Kidneys - Anatomy PDF

KIDNEYS - ( SURFACES )  The kidneys Are paired retroperitoneal T12 structures that are normally located between the transverse processes of T12-L3 vertebrae, with the left kidney more superior in position L3 than the right. Each kidney lies, on the posterior abdominal wa...

KIDNEYS - ( SURFACES )  The kidneys Are paired retroperitoneal T12 structures that are normally located between the transverse processes of T12-L3 vertebrae, with the left kidney more superior in position L3 than the right. Each kidney lies, on the posterior abdominal wall, lateral to vertebral column. The upper poles are normally oriented more medially and posteriorly than the lower poles.  RENAL SINUS & HILUM The hilum leads to a large cavity, called the renal sinus, within the kidney, which contains the renal pelvis, calyces, major branches of the renal artery and vein, and lymphatic vessels.  Hilum The renal hilum is the entry and exit site for structures to the kidneys: vessels, nerves, Major calyx Minor calyx lymphatics, and ureters. ( directed medially ). Emerging from the hilum is the Renal pelvis renal pelvis, which is formed from the major and minor calyxes in the kidney. The arrangement of structures at the renal hilum, is: renal vein, renal artery and pelvis. (VAU )  Renal cortex & medulla Renal Pyramids in medulla Each kidney consists of an outer renal cortex, an inner renal medulla, and a renal pelvis. Blood is filtered in the renal cortex. Renal cortex The renal medulla contains the renal pyramids, where urine formation takes place. Urine passes from the renal pyramids into the renal pelvis. Blood supply & lymph drainage  ANTERIOR RELATION OF KIDNEY The anterior surface The anterior surface of the right kidney is of the left kidney is related to the right related to the lobe of liver, spleen, pancreas, descending part of stomach, left colic duodenum, the right flexure, jejunum, colic flexure, and and the left colic small intestine. vessels.  The posterior surface of both kidneys are related to certain neurovascular structures and muscles: 1- Artery: subcostal artery. 2- Bones: 11th and 12th ribs. 3- Nerves: subcostal, iliohypogastric, and ilioinguinal nerves. 4- Muscles: diaphragm, psoas, quadratus and transversus abdominis. RENAL FASCIA & FAT Each kidney is held in place by connective tissue, called renal fascia, anterior & posterior (Gerota's fascia). And is surrounded by a thick layer of adipose tissue, called perirenal fat, which helps to protect it.  Fascia & fat A tough, fibrous, connective tissue renal capsule closely envelopes each kidney and provides support for the soft tissue that is inside. The pararenal fat : is a variable collection of adipose tissue between the posterior surface of the kidney and the posterior Posterior abdominal wall capsule abdominal wall Each kidney is held in place by Renal fascia ( Gerota’s fascia ): anchors connective tissue, called renal the kidneys in place and protects them fascia, and is surrounded by a from trauma or injury. thick layer of adipose tissue, called perirenal fat,(located in the Additionally, it maintains the kidneys' retroperitoneal cavity ). position relative to other abdominal organs. A tough, fibrous, connective tissue renal capsule closely The capsule : help to support the kidney envelopes each kidney mass and protect the vital tissue from injury. The pararenal fat : is a variable collection of adipose tissue Perirenal fat : protects the kidneys and between the posterior surface of renal blood vessels from external physical the kidney and the posterior stimulation. abdominal wall Adrenal glands, also known as suprarenal glands, are small, triangular-shaped glands located on top of both kidneys. The adrenal glands are located on both sides of the body in the retroperitoneum, above and slightly medial to the kidneys. The right adrenal gland is pyramidal in shape, whereas the left is semilunar or crescent shaped and somewhat larger. BLOOD SUPPLY OF SURARENAL GLANDS Inferior phrenic a Renal o r t a I v c MCQs: EXAMPLES OF QUESTIONS 1-regarding the kidney, one of the following is related? A-located between T10 & L4 B-retroperitoneal C-lies on the anterior abdominal wall D-the upper pole is directed laterally Written: 1-Describe the anterior relation of both kidneys? 2-regarding the hilum of kidney, one is related? 2-Describe the posterior relation of both kidneys? A-the hilum is for the entry of vessels only B-emerging from the hilum is the renal pelvis 3-Describe the attachment of perirenal fascia & fat C- The arrangement of structures at the renal hilum, is and discuss their role in renal & suprarenal support? UAV D-the hilum is for the exit of nerves 3-regarding blood supply of kidney, one is related? A-mainly through the renal artery B-the arteries do not communicate with one another C-the arcuate arteries has no branches D-venous drainage is different than the arteries ( not function ) (permanent kidney)  THE PRONEPHROS In the 4th week the intermediate mesoderm of the cervical region forms 7 cells clusters ( nephrotomes ) It is transitory, non functional and regress completely by the 5th week of gestation.  