Lesson No 14
The TRACHEA is
a tube, which consists of 16-20 semicircular cartilages, joint each other by annular ligaments. Last built by connective tissue with smooth muscular fibres.
Behind semi-rings communicate by each other by membranous tracheal wall.
Trachea (windpipe) extends from VI cervical to V thoracic vertebra, where it
ramifies on two principal bronchi. This place is tracheal bifurcation.
Trachea has cervical part and thoracic part. Cervical part at the front
covered by infrahyoid muscles and isthmus of thyroid
gland that accords to the second-third tracheal ring. Esophagus (gullet) passes behind the trachea. Thoracic part
of trachea is situated in superior mediastinum. The trachea has an inner
diameter of about
There are about fifteen to twenty incomplete C-shaped cartilaginous rings that reinforce the anterior and lateral sides of the trachea to protect and maintain the airway, leaving a membranous wall (pars membranacea) dorsally without cartilage. The trachealis muscle connects the ends of the incomplete rings and contracts during coughing, reducing the size of the lumen of the trachea to increase the air flow rate. The esophagus lies posteriorly to the trachea. The cartilaginous rings are incomplete to allow the trachea to collapse slightly so that food can pass down the esophagus. A flap-like epiglottis closes the opening to the larynx during swallowing to prevent swallowed matter from entering the trachea. Lined with respiratory epithelium.
The LUNGS are the pair parenchymatic organs, which occupy larger part of thoracic cavity. Each lung has a pulmonal base and apex; costal surface, diaphragmatic surface, interlobar surface and medial surface. Medial surface subdivides into posterior (vertebral) surface and anterior (mediastinal) surface. They distinguish anterior margin and inferior margin on lungs. There is pulmonal hilus on mediastinal surface through which pulmonary artery, bronchi and nerves, enter into the lung, lymphatic vessels and pulmonary veins leave the lungs. All these elements, which enter and exite from lungs gates, form a pulmonary root.† The lungs are the essential organs of respiration; they are two in number, placed one on either side within the thorax, and separated from each other by the heart and other contents of the mediastinum. The substance of the lung is of a light, porous, spongy texture; it floats in water, and crepitates when handled, owing to the presence of air in the alveoli; it is also highly elastic; hence the retracted state of these organs when they are removed from the closed cavity of the thorax. The surface is smooth, shining, and marked out into numerous polyhedral areas, indicating the lobules of the organ: each of these areas is crossed by numerous lighter lines.
Arrangement of vessels and bronchus in left pulmonary root: from above downwards: pulmonary artery, bronchus and vein (ј¬V). Arrangement of vessels and bronchus in right pulmonary root (from above downwards): bronchus, pulmonary artery, and vein (BAV). On lateral surface of lungs oblique fissura passes, which subdivides each lung into superior lobe and inferior lobe. At birth the lungs are pinkish white in color; in adult life the color is a dark slaty gray, mottled in patches; and as age advances, this mottling assumes a black color. The coloring matter consists of granules of a carbonaceous substance deposited in the areolar tissue near the surface of the organ. It increases in quantity as age advances, and is more abundant in males than in females. As a rule, the posterior border of the lung is darker than the anterior.
The right lung usually weighs about
Each lung is conical in shape, and presents for examination an apex, a base, three borders, and two surfaces.
The apex (apex pulmonis)
is rounded, and extends into the root of the neck, reaching from 2.5 to
The base (basis pulmonis) is broad, concave, and rests upon the convex surface of the diaphragm, which separates the right lung from the right lobe of the liver, and the left lung from the left lobe of the liver, the stomach, and the spleen. Since the diaphragm extends higher on the right than on the left side, the concavity on the base of the right lung is deeper than that on the left. Laterally and behind, the base is bounded by a thin, sharp margin which projects for some distance into the phrenicocostal sinus of the pleura, between the lower ribs and the costal attachment of the diaphragm. The base of the lung descends during inspiration and ascends during expiration.
Surfaces.ЧThe costal surface (facies costalis; external or thoracic surface) is smooth, convex, of considerable extent, and corresponds to the form of the cavity of the chest, being deeper behind than in front. It is in contact with the costal pleura, and presents, in specimens which have been hardened in situ, slight grooves corresponding with the overlying ribs.
The mediastinal surface (facies mediastinalis; inner surface) is in contact with the mediastinal pleura. It presents a deep concavity, the cardiac impression, which accommodates the pericardium; this is larger and deeper on the left than on the right lung, on account of the heart projecting farther to the left than to the right side of the median plane. Above and behind this concavity is a triangular depression named the hilum, where the structures which form the root of the lung enter and leave the viscus. These structures are invested by pleura, which, below the hilus and behind the pericardial impression, forms the pulmonary ligament. On the right lung, immediately above the hilus, is an arched furrow which accommodates the azygos vein; while running upward, and then arching lateralward some little distance below the apex, is a wide groove for the superior vena cava and right innominate vein; behind this, and nearer the apex, is a furrow for the innominate artery. Behind the hilus and the attachment of the pulmonary ligament is a vertical groove for the esophagus; this groove becomes less distinct below, owing to the inclination of the lower part of the esophagus to the left of the middle line. In front and to the right of the lower part of the esophageal groove is a deep concavity for the extrapericardiac portion of the thoracic part of the inferior vena cava. On the left lung, immediately above the hilus, is a well-marked curved furrow produced by the aortic arch, and running upward from this toward the apex is a groove accommodating the left subclavian artery; a slight impression in front of the latter and close to the margin of the lung lodges the left innominate vein. Behind the hilus and pulmonary ligament is a vertical furrow produced by the descending aorta, and in front of this, near the base of the lung, the lower part of the esophagus causes a shallow impression.
Borders.ЧThe inferior border (margo inferior) is thin and sharp where it separates the base from the costal surface and extends into the phrenicocostal sinus; medially where it divides the base from the mediastinal surface it is blunt and rounded.
The posterior border (margo posterior) is broad and rounded, and is received into the deep concavity on either side of the vertebral column. It is much longer than the anterior border, and projects, below, into the phrenicocostal sinus.
The anterior border (margo anterior) is thin and sharp, and overlaps the front of the pericardium. The anterior border of the rightlung is almost vertical, and projects into the costomediastinal sinus; that of the left presents, below, an angular notch, thecardiac notch, in which the pericardium is exposed. Opposite this notch the anterior margin of the left lung is situated some little distance lateral to the line of reflection of the corresponding part of the pleura.
Mediastinal surface of right lung.
Right lungs, except oblique fissure, has a horizontal fissure passes on level of the IV ribs, which separates middle and inferior lobes of the right lung. Left lung is more narrow and longer than right one and in area of anterior margin it has cardiac notch of left lung, limited from below by uvula. The principal bronchi, turning into lung gates, subdivide into bronchi of second order, which ventilate lung lobes (lobar bronchi). There are 2 lobar bronchi in left lung, and 3 - in right lung. The lobar bronchi subdivide into bronchi of third order, which ventilate lung area, dissociated from neighboring by stratum of connective tissue, which is called as lung segment. That's why these bronchi are called as by segmental bronchi. According to San Paulo nomenclature in superior lobe of right lung situated 3 segments, in middle - 2, and in inferior 5 segments; in right lung they count 10 segments. In superior lobe of left lung count 4 (or 5) segments, and in inferior lobe - 6 (or 5) segments. So, in left lung counts also 10 segments.
