ANA 202b - The Suprarenal Glands, Chromaffin System, Kidneys, Ureters, and Neurovascular Supply PDF

**GROSS ANATOMY** Suprarenal gland and chromoffin system. **SUPRARENAL GLAND** The suprarenal or adrenal glands are endocrine glands which help to maintain water and electrolyte balance. Adrenaline or epinephrine help the body to prepare for emergency or stressful situations. It gets the body rea...

**GROSS ANATOMY** Suprarenal gland and chromoffin system. **SUPRARENAL GLAND** The suprarenal or adrenal glands are endocrine glands which help to maintain water and electrolyte balance. Adrenaline or epinephrine help the body to prepare for emergency or stressful situations. It gets the body ready for "fight or flight" response. Lack of secretion of the cortical part leads to Addison's disease. **Subdivision** The suprarenal glands are a pair of endocrine gland situated on the posterior abdominal wall over the upper pole of the kidneys behind the peritoneum. They are made of 2 parts: a. An outer cortex of mesodermal origin, which secrets a number of steroid hormones. b. An inner medulla of neural crest origin, which is made up of chromaffin cells and secretes catecholamines: adrenaline(epinephrine) and noradrenaline (norepinephrine). **Location:** Each gland has in the epigastric, at the upper pole of the kidney, in front of the crus of the diaphragm, opposite the vertebral end of the 11^th^ intercoastal space and the 12^th^ rib. **Size, shape and weight:** Each gland measures 50mm in height, 30mm in breath and 10mm in thickness. It is approximately one-third of the size of kidney at birth and about 1/30^th^ of it in adults. It weighs about 5g, the medulla forming 1/10^th^ of the gland. Right suprarenal gland is triangular or pyramidal in shape and the left is semilunar in shape. **Sheaths:** The suprarenal glands are immediately surrounded by areolar tissue. Outside the fatty sheath, there is the perirenal fascia. Between the 2 layers of fascia lies the suprarenal gland. The 2 layers are not fused above the suprarenal. The perirenal space, is open and is in continuity with bare area of liver on the right side and with subphrenic extra peritoneal space on the left side. The gland is separated from the kidney by a septum. **Right Suprarenal Gland** The right suprarenal gland is triangular to pyramidal in shape. It has: 1. An apex 2. A base 3. Two surface - anterior and posterior 4. Three borders -- anterior, medial and lateral **Left Suprarenal Gland** The left gland is semilunar. It has: 1. Two ends -- upper (narrow) and lower (rounded end). 2. Two borders -- medial (convex) and lateral (concave). 3. Two surfaces -- anterior and posterior **Structure and Function** Naked eye examination of a cross-section of the suprarenal gland shows an outer part, called the cortex, which forms the main mass of the gland, and a thin inner part, called the medulla, which forms only about one-tenth of the gland. The two parts are absolutely distinct from each other structurally, functionally and developmentally. Comparism of right and left suprarenal glands. +-----------------------+-----------------------+-----------------------+ | | **Right suprarenal | **Left suprarenal | | | gland** | gland** | +=======================+=======================+=======================+ | Shape | Pyramidal | Semilunar | +-----------------------+-----------------------+-----------------------+ | Parts and relations | Apex: Bare area of | Upper end: close to | | | liver | spleen | | | | | | | Base: Upper pole of | Lower end: Presents | | | right kidney | hilum, left vein | | | | emerges from her | +-----------------------+-----------------------+-----------------------+ | Anterior surface | Inferior vena cava, | Cardiac end of | | | bare area of liver | stomach, pancreas | | | | with splenic artery | +-----------------------+-----------------------+-----------------------+ | Posterior surface | Right crus of | Left crus of | | | diaphragm, right | diaphragm, left | | | kidney | kidney | +-----------------------+-----------------------+-----------------------+ | Anterior border | Presents hilum, right | \- | | | vein emerges | | +-----------------------+-----------------------+-----------------------+ | Medial border | Coeliac ganglion | Coeliac ganglion | +-----------------------+-----------------------+-----------------------+ | Lateral border | Liver | Stomach | +-----------------------+-----------------------+-----------------------+ **The cortex is composed of 3 zones** 1. The outer, zona glomerulosa which produces mineralocorticoids that affect electrolyte and water balance of the body. 2. The middle, zona fascilculata which produces glucocorticoids. 