Editing Urinary tract

== '''Kidney''' ==

* Paired bean-shaped organs     that regulate fluid balance and filter wastes from the body

=== '''Embryology''' ===

** Three separate excretory      organs appear in development, which succeed each other in time and space,      such that only the last is retained
*** Pronephros
**** Present only as clusters        of cells at the cranial part of the urogenital ridge
**** Only the duct persists,        which becomes known as the mesonephric (Wolffian) duct, which opens        caudally into the cloaca
*** Mesonephros
**** A ridge becomes visible,        the mesonephric ridge or mesonephros
**** Mesonephric tubules, the        first tubules, develop individually here and open into the mesonephric        duct
**** Some of these ducts        develop into genital structures such as epididymis
*** Metanephros (the true       precursor of the kidney)
**** Forms caudal to the        mesonephros as a mass of new tubules
**** This mass induces a bud,        the ureter, to grow from the caudal end of the mesonephric duct
**** Ureteric bud then        separates from the mesonephric duct, leaving it to form part of the        bladder and ductus deferens
**** Metanephros continues to        develop in the pelvis and is supplied by internal iliac artery. It        gradually migrates cranially, acquiring new blood supply from aorta.
**** At first, the hilum is        anterior, but the kidney rotates 90 degrees medially

=== '''Structure''' ===

** Lies in the paravertebral      gutter between T12 and L3
** Right kidney is lower due to      the liver
** Hilum
*** Contains renal vessels,       renal pelvis and a variable amount of fat (usual order of vein, artery,       ureter from front to back)
*** In the right kidney it lies       just below the trans-pyloric plane, and in the left it lies just above
** Renal pelvis
*** Funnel-shaped commencement       of the ureter
*** Usually the most posterior       of the three main structures
*** Receive two or three major       calyces
*** Lined by transitional       epithelium (like the ureter)
** Coverings
*** Covered by a strong capsule       - gives glistening appearance
*** Perinephric fat lies       outside the renal capsule - plays a part in retaining the kidney in       position
*** Renal fascia surrounds the       perinephric fat and separates the kidney from the adrenal gland - firmly       attached at the hilum to the renal vessels and ureter (also stabilises       the kidney)
** Internal structure
*** Cortex - beneath the       capsule, extends towards the pelvis as the renal columns
*** Medulla - lies between the       columns as the renal pyramids (darker and triangular striated areas)
*** The apices of several       pyramids open together into a renal papilla, each of which projects into       a minor calyx
*** The minor calcyes unite to       form two or three major calyces, which opens into the renal pelvis

=== '''Relations''' ===

** Posteriorly
*** Diaphragm
*** Quadratus lumborum muscles,       with overlap medially onto psoas and laterally onto transversus       abdominis
*** Costodiaphragmatic recess       of the pleura
*** Subcostal vein, artery and       nerve
*** Iliohypogastric and       ilioinguinal nerves - as they emerge from lateral border of psoas
** Anteriorly
*** Peritoneum of the posterior       abdominal wall
*** Right - D2, hepatic       flexure, ascending branch of right colic artery, hepatorenal pouch of       the greater sac
*** Left - tail of pancreas,       splenic flexure, upper left colic artery, peritoneum of the lesser sac
*

*

=== '''Arterial     supply''' ===

** Renal arteries (from aorta,      L2)
** Five segmental branches to      each kidney
*** Anterior division - apical,       upper, middle and lower segments
*** Posterior division -       posterior segment
***
** Aberrant renal arteries -      segmental vessels from aorta to lower pole

=== '''Venous     drainage''' ===

** Renal veins lie in front of      the renal arteries, and behind the pancreas, and join the IVC at right      angles, at level of L2
** Each emerges from the hilum      as five or six tributaries which soon unite
** Left:
*** 7.5cm long
*** Crosses in front of aorta
*** Receives left suprarenal       vein and gonadal vein
*** Connected with left       ascending lumbar, and hence connected to azygos system
** Right
*** 2.5cm long
*** Drains only its own kidney,       except for sometimes the right testicular vein

=== '''Lymphatics''' ===

** Para-aortic nodes
** Surface of upper pole may      drain through the diaphragm into nodes in the posterior mediastinum

=== '''Innervation''' ===

** Sympathetic preganglionic      (T12-L1) - through the coeliac, renal and superior hypogastric plexuses
** Afferent fibres (pain)      accompany the sympathetic nerves and radiate to the back
** Some PNS supply from the      vagus of uncertain function