Bronchi and bronchioles. The lungs have been widely separated and tissue cut away to expose the air-tubes:
Segmental bronchi dichotomically (each on two) divides by bronchi of following orders, while do not pass as far as bronchi, which ventilate lung area, that has a volume 1мм3. This area is called by pulmonary lobule and bronchi, which ventilate it, are called lobular bronchi. Lesser bronchi contain more connective tissue in their wall and less cartilaginous tissue. From each lobular bronchus 16-18 terminal bronchiole start, their wall does not contain cartilaginous tissue. Bronchial tree includes branching of the bronchi starting from the principal bronchi and finishing by terminal bronchioli. Next branching of the bronchial tubes they call acynus Ц morpho-functional lung unit.
Fissures and Lobes of the Lungs.ЧThe left
lung is divided into two
lobes, an upper and a lower, by an interlobular fissure, which extends from the
costal to the mediastinal surface of the lung both
above and below the hilus. As seen on the surface,
this fissure begins on the mediastinal surface of the
lung at the upper and posterior part of the hilus,
and runs backward and upward to the posterior border, which it crosses at a
lung is divided into three
lobes, superior, middle, and inferior, by two interlobular fissures. One of
these separates the inferior from the middle and superior lobes, and
corresponds closely with the fissure in the left lung. Its direction is,
however, more vertical, and it cuts the lower border about
The right lung, although shorter by
The Root of the Lung (radix pulmonis).ЧA little above the middle of the mediastinal surface of each lung, and nearer its posterior than its anterior border, is its root, by which the lung is connected to the heart and the trachea. The root is formed by the bronchus, the pulmonary artery, the pulmonary veins, the bronchial arteries and veins, the pulmonary plexuses of nerves, lymphatic vessels, bronchial lymph glands, and areolar tissue, all of which are enclosed by a reflection of the pleura. The root of the right lung lies behind the superior vena cava and part of the right atrium, and below the azygos vein. That of the left lung passes beneath the aortic arch and in front of the descending aorta; the phrenic nerve, the pericardiacophrenic artery and vein, and the anterior pulmonary plexus, lie in front of each, and the vagus and posterior pulmonary plexus behind each; below each is the pulmonary ligament.
The chief structures composing the root of each lung are arranged in a similar manner from before backward on both sides, viz., the upper of the two pulmonary veins in front; the pulmonary artery in the middle; and the bronchus, together with the bronchial vessels, behind. From above downward, on the two sides, their arrangement differs, thus:
On the right side their position isЧeparterial bronchus, pulmonary artery, hyparterial bronchus, pulmonary veins, but on the left side their position isЧpulmonary artery, bronchus, pulmonary veins. The lower of the two pulmonary veins, is situated below the bronchus, at the apex or lowest part of the hilus.
Divisions of the Bronchi.ЧJust as the lungs differ from each other in the number of their lobes, so the bronchi differ in their mode of subdivision.
bronchus gives off, about
bronchus passes below the level
of the pulmonary artery before it divides, and hence all its branches are hyparterial; it may therefore be looked upon as equivalent to that
portion of the right bronchus which lies on the distal side of its eparterial branch. The first branch of the left bronchus
Structure.ЧThe lungs are composed of an external serous coat, a subserous areolar tissue and the pulmonary substance or parenchyma. The serous coat is the pulmonary pleura; it is thin, transparent, and invests the entire organ as far as the root. The subserous areolar tissue contains a large proportion of elastic fibers; it invests the entire surface of the lung, and extends inward between the lobules.
The parenchyma is composed of secondary lobules which, although closely connected together by an interlobular areolar tissue, are quite distinct from one another, and may be teased asunder without much difficulty in the fetus. The secondary lobules vary in size; those on the surface are large, of pyramidal form, the base turned toward the surface; those in the interior smaller, and of various forms. Each secondary lobule is composed of several primary lobules, the anatomical units of the lung. The primary lobule consists of an alveolar duct, the air spaces connected with it and their bloodvessels, lymphatics and nerves.
bronchi divide and subdivide
throughout the entire organ, the smallest subdivisions constituting the lobular
bronchioles. The larger divisions consist of: (1) an outer coat of
fibrous tissue in which are found at intervals irregular plates of hyaline
cartilage, most developed at the points of division; (2) internal to the
fibrous coat, a layer of circularly disposed smooth muscle fibers, the
bronchial muscle; and (3) most internally, the mucous membrane, lined by
columnar ciliated epithelium resting on a basement membrane. The corium of the
mucous membrane contains numerous elastic fibers running longitudinally, and a
certain amount of lymphoid tissue; it also contains the ducts of mucous glands,
the acini of which lie in the fibrous coat. Thelobular bronchioles differ from the larger tubes in
containing no cartilage and in the fact that the ciliated epithelial cells are
cubical in shape. The lobular bronchioles are about
Part of a secondary lobule from the depth of a human lung, showing parts of several primary lobules. 1, bronchiole; 2, respiratory bronchiole; 3, alveolar duct; 4, atria; 5, alveolar sac; 6, alveolus or air cell: m, smooth muscle; a, branch pulmonary artery; v, branch pulmonary vein; s, septum between secondary lobules
Each bronchiole divides into two or more respiratory bronchioles, with scattered alveoli, and each of these again divides into several alveolar ducts, with a greater number of alveoli connected with them. Each alveolar duct is connected with a variable number of irregularly spherical spaces, which also possess alveoli, the atria. With each atrium a variable number (2Ц5) ofalveolar sacs are connected which bear on all parts of their circumference alveoli or air sacs.
The alveoli are lined by a delicate layer of simple squamous epithelium, the cells of which are united at their edges by cement substance. Between the squames are here and there smaller, polygonal, nucleated cells. Outside the epithelial lining is a little delicate connective tissue containing numerous elastic fibers and a close net-work of blood capillaries, and forming a common wall to adjacent alveoli
The fetal lung resembles a gland in that the alveoli have a small lumen and are lined by cubical epithelium. After the first respiration the alveoli become distended, and the epithelium takes on the characters described above.
Vessels and Nerves.ЧThe pulmonary artery conveys the venous blood to the lungs; it divides into branches which accompany the bronchial tubes and end in a dense capillary net-work in the walls of the alveoli. In the lung the branches of the pulmonary artery are usually above and in front of a bronchial tube, the vein below.
The pulmonary capillaries form plexuses which lie immediately beneath the lining epithelium, in the walls and septa of the alveoli and of the infundibula. In the septa between the alveoli the capillary net-work forms a single layer. The capillaries form a very minute net-work, the meshes of which are smaller than the vessels themselves; their walls are also exceedingly thin. The arteries of neighboring lobules are independent of each other, but the veins freely anastomose.
The pulmonary veins commence in the pulmonary capillaries, the radicles coalescing into larger branches which run through the substance of the lung, independently of the pulmonary arteries and bronchi. After freely communicating with other branches they form large vessels, which ultimately come into relation with the arteries and bronchial tubes, and accompany them to the hilus of the organ. Finally they open into the left atrium of the heart, conveying oxygenated blood to be distributed to all parts of the body by the aorta.