3. The inner, zona reticularis which produces sex hormones. The medulla is composed of chromaffin cells that secrete adrenaline and noradrenalie. It contains cells in groups with a lot of capillaries. Autonomic ganglion cells are also seen. **Arterial supply:** Each gland is supplied by: 1. The superior suprarenal artery, a branch of the inferior phrenic artery. 2. The middle suprarenal artery, a branch of the abdominal aorta. 3. The inferior suprarenal artery, a branch of the renal artery. **Venous drainage** Each gland is drained by one vein. The right suprarenal vein drains into the inferior vena cava, and the left suprarenal vein into the left renal vein. **Nerve supply** The suprarenal medulla has a rich nerve supply through myelinated preganglionic sympathetic fibres. The chromaffin cells in it are considered homologous with postganglionic sympathetic neurons. **Lymphatic drainage** Lymphatic for the suprarenal glands drain into the lateral aortic nodes. **Accessory suprarenal glands** These are small masses of cortical tissue often found in the areolar tissue around the glands and sometimes in the spermatic cord, the epididymis, and the broad ligament of the uterus. **Clinical Anatomy** Suprarenal gland can be demonstrated radiologically by the computerized tomography (CT) scan. Insufficiency of cortical secretion due to atrophy or tuberculosis of the cortex results in Addison's disease. It is characterized by muscular weakness, low blood pressure, anaemia, pigmentation of skin and terminal circulatory and renal failure. Excessive cortical secretion due to hyperplasia of the cortex may produce various effects: a. In adult, hyperglucocorticism causes cushing's syndrome, which is charaterised by obesity, hirsutism, diabetes and hypogonadism. b. In women, excessive androgens may cause masculinisation (virilism). c. In men, excessive oestrogens may cause feminization and breast enlargement. d. In children, excessive sex hormones cause adrenogenital syndrome, cortical hyperplasia. In female foetus, excessive androgens cause female pseudohermaphroditism, in the male foetus, it causes excessive development of external genital organs. Bilateral removal of adrenal glands (adrenalectomy) is done as a treatment of some advanced and inoperable cases of disseminated carcinoma of the breast and prostate which do not respond to radiotherapy and which are considered to be dependent on hormonal control. Benign tumors of the suprarenal medulla (pheochromocytoma) cause attacks of hypertension associated with palpitation, headache, excessive sweating and pallor of skin. **Histology:** Cortex: It consists of 3 zones. Outer zone is zona glumerulosa which contains groups of columnar cells with spherical nuclei. Middle zone or zona fasciculate has cells arranged in vertical rows. Cells have lots of vacuoles in the cytoplasm. The inner zone or zona reticularis contains cells in an anastomosing network. These cells are less vacuolated. Medulla: It is composed of chromaffin cells, arranged in small groups, surrounded by capillaries. In between these cells are autonomic ganglion cells. **Development:** The cortex of the gland develop from mesoderm of coelomic epithelium while the medulla is derived from the neural crest cells (neuroectoderm). **\ ** **CHROMAFFIN SYSTEM** Chromaffin system is made up of cells which have an affinity for certain salt of chromic acid. Such cells are called chromaffin cells or pheochromocytes. These are situated close to sympathetic ganglia because both of them develop from the cells of the neural crest. Chromaffin cells secrete adrenaline and noradrenaline. This system includes the following groups of cells. 