Lecture 22: Vessels, Nerves & Lymphatics of Pelvis Flashcards
What is the major artery going to the pelvis?
Internal iliac
What are the arterial branches coming from outside of the pelvis?
Ovarian/testicular: direct branch of abdominal aorta just below renal artery
Superior rectal: branch of inferior mesenteric to sigmoid colon and upper rectum
Median sacral
What are the posterior artery branches?
Iliolumbar, lateral sacral, superior gluteal
What are the anterior artery branches?
Obturator, inferior gluteal, internal pudendal
What does the internal pudendal artery give off?
Inferior rectal artery
What arteries in the female pelvis anastomose extensively?
Uterine and vaginal arteries
What is characteristic of the uterine artery?
Tortuous course - coiled to allow for expansion of the uterus in pregnancy
What is the arterial supply to the rectum and anal canal above the pectinate line?
Superior rectal artery
What is the arterial supply to the rectum and anal canal below the pectinate line?
Middle and inferior rectal arteries
What are the features of end organs (blood supply)?
Supplied by end arteries - do not apply vasoconstrictors to these areas ) fingers, toes, nose, penis)
What are the large visceral venous plexuses in the pelvis?
Vesical, prostatic, uterovaginal, rectal
Where do veins in the pelvis drain and what does this communicate with?
Tributaries of the internal iliac vein - communicates with internal vertebral venous plexus
What is the consequence of vein communication?
Spread of infection and cancer
Where does the prostatic venous plexus normally drain?
IVC
What happens when there is retrograde drainage of the prostatic venous plexus?
Drain via anterior sacral veins - spread of cancer into vertebral canal (more common in bone)
How is erection maintained?
Cavernous tissue engorged with blood - compressed veins, preventing venous return
Where does the superior rectal vein drain?
Portal venous system via inferior mesenteric
What happens due to the portosystemic anastomoses between rectal veins?
Superior (portal) and middle and inferior (systemic) - elevation of venous pressure, varies, haemorrhage
What do haemorrhoids in the upper anal canal lead to?
Discomfort
What do haemorrhoids in the lower anal canal lead to?
Pain
Where does pelvic viscera lymph drain to?
Directly to deep nodes (inguinal)
What is the lymph drainage of the testes and what problems does this cause?
Drain to lymph nodes on posterior ab wall, not palpable, cancer not detected until supraclavicular nodes (last sentinel nodes)
What is the lymph drainage for the sacrum?
Develops from anterior ab wall so drains to inguinal lymph nodes
What are the spinal segments of the sacral plexus?
S2,3,4
What are the main parietal branches of the sacral plexus?
Obturator and pudendal nerves
What is the pathway of the pudendal nerve?
S2, 3, 4, makes a brief appearance in pelvic cavity via GSF then immediately exits via LSF to supply pelvic floor from below
Why doesn’t a pudendal nerve block paralyse the pelvic floor?
Pelvic floor branches given off early, not affected by block
What does the superior hypogastric plexus do?
Sympathetic - contract sphincters and constrict arteries
What do the pelvic splanchnic nerves do?
Parasympathetic - cavernous nerves to smooth muscle in walls of viscera
What nerves does the inferior hypogastric plexus carry and where is it?
Mixed - adjacent to viscera
What are junctional zones in the perineum?
Where endodermal and ectodermal structures form an interface. Sites of overlap of vessels supply and drainage. Blood vessels overlap but there is a non-overlap between nerves
How does defeacation occur?
Faeces collects in lower anal canal, stretch stimulates afferent fibres (PNS), stimulates contraction of rectal wall – inhibit SNS – relax internal anal sphincter, pudendal nerve voluntarily relaxes external sphincters
How does erection occur
Parasympathetic stimulation – dorsal artery dilation, compression of veins (restricted venous drainage), erection PNS, ejaculation SNS
What types of autonomics do pain fibres pass with above and below the pelvic pain line?
Above pelvic pain line visceral afferent pain fibres pass with sympathetics (T1-L2), and below pain fibres pass with parasympathetics (S2-4)
Where is the trigone in relation to the pelvic pain line and where is pain referred?
Below - pain referred to penis/clitoris or perineum