The bronchial arteries supply blood for the nutrition of the lung; they are derived from the thoracic aorta or from the upper aortic intercostal arteries, and, accompanying the bronchial tubes, are distributed to the bronchial glands and upon the walls of the larger bronchial tubes and pulmonary vessels. Those supplying the bronchial tubes form a capillary plexus in the muscular coat, from which branches are given off to form a second plexus in the mucous coat; this plexus communicates with small venous trunks that empty into the pulmonary veins. Others are distributed in the interlobular areolar tissue, and end partly in the deep, partly in the superficial, bronchial veins. Lastly, some ramify upon the surface of the lung, beneath the pleura, where they form a capillary network.
The bronchial vein is formed at the root of the lung, receiving superficial and deep veins corresponding to branches of the bronchial artery. It does not, however, receive all the blood supplied by the artery, as some of it passes into the pulmonary veins. It ends on the right side in the azygos vein, and on the left side in the highest intercostal or in the accessory hemiazygos vein.
Nerves.ЧThe lungs are supplied from the anterior and posterior pulmonary plexuses, formed chiefly by branches from the sympathetic and vagus. The filaments from these plexuses accompany the bronchial tubes, supplying efferent fibers to the bronchial muscle and afferent fibers to the bronchial mucous membrane and probably to the alveoli of the lung. Small ganglia are found upon these nerves.
Acynus contains 14-16 respiratory bronch≥oli, which are ramification of one terminal bronch≥oli and they have alveoli in the wall. Each respiratory bronch≥ forms to 1500 alveolar ductuli, which terminate in alveolar saccule. One pulmonary lobule contains 16-18 acynuses. The acynus is covered by network of vessels. Gas-exchange between external environment and blood takes place here.
Parenchyma of the lungs and walls of thoracic cavity covered by serous membrane named pleura. Sheet of pleurae which covers the lung called visceral, and one which covers inner walls of thoracic cavity named parietal. Parietal pleura pass into visceral one in place of pulmonal ligament which lies in frontal plane. Parietal pleura divided into some portions: costal portion, diaphragmatic, mediastinal portion and has a cupola of pleurae.
Front view of thorax, showing the relations of the pleuræ and lungs to the chest wall. Pleura in blue; lungs in purple.
Narrow fissure pleural cavity contains some serous liquid situated between parietal and visceral pleurae. In areas, where one part of parietal pleurae continues into other, recesses form, into which lung deepens during taking a deep breath. They distinguish a costodiaphragmatic recess (largest), diaphragmaticоmediastinal recess, vertebrоmediastinal recess and costomediastinal recess.
The MEDIASTINUM is complex of organs, which is situated between two pleural sacs. Mediastinum is limited - at front by sternum, behind by thoracic part of backbone, from sides - by right and left mediastinal pleurae. Its superior boundary is superior foramen of thoracic cavity, and inferior - diaphragm. Conventionally horizontal plane, carrying out from joint of manubrium sterni and corpus sterni to cartilage between IV-V thoracic vertebrae, divides mediastinum into superior mediastinum and inferior mediastinum.
In superior mediastinum thymus gland, superior cava vein, aortal arch, part of trachea, superior part of thoracic esophageal portion, suitable parts of thoracic lymphatic duct, sympathetic trunks, vagus and phrenic nerves are situated.
Transverse section through the upper margin of the second thoracic vertebra.
Inferior mediastinum into its turn subdivides into anterior mediastinum, middle mediastinum and posterior mediastinum. Anterior mediastinum is situated between body by sternum and anterior wall of pericardium. Internal thoracic arteries and veins, lymphatic nodes and vessels are situated here. On middle mediastinum heart, covered by pericardium, phrenic nerves and inner pericardial portions of big vessels are located. Posterior mediastinum is situated between posterior pericardial wall and backbone. Thoracic part of aorta, azygos and hemiazygos veins, sympathetic trunks, splanchnic nerves, vagus nerves, esophagus, thoracic duct, lymphatic nodes passes here.
A transverse section of the thorax, showing the contents of the middle and the posterior mediastinum. The pleural and pericardial cavities are exaggerated since normally there is no space between parietal and visceral pleura and between pericardium and heart.
In surgery mediastinum is subdivided by frontal plane, carrying out through trachea and lung root, into anterior mediastinum and posterior mediastinum. In anterior mediastinum heart, ascending aorta, aortal arch, superior vena cava, trachea, lung root elements, phrenic nerves and thymus gland are placed. In posterior mediastinum esophagus, descending aorta, inferior vena cava, azygos and hemiazygos veins, splanchnic nerves, sympathetic trunk, thoracic lymphatic duct and vagus nerves are situated.
Boundaries of LUNGs and PLEURAe. The
superior border of lung and pleura (pleura cupola) coincide and situated
Anterior lung boundary path also coincides with by anterior
pleural border. It passes from top of the lung to sternоclavicular
joint, passes over middle the manubrium sterni,
sternal body from II to IV costal cartilage. Anterior boundary of left lung
deviates here to the left, passes on parasternal line till VI rib, where
continues into inferior border. Anterior boundary path of right lung passes
along the border of left lung, but gradually deviates to the right and on level
of the VI costal cartilage on right parasternal line continues into inferior
border. Inferior boundary path of right lung is situated 1-
І on medioclavicular line - at level of the VI ribs,
І on anterior axillar line - on level of the VII ribs,
І on middle axillar line - on level of the VIII ribs,
І on posterior axillar line - on level of the IX ribs,
І on scapular line - on level of the ’ ribs,
І on paravertebral line - on level of the XI heads of rib.
URINARY SYSTEM includes pair organ - kidney (organ producing urine) and organs, which store up and bring out urine (ureters, urinary bladder and urethra).
Two Kidneys are pair parenchymatic organs, which positioned in abdominal cavity behind peritoneum (retroperitoneal position) in right and left lumbar regions. Kidney is projected on front abdominal wall in epigastric, lateral and umbilical regions. Right kidney extends from Th 12 vertebra till L 3 lumbar vertebra, left one - from Th 11 vertebra till L 2 lumbar vertebra.
Posterior abdominal wall, after removal of the peritoneum, showing kidneys, suprarenal capsules, and great vessels.
Posterior surface of each kidney in superior part adjoins to diaphragm, and in middle and inferior - to muscular bed, which is formed by muscle: psoas major, quadratus lumborum and transverse abdominis. To anterior surface of left kidney adrenal gland adjoins above, to superolateral part - spleen, to middle portion - stomach and pancreas, inferiorly - medially is loops of small intestine, and superolaterally - colon. To anterior surface of right kidney suprarenal gland adjoins above, to middle part - liver, to medial margin - duodenum, to inferiomedial - loops of small intestine and to inferiolateral - large intestine.
Vertical section of kidney.
Each kidney has superior extremity and inferior extremity, anterior surface and posterior surface, medial margin (concave) and lateral margin (convex). On medial margin are situated the renal hilus, where artery, nerves enter, and vein, lymphatic and renal pelvis exit. The renal hilus gets into kidneys, forming a renal sinus, filled by adipose tissue, also major renal calices and minor renal calices and initial part of renal pelvis are present there.