1. Suprarenal medulla 2. Paraganglia 3. Para-aortic bodies 4. Coccygeal body 5. Small masses of chromaffin cells scattered irregularly amongst ganglia of sympathetic chain, splanchnic nerves, autonomic plexuses and may be closely related to various organs like heart, liver, kidney, ureter, prostate, epididymis etc. **Paraganglia** These are rounded nodules of chromaffin tissue, about 2mm in diameter, situated inside or closely related to the ganglia of the sympathetic chain. In adults, they are generally represented by microscopic remnants only. **Para-Aortic Bodies:** Two para-aortic bodies, each about 1cm long, lie on each side of the origin of the inferior mesenteric artery. They are connected together above the artery to form an inverted horseshoe, or an H-shaped body. They develop during foetal life, attain their maximum size in the first 3 years of life, and gradually atrophy to disappear by the age of 14 years. The chromaffin cells of the para aortic bodies secrete noradrenaline. **Kidney** Definition: Kidneys are a pair of excretory organs situated on the posterior abdominal wall, one on each side of the vertebral column, behind the peritoneum. They remove waste products of metabolism and excess of water and salts from the blood, and maintain its pH. Location: The kidneys occupy the epigastric, hypochondriac, lumbar and umbilical region. Vertically, they extend from the upper border of the 12^th^ thoracic vertebra to the centre of the body of 3^rd^ lumbar vertebra. The right kidney is slightly lower than the left, and the left kidney is a little nearer to the median plane than the right. The transpyloric plane passes through the upper part of the hilus of the right kidney, and through the lower part of the hilus of the left kidney. **Shape, Size, weight and orientation:** Each kidney is about 11cm long, 6cm broad, and 3cm thick. The left kidney is a little longer and narrower than the right kidney. On an average, the kidney weighs 150g in males and 135g in females. The kidneys are reddish brown in colour. The long axis of the kidney is directed downwards and laterally, so that the upper poles are nearer to the median plane than the lower poles. The transverse axis is directed laterally and backwards. In the foetus, the kidneys are lobulated and is made up of about 12 lobules. After birth, the lobules gradually fuse, so that in adults the kidney is uniformly smooth. However the evidence of foetal lobulation may persist. **External Features:** Each kidney is bean-shaped. It has upper and lower poles, medial and lateral borders, and anterior and posterior surfaces. **Poles** The upper pole is broad and is in close contact with the corresponding suprarenal gland. The lower pole is pointed. **Surfaces** The anterior surface is said to be irregular and the posterior suffice flat, but it is often difficult to recognize the anterior and posterior aspects of the kidney by looking at the surfaces. The proper way to do this is to examine the structures present in the hilum as described below. **Boarders** The lateral border is convex. The medial border is concave. It middles part shows a depression, the hilus or hilum. **Hilum** The following structures are seen in the hilum from anterior side to posterior side. 1. The renal vein 2. The renal artery 3. The renal pelvis, which is the expanded upper and of the ureter Examination of these enables the anterior and posterior aspects of the kidney to be distinguished from each other. As the pelvis is continuous inferiorly with the ureter, the superior and inferior poles of the kidney can also be distinguished by examining the hilum so it is possible to determine the side of which a kidney belongs by examining the structures in the hilum. Commonly, one of the branches of the renal artery enters the hilus behind the renal pelvis, and a tributary of the renal vine may be found in the same plane. **Relations of the Kidneys** The kidneys are retroperitoneal organs and are only partly covered by peritoneum exteriorly. **Relations common to the two Kidneys** 1. The upper pole of each kidney is related to the corresponding suprarenal gland. The lower poles lie about 2.5cm above the iliac crests. 2. The medial borders of each kidney is related to: a. The suprarenal gland, above the hilus, and b. To the ureter below hilus 3. Posterior relations. The posterior surfaces of both kidneys are related to the following a. Diaphragm b. Medial and lateral arcuate ligaments c. Psoas major d. Quadratus lumborum e. Transversus abdominis f. Subcostal vessels g. Subcostal, iliohypogastric and iliomguinal nerves in addition, the right kidney is related to twelfth rib and the left kidney to eleventh and twelfth ribs. Other relations of the left kidney **Anterior Relations** Left suprarenal gland, spleen, stomach, pancreas, splevic vessels, splenic flexure and descending colour and jejunum. Other relations of the Right Kidney **Anterior relations:** Right suprarenal gland, liver, second part of duodenum, Heptic flexor of colour, small intestine out of these, the hepatic