Kidney Anatomy PDF

THE KIDNEY Site: Retroperitoneal paired structures They are normally located to either side of the vertebral column between the transverse processes of T12-L3 vertebrae. The right kidney is lower in position than the left kidney by about 2cm due to the right hepatic lobe. The long axi...

THE KIDNEY Site: Retroperitoneal paired structures They are normally located to either side of the vertebral column between the transverse processes of T12-L3 vertebrae. The right kidney is lower in position than the left kidney by about 2cm due to the right hepatic lobe. The long axis of the kidney is directed downward , laterally being parallel to the lateral border of the psoas muscle. The upper poles are normally oriented more medially and posteriorly than the lower poles. Size: In adults, the normal kidney is 9-15 cm long in males & 3-5 cm wide. The left kidney is usually slightly larger than the right does not exceed 1.5cm Shape: The kidney is bean shaped. It has: two poles: superior broad (due to suprarenal gland) and pointed inferior pole. Anterior and posterior surfaces and lateral and medial borders. Structure (Fig 2.2) The kidneys are surrounded by perirenal fat. Covered by outer fibrous capsule.  The kidney itself can be divided into The renal parenchyma consists of renal cortex and medulla. the renal sinus containing renal pelvis, calyces, renal vessels, nerves, lymphatics and perirenal fat. The renal cortex, peripherally under the capsule, consists of glomeruli and renal tubules. with a normal thickness is 2.5 cm. The Renal Medulla consists of 10-14 renal pyramids, which have their base to the periphery and their conical end (tip) directed towards the renal hilum and called papillae which indent the minor calyx. These pyramids are separated from each other by an inward extension of the renal cortex called renal columns. The renal lobe consists of the renal pyramid with the associated overlying renal cortex and adjacent renal columns. The collecting system: (fig 2.3) o Calyces Medulla sits in the fornix of the minor calyx. The fornix is sharp and concave. Papillae drain into minor calyces. Minor calyces coalesce to form 3 or 4 major calyces. Major calyces form the form of the pelvis. o Renal Pelvis: broad dilated part of the urine collecting system, located in the hilum. The pelvis may be intrarenal or partially or entirely extrarenal. Renal pelvis drains into the ureter.  The renal hilum is the entry to the renal sinus. It contains the renal vessels and nerves, fat and the renal pelvis, which typically emerges posterior to the renal vessels, with the renal vein being anterior to Fig (2.2) diagram illustrates renal structure. Fig (2.3) diagram of renal collecting system The ureters It measures about 25-30 cm long. It has three parts (fig2.4) ✓ abdominal ureter: from the renal pelvis to the pelvic brim ✓ pelvic ureter: from the pelvic brim to the bladder ✓ intravesical or intramural ureter: within the bladder wall The ureter has a diameter of 3 mm but there are three narrowing sites, which are the most common sites of renal calculus obstruction: ✓ at the pelviureteric junction (PUJ) of the renal pelvis and the ureter ✓ as the ureter enters the pelvis and crosses over the common iliac artery bifurcation ✓ at the vesicoureteric junction (VUJ) as the ureter obliquely enters the bladder wall. Fig (2.4) diagram showing ureter The Urinary Bladder Site: Pelvic extra-peritoneal fat Shape: Pyramidal shape base posteriorly: has four surfaces: the superior surface (dome) the two inferolateral surfaces (which meet at an apex behind the pubic symphysis) and the posterior–inferior surface (fig2.5) The external features of the bladder are: (fig2.5) ✓ Apex (superior surface) located superiorly, pointing towards the pubic symphysis. It is connected to the umbilicus by the median umbilical ligament (a remnant of the urachus). ✓ Body – main part of the bladder, located between the apex and the fundus. ✓ Fundus (or base, posteroinferior surface) – located posteriorly. It is triangular-shaped, with the tip of the triangle pointing backwards. ✓ Neck – formed by the convergence of the fundus and the two inferolateral surfaces. It is a 2–3 cm long, funnel-shaped extension of the body that traverses the urogenital diaphragm fand connects with the urethra. Fig(2.5) diagram illustrates bladder shape and walls.  The trigone region (fig 2.6) sits at the bladder base between the inlet of the two ureters and the urethral opening. Fig(2.6) urinary bladder trigone The wall of the bladder is mainly composed of smooth muscle, called the detrusor muscle. At the neck of the bladder, the detrusor muscle fibers form the involuntary internal sphincter. Internally, the appearance of the bladder wall depends on the state of distention of the organ: it is thick and trabeculated when collapsed, thin and smooth once distended. The ureters enter the bladder wall inferomedially on opposite sides at an oblique angle. The Urethra Male urethra: 15-20cm in length Parts (fig2.7) ✓ Posterior urethra: begins at the neck of the bladder, terminates at the urogenital diaphragm and can be subdivided into prostatic and membranous parts. ✓ Anterior urethra: extends from the inferior margin of the urogenital diaphragm to the external urethral meatus and can be subdivided into bulbous and penile parts. 