The urinary organs comprise the kidneys, which secrete the urine, the ureters, or ducts, which convey urine to the urinary bladder, where it is for a time retained; and the urethra, through which it is discharged from the body.
The kidneys are situated in the posterior part of the abdomen, one on either side of the vertebral column, behind the peritoneum, and surrounded by a mass of fat and loose areolar tissue. Their upper extremities are on a level with the upper border of the twelfth thoracic vertebra, their lower extremities on a level with the third lumbar. The right kidney is usually slightly lower than the left, probably on account of the vicinity of the liver. The long axis of each kidney is directed downward and lateralward; the transverse axis backward and lateralward.
Each kidney is about
The kidney has a characteristic form, and presents for examination two surfaces, two borders, and an upper and lower extremity.
Relations.ЧThe anterior surface (facies anterior) of each kidney is convex, and looks forward and lateralward. Its relations to adjacent viscera differ so completely on the two sides that separate descriptions are necessary.
Anterior Surface of Right Kidney.ЧA narrow portion at the upper extremity is in relation with the right suprarenal gland. A large area just below this and involving about three-fourths of the surface, lies in the renal impression on the inferior surface of the liver, and a narrow but somewhat variable area near the medial border is in contact with the descending part of the duodenum. The lower part of the anterior surface is in contact laterally with the right colic flexure, and medially, as a rule, with the small intestine. The areas in relation with the liver and small intestine are covered by peritoneum; the suprarenal, duodenal, and colic areas are devoid of peritoneum.
Anterior Surface of Left Kidney.ЧA small area along the upper part of the medial border is in relation with the left suprarenal gland, and close to the lateral border is a long strip in contact with the renal impression on the spleen. A somewhat quadrilateral field, about the middle of the anterior surface, marks the site of contact with the body of the pancreas, on the deep surface of which are the lienal vessels. Above this is a small triangular portion, between the suprarenal and splenic areas, in contact with the postero-inferior surface of the stomach. Below the pancreatic area the lateral part is in relation with the left colic flexure, the medial with the small intestine. The areas in contact with the stomach and spleen are covered by the peritoneum of the omental bursa, while that in relation to the small intestine is covered by the peritoneum of the general cavity; behind the latter are some branches of the left colic vessels. The suprarenal, pancreatic, and colic areas are devoid of peritoneum.
The Posterior Surface (facies posterior) of each kidney is directed backward and medialward. It is imbedded in areolar and fatty tissue and entirely devoid of peritoneal covering. It lies upon the diaphragm, the medial and lateral lumbocostal arches, the Psoas major, the Quadratus lumborum, and the tendon of the Transversus abdominis, the subcostal, and one or two of the upper lumbar arteries, and the last thoracic, iliohypogastric, and ilioinguinal nerves. The right kidney rests upon the twelfth rib, the left usually on the eleventh and twelfth. The diaphragm separates the kidney from the pleura, which dips down to form the phrenicocostal sinus, but frequently the muscular fibers of the diaphragm are defective or absent over a triangular area immediately above the lateral lumbocostal arch, and when this is the case the perinephric areolar tissue is in contact with the diaphragmatic pleura.
Borders.ЧThe lateral border (margo lateralis; external border) is convex, and is directed toward the postero-lateral wall of the abdomen. On the left side it is in contact at its upper part, with the spleen.
The medial border (margo medialis; internal border) is concave in the center and convex toward either extremity; it is directed forward and a little downward. Its central part presents a deep longitudinal fissure, bounded by prominent overhanging anterior and posterior lips. This fissure is named the hilum, and transmits the vessels, nerves, and ureter. Above the hilum the medial border is in relation with the suprarenal gland; below the hilum, with the ureter.
Extremities.ЧThe superior extremity (extremitas superior) is thick and rounded, and is nearer the median line than the lower; it is surmounted by the suprarenal gland, which covers also a small portion of the anterior surface.
extremity (extremitas inferior) is smaller and thinner
than the superior and farther from the median line. It extends to within
The relative position of the main structures in the hilum is as follows: the vein is in front, the artery in the middle, and the ureter behind and directed downward. Frequently, however, branches of both artery and vein are placed behind the ureter.
Fixation of the Kidney. The kidney and its vessels are imbedded in a mass of fatty tissue, termed theadipose capsule, which is thickest at the margins of the kidney and is prolonged through the hilum into the renal sinus. The kidney and the adipose capsule are enclosed in a sheath of fibrous tissue continuous with the subperitoneal fascia, and named the renal fascia. At the lateral border of the kidney the renal fascia splits into an anterior and a posterior layer. The anterior layer is carried medialward in front of the kidney and its vessels, and is continuous over the aorta with the corresponding layer of the opposite side. The posterior layer extends medialward behind the kidney and blends with the fascia on the Quadratus lumborum and Psoas major, and through this fascia is attached to the vertebral column. Above the suprarenal gland the two layers of the renal fascia fuse, and unite with the fascia of the diaphragm; below they remain separate, and are gradually lost in the subperitoneal fascia of the iliac fossa. The renal fascia is connected to the fibrous tunic of the kidney by numerous trabeculæ, which traverse the adipose capsule, and are strongest near the lower end of the organ. Behind the fascia renalis is a considerable quantity of fat, which constitutes the paranephric body. The kidney is held in position partly through the attachment of the renal fascia and partly by the apposition of the neighboring viscera.
To parenchyma of the kidney a fibrous capsule adjoins. Outside from last a fatty capsule is situated, which noticeable better near posterior surface of kidney. More outer from adipose capsule renal fascia disposed, which consists of anterior sheet and posterior sheet. They fused together by superior edges and laterally. From renal fascia stratums of connective tissue draw to fibrous capsule kidney, which fix a kidney. Peritoneum adjoins to anterior sheet of renal fascia. Kidneys are fixed by abdominal pressure, renal fascia, muscular bed, renal vessels and nerves, which form a renal leg.
Sagittal section through posterior abdominal wall, showing the relations of the capsule of the kidney.
General Structure of the Kidney.ЧThe kidney is invested by a fibrous tunic, which forms a firm, smooth covering to the organ. The tunic can be easily stripped off, but in doing so numerous fine processes of connective tissue and small bloodvessels are torn through. Beneath this coat a thin, wide-meshed net-work of unstriped muscular fiber forms an incomplete covering to the organ. When the capsule is stripped off, the surface of the kidney is found to be smooth and even and of a deep red color. In infants fissures extending for some depth may be seen on the surface of the organ, a remnant of the lobular construction of the gland. The kidney is dense in texture, but is easily lacerable by mechanical force. If a vertical section of the kidney be made from its convex to its concave border, it will be seen that the hilum expands into a central cavity, the renal sinus, this contains the upper part of the renal pelvis and the calyces, surrounded by some fat in which are imbedded the branches of the renal vessels and nerves. The renal sinus is lined by a prolongation of the fibrous tunic, which is continued around the lips of the hilum. The renal calyces, from seven to thirteen in number, are cup-shaped tubes, each of which embraces one or more of the renal papillæ; they unite to form two or three short tubes, and these in turn join to form a funnel-shaped sac, the renal pelvis. The renal pelvis, wide above and narrow below where it joins the ureter, is partly outside the renal sinus. The renal calyces and pelvis form the upper expanded end of the excretory duct of the kidney.