and intestinal surfaces are covered by peritoneum. The lateral border of the right kidney is related to the right lobe of the liver and to the hepatic flexure of the colon. **Capsules or coverings of kidneys** **The fibrous capsule:** This is thin membrane which closely invests the kidney and links the renal sinus. Normally, it can be easily stripped of from the kidney, but in certain diseases, it becomes adherent and cannot be stripped. **Perirenal or Perinephric fat** This is a layer of adipose tissue lying outside the fibrous capsule. It is thickest at the borders of the kidney and fills up the extra space in the renal sinus. **Renal Fascia** The perirenal fascia was originally described as being made up of two separate layers. Posterior layer was called fascia of Zukerkandal and anterior layer as fascia of Gerota, but is of single multilaminated structure which is fused posteromedially with muscular fascia of psoas major and quadratus limborum muscles. The fascia then extends laterally behind the kidney as bilaminated sheet, which divides at a variable point into thin layer which causes around the front of kidney as anterior perirenal fascia and a thicker posterior layer which continues autevolaterally as the lateral canal fascia/posterior perirenal fascia. The superior aspect of perirenal space is open and is in continuity to the bare area of liver on the right side and with subphrenic extraperitoneal space on the left side. On the right side at the level of upper pole of kidney, anterior fascia blends with inferior coronary layer and bare area of liver. On the left side, anterior layer fuses with gastrophrenic ligament. Posterior layer on both right and left sides fuses with fascia of muscles of posterior abdominal wall, i.e. psoos major and quadratus lumborum as well as with fascia on the inferior aspect of thoracoabdominal diaphragm. Medially, the anterior layer is continuous from one to the other kidney and the posterior layer is attached either side of vertebra. Below, both the layers extend along the ureter and fuse with iliac fascia. **Pararrenal or Paranephric Body (fat)** It consist of a variable amount of fat lying outside the renal fascia. It is more abundant posteriorly and towards the lower pole of the kidney. It fills up the paravertebral gutter and forms a cushion for the kidney. **Structure** Naked eye examination of a coronal section of the kidney shows: 1. An outer - reddish brown cortex 2. An inner - pale medulla 3. A space - the renal sinus The renal medulla is made up of about 10 conical masses, called the renal pyramids. Their apices from the renal papillae which indent the minor calyces. The renal cortex is divisible into two parts: a. Cortical arches or cortical lobules, which form caps over the bases of the pyramids. b. Renal column, which dip in between the pyramids. Each pyramid along with the overlying cortical arch forms a lobe of the kidney. The renal sinus is a space that extends into the kidney from the hilus. It contains. a Branches of the renal artery b\. Tributaries of the renal vein c\. The renal pelvis. The pelvis divided into 2 to 3 major calyces, and these in their turn divide into 7 to 13 minor calyces. Each minor calyx ends in an expansion which is indented by one to three renal papillae **Structure of Uriniferous Tubule** Each kidney is composed of 1-3 million uriniferous tubules. Each tubule consists of 2 parts which are embroyologically distinct from each other. These are as follows: The excretory part, called the nephron, which elaborate urine. Nephron is the functional unit of the kidney, and comprises. a. Renal corpuscle or Malpighian corpuscle made up of glomerulus, a lift of capillaries and Bowman's capsule. b. Renal tubule (for selective resumption of substances from the glomerular filtrate) made up of the proximal convoluted tubule, loop of Heule with its descending and ascending limbs, and the distal convoluted tubule. The collecting part beings as a functional tubule from the distal convoluted tubule. Many tubules write together to form the ducts of Bellini which open into the minor calyces through the renal papillae. Juxtaglomerular apparatus is formed at the vascular pole of glomerulus which is intimately related to its own ascending limb of the Henle's loop near the distal convoluted tubule. The apparatus consists of the a. Macula densa, formed by altered cells of the distal convoluted tubule. b. Juxtaglomerular cells, formed by the epithelioid cells