Pelvic anatomy Flashcards
What landmarks make up the pelvic inlet?
The sacral promontory, the iliopectineal line and pubic symphysis
What is the pelvic inlet?
The boundary the pelvic cavity and the abdominal cavity
What are the innominate bones of the pelvis?
ilium, ischium, pubis
How many bones form the sacrum?
5 fused sacral vertebrae
What is the true pelvis
The true pelvis (lesser pelvis) is the area between the pelvic outlet and pelvic inlet
What is the diagonal conjugate line?
The distance from the sacral promontory to the inferior margin of the pubic ramus (approx 11cm)
What are the attachments of the sacrotuberous ligament?
Lateral sacrum and coccyx to the ischial tuberosity
What are the attachments of the sacrospinous ligament and where does it run in relation to the sacrotuberous ligament?
Scrospinous ligament runs from the lateral sacrum and coccyx to the ischial spines and runs anterior to the sacrotuberous ligament
What is the role of the sacrospinus and sacrotuberous ligaments?
They keep the sacrum in the correct position relative to the pelvis, so that weight bearing of the skeleton doesn’t cause them to flare outwards posteriorly but to be drawn anteriorly to the ischial spines and tuberosities of the pelvis. Their positioning also creates the lesser and greater sciatic foramen
What are the boundaries of the lesser sciatic foramen?
Sacrotuberous ligament, sacrospinous ligament, ischial spine and tuberosity
What are the boundaries of the greater sciatic foramen?
Anteriorly - greater sciatic notch of the ilium.
Posteriorly- Sacrotuberous ligament
Inferiorly - sacrospinous ligament
superiorly - anterior sacroiliac ligament
What are the boundaries of the obturator foramen?
Pubis superiorly and medially and ischium inferiorly and laterally
Where is the urogenital diaphragm located and what passes through it?
It is the muscular diaphragm which covers the area under the pubic arch - it allows the passage of the urethra, the opening of the vagina, it is an old term made of a inferior layer (the perineum) and a superior layer the pelvic diaphragm
What is the inferior border of the urogenital diaphragm and what lies above it?
The perineal membrane is the inferior body (closest to body surface and above that membrane lies the pelvic fascia
What are the attachments for the perineal membrane?
Inferior margins of the pubic rami and ischium laterally
What are the attachments for the obturator internus?
The internal aspect of the obturator foramen (overlying the obturator membrane) and then it passes posteriorly through the less sciatic foramen to the greater trochanter of the femur
What is the function of the obturator internus?
lateral rotation of the femur
What are the attachment points of the piriformis muscle?
the lateral border of the sacrum, it passes over the sarotuberous and sacrospinous ligaments and out of the greater sciatic foramen to attach to the greater trochanter of the femur
What is the function of the piriformis?
lateral rotation of the femur
What are the attachment points of the coccygeus muscle?
It forms part of the pelvic floor and it runs from the coccyx, anterior to the sacrospinous ligament and inserts into ischial spine
What is the pelvic fascia?
Fascia that overlies the obturator internus, pirformis and coccygeus to form insertion points for pelvic floor muscles
What makes the pelvic diaphragm or floor?
The levator ani and the coccygeus muscle
What is the course and function of the puborectalis muscle?
The puborectalis muscle forms part of the pelvic floor as part of a group of muscle fibers that make up the levator ani. It attaches to the pubic rami and forms a sling around the back of rectum at the junction between the rectum and the anal canal, forming part of the external sphincter function
What is the levator ani composed of?
Puborectalis, pubococcygeus, iliococcygeus
What is the inguinal ligament composed of?
It is the rolled lower margin of the aponeurosis of the external oblique muscle.
What are the attachments for the inguinal ligament?
ASIS to pubic tubercle
What is the course and function of the psoas muscle?
Attaches at the lateral aspects of the lumbar vetebrae, descends into the greater pelvis running along the ileopectineal line, under the inguinal ligament and out into the thigh where it attaches to the greater trochanter - it’s function is hip flexion
Where does the aortic artery bifurcate?
At the 4th lumbar vertebra (into common iliac arteries)
Where does the common iliac artery bifurcate?
They follow the course of the psoas muscle and bifurcate in front of the sacroiliac joints
Where does the external iliac artery run?
Along the inferior border of the psoas muscle as it courses along the iliopectineal line within the greater pelvis towards and inferior to the inguinal ligament