The kidney is composed of an internal medullary and an external cortical substance.
The medullary substance (substantia medullaris) consists of a series of red-colored striated conical masses, termed therenal pyramids, the bases of which are directed toward the circumference of the kidney, while their apices converge toward the renal sinus, where they form prominent papillæ projecting into the interior of the calyces.
The cortical substance (substantia corticalis) is reddish brown in color and soft and granular in consistence. It lies immediately beneath the fibrous tunic, arches over the bases of the pyramids, and dips in between adjacent pyramids toward the renal sinus. The parts dipping in between the pyramids are named the renal columns (Bertini), while the portions which connect the renal columns to each other and intervene between the bases of the pyramids and the fibrous tunic are called the cortical arches. If the cortex be examined with a lens, it will be seen to consist of a series of lighter-colored, conical areas, termed the radiate part, and a darker-colored intervening substance, which from the complexity of its structure is named the convoluted part. The rays gradually taper toward the circumference of the kidney, and consist of a series of outward prolongations from the base of each renal pyramid.
Renal parenchyma consists of cortex (superficially) and medulla
(deep location). In medulla they distinguish 7-10 renal pyramids, each
from which has a base of renal pyramids and a top (apex). Last
terminates in renal papilla where cribriform area disposed. The
stratums of cortical matter, which form the renal columns, lie between
pyramids. Cortical matter consists of convoluted part, between
which the stratums of medulla are
contained. They have a name medullar rays (radiata
part). Each renal pyramid forms renal lobe, and one convoluted
part and one radita part form renal lobule in
cortex. From top of renal pyramid urine gets into minor renal calices (7-
The glomerulus is a lobulated net-work of convoluted capillary bloodvessels, held together by scanty connective tissue. This capillary net-work is derived from a small arterial twig, the afferent vessel, which enters the capsule, generally at a point opposite to that at which the latter is connected with the tubule; and the resulting vein, the efferent vessel, emerges from the capsule at the same point. The afferent vessel is usually the larger of the two. The glomerular or BowmanТs capsule, which surrounds the glomerulus, consists of a basement membrane, lined on its inner surface by a layer of flattened epithelial cells, which are reflected from the lining membrane on to the glomerulus, at the point of entrance or exit of the afferent and efferent vessels. The whole surface of the glomerulus is covered with a continuous layer of the same cells, on a delicate supporting membrane. Thus between the glomerulus and the capsule a space is left, forming a cavity lined by a continuous layer of squamous cells; this cavity varies in size according to the state of secretion and the amount of fluid present in it. In the fetus and young subject the lining epithelial cells are polyhedral or even columnar.
The renal tubules, commencing in the renal corpuscles, present, during their course, many changes in shape and direction, and are contained partly in the medullary and partly in the cortical substance. At their junction with the glomerular capsule they exhibit a somewhat constricted portion, which is termed the neck. Beyond this the tubule becomes convoluted, and pursues a considerable course in the cortical substance constituting the proximal convoluted tube. After a time the convolutions disappear, and the tube approaches the medullary substance in a more or less spiral manner; this section of the tubule has been called the spiral tube. Throughout this portion of their course the renal tubules are contained entirely in the cortical substance, and present a fairly uniform caliber. They now enter the medullary substance, suddenly become much smaller, quite straight in direction, and dip down for a variable depth into the pyramids, constituting the descending limb of HenleТs loop. Bending on themselves, they form what is termed the loop of Henle, and reascending, they become suddenly enlarged, forming theascending limb of HenleТs loop, and reënter the cortical substance. This portion of the tubule ascends for a short distance, when it again becomes dilated, irregular, and angular. This section is termed the zigzag tubule; it ends in a convoluted tube, which resembles the proximal convoluted tubule, and is called the distal convoluted tubule. This again terminates in a narrowjunctional tube, which enters the straight or collecting tube.
The straight or collecting tubes commence in the radiate part of the cortex, where they receive the curved ends of the distal convoluted tubules. They unite at short intervals with one another, the resulting tubes presenting a considerable increase in caliber, so that a series of comparatively large tubes passes from the bases of the rays into the renal pyramids. In the medulla the tubes of each pyramid converge to join a central tube (duct of Bellini) which finally opens on the summit of one of the papillæ; the contents of the tube are therefore discharged into one of the calyces.
Structure of the Renal Tubules.ЧThe renal tubules consist of a basement membrane lined with epithelium. The epithelium varies considerably in different sections of the tubule. In the neck the epithelium is continuous with that lining the glomerular capsule, and like it consists of flattened cells each containing an oval nucleus (Fig. 1132). The two convoluted tubules, the spiral and zigzag tubules and the ascending limb of HenleТs loop, are lined by a type of epithelium which is histologically the same in all. The cells are somewhat columnar in shape and dovetail into one another of their lateral aspect. Each has a striated border next the lumen of the tube, its inner part is granular and its outer portion vertically striated. The nucleus is spherical and situated about the center of the cell. In the descending limb of HenleТs loop the epithelium resembles that found in the glomerular capsule and the commencement of the tube, consisting of flat, clear epithelial plates, each with an oval nucleus. The nuclei alternate on opposite surfaces of the tubule so that the lumen remains fairly constant.
In the straight tube the epithelium is clear and cubical: in its papillary portion the cells are distinctly columnar and transparent.
BLOOD SUPPLYING of KIDNEYS. Kidney supplied by renal artery, which ramifies in hilus area into anterior branch and posterior branch. Last divide by segmental arteries, and segmental branches - into interlobar arteries, which ramify on border of cortex and medulla into arcuate arteries. Arcuate arteries give off the radial cortical (interlobular) arteries in cortical matter. They give beginning for numerous of afferent vasa, which disintegrate into arterial capillaries and form a renal glomerulus. From renal glomerulus moves away efferent vasa, which disintegrates into secondary arterial capillaries, that enshrouds the tubules of nephron. Such system of blood supplying, when arterial vessels have double disintegration into cappillaries called as renal miracle arterial rete. Venous capillaries form in cortical matter stellate venullae, which fall into arcuate veins. Arcuate veins continue into interlobar veins, last form a renal vein, which empties in inferior vena cava.
FORMINg and transportation of URINE within the KIDNEY. Primary urine arises by filtration blood plasma in nephron capsule, which envelops each renal glomerulus. Capsule of renal glomerulus together with glomerulus form a renal corpuscle, which is situated in convoluted part of cortex. Proximal canalicule of nephron passes from renal corpuscle, which continues into nephron loop (ansa of Henle). Last continues into distal part of nephron canalicule which falling into collecting duct. All of above counted urinary tubules braid by thick net of secondary arterial capillaries and by reabsorbtion secondary urine here is formed. The elements, where urine is formed, compose function and structural kidney unit Ц nephron:
After nephron urine streams into straight colligens (collecting) tubules, which terminate by pappillar foramens on top of renal pyramid. Last open on cribriform area into minor renal calices. From small renal calices urine flows into major renal calices, which join together and form a renal pelvis, last continues into ureter.