in the meida of the afferent arteriole. c. Some agranular cell between macular densa and the glomerulus proper. **Lymphatic Drainage:** The lymphatic drainage of the kidney drain into the lateral aortic nodes located at the level of origin of the renal arteries (L2). **Nerve Supply** The kidney is supplied by the renal plexus, on off shoot of the coeliar plexus. It contains sympathetic (T10-L1) fibres which are chiefly vasomotor. The afferent nerves of the kidney belong to segments T10 to T12. **Histology of the Kidney** The cortex of kidney shows cut sections of glomeruli, many sections of proximal convoluted tubule, some section of distal convoluted tubule and a few collecting ducts. Section through the pyramid of the medulla shows light staining collecting ducts, sections of loop of Henle, thick and thin segments of descending and ascending limbs, capillaries and connective tissues. **Clinical Anatomy** The angle between the lower border of the 12^th^ rib and the enter border of the erector spinae is known as the renal angle. It overlies the lower part of the kidney. Tenderness in the kidney is elicited by applying pressure over this angle, with the thumb. Blood from a ruptured kidney or pus in a perinephric abscess first distends the renal fascia, them forces its way within the renal fascia downwards into the pelvis. It cannot cross to opposite side because of the fascial septum and midline attachment of the renal fascia. Kidney is palpated bimanually, with one hand placed in front and the other hand behind the flank. When enlarged, the lower pole of kidney becomes palpable on deep inspiration. A floating kidney can move up and down within the renal fascia, but not from side to side. In such condition, the posterior layer of renal fascia can be sutured with diaphragm and kidney can be fixed in position. The common diseases of kidney are nephritis, pyelonephritis, tuberculosis of kidney, renal stones and tumours. Common manifestations of a kidney disease are renal oedema and hypertension. Raised blood urea indicates suppressed kidney function and renal failure. Kidney transplantation can be done in selected cases. One common congenital condition of kidney is polycystic kidney which leader to hypertension. In cases of chronic renal failure, dialysis needs to be done. It can be done as peritoneal dialysis or haemodialysis. The kidneys are likely to be injured due to penetrating injuries to lower thoracic cage. These may also be injured by kicks in the renal angle between the vertebral column and 12^th^ ribs. Kidney is likely to have stones (Staghorn Stone) as urine gets concentrated here. Kidney stone lies on the body of vertebra. Gall stones lie anterior to body of vertebra. **URETER** The ureters are a pair of narrow, thick-walled muscular tubes which convey urine from the kidney to the urinary bladder. They lie deep to the peritoneum, closely applied to the posterior abdominal wall in the upper part, and to the lateral pelvic wall in the lower part. **Dimensions** Each ureter is about 25cm (10 inches) long, of which the upper half (5 inches) the pelvis. It measures about 3mm in diameter, but it is slightly constricted at five places. **Course** The ureter begins with the renal sinus as a funnel shaped dilatation, called the renal pelvis. The pelvis issues from the hilus of the kidney, descends along its medial margin, or partly behind it. Gradually, it narrows till the lower end of the kidney where it becomes the ureter proper. The ureter passes downwards and slightly medially on the tips of transverse processes and the psoas major muscle, and enters the pelvis by crossing in front of the termination of the common iliac artery. In the lesser or true pelvis, the ureter at first runs downwards, and slightly backwards and internally, following the exterior margin of the greater sciatic notch. Opposite the ischial spine, it turns forwards and medially to reach the base of the urinary bladder. **Normal Constrictions** The ureter is slightly constricted at 5 places 1. At the pelviureteric junction 2. At the brain of the lesser pelvis 3. Point of crossing of ureter by ductus deferens or broad ligament of uterus 4. During its oblique passage through the bladder wall 5. At its opening in lateral angle of trigone. **Relations** **Renal Pelvis** In the renal sinus, branches of renal vessels lie both in front and behind it. Outside the kidney Anteriorly - on the right side, there are the renal vessel and the second