MESONEPHROS It develops caudal to the pronephros It consists of a series of tubules that drain into the nephric duct By the 4th month of gestation, it is completely disappears  THE METANEPHROS -It is the 3rd and final stage of kidney development -The metanephros forms the definitive kidney. -It appears in the 5th week of development and becomes functional around the 12th week. N.B.: The blastema is a collection of relatively undifferentiated progenitor cells that proliferate and repattern to form the internal tissues  Renal ascent : -During the 5th & 6th weeks, the mature kidney lie in the pelvis with the hilum pointed anteriorly. As the pelvis & abdomen grow, each kidney ascends, and rotates through 90° such that the renal hilum is directed medially. Till it reaches its final position. Migration and rotation are completed by the eighth week of gestation.  Ureteric bud At the fifth week: of development, the ureteric bud arises as a diverticulum from the mesonephric (Wolfian) duct. The bud grows laterally and invades the center of the metanephric blastema, (the primordial renal tissue). The meeting of these two tissues causes changes in the bud and the metanephros.  The metanephric blastema & ureteric bud A. Derivatives of the metanephric blastema: Epithelial cells lining Bowman’s capsule Proximal convoluted tubules Descending thick limbs of the loops of Henle Thin limbs of the loops of Henle Ascending thick limbs of the loop of Henle Distal convoluted tubules B. Derivatives of the ureteric bud: Collecting tubules and ducts Minor and major calyces Ureters The fate of mesonephric duct in male The mesonephric (Wolffian) duct develops into the seminal vesicles, ductus deferens, and epididymis, Efferent ductules whereas the mesonephric tubules form the efferent ductules. Paroophoron & epoophoron  The fate of mesonephric (Wolffian) duct in female It regresses in females during embryological development. Remnants of this duct are: Epoophoron which is found between ovary and fallopian tissue. Paroophoron is found in below the epoophoron. Gartner's ducts are usually present in the vagina and cervix. N.B.: oophoron = ovary  Polycystic kidney disease (PKD). PKD is a genetic condition in which multiple cysts One kidney may be (abnormal sacs missing (renal containing fluid) grow agenesis). in the kidneys. One or both kidneys Horseshoe kidney, may be abnormally the most common small (renal fusion anomaly, hypoplasia). part of occurs when renal a kidney does not parenchyma on each fully develop. side of the vertebral column is joined at the corresponding (usually lower) poles  CONGENITAL ANOMALY OF URETER Ureteral duplication is the most common anomaly of the urinary tract. Abnormal enlargement of the ureter caused by any blockage that prevents urine from draining into the bladder. Strictures are often congenital, meaning they are present at birth. The posterior abdominal wall is formed by the lumbar vertebrae, pelvic girdle, posterior abdominal muscles and their associated fascia. Major vessels, nerves and organs are located on the inner surface of the posterior abdominal wall.  Psoas Major Attachments: T12 Originates from : The transverse processes and vertebral bodies of T12 – L5. Insertion : It passes deep to the inguinal ligament, to attach the lesser trochanter of the L5 femur. Actions: Flexion of the thigh at the hip and lateral Inguinal ligament flexion of the vertebral column. Innervation: Anterior rami of L1 – L3 nerves. Lesser trochanter  T12 The psoas minor L1 Attachments: Originates from : the vertebral bodies of T12 and L1 Insertion : to a ridge on the superior ramus of the pubic bone, known as the pectineal line. Actions: Flexion of the vertebral column. Innervation: Anterior rami of the L1 spinal nerve.  Quadratus Lumborum Attachments: Originates from : the iliac crest and iliolumbar ligament. Insertion : into the transverse processes of L1 – L4 and the inferior border of the 12th rib. Actions: Extension and lateral flexion of the vertebral column. It also fixes the 12th rib during inspiration. Innervation: Anterior rami of T12 – L4 nerves.  Iliacus It combines with the psoas major to form the iliopsoas – the major flexor of the thigh. Attachments: Originates from: the surface of the iliac fossa and anterior inferior iliac spine. Its fibers combine with the tendon of the psoas major, inserting into the lesser trochanter of the femur. Actions: Flexion and lateral rotation of the thigh at the hip joint. Innervation: Femoral nerve (L2 – L4).  The lumbar plexus -The lumbar plexus supplies the skin and musculature of the lower limb. It is located in the lumbar region, within the substance of the psoas major muscle and anterior to the transverse processes of the lumbar vertebrae. -Formed by the lower thoracic and lumbar ventral nerve roots. (T12 to L5 )  Branches of lumbar plexus 1 -They supply motor and sensory innervation to the lower limb and 2 pelvic girdle. 