The kidney is plentifully supplied with blood by the renal artery, a large branch of the abdominal aorta. Before it enters the kidney, each artery divides into four or five branches which at the hilum lie mainly between the renal vein and ureter, the vein being in front, the ureter behind; one branch usually lies behind the ureter. Each vessel gives off some small branches to the suprarenal glands, to the ureter, land to the surrounding cellular tissue and muscles. Frequently a second renal artery, termed the inferior renal, is given off from the abdominal aorta at a lower level, and supplies the lower portion of the kidney, while occasionally an additional artery enters the upper part of the kidney. The branches of the renal artery, while in the sinus, give off a few twigs for the nutrition of the surrounding tissues, and end in the arteriæ propriæ renales, which enter the kidney proper in the renal columns. Two of these pass to each renal pyramid, and run along its sides for its entire length, giving off in their course the afferent vessels of the renal corpuscles in the renal columns. Having arrived at the bases of the pyramids, they form arterial arches or arcades which lie in the boundary zone between the bases of the pyramids and the cortical arches, and break up into two distinct sets of branches devoted to the supply of the remaining portions of the kidney.
The interlobular arteries are given off at right angles from the side of the arterial arcade looking toward the cortical substance, and pass directly outward between the medullary rays to reach the fibrous tunic, where they end in the capillary net-work of this part. These vessels do not anastomose with each other, but form what are called end-arteries. In their outward course they give off lateral branches; these are the afferent vessels for the renal corpuscles; they enter the capsule, and end in the glomerulus. From each tuft the corresponding efferent vessel arises, and, having made its egress from the capsule near to the point where the afferent vessel enters, breaks up into a number of branches, which form a dense plexus around the adjacent urinary tubes.
The second set of branches from the arterial arcades supply the renal pyramids, which they enter at their bases; and, passing straight through their substance to their apices, terminate in the venous plexuses found in that situation. They are called thearteriæ rectæ. The efferent vessels from the glomeruli nearest the medulla break up into leashes of straight vessels (false arteriæ rectæ) which pass down into the medulla and join the plexus of vessels there.
The renal veins arise from three sources, viz., the veins beneath the fibrous tunic, the plexuses around the convoluted tubules in the cortex, and the plexuses situated at the apices of the renal pyramids. The veins beneath the fibrous tunic (venæ stellatæ) are stellate in arrangement, and are derived from the capillary net-work, into which the terminal branches of the interlobular arteries break up. These join to form the interlobular veins, which pass inward between the rays, receive branches from the plexuses around the convoluted tubules, and, having arrived at the bases of the renal pyramids, join with the venæ rectæ, next to be described.
The venæ rectæ are branches from the plexuses at the apices of the medullary pyramids, formed by the terminations of the arteriæ rectæ. They run outward in a straight course between the tubes of the medullary substance, and joining, as above stated, the interlobular veins, form venous arcades; these in turn unite and form veins which pass along the sides of the pyramids (Fig. 1128).
These vessels, venæ propriæ renales, accompany the arteries of the same name, running along the entire length of the sides of the pyramids, and quit the kidney substance to enter the sinus. In this cavity they join the corresponding veins from the other pyramids to form the renal vein, which emerges from the kidney at the hilum and opens into the inferior vena cava; the left vein is longer than the right, and crosses in front of the abdominal aorta.
The lymphatics of the kidney are described on page 712.
Nerves of the Kidney.ЧThe nerves of the kidney, although small, are about fifteen in number. They have small ganglia developed upon them, and are derived from the renal plexus, which is formed by branches from the celiac plexus, the lower and outer part of the celiac ganglion and aortic plexus, and from the lesser and lowest splanchnic nerves. They communicate with the spermatic plexus, a circumstance which may explain the occurrence of pain in the testis in affections of the kidney. They accompany the renal artery and its branches, and are distributed to the bloodvessels and to the cells of the urinary tubules.
Connective Tissue (intertubular stroma).ЧAlthough the tubules and vessels are closely packed, a small amount of connective tissue, continuous with the fibrous tunic, binds them firmly together and supports the bloodvessels, lymphatics, and nerves.
Variations.ЧMalformations of the kidney are not uncommon. There may be an entire absence of one kidney, but, according to Morris, the number of these cases is Уexcessively smallФ: or there may be congenital atrophy of one kidney, when the kidney is very small, but usually healthy in structure. These cases are of great importance, and must be duly taken into account when nephrectomy is contemplated. A more common malformation is where the two kidneys are fused together. They may be joined together only at their lower ends by means of a thick mass of renal tissue, so as to form a horseshoe-shaped body, or they may be completely united, forming a disk-like kidney, from which two ureters descend into the bladder. These fused kidneys are generally situated in the middle line of the abdomen, but may be misplaced as well. In some mammals, e. g., ox and bear, the kidney consists of a number of distinct lobules; this lobulated condition is characteristic of the kidney of the human fetus, and traces of it may persist in the adult. Sometimes the pelvis is duplicated, while a double ureter is not very uncommon. In some rare instances a third kidney may be present.
One or both kidneys may be misplaced as a congenital condition, and remain fixed in this abnormal position. They are then very often misshapen. They may be situated higher, though this is very uncommon, or lower than normal or removed farther from the vertebral column than usual; or they may be displaced into the iliac fossa, over the sacroiliac joint, on to the promontory of the sacrum, or into the pelvis between the rectum and bladder or by the side of the uterus. In these latter cases they may give rise to very serious trouble. The kidney may also be misplaced as a congenital condition, but may not be fixed; it is then known as afloating kidney. It is believed to be due to the fact that the kidney is completely enveloped by peritoneum which then passes backward to the vertebral column as a double layer, forming a mesonephron which permits movement. The kidney may also be misplaced as an acquired condition; in these cases the kidney is mobile in the tissues by which it is surrounded, moving with the capsule in the perinephric tissues. This condition is known as movable kidney, and is more common in the female than in the male. It occurs in badly nourished people, or in those who have become emaciated from any cause. It must not be confounded with the floating kidney, which is a congenital condition due to the development of a mesonephron. The two conditions cannot, however, be distinguished until the abdomen is opened or the kidney explored from the loin.
The URETERS are pair organ length 25-«0 cm, which lies retroperitoneally. Ureter has abdominal part, pelvic part and intramural part. Last lies in the wall of urinary bladder and opens on its fundus by foramen. Ureters wall consists of external membrane, muscular membrane and mucous membrane. Muscular membrane has external circular and internal longitudinal layers.
Ureter has follow narrow places:
Х at transition of renal pelvis into ureter;
Х at transition of abdominal part into pelvic part;
Х at transition of ureters into urinary bladder.†††††††
The ureters are the two tubes which convey the urine from the kidneys to the urinary bladder. Each commences within the sinus of the corresponding kidney as a number of short cup-shaped tubes, termed calyces, which encircle the renal papillæ. Since a single calyx may enclose more than one papilla the calyces are generally fewer in number than the pyramidsЧthe former varying from seven to thirteen, the latter from eight to eighteen. The calyces join to form two or three short tubes, and these unite to form a funnel-shaped dilatation, wide above and narrow below, named the renal pelvis, which is situated partly inside and partly outside the renal sinus. It is usually placed on a level with the spinous process of the first lumbar vertebra.