=== '''Variant     anatomy''' ===

** Persistence of fetal      arteries (30%) - especially a vessel to the lower pole from aorta
** Horseshoe kidney - fusion of      the lower poles (1 in 800). Ascent of kidney limited by IMA.
** Renal agenesis (1 in 500)

=== '''Functions of     the kidney:''' ===

** Eliminate water-soluble      waste products of metabolism
** Eliminate water-soluble      drugs
** Fluid and electrolyte      homeostasis
** Acid-base balance
** Blood pressure control      (renin-angiotensin system)
** Endocrine function -      erythropoietin and vitamin D production



== '''Ureter''' ==

* Paired fibromuscular tubes     that convey urine from the kidneys to the bladder

=== '''Embryology''' ===

** Mesodermal origin
** Derived by a process of      budding from the caudal end of the mesonephric duct

=== '''Structure''' ===

** 25cm long
** Narrow points (most common      sites of calculus obstruction): pelviureteric junction, where it crosses      the pelvic brim, and as it passes through the bladder wall
** Whitish, non-pulsatile cord      that vermiculates when gently pinches by forceps

=== '''Sections''' ===

** Abdominal - from renal      pelvis to pelvic brim
** Pelvic - from pelvic brim to      bladder
** Intravesical - within      bladder wall

=== '''Course''' ===

** Retroperitoneal, along      surface of psoas major, in front of tips of transverse processes
** Crosses IN FRONT of      genitofemoral nerve
** Crosses BEHIND the gonadal      vessels, to lie medial to them
** '''Right:''' upper part is protected      behind D3. Lower down crossed anteriorly by right colic and ileocolic      vessels and root of mesentery. Protect it during RHC, even if it's not      visualised, by ensuring gonadal vessels lie posteriorly.
** '''Left:''' lateral to IMA and IMV,      crossed anteriorly by left colic vessels, and by the apex of the sigmoid      mesocolon at the pelvic brim.
** On '''both''' sides, leaves the psoas      muscle at the bifurcation of the common iliac artery, crossing      anteriorly, and passes into the pelvis anterior to SIJ. Course anteriorly      to internal iliac vessels down the lateral pelvic sidewall.
** At the level of the ischial      spine, turn forwards and medially to enter the posterolateral wall of the      bladder, where it runs an oblique 1-2cm course, before opening into the      bladder at the internal ureteric orifice.
*** In men, they are posterior       to the vas.
*** In women, the ureters are       immediately posterior to the ovaries, then cross in the base of the       broad ligaments, where they pass behind and then under the uterine       arteries.
*** Ureters tend to lie       anterior to dissection around the rectum.
** Injuries most commonly occur      near the lower pole of the kidney on the left, or in the pelvis if      anatomy is difficult and distorted

=== '''Relations''' ===

** Abdominal
*** Posterior - psoas,       genitofemoral nerve, tips of L2-L5 TPs, common iliac vessels
*** Anterior left - gonadal       vessels, left colic vessels, sigmoid mesentery and colon
*** Anterior right - descending       duodenum, gonadal vessels, root of mesentery, right colic, ileocolic and       superior mesenteric vessels
** Pelvic
*** Posterior - SIJ, IIA
*** Anterior - vas       deferens/uterine artery
*** Inferior - seminal       vesicle/lateral fornix of vagina

=== '''Surface     markings''' ===

** On anterior abdo wall: from      tip of 9th costal cartilage to the bifurcation of the common iliac artery
** Radiographic course: medial      to tips of the transverse processes of the lumbar vertebrae; crosses      pelvic brim at SIJ; then passes to ischial spine; then to the pubic      tubercle.

=== '''Blood supply''' ===

** Upper end: ureteric branch      of renal artery
** Middle: branches from      abdominal aorta, gonadal, common iliac and internal iliac arteries
** Lower: branches from      inferior and superior vesical and uterine arteries
** All blood vessels anastomose      with each other in ureteric adventitia.

=== '''Lymphatic     drainage''' ===

** Abdominal portion -      para-aortic nodes below the renal arteries
** Pelvic portion - nodes on      the sidewall of the pelvis, alongside the internal iliac arteries

=== '''Innervation''' ===

** SNS - coeliac and      hypogastric plexuses
** PNS - pelvis splanchnic      nerves

=== '''Variant     anatomy''' ===

** Duplex ureter
** Bifid ureter
** Ureterocoele

=== '''Microscopic     anatomy''' ===

** Lined by transitional      epithelium


[[Category:Anatomy]]