1. The prostatic urethra courses within the prostate, the paired ejaculatory duct orifices open on it. 2. The Membranous urethra (Posterior urethra) is the shortest, narrowest and least mobile urethral segment located within the urogenital diaphragm.it contains the external urethral sphincter. 3. The Bulbous urethra traverses through root of penis. Bulbourethral (or Cowper’s) glands open into the bulbar urethra approximately 2.5 cm below the perineal membrane. 4. The Penile urethra is the longest urethral segment.it extend externally beyond root of penis. The distal portion of the penile urethra is dilated at the glans penis. This dilation is called the fossa navicularis.  Fig (2.7) shows male urethral parts. Female urethra (fig2.8) The female urethra is much shorter than the male urethra about 4cm in length. The female urethra is not divided into discrete segments. The paraurethral glands of Skene are homologous to the male prostate and secrete mucus into the urethra. Fig (2.8) shows female urethra. Radiological anatomy KUB (kidney,ureter,bladder) (fig2.9) Fig (2.9) KUB with illustration diagram on the left side Kidneys (fig2.9&2.10) o Kidney shadows are easily identified due to the natural contrast provided by the perirenal fat which allows the differentiation between the kidneys and the psoas muscle. o Intrarenal anatomy is never visible. o the long axis of kidney is seen parallel to the psoas muscle o Kidney length should not be less than three vertebral body lengths, and no more than four vertebral body lengths. o Their size is approximately that of three-and-a-half lumbar vertebrae and their associated discs on a radiograph. o The kidneys are relatively larger in the child (approximately four vertebral bodies in height) o The kidneys are seen to move with changes from supine to erect positions and, because of their relationship with the diaphragm, to move with respiration. Normally the ureters are not visualized but a knowledge of its course in relation to the skeleton is necessary when looking for radio-opaque calculi The ureters pass anterior to the tips of the transverse processes of L2 – L 5 lumbar vertebrae and anterior to the sacro- iliac joint. They then curve laterally at the ischial spines and medially again to the bladder (fig2.9&2.10) Urinary bladder always be seen as a rounded soft tissue mass if it is full of urine (fig2.9&2.10) Fig (2.10) diagram illustrating KUB. IVU (intravenous urography) Opacification of urinary system by intravenous contras medium Phases: 1. Scout KUB film: before contrast administration 2. Nephrogenic phase (fig2.11b) o immediately after contrast injection within 30–60 seconds o the parenchymal opacification of the kidney by contrast medium in renal tubules o It is better able to define the morphologic features already described in the plain film. 3. Secretory (phylogram) phase (5 minutes &15 minutes with compression films (fig2.11c):the renal cavities are well opacified, the compression producing calyceal distension. Minor and major calyces are seen. These are connected to the pelvis of the kidney by infundibula, which may be long or short. the papillae are conical and indent the calyces with surrounding sharp fornices Several papillae may indent a single calyx – known as a complex calyx – an arrangement that is more common in the upper pole 4. 30 minutes film(ureterogram) (fig2.12&2.13) The ureters are either completely or partly visible when filled with contrast The ureter passes anteriorly from the kidney to its position near the psoas muscle Prone views aid ureteric filling. 5. 45 minutes film (cytogram)(fig2.13): shows smooth filling of urinary bladder by contrast. The corrugations of the bladder wall are seen. The smooth impression of the uterus may be seen postero- superiorly The prostatic impression is seen inferiorly in the 6. Post voiding films: empty bladder  Fig (2.11) Urography. Kidney. a Plain film radiography. The kidneys (arrowheads) b Nephrographic phase. c Excretory phase the arrow indicates the papilla. C, major calix; Ca, minor calix;P, pelvis Fig (2.12) The image shows the three segments of the ureter: lumbar (1), pelvic (2) and intramural (3). The bladder is in the filling phase.  Fig(2.13) IVU film Ascending(retrograde) cysto-uretherogram Smooth filling of urinary bladder through urethra demonstrating parts of male urthera (fig 2.14,2.15&2.16) Fig (2.14) retrograde cystourethrography illustrating parts of male urethra  Fig (2.15) A diagram illustrating detailed anatomy of cystourethrography Fig (2.16) retrograde cystourethrography with labelled structures