Anatomy of the renal system Professor Nawfal K. Al-Hadithi
Objectives To describe the posterior abdominal wall To identify the main anatomical landmarks of the kidneys & ureters To describe the suprarenal glands
The posterior abdominal wall: Psoas Major: Origin: L1-L4 & discs between Insertion: Lesser femoral trochanter (in common with iliacus) Nerve Supply: L1,4 segmental Action: Flexor of hip, flexor of trunk on lower limb Iliacus: Origin: Iliac fossa of hip bone Insertion: Lesser trochanter (in common with psoas) Nerve Supply: Femoral nerve in the iliac fossa Action: Like psoas major
Quadratus lumborum: Origin: Iliolumbar ligament & transverse process of L5 Insertion: Lower border of the 12th rib & transverse process of the upper 4 lumbar vertebrae Nerve Supply: T12-L3 Action: Assists in respiration by holding down the 12th rib PM
The thoracolumbar fascia: -This strong fascial structue lies in the PAW enclosing muscular compartments & gives attachment to many other muscles. Anterior layer: - Covers QL - Attached medially to psoas Fascia Middle Layer: - Behind QL & anterior to erector spinae - Attached medially to the tips of TP of lumbar spines Posterior Layer: - Behind erector spinae - Attached medially to the spines of the vertebrae All the 3 layers fuse laterally with the conjoint lamellae of internal oblique & transversus muscles
The diaphragm in the PAW: Trace the ring shaped origin from behind forward: 1-crura: Right: from upper 3 lumbar vertebrae Left: from upper 2 lumbar vertebrae 2- Arcuate ligaments: Medial: thickenings in psoas fascia Lateral: Thickening in the anterior layer of lumbar fascia
The kidneys: Size & shape: 10-12 X 5-6 X 3 cm The left is taller, narrower & higher than the right Position: In the upper lumbar - lower thoracic region (upper border at T12 level) The posterior surface lies posteromedial on the forward projecting vertebral column & psoas (anterior surface will be anterolateral & the hilum will be anteromedial
Stab in the 11 th intercostal space on the left side posteriorly may harm: 1- Pleura 2- Left lung 3- Left kidney 4- Left suprarenal gland 5- Spleen 4 3 5 2
Perinephric fat: The extraperitoneal connective tissue is modified at the site of kidneys into a fatty collection which almost completely surrounds the kidney & fills its sinus Perinephric (renal) fascia: A membranous layer surrounding the fat A septum passes from this fascia in between the kidney & suprarenal glands Extends beyond the kidney to surround renal vessels & the ureter The posterior layer of this fascia blends with fascia transversalis Paranephric fat: lies most external
Nephrectomy keeps the adrenal in place!
Gross structure of the kidney: Cortex: Thick, dark, granular consists mainly of glomeruli & part of the collecting system Medulla: Faint & radial in appearance because of its main ductal & tubular composition Medullary (renal) pyramids: The medulla appears in longitudinal sections as pyramids with their apices towards the hilum & bases towards the cortex MP RC Renal columns: The projections of the cortex in between these medullary pyramids reaching the renal sinus
Renal papillae: The terminal apices of medullary pyramids 8-12 in number Received into the cup shaped minor calyces (usually 8 in number) Minor calyces drain into 2-3 major calyces which drain the kidney usually in thirds Major calyces collect the urine into the renal pelvis which leaves the hilum behind the renal vessels & continues down as the ureter
Relations of the kidneys: Posterior relations (identical for both): Diaphragm 1- Upper 1/3: Dome of the diaphragm 2- Lower 2/3: -Medial : Psoas major -Middle : Quadratus lumborum -Lateral : Transversus abdominis
Anterior relations: Right kidney Left kidney Medial Lateral Medial Lateral 2 1 Upper Adrenal gland Liver Adrenal gland Stomach Middle Lower Duodenum (2 nd part) Coils of SI Liver Hepatic flexure Tail of pancreas Coils of SI Spleen Splenic flexure 4 5 3 1-Suprarenal gland 2-Liver 3- Duodenum (2 nd part) 4- Hepatic flexure of colon 5- Jejunum 6- Stomach 7- Spleen 8- Tail of pancreas 9- Splenic flexure of colon 1 6 5 8 7 9