3 -A useful memory aid for the branches of the lumbar plexus is: I, I Get Leftovers On Fridays. 4 This stands for: 1- Iliohypogastric, 2-Ilioinguinal, 3-Genitofemoral, 4-Lateral cutaneous nerve of the thigh, 5-Obturator 6 5 6-and Femoral.  Aorta Begins at the left ventricle of the heart, as the ascending aorta, extending upward into the chest to form an arch. It then continues downward into the thorax and abdomen, as descending aorta where it branches into 2 terminals called the common iliac arteries. Branches of Aorta Common iliac veins  Examples of Questions MCQs: Written: 1-regarding quadratus lumborum, one is related? A-it takes its origin from the iliac crest 1-Describe site, formation & branches of lumbar plexus? B-inserted into L2 & L5 2-List the branches of abdominal aorta? C-inserted into the 11th rib 3- List the tributaries of inferior vena cava? D-innervated by L3 only  Clinical Relevance: Psoas Sign -The psoas sign is a medical sign that indicates irritation to the iliopsoas group of muscles. -The sign is elicited by flexion of the thigh at the hip. -The test is positive if the patient reports lower abdominal pain. -A right sided psoas sign is an indication of appendicitis. -As the iliopsoas contracts, it comes into contact with the inflamed appendix, producing pain. &4 The ureter  The ureter male The ureter -Enters the pelvis, where it crosses the common iliac vessels (at the bifurcation ). -In the female, the ureter lies in relation to the wall of the pelvis, (the posterior boundary of a shallow depression named the ovarian fossa), in which the ovary is situated. Remember “Ureter under the uterine artery “ Ovarian fossa female  Vessels & viscera Vessels & colon 1- 1- 2- 2- 3- 3- 4- 4- 5-  Relations POSTERIOR of ureter OF URETER RELATION It has three natural constrictions: The first at the ureteropelvic junction, The second at the pelvic brim where it crosses the iliac vessels. The third at the uretero‐vesical junction Clinical importance of the constrictions: Are common sites for the arrest of the ureteric stones SURFACE MARKING OF URETER POSTERIOR ASPECT L1 PSIS ARTERIAL SUPPLY OF URETER  The bladder The bladder Is located in the lesser pelvis when empty and extends into the abdominal cavity when full. The bladder is a distensible organ and is typically able to hold up to 500 milliliters of urine. The urinary bladder has four anatomical surfaces: superior, inferior ( base ), right inferolateral, and left inferolateral. The neck of the bladder is the constricted part of the bladder that leads to the urethra. It has apex which is directed anteriorly & connected to the urachus  Neck of the bladder In female : the bladder neck is a group of muscles that connect the bladder to the urethra. the muscles tighten to hold urine in the bladder, and relax to Internal sphincter release it through the urethra. Internal sphincter in males, the bladder neck is continuous with the prostate and both serve together as the internal External sphincter urethral sphincter. External sphincter Anterior relation of bladder The space anterior to the bladder and behind the abdominal wall is called retropubic space. The space enables various filling conditions of the urinary bladder.  Posterior relation of the bladder In males, the genital ducts In female posteriorly, the & the rectum is located anterior wall of the vagina posterior to the bladder. sits behind the bladder. Female Peritoneal covering Male Peritoneum of the bladder covers the bladder's superior surface and is related posteriorly to uterus forming recto- uterine (Douglas- pouch) in female or recto-vesical pouch in male. While the peritoneum which is reflected onto the anterior surface of the uterus & bladder is called Vescio-uterine pouch in female.  BLOOD SUPPLY & LYMPH DRAINAGE of the bladder Internal iliac a. Superior vesical a. Inferior vesical a. The lymphatic drainage of the bladder Lymph drainage of the bladder into the external iliac nodes, sometimes on the common iliac node and widely on internal iliac nodes. Nerve supply of the bladder N.B.: The pelvic splanchnic nerves, also known as nervi erigentes, are preganglionic parasympathetic nerve fibers.  Male urethra The internal urethral sphincter (IU) The internal sphincter is a continuation of the detrusor male urethra muscle and is made of smooth muscle, therefore it is Subdivided into 3 parts: Prostatic under involuntary or autonomic control. urethra. 3-4 cm Membranous urethra. 