part of the duodenum. On the left side, there are the renal vessels, the pancreas, the peritoneum and the jejunum. Posteriorly -- Psoas major muscle. Abdominal part of Ureter. Anteriorly- on the right side, the ureter is related to third part of the duodenum, peritoneum, right colic vessels, ileocolic vessels, gonadal vessels, root of the mesentery and terminal part of the ileum. On the left side, the ureter is related to; peritoneum gonadal artery, left colic vessels, sigmoid colon, sigmoid mesocolon. Posteriorly, the ureter lies on; Psoas major, tips of transverse processes, genitofemoral nerve. Medially, on the right side, there is the inferior vena cava, on the left side, there is the left gonadal vein, and still further medially, the inferior mesenteric vein. **Pelvic part of Ureter** In its backward and downward course, the relations are as follows; Posteriorly - internal iliac artery, commencement of the anterior trunk of the internal iliac artery, internal iliac vein, lumbosacral trunk and sacroiliac joint. Laterally; fascia covering the obturator internus, superior vesical artery, obturator nerve, obturator artery, obturator vein, inferior vesical vein, middle rectal artery. In the female, it forms the posterior boundary of the ovarian fossa. In its downward and forward course, the relations of ureter are different in males and females. **In males:** 1. Ductus deferense crosses the ureter superiorly from lateral to medial side. 2. Seminal vesicle lies below and behind the ureter. 3. Vesical vein surround the terminal part of ureter. **In females** 1. The ureter lie in the extraperitoneal connective tissue in the lower and medial part of the broad ligament of the uterus. 2. Uterine artery lies first above and in front of the ureter for a distance of about 2.5cm and then crosses it superiorly from lateral to medial side. 3. The ureter lies about 2cm lateral to the supravaginal portion of the cervix. It runs slightly above the lateral fornix of the vagina. 4. The terminal portion of the ureter lies anterior to the vagina. **Intravesical Part** The intravesical oblique course of the ureter has a valvular action, and prevents regurgitation of urine from the bladder to the ureter. The ureteric opening lie about 5cm apart in a distended bladder, and only 2.5cm apart in an empty bladder. **Blood Supply** The ureter is supplied by 3 sets of long arteries. 1. The upper part receives branches from the renal artery. It may also receive branches from the gonadal, or colic vessels. 2. The middle part receive branches from the gonadal, or iliac vessels. 3. The pelvic part is supplied by branches from the vesical, middle rectal, or uterine vessels. The arteries to the ureter lie closely attached descending branches which first form a plexus on the surface of the ureter, and then supply it. The upper and middle parts receive branches from medial side, while the pelvic part gets its arterial supply from lateral side. **Nerve Supply** The ureter is supplied by sympathetic from T10 to L1 segments and parasympathetic from S2 to S4 nerves. They reach the ureter through the renal, aortic and hypogastric plexuses. All the nerves appear to be sensory in function. **Histology** Ureter is composed of 1\. The innermost mucons membrane 2\. Middle layer of well-developed smooth muscle layer 3\. Outer tunica adventitia The epithelial lining is of transitional epithelium. Muscle coat in upper 2/3 has inner longitudinal and outer circular fibres. Lower 1/3 comprises an additional outer longitudinal layer. Connective tissue forms the outer layer. **Clinical Anatomy** **Ureteric Clonic:** This term is used for severe pain due to a ureteric stone or calculus which causes spasm of the ureter. The pain start in the loin and radiates down to the groin, the scrotum or the labium majus and the inner side of the thigh. Note that the pain is referred to the cutaneous areas innervated by segments, mainly T11 to L2, which also supply the ureter. **Ureteric Stone**: A ureteric stone is liable to become impacted at one of the sites of normal constriction of the ureter, e.g pelviureteric junction, brim of pelvis and intravesical course. **Duplex Ureter:** Two ureters drain renal pelvis on one side called duplex system. **Ectopic Ureter:** Single ureter and longer ureter insert more caudally and medially than normal one. **Ureteroceles:** Cystic dilatation of lower end of ureter. **Two types of dialysis** a. Peritoneal dialysis b. Haemodialysis