Anatomy Lecture Notes: Digestive System PDF

— Lecture 23 — Digestive System (Part-1) Organs of the Digestive System General Concepts of the Digestive System Abdomen is a cylindrical chamber extending from the inferior aspect of the thorax to superior margin of pelvis. Abdomen and pelvic cavity are continuous. Abdomino-pelvic space is called p...

— Lecture 23 — Digestive System (Part-1) Organs of the Digestive System General Concepts of the Digestive System Abdomen is a cylindrical chamber extending from the inferior aspect of the thorax to superior margin of pelvis. Abdomen and pelvic cavity are continuous. Abdomino-pelvic space is called peritoneal cavity. Abdominal viscera are suspended within peritoneum. Oral Cavity Buccal cavity or mouth extends from lips to pharynx. It divides into two parts: 1. Vestibule which lies between the lips and the cheeks externally, the gums and teeth internally. 2. Mouth cavity proper extends from the teeth in front, to the root of the tongue behind. Boundaries of oral cavity: 1. Superior/ roof: Hard palate and soft palate (posterior). 2. Anterior and lateral: Cheeks, lips, and teeth. 3. Posterior: Uvula, palatine tonsils, and root of tongue. 4. Inferior: Tongue-skeletal muscle. Tongue The tongue is a mass of striated muscle covered with mucous membrane. The mucous membrane of the upper surface of the tongue can be divided into anterior 2/3rd or oral part and posterior 1/3rd or pharyngeal part by a V-shaped sulcus, the sulcus terminalis. Sensory nerve supply of the tongue: Anterior 2/3rd oral part: General sensory supply by lingual nerve, a branch of the mandibular nerve (CN-V) Special sensory supply (taste) by chorda tympani, a branch from facial (CN-VII) nerve. Posterior 1/3rd pharyngeal part: General and special sensory supply (taste) by glossopharyngeal (CN-IX) nerve. Motor nerve supply of the tongue: supply to the muscles of the tongue is from hypoglossal nerve (CN-XII). Salivary Glands Salivary glands are glands that open or secrete into the oral cavity. Minor salivary glands are located throughout the submucosa of the oral cavity. The larger salivary glands include the paired parotid, submandibular, and sublingual glands. Parotid gland: Largest salivary gland located on the lateral side of face, anterior to ear. Its duct empties in the vestibule of the mouth opposite the 2nd upper molar tooth. Submandibular gland: It lies on the medial surface of mandible. It is divided into superficial and deep parts by the mylohyoid muscle. Its duct drains into the floor of the mouth near lingual frenulum posterior to lower incisors. Sublingual gland: It is the smallest of salivary glands. It has both serous and mucous acini, with the latter predominating. It is drained by 10 small ducts which open in the floor of mouth near lingual frenulum. Wall of the GI Tract The wall of the GIT consists of four layers: Consists of: Inner epithelial lining that vary with location. Mucosa Lamina propria is a layer of areolar connective tissue under the epithelium. Muscularis mucosae is a thin smooth muscles layer under lamina propria. Layer of dense irregular connective tissue that surrounds the mucosa. Submucosa It contains blood vessels, nerves (Meissner’s plexus), lymphatic vessels and glands. Smooth muscles arranged in two layers except in stomach (3 layers): An inner circular muscle (squeezes the gut) Muscularis Externa An outer longitudinal muscle layer (shortens the gut for movement of materials). Myenteric nerve plexus is present between the inner circular and outer longitudinal muscles. Serosa Visceral peritoneum that covers the muscularis externa along most of the digestive tract. Note: Don’t confuse between Meissner’s plexus in Submucosa and Myenteric nerve plexus in Muscularis Externa. Esophagus The esophagus is a muscular tube that connects pharynx to the stomach. Major portion of the esophagus lies in neck and thorax. The muscles of the upper third of the esophagus is skeletal muscle, the lower thirds is smooth, and middle is mixed. It pierces the diaphragm, at T10 vertebral level. Blood supply Arteries: Inferior thyroid arteries and left gastric artery. Veins: Inferior thyroid veins and left gastric vein (tributary of portal vein). The Stomach The stomach is a muscular sac, lies in the epigastric, umbilical, and left hypochondriac regions of the abdomen. It has four main regions: 1. Cardia: It surrounds the superior opening of the stomach. 2. Fundus: The rounded dome like portion superior to the cardiac orifice of stomach. 3. Body: The main portion of the stomach. It extends from the cardiac opening to the angular notch. 4. Pylorus: Connects stomach to duodenum. It is divided into the pyloric antrum and pyloric canal. The Pyloric canal opens in the duodenum Pyloric Sphincter The pyloric opening opens into the duodenum and is surrounded by the pyloric sphincter, which is a layer of thickened circular smooth muscles. It controls the rate