Renal arteries: Arise from the sides of the aorta at L2 level The right artery crosses behind the IVC, right renal vein, head of pancreas & 2nd part of duodenum (longer & lower than the left) The left artery crosses behind the left renal vein, splenic vessels & body of pancreas When reaches the hilum of the kidney, renal arteries divide into upper, middle & lower branches each will further divide into anterior & posterior interlobar arteries Branches: 1- Inferior suprarenal artery 2- Ureteric artery
Aberrant renal artery: A congenital anomaly whereby an additional renal artery rises from the aorta lower than the main artery & enter the hilum of the kidney behind the pelviureteric junction compressing it leading to hydronephrosis An aberrant artery higher than the original one is a rarer variety & usually harmless
Renal veins: Right renal vein; 2.5 cm long Crosses in front of the right renal artery behind the 2nd part of duodenum & head of pancreas to the IVC Left renal vein; 7.5 cm long Crosses in front of the corresponding artery behind the pancreatic body & splenic vessels then anterior to the aorta to reach the IVC The left renal vein receives: 1- The left suprarenal vein 2- The left gonadal vein
Renal lymphatics: Cysterna chyli Para-aortic (lumbar) nodes Lymphatic plexus in the perinephric fat Subcapsular plexus Lymphatic plexus in the renal cortex
Renal nerves: Accompany renal vessels from the coeliac plexus ( autonomic): Affect the urine amount by vasoconstriction & vasodilatation There is no secretory effect of nerves on the kidney Sensory input is transmitted by T10-T12
Pelvic kidney: In the pelvis or anywhere between this site & normal position. They take their vessels from lower aorta or the iliac vessels. Horseshoe kidney: The 2 kidneys unite with each other in front of the aorta just below the origin of the IMA Their blood supply is similar to the previous anomaly.
The ureters: 25 cm long tube 1/2 of its length lie in the abdomen & 1/2 in the pelvis The abdominal part: Descends from renal pelvis obliquely in the direction of the corresponding sacroiliac joint joint Crossed by the corresponding gonadal & colic vessels Crosses the front of the bifurcation of the common iliac artery & descends in the pelvis
Pelvic part: Descend first on the lateral pelvic wall Directed anteromedially passing inferior to the ductus deferens (male) or the uterine artery (female) Penetrate the bladder wall obliquely from its posterolateral angle, creating a one-way valve
Blood Supply: - Upper 1/3 : Renal vessels - Middle 1/3 : Gonadal vessels - Lower 1/3 : Vesical vessels Nerve Supply: - Upper 1/2 : T11-L2 accompanying the gonadal vessels - Lower 1/2 : hypogastric plexus
Ureteric colic refers to skin areas supplied by T11-L2 Skin covering lower ribs Flanks Scrotum or labium majus
Clinically: In K.U.B, ureters lie at the tips of lumbar transverse processes Calculus may be entrapped in the pelvic ureter at 3 sites: 1- At the pelvi-ureteric junction 2- At the pelvic brim, whenthe ureter crosses the common iliac bifurcation 2- At the vesico-ureteric junction
The suprarenal glands: A pair of endocrine glands applied to the superomedial aspect of the kidneys with their hila lying anteriorly The right gland is triangular lying on the right crus of the diaphragm in relation to the IVC & right lobe of the liver anteriorly The left one is semilunar lying on the left crus of the diaphragm in relation to the stomach (above) & pancreas (below) in the stomach bed
Blood Supply: 1- Superior suprarenal a.; from the inferior phrenic a. 2- Middle suprarenal a.; from the abdominal aorta. 3- Inferior suprarenal a.; from the renal a. Veins: 1- Rt suprarenal vein; drains to the IVC 2- Lt suprarenal vein; drains to the left renal vein Lymph: To the superior group of lumbar LN Sympathetic supply: From the coeliac plexus; affecting the secretion of the gland & are vasomotor. The gland has no parasymp. supply.