prevent rotation of sacrum
Together with the hip bone create greater and lesser sciatic foramina
Anterioposterior compression of pelvis (car accidents) produces fractures in ______ _____ .
Pelvic rami (pubic rami and ischial rami)
Lateral forces squeeze _________ and ilia together breaking both.
Acetabulum
What are the weak areas of pelvis?
Pubic rami
Acetabulum
SI joints
Ala
At what level are greater pelvis and lesser (true) pelvis separated?
L5/S1
Boundaries of lesser (true) pelvis
Superiorly: pelvic brim (pelvic inlet)
Inferiorly: Pelvic diaphragm
Laterally and Anteriorly: lower 1/2 of the hip bones
Posteriorly: sacrum and coccyx
Which lines demarcate pelvic brim (pelvic inlet)?
Arcuate and pectineal lines.
Greater (false) pelvis is superior to ____ ______, occupied by ________ _________.
pelvic brim; abdominal viscera
Which bone predominantly bears abdominal weight?
Pubic bone
Male vs Female pelves (android vs gynecoid)
- Pelvic outlet
- Pubic arch and subpubic angle
- Obturator foramen
- Greater sciatic notch
- Small; large
- Narrow (<70degrees); wide (>70degrees)
- Round; oval
- Narrow; almost 90 degrees
What are the major pelvic wall muscles?
Obturator Internus
Piriformis
Coccygeus
Obturator Internus
Origin: ilium/ischium surface, obturator membrane
Insertion: greater trochanter
Innervation: obturator n
Piriformis
Origin: S2-4 surface; superior margin of greater sciatic notch; STL
Insertion: greater trochanter
Innervation: S1–S2
Coccygeus
Origin: ischial spine
Insertion: inferior end of sacrum and coccyx
Innervation: S4–S5
What muscle supports pelvic viscera and flexes coccyx?
Coccygeus
Four muscles that make up the pelvic diaphragm? What are the origins?
- (ischio)coccygeus m (ischial spine)
- Iliococcygeus m (tendinous arch)
- Pubococcygeus m (pubis)
- Puborectalis m (pubis)
What three muscles of pelvic diaphragm elevate the anus and are together called levator ani?
Iliococcygeus
Pubococcygeus
Puborectalis
Thickening of obturator fascia between ischial spine and body of pubis
Tendinous arch of levator ani.
Which muscle loops around the anorectal angle?
Puborectalis m
T/F: Puborectalis m is distinct from internal and external anal sphincters.
True
Passageway for utethra and rectum, and in females also the vagina
Unogenital (levanor) hiatus
What are the most medial muscles forming the urogenital hiatus that are the closest to the vagina and are most likely to get torn during childbirth?
Pubococcygeus m
Puborectalis m
Dimond shaped space inferior to pelvic floor (diaphragm) filled with primarily fat
Ischiorectal fossae
Ischiorectal fossae can be divided into two triangles, what are those?
Urogenital triangle
Anal triangle
What is the role of ischiorectal fossa?
Allows movement of pelvic diaphragm and expansion of the anal canal
Contains neurovasculature to the anal canal (and some to perineum)
Where is ischiorectal fossae in relation to the perineal membrane?
Extends anteriorly above the perineal membrane.
Where does the anal canal begin?
At the level where rectum ‘perforates’ levator ani.
What structures does the anal canal consist of?
Anal columns
Anal valves
Anal sinuses
At what level is rectosigmoid juncton?
S3
What type of muscle is the internal anal sphincter?
Smooth circular muscle (involuntary)
What type of muscle is the external anal sphincter?
Skeletal muscle (voluntary)
Internal anal sphincter is responsible for what percent of the resting anal tone?
55-85%
What parts does the external anal sphincter consist of?
Subcutaneous
Superficial
Deep
Essentially enlarged and collapsed version (varicosity) of normal venous anatomy?
Hemorrhoids
Hemorrhoids are a major clinical consequence of what?
Portal hypertension
T/F External hemorrhoids are not painful
False, internal hemorrhoids are not painful
What nerves innervate the anus above pectinate line?
Inferior hypogastric plexus (autonomic)
What nerves innervate the anus bellow the pectinate line?
Inferior rectal nerves (somatic)
What veins drain blood from anus above the pectinate line?
Superior rectal vein (portal)
What veins drain blood from anus bellow the pectinate line?
Inferior rectal vein (systemic)
What types of hemorrhages are found in anus above the pectinate line?
Internal hemorrhages (not painful)
What types of hemorrhages are found in anus bellow the pectinate line?
External hemorrhages (painful)
What is the destination of lymph vessels above the pectinate line?
Internal iliac lymph nodes, inferior mesenteric
What is the destination of lymph vessels bellow the pectinate line?
Superficial lymph nodes
What is the embryological epithelial origin of anus above the pectinate line?
endoderm
What is the embryological epithelial origin of the anus bellow the pectinate line?
ectoderm