Proper measures from 25 to
The abdominal part (pars abdominalis) lies behind the peritoneum on the medial part of the Psoas major, and is crossed obliquely by the internal spermatic vessels. It enters the pelvic cavity by crossing either the termination of the common, or the commencement of the external, iliac vessels.
At its origin the right ureter is usually covered by the descending part of the duodenum, and in its course downward lies to the right of the inferior vena cava, and is crossed by the right colic and ileocolic vessels, while near the superior aperture of the pelvis it passes behind the lower part of the mesentery and the terminal part of the ileum. The left ureter is crossed by the left colic vessels, and near the superior aperture of the pelvis passes behind the sigmoid colon and its mesentery.
part (pars pelvina) runs at first downward on the lateral wall of
the pelvic cavity, along the anterior border of the greater sciatic notch and
under cover of the peritoneum. It lies in front of the hypogastric
artery medial to the obturator nerve and the
umbilical, obturator, inferior vesical,
and middle hemorrhoidal arteries. Opposite the lower
part of the greater sciatic foramen it inclines medialward,
and reaches the lateral angle of the bladder, where it is situated in front of
the upper end of the seminal vesicle and at a distance of about
In the female, the ureter forms, as it 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. It then runs medialward and forward on the
lateral aspect of the cervix uteri and upper part of the vagina to reach the
fundus of the bladder. In this part of its course it is accompanied for about
The ureter is composed of three coats: fibrous, muscular, and mucous coats.
The fibrous coat (tunica adventitia) is continuous at one end with the fibrous tunic of the kidney on the floor of the sinus; while at the other it is lost in the fibrous structure of the bladder.
In the renal pelvis the muscular coat (tunica muscularis) consists of two layers, longitudinal and circular: the longitudinal fibers become lost upon the sides of the papillæ at the extremities of the calyces; the circular fibers may be traced surrounding the medullary substance in the same situation. In the ureter proper the muscular fibers are very distinct, and are arranged in three layers: an external longitudinal, a middle circular, and an internal, less distinct than the other two, but having a general longitudinal direction. According to Kölliker this internal layer is found only in the neighborhood of the bladder.
The mucous coat (tunica mucosa) is smooth, and presents a few longitudinal folds which become effaced by distension. It is continuous with the mucous membrane of the bladder below, while it is prolonged over the papillæ of the kidney above. Its epithelium is of a transitional character, and resembles that found in the bladder. It consists of several layers of cells, of which the innermostЧthat is to say, the cells in contact with the urineЧare somewhat flattened, with concavities on their deep surfaces into which the rounded ends of the cells of the second layer fit. These, the intermediate cells, more or less resemble columnar epithelium, and are pear-shaped, with rounded internal extremities which fit into the concavities of the cells of the first layer, and narrow external extremities which are wedged in between the cells of the third layer. The external or third layer consists of conical or oval cells varying in number in different parts, and presenting processes which extend down into the basement membrane. Beneath the epithelium, and separating it from the muscular coats, is a dense layer of fibrous tissue containing many elastic fibers.
Vessels and Nerves.ЧThe arteries supplying the ureter are branches from the renal, internal spermatic, hypogastric, and inferior vesical.
The nerves are derived from the inferior mesenteric, spermatic, and pelvic plexuses.
Variations.ЧThe upper portion of the ureter is sometimes double; more rarely it is double the greater part of its extent, or even completely so. In such cases there are two openings into the bladder. Asymmetry in these variations is common.
Vesica Urinaria is a musculomembranous sac which acts as a reservoir for the urine; and as its size, position, and relations vary according to the amount of fluid it contains, it is necessary to study it as it appears (a) when empty, and (b) when distended.) In both conditions the position of the bladder varies with the condition of the rectum, being pushed upward and forward when the rectum is distended.
The Empty Bladder.ЧWhen hardened in situ, the empty bladder has the form of a flattened tetrahedron, with its vertex tilted forward. It presents a fundus, a vertex, a superior and an inferior surface. The fundus is triangular in shape, and is directed downward and backward toward the rectum, from which it is separated by the rectovesical fascia, the vesiculæ seminales, and the terminal portions of the ductus deferentes. The vertex is directed forward toward the upper part of the symphysis pubis, and from it the middle umbilical ligament is continued upward on the back of the anterior abdominal wall to the umbilicus. The peritoneum is carried by it from the vertex of the bladder on to the abdominal wall to form the middle umbilical fold. The superior surface is triangular, bounded on either side by a lateral border which separates it from the inferior surface, and behind by a posterior border, represented by a line joining the two ureters, which intervenes between it and the fundus. The lateral borders extend from the ureters to the vertex, and from them the peritoneum is carried to the walls of the pelvis. On either side of the bladder the peritoneum shows a depression, named the paravesical fossa. The superior surface is directed upward, is covered by peritoneum, and is in relation with the sigmoid colon and some of the coils of the small intestine. When the bladder is empty and firmly contracted, this surface is convex and the lateral and posterior borders are rounded; whereas if the bladder be relaxed it is concave, and the interior of the viscus, as seen in a median sagittal section, presents the appearance of a V-shaped slit with a shorter posterior and a longer anterior limbЧthe apex of the V corresponding with the internal orifice of the urethra. The inferior surface is directed downward and is uncovered by peritoneum. It may be divided into a posterior or prostatic area and two infero-lateral surfaces. The prostatic area is somewhat triangular: it rests upon and is in direct continuity with the base of the prostate; and from it the urethra emerges. The infero-lateral portions of the inferior surface are directed downward and lateralward: in front, they are separated from the symphysis pubis by a mass of fatty tissue which is named the retropubic pad;behind, they are in contact with the fascia which covers the Levatores ani and Obturatores interni.
When the bladder is empty it is placed entirely within the pelvis, below the level of the obliterated hypogastric arteries, and below the level of those portions of the ductus deferentes which are in contact with the lateral wall of the pelvis; after they cross the ureters the ductus deferentes come into contact with the fundus of the bladder. As the viscus fills, its fundus, being more or less fixed, is only slightly depressed; while its superior surface gradually rises into the abdominal cavity, carrying with it its peritoneal covering, and at the same time rounding off the posterior and lateral borders.
Distended Bladder.ЧWhen the
bladder is moderately full it contains about
Male pelvic organs seen from right side. Bladder and rectum distended; relations of peritoneum to the bladder and rectum shown in blue. The arrow points to the rectovesical pouch.
The Bladder in the Child. In the newborn child the internal urethral orifice is at the level of the upper border of the symphysis pubis; the bladder therefore lies relatively at a much higher level in the infant than in the adult. Its anterior surface Уis in contact with about the lower two-thirds of that part of the abdominal wall which lies between the symphysis pubis and the umbilicusФ (Symington 177). Its fundus is clothed with peritoneum as far as the level of the internal orifice of the urethra. Although the bladder of the infant is usually described as an abdominal organ, Symington has pointed out that only about one-half of it lies above the plane of the superior aperture of the pelvis. Disse maintains that the internal urethral orifice sinks rapidly during the first years, and then more slowly until the ninth year, after which it remains sta when it again slowly descends and reaches its adult position.