1—1.5 cm The external urethral sphincter (EU) Spongy urethra (penile ) 15 cm is located in the urogenital diaphragm and it is made up of striated muscle, (under voluntary control). Internal urethral sphincter Urogenital diaphragm In female, the urethra is about 4 cm long, and exits the body between the clitoris and the Female urethra vagina, extending from the internal to the external urethral orifice. The female urethra contains an internal sphincter and an external sphincter. In females, both the bladder neck and urethra contact the anterior wall of the vagina. Urogenital diaphragm  SURGICAL ANATOMY With the patient in the supine position the empty bladder lies at about the level of the symphysis pubis, as the bladder distends it rises out of the pelvis to become, for practical purposes, an intra-abdominal organ. In female the bladder rests directly upon the pelvic diaphragm. Cystectomy :is a surgery to remove the urinary bladder, a procedure to remove the entire bladder is called a radical cystectomy. In men, this typically includes removal of the prostate and seminal vesicles. A cystopexy is surgical fixation of the bladder to the wall of the abdomen. Cystopexy is most often performed on females, since problems with the bladder occur more in females than in males.  Examples of questions 1-Describe the parts, relations, sites of normal constrictions, & arterial supply of the ureter? 2-Describe the urinary bladder, male & female urethra regarding their: a) Parts and sphincters. b) Relations and peritoneal covering.  Sphincters 1) The internal urethral sphincter (IUS), which consists of smooth muscle and is continuous with the detrusor muscle and under involuntary control, located at the bladder's inferior end, at the junction of the urethra with the urinary bladder. 2) The external urethral sphincter (EUS), which is made up of striated muscle and is under voluntary, located in the urogenital diaphragm. In females: Both the bladder neck and urethra contact the anterior wall of the vagina; this positioning allows the bladder neck to be mobile but it is subject to stress. In female : The bladder closure mechanism works under the influence of a force that presses downward ("stress"). This "stress" is caused by the relative weakness of the pelvic floor.  CLOACA The cloaca is the common compartment of the urogenital and anorectal channels in the 5th developmental week of humans that subdivides into two separate passages during the 6th and 7th weeks. As the embryo grows, a mesodermal urorectal septum divides the cloaca into a ventral urogenital sinus and dorsal anorectal canal. A B Urogenital m. Anal m. N.B.: The cloaca formed by ectoderm and endoderm (coming into contact with each other).  Development of urinary bladder The development of the bladder begins during the 4th week when the urorectal septum divides the cloaca into two parts, the rectum posteriorly and the urogenital sinus anteriorly. The urogenital sinus will continue to grow to form the bladder. So, the urinary bladder is formed partly from the endodermal cloaca and partly from the ends of the mesonephric duct ( to form the trigone). N.B.:mesonephric duct = Wolffian duct rectum  THE TRIGONE The mesonephric ducts is gradually absorbed into the wall of the urogenital sinus, forming the trigone ( mesoderm )  ANOMALIES OF THE URINARY BLADDER 1-Exstrophy The most common anomalies Exstrophy of the bladder of the bladder are : (ectopia vesicae): 1- exstrophy (turned outside) the bladder develops 2-urachal anomalies outside the fetus. It is 3-diverticula due to an incomplete 4- duplication fusion of anterior wall of the bladder and inferior portion of the anterior abdominal wall.  1 Urachus A fibrous cord that connects the urinary bladder to the umbilicus. Urachus is formed as the allantoic stalk during fetal development 2 3 2- Urachal anomalies The majority of urachal anomalies can be classified into one of the following groups: 1-patent urachus (most common, 48%), 2-urachal sinus and cyst (18%), in which the umbilical end of the structure fails to close. 3-urachal diverticulum (3%).  Bladder anomalies 4-Duplication 3-diverticula The bladder may be divided in two parts by Bladder diverticula, an out-pouching of a complete or incomplete septum. the bladder, may occur congenitally.  Fate & derivatives of the primitive urogenital sinus Vesico-urethral Urogenital sinus Pelvic part Phallic part Development of the bladder & urethra Lower part of vesico-urethral canal forms the upper part of prostatic urethra The pelvic part of the definitive urogenital sinus forms the lower part of prostatic urethra and membranous part. The phallic part of the definitive urogenital sinus will form the penile urethra.(spongy or bulbar urethra)  Urethral anomalies 1-Hypospadius: Is the most common anomaly, In which the urethra opens along the inferior aspect of penis 2-Epispadius: Is a rare abnormality, in which The urethral meatus is found in the dorsum of penis. Female urethra Lower part of vesico-urethral and the pelvic part of the definitive urogenital sinus will form female urethra  Examples of Question 1-Explain the congenital anomalies of the urinary bladder? 2-List the developmental components of urethra in male?.