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
What are the branches of the external iliac artery?
The inferior epigastric artery, the deep circumflex artery and the femoral artery
Which nerves form the sciatic nerve?
L4 and L5 (lumbosacral trunk) and anterior divisions of S1,S2,S3
Where does the sciatic nerve exit the pelvis?
Via the greater sciatic foramen (anterior to the piriformis)
Where does the obturator nerve branch from?
L2, 3, 4 (anterior divisions)
Where does the obturator nerve exit the pelvis?
Through the obturator foramen
What is the function of the obturator nerve?
Sensation of medial upper thigh and adductor muscles
IT DOES NOT INNERVATE OBTURATOR INTERNUS
What kind of joint is the pubic symphysis?
A secondary cartilaginous joint (hyaline cartilage and fibrocartilage disc)
What is a primary cartilaginous joint?
Synchondrosis - hyaline cartilage that ossifies with age (see in children in growth plates)
What is a secondary cartilaginous joint?
Symphysis - hyaline cartilage joined by fibrocartilage
Give examples of secondary cartilaginous joints vs. fibrous joints
secondary cartilaginous - pubic symphysis, intervertebral discs (partially mobile but less than synovial
fibrous joints - suture lines of the skull - immobile
Where does the lateral femoral cutaneous nerve of the thigh arise from?
L2/L3 (posterior division)
What condition does compression of the lateral femoral cutaneous nerve cause?
meralgia paraesthesia
What is meralgia paraesthesia?
entrapment of the lateral femoral nerve causing altered sensation in the anterolateral thigh - can be caused by pregnancy
Where does the pudendal nerve arise from?
S2, S3, S4
What route does the pudendal nerve take to get to the perineum?
From S2, S3 S4 out of the greater sciatic foramen and then into the perineum via the lesser sciatic foramen
What is the iliolumbar artery a branch of?
The posterior branch of the internal iliac artery
What is the superior gluteal artery a branch of?
Posterior branch of the internal iliac artery
How does the superior gluteal artery exit the pelvis?
Through the greater sciatic foramen as a branch of the internal iliac artery
Where does the obturator artery arise from?
The anterior branch of the internal iliac artery
What are the boundaries of the femoral triangle?
superior - inguinal ligament medial - abductor longus lateral - sartorius Roof - fascia lata floor -pectineus, abductor longus, ilipsoas
Which structures run through the femoral triangle?
lateral to medial (femoral nerve>femoral artery> femoral vein), femoral sheath, the saphenofemoral venous junction, deep inguinal lymph nodes
What are the borders of the deep perineal pouch?
Old term (urogenital diaphragm) new term: perineum inferiority and pelvic diaphragm superiorly
Where is the Bartholin gland located?
Superficial gland in females
Where are the bulbourethral glands located?
Deep perineal pouch in males
What portion of the urethra passes through the deep perineal pouch?
Males- membranous urethra
Females- proximal portion of the urehtra
What two pouches does the pelvic peritoneum form in females?
uterovesicle and rectovesicle (pouch of douglas)
Wha tis the broad ligament formed from?
pelvic peritoneum draping over the uterus
Where in relation to the sacrum does the rectum start?
S3
What are the lowest parts of the peritoneum?
rectovesicle pouch (males) and rectouterine pouch (females- pouch of douglas)
When does the rectum become the anal canal?
When it pierces through puborectalis of the pelvic floor
Venous drainage of the rectum
superior rectal vein to inferior mesenteric vein to portal system and middle/inferior rectal veins drain into the internal iliac vein
Where do the ureters cross the pelvic brim?
At the bifurcation of the common iliac vessels
Which artery crosses the ureter in the pelvis?
The uterine artery, lateral to the fornices of the vagina
Where does the median umbilical ligament attach to?
apex of bladder to umbilicus (remnant of the urachus)
Length of the male urethra
approx 20cm
Where is the external urethral sphincter in males?
After the apex of the prostate, the membranous urethra passes through the deep perineal pouch, the external urehtral sphincter is here before it passes through the perineal membrane
Anterior and posterior scrotal arteries are branches of which artery and what do they supply?
Supply the scrotum
anterior scrotal artery - deep external pudendal artery from femoral artery
posterior scrotal artery from internal pudendal artery from the internal iliac artery
How many lobules are in each testicle?
250-400
Innervation of the testes
T10
What is the vaginal artery a branch of?
The internal iliac artery
Where does the ovarian lymph drain to?
para-aortic nodes
Where does the fallopian tube lymph drain to?
para-aortic nodes
Where does the vaginal lymph drain to?
upper 2/3 internal and external iliac nodes
lower 1/3 inguinal nodes
Where does cervical lymph drain to?
para-aortic nodes
Innervation of the anal sphincters
internal - pelvic splachnic (S4)
external -inferior rectal (from pudendal nerve) and perineal branch of S4
