Pelvic Floor, Vessels and Nerves Flashcards
At what vertebral level does the aorta bifurcate? What vessels are formed?
L4
Left and right common iliac arteries
The common iliac arteries each split giving two further arteries: the internal and external iliac arteries. What happens to the external iliac artery?
Gives off the inferior epigastric artery before passing deep to the inguinal ligament and becoming the femoral artery of the lower limb
The inferior epigastric artery ascends on the anterior abdominal wall and anastomoses with which vessel?
Superior epigastric artery
The internal iliac artery supplies most of the pelvic viscera, the pelvic and lower abdominal walls and the perineum, as well as sending branches to the lower limb.
Which other arteries supply pelvic structures?
Gonadal
Ureteric
Inferior mesenteric artery
What structure forms the median umbilical ligament?
Urachus
What structure forms the medial umbilical ligament?
Umbilical artery
What structure forms the lateral umbilical ligament?
Inferior mesenteric artery
In a male, what is supplied by the inferior vesical artery?
Bladder and prostate
Which branches of the internal iliac artery pass out of the pelvis? What do they supply?
Superior and inferior gluteal arteries, supply gluteal region
Internal pudendal artery, supplies the perineum
Through which structure does the internal pudendal artery leave the pelvis?
Greater sciatic foramen
Which branches of the internal pudendal artery supply the erectile tissues of the penis?
Dorsal arteries of penis, deep arteries of penis, arteries of bulb of penis
Which branches of the internal pudendal artery supply the erectile tissues of the clitoris and vestibule?
Dorsal arteries of clitoris, deep arteries of clitoris
Into which vessels do the gonadal veins drain?
Left: Left renal vein
Right: IVC
Lymph from majority of pelvic viscera drains into which nodes?
Internal iliac lymph nodes
The internal iliac nodes drain into which nodes?
External iliac nodes, then pre-aortic nodes
Into which lymph nodes do the gonads drain?
Left and right lumbar lymph nodes
What nerves are present in the pelvis?
Obturator nerve
Sacral plexus (and branches)
Sympathetic nerves
Parasympathetic nerves
The sacral plexus is formed by the ventral rami of __?__
the first four sacral nerves, as well as L4 and L5
The sciatic and pudendal nerves are branches from __?__
sacral plexus
The sciatic and pudendal nerves leave the pelvis via __?__
the greater sciatic foramen
Within the pelvis, the sacral plexus supplies the muscle of __1__ and gives rise to a parasympathetic outflow, the __2__ nerves (stemming from __3__).
1) the pelvic floor
2) pelvic splanchnic
3) S2-S4
Sympathetic fibres to pelvic viscera are supplied by the __1__ and __2__ nerves, which branch off the __3__, eventually joining the pelvic plexus.
1) thoracic splanchnic
2) lumbar splanchnic
3) sympathetic chain
From where does the piriformis muscle arise?
Anterior aspect of sacrum
After arising from the sacrum, what path does the piriformis muscle take?
Leaves pelvic cavity via the greater sciatic foramen, inserting at greater trochanter of femur
From where does the obturator internus muscle originate?
Deep surface of obturator membrane and the bone surrounding the obturator foramen
After arising from the obturator membrane and the bone surrounding the obturator foramen, what path does the obturator internus muscle take?
Leaves pelvic cavity via the lesser sciatic foramen, inserting at greater trochanter of femur
What are the actions of piriformis and obturator internus?
Lateral rotation and abduction of femur at hip joint
What travels through the obturator canal?
Obturator neurovascular bundle (artery, vein, nerve)
What does the pelvic floor separate?
Pelvic cavity and perineum
What muscles form the pelvic floor?
Levator ani anteriorly and coccygeus muscle posteriorly on each side
The two levator ani muscles are attached laterally to the pelvic wall; to which structures?
Ischial spine, tendinous arch, pubic bone
The two levator ani muscles converge in the midline. How are they arranged?
They interdigitate around the urogenital and anal hiatuses
What is the perineal body? What is its function?
Fibrous structure posterior to urogenital hiatus and in front of rectum. Point of convergence for levator ani muscles.
Helps to stabilise the pelvic floor
What are the attachments of coccygeus muscle?
Ischial spine to sacrum and coccyx
What structure is adhered to the gluteal surface of coccygeus muscle?
Sacrospinous ligament
Which muscle forms a sling around the rectum? What is its function?
Puborectalis muscle.
Pulls the gut tube forwards so that the anal canal descends at an angle of approximately 90 degrees to the rectum. This angle is important in maintaining faecal continence
What is an episiotomy? When and why is it carried out?
A cut through the pelvic floor between the vagina and rectum (perineal body) to enlarge the vaginal canal.
What happens to the angle between the anal canal and rectum when the puborectalis muscle relaxes? Does this aid or inhibit defecation?
When puborectalis relaxes, the angle increases - becomes more obtuse; allowing defecation.
When it contracts, angle becomes more acute.