Sagittal section through the pelvis of a newly born female child
In the female, the bladder is in relation behind with the uterus and the upper part of the vagina. It is separated from the anterior surface of the body of the uterus by the vesicouterine excavation, but below the level of this excavation it is connected to the front of the cervix uteri and the upper part of the anterior wall of the vagina by areolar tissue. When the bladder is empty the uterus rests upon its superior surface. The female bladder is said by some to be more capacious than that of the male, but probably the opposite is the case.
Median sagittal section of female pelvis
Ligaments.ЧThe bladder is connected to the pelvic wall by the fascia endopelvina. In front this fascial attachment is strengthened by a few muscular fibers, the Pubovesicales, which extend from the back of the pubic bones to the front of the bladder; behind, other muscular fibers run from the fundus of the bladder to the sides of the rectum, in the sacrogenital folds, and constitute the Rectovesicales.
The vertex of the bladder is joined to the umbilicus by the remains of the urachus which forms the middle umbilical ligament,a fibromuscular cord, broad at its attachment to the bladder but narrowing as it ascends.
From the superior surface of the bladder the peritoneum is carried off in a series of folds which are sometimes termed the false ligaments of the bladder. Anteriorly there are three folds: the middle umbilical fold on the middle umbilical ligament, and twolateral umbilical folds on the obliterated hypogastric arteries. The reflections of the peritoneum on to the side walls of the pelvis form the lateral false ligaments, while the sacrogenital folds constitute posterior false ligaments.
Interior of the Bladder
The mucous membrane lining the bladder is, over the greater part of the viscus, loosely attached to the muscular coat, and appears wrinkled or folded when the bladder is contracted: in the distended condition of the bladder the folds are effaced. Over a small triangular area, termed the trigonum vesicæ, immediately above and behind the internal orifice of the urethra, the mucous membrane is firmly bound to the muscular coat, and is always smooth. The anterior angle of the trigonum vesicæ is formed by the internal orifice of the urethra: its postero-lateral angles by the orifices of the ureters. Stretching behind the latter openings is a slightly curved ridge, the torus uretericus, forming the base of the trigone and produced by an underlying bundle of non-striped muscular fibers. The lateral parts of this ridge extend beyond the openings of the ureters, and are named the plicæ uretericæ; they are produced by the terminal portions of the ureters as they traverse obliquely the bladder wall. When the bladder is illuminated the torus uretericus appears as a pale band and forms an important guide during the operation of introducing a catheter into the ureter.
The orifices of the ureters are placed at the postero-lateral
angles of the trigonum vesicæ,
and are usually slit-like in form. In the contracted bladder they are about
The internal urethral orifice is placed at the apex of the trigonum vesicæ, in the most dependent part of the bladder, and is usually somewhat crescentic in form; the mucous membrane immediately behind it presents a slight elevation, the uvula vesicæ, caused by the middle lobe of the prostate.
The male urethra laid open on its anterior (upper) surface
The bladder is composed of the four coats: serous, muscular, submucous, and mucous coats.
The serous coat (tunica serosa) is a partial one, and is derived from the peritoneum. It invests the superior surface and the upper parts of the lateral surfaces, and is reflected from these on to the abdominal and pelvic walls.
The muscular coat (tunica muscularis) consists of three layers of unstriped muscular fibers: an external layer, composed of fibers having for the most part a longitudinal arrangement; a middle layer, in which the fibers are arranged, more or less, in a circular manner; and an internal layer, in which the fibers have a general longitudinal arrangement.
The fibers of the external layer arise from the posterior surface of the body of the pubis in both sexes (musculi pubovesicales), and in the male from the adjacent part of the prostate and its capsule. They pass, in a more or less longitudinal manner, up the inferior surface of the bladder, over its vertex, and then descend along its fundus to become attached to the prostate in the male, and to the front of the vagina in the female. At the sides of the bladder the fibers are arranged obliquely and intersect one another. This layer has been named the Detrusor urinæ muscle.
The fibers of the middle circular layer are very thinly and irregularly scattered on the body of the organ, and, although to some extent placed transversely to the long axis of the bladder, are for the most part arranged obliquely. Toward the lower part of the bladder, around the internal urethral orifice, they are disposed in a thick circular layer, forming the Sphincter vesicæ, which is continuous with the muscular fibers of the prostate.
The internal longitudinal layer is thin, and its fasciculi have a reticular arrangement, but with a tendency to assume for the most part a longitudinal direction. Two bands of oblique fibers, originating behind the orifices of the ureters, converge to the back part of the prostate, and are inserted by means of a fibrous process, into the middle lobe of that organ. They are the muscles of the ureters, described by Sir C. Bell, who supposed that during the contraction of the bladder they serve to retain the oblique direction of the ureters, and so prevent the reflux of the urine into them.
The submucous coat (tela submucosa) consists of a layer of areolar tissue, connecting together the muscular and mucous coats, and intimately united to the latter.
The mucous coat (tunica mucosa) is thin, smooth, and of a pale rose color. It is continuous above through the ureters with the lining membrane of the renal tubules, and below with that of the urethra. The loose texture of the submucous layer allows the mucous coat to be thrown into folds or rugæ when the bladder is empty. Over the trigonum vesicæ the mucous membrane is closely attached to the muscular coat, and is not thrown into folds, but is smooth and flat. The epithelium covering it is of the transitional variety, consisting of a superficial layer of polyhedral flattened cells, each with one, two, or three nuclei; beneath these is a stratum of large club-shaped cells, with their narrow extremities directed downward and wedged in between smaller spindle-shaped cells, containing oval nuclei. The epithelium varies according as the bladder is distended or contracted. In the former condition the superficial cells are flattened and those of the other layers are shortened; in the latter they present the appearance described above. There are no true glands in the mucous membrane of the bladder, though certain mucous follicles which exist, especially near the neck of the bladder, have been regarded as such.
Vessels and Nerves.ЧThe arteries supplying the bladder are the superior, middle, and inferior vesical, derived from the anterior trunk of the hypogastric. The obturator and inferior gluteal arteries also supply small visceral branches to the bladder, and in the female additional branches are derived from the uterine and vaginal arteries.
The veins form a complicated plexus on the inferior surface, and fundus near the prostate, and end in the hypogastric veins.
The nerves of the bladder are (1) fine medullated fibers from the third and fourth sacral nerves, and (2) non-medullated fibers from the hypogastric plexus. They are connected with ganglia in the outer and submucous coats and are finally distributed, all as non-medullated fibers, to the muscular layer and epithelial lining of the viscus.
Abnormalities.ЧA defect of development, in which the bladder is implicated, is known under the name of extroversion of the bladder. In this condition the lower part of the abdominal wall and the anterior wall of the bladder are wanting, so that the fundus of the bladder presents on the abdominal surface, and is pushed forward by the pressure of the viscera within the abdomen, forming a red vascular tumor on which the openings of the ureters are visible. The penis, except the glans, is rudimentary and is cleft on its dorsal surface, exposing the floor of the urethra, a condition known as epispadias. The pelvic bones are also arrested in development.