Pelvic anatomy Flashcards
What are the boundaries of the true pelvis?
Pelvic inlet and pelvic outlet
Which bones form the acetabulum?
The iliac, pubic and ischium bones
Role of the acetabulum
Hip joint - articulates with the head of the femur
Which bones surround the obturator foramen?
The pubic bone and the ischium bone
Which vertebral level does the iliac crest lie at?
L4
What level does the aortic artery bifurcate?
L4
Where does the iliacus muscle lie?
Iliac fossa (internal aspect of the ilium) - inserting into the lesser trochanter of the femur
Where does the sacrospinous ligament run?
Sacrum to ischial spine
Where does the sacrotuberous ligament run?
Sacrum to ischial tuberosity
Which is more posterior; sacrospinous or sacrotuberous ligaments?
Sacrotuberous
How many sacral formina are there?
4
What constitutes the iliopectineal line?
The arcuate line of the ilium to the pectineal line of the pubis. Both sides together form the inlet of the true pelvis
What is the diagonal conjugate line of the pelvis?
From the inferior aspect of the pubic symphysis to the sacral promontory. It is also called the true conjugate line
How long is the diagonal conjugate line?
12cm
How long is the obstetric conjugate line?
11cm
What is the obstetric conjugate line of the pelvis?
From posterior aspect of the pubic symphysis to the sacral promontory
What is the pelvic outlet?
Diagonal line from coccyx to pubic symphysis
What kind of joint is the sacro-iliac joint?
Synovial
How does the obturator internus muscle exit the pelvis?
Posteriorly via the lesser sciatic foramen
What does the obturator internus muscle lie over?
The obsturator membrane
Function of the obturator internus muscle
Lateral rotation of the thigh
Where does the obturator internus muscle insert into?
The greater trochanter of the femur
How does the piriformis exit the pelvis?
Via the greater sciatic foramen
What are the insertion points of the piriformis?
The antero-lateral border of the sacrum - travels through the greater sciatic foramen to the greater trochanter of the femur
What is the function of the piriformis?
Lateral hip rotation
Which ligament lies behind the coccygeus?
Sacrospinous ligament
Where does the coccygeus run?
From the infero-anterior border of the sacrum and coccyx to the ischial spine (anterior to the sacrospinous ligament)
What is the origin of the levator ani?
The medial surface of the obturator internus muscle fascia
Where and what is the perineal body?
A mass of fibres lying between the urogenital triangle and the anal triangle
Which muscles form the levator ani?
Levator prostate/sphincter vaginae (pubic bone to perineal body)
Puborectalis (pubic bone, loops around behind the anal canal and rectum)
Pubococcygeus
Iliococcygeus
Which muscles form the pelvic diaphragm?
The levator ani and the coccygeus
How does the psoas muscle exit the pelvis?
Inferior to the inguinal ligament
Where does the common iliac artery bifurcate?
At the superior level of the sacroiliac joint
How does the external iliac artery exit the pelvis?
Anterior to the psoas muscle, inferior to the inguinal ligament, over the pelvic brim - it becomes the femoral artery
Which branches does the external iliac artery give off before leaving the pelvis?
Inferior epigastric
Deep circumflex iliac
Which nerves form the lumbosacral trunk?
Anterior rami of L4 L5
S1 S2 S3
How does the sciatic nerve exit the pelvis?
Via the greater sciatic foramen
How does the obturator nerve exit the pelvis?
Via the obturator canal
Which nerves innervate the obturator nerve?
L2, L3, L4
Which nerves does the pudendal nerve arise from?
S2 S3 S4
How does the pudendal nerve enter the perineum?
It exits the pelvis via the greater sciatic foramen and then re-enters the pelvis via the lesser sciatic foramen to serve the perineum
Where does the iliolumbar artery arise from?
The internal iliac artery
How does the iliolumbar artery exit the pelvis?
It passes from the internal iliac artery under the psoas muscle and superiorly out of the false pelvis
How does the superior gluteal artery exit the pelvis
Via the greater sciatic foramen
Where does the superior gluteal artery arise from?
The internal iliac artery
Where does the obturator artery arise form and how does it exit the pelvis?
It arises from the internal iliac artery and exits the pelvis via the obturator canal
Where does the uterine artery arise from?
The internal iliac
Where does the middle rectal artery arise from?
The internal iliac
How does the external iliac vein enter pelvis?
It arises from the femoral vein via the femoral sheath and enters under the inguinal ligament
At which vertebral level does the rectum start?
S3
When does the rectum end?
As it passes through the pelvic floor it becomes the anal canal
Describe the route of the ureter as it enters the pelvis
Anterior to the bifurcation of the iliac artery it courses down towards the iliac spine and then follows the lateral wall to the lateral fornix of the vagina to the bladder
Where do the ovaries lie?
Close the point where the external and internal iliac arteries separate and the ureters enter the pelvis
What is the pouch of Douglas?
A peritoneal fold from the anterior wall of the rectum to the posterior fornix of the vagina
What is the uterovesical pouch?
A peritoneal fold between the anterior body of the uterus and posterior aspect of the bladder
Where does the uterine artery cross the ureter?
Near the lateral fornix of the vagina. The uterine artery crosses anterior to the ureter
Which muscle forms the bulk of the levator ani?
Pubococcygeus
What does the linea terminalis consist of?
Arcuate line
Pectineal line
Pubic crest
Which structures pass through the lesser sciatic foramen?
Internal pudendal vessels and pudendal nerve re-enter the pelvis via the lesser sciatic foramen
The tendon and nerve of the obturator internus muscle passes out of the pelvis via the lesser sciatic foramen
Which muscle passes through the greater sciatic foramen?
Piriformis
Which muscle passes through the lesser sciatic foramen?
Tendon of the obturator internus
How does the posterior femoral cutaneous nerve exit the pelvis?
Via the greater sciatic foramen
How does the sciatic nerve exit the pelvis?
Via the greater sciatic foramen
What kind of joint is the sacroiliac joint?
Synovial
What kind of joint is the pubic symphysis?
Secondary cartilaginous
What is an example of a primary cartilaginous joint?
Growth plate fusion
What is an example of a secondary cartilaginous joint in the pelvis?
Pubic symphysis
Which joint in the pelvis is synovial?
Sacroiliac
