Editing Kidneys (section)

== Renal vasculature ==

* Each kidney is commonly supplied by a single renal artery, which arises directly from the abdominal aorta, and a single renal vein usually drains directly to the IVC

=== Arterial supply ===
* '''Summary of branching:'''
** '''Main renal artery -->'''
** '''Anterior vs. posterior branch -->'''
** '''Segmental arteries -->'''
** '''Lobar arteries -->'''
** '''Interlobar arteries -->'''
** '''Arcuate arteries -->'''
** '''Interlobular arteries -->'''
** '''Afferent arteriole -->'''
** '''Glomerulus -->'''
** '''Efferent arteriole'''
* '''<span style="color:#ff0000">Anterior and posterior branch of main renal artery</span>'''
** '''<span style="color:#ff0000">Anterior branch</span>'''
*** '''<span style="color:#ff0000">Supplies the anterior aspect, comprising ≈2/3 of the total kidney</span>'''
*** '''Divides into segmental arteries (4):'''
***# '''Apical'''
***# '''Upper'''
***# '''Middle'''
***# '''Lower'''
** '''<span style="color:#ff0000">Posterior branch</span>'''
*** '''<span style="color:#ff0000">Supplies the posterior aspect, comprising ≈1/3 of the total kidney</span>'''
*** '''Becomes the posterior segmental artery'''
*** '''Represents the first and most consistent branch, which separates from the renal artery before it enters the renal hilum'''
*** A small apical segmental branch may originate from this posterior branch, but it arises most commonly form the anterior division
* '''<span style="color:#ff0000">Segmental arteries</span>'''
** '''<span style="color:#ff0000">End arteries</span>''' that do not anastomose significantly with other segmental arteries.
*** '''<span style="color:#ff0000">Clinical implication: Occlusion or injury to a segmental branch will cause segmental renal infarctions.</span>'''
** '''<span style="color:#ff0000">The posterior segmental artery from the posterior division passes posterior to the renal pelvis while the others pass anteriorly pass anterior to the renal pelvis</span>'''
*** '''Clinical implication: If the posterior segmental branch passes anterior to the ureter, UPJO may occur'''
*** '''There is a longitudinal avascular plane (line of Brodel) between the posterior and anterior segmental arteries just posterior to the lateral aspect of the kidney through which incision results in significantly less blood loss'''
**** Posterior calyces along the line of Brodel are preferred
* '''Variations to renal vascular occur in 25-40% of kidneys'''
** '''Accessory renal arteries are seen in 25-28% of patients''' and are considered the sole arterial supply to a specific portion of the renal parenchyma
***'''Clinical implication: presence of accessory renal artery may contraindicate laparoscopic donor nephrectomy'''
** '''Blood supply to an ectopic kidney originates from adjacent vessels'''

=== Venous drainage ===
* '''Correlates closely with the arterial supply, with the exception that venous drainage has extensive collateral communication. unlike the arterial supply'''
* 3-5 segmental renal veins eventually unite to form the renal vein
* '''The right and left renal veins lie anterior to the right and left renal arteries and drain into the IVC.'''
* '''<span style="color:#ff0000">The right renal vein is 2-4 cm, the left renal vein is 6-10 cm.</span>'''
* '''<span style="color:#ff0000">The longer left renal vein receives the left adrenal vein and the left gonadal (testicular or ovarian) vein.</span>''' 
**'''<span style="color:#ff0000">The left renal vein also may receive a lumbar vein,</span> which could be easily avulsed during surgical manipulation of the left renal vein.'''
* '''The left renal vein traverses the acute angle between the superior mesenteric artery anteriorly'''
** '''Nutcracker syndrome most often refers to compression of the left renal vein between the superior mesenteric artery and aorta'''
** Insert figure
** '''Anomalies of the renal veins are less common than those of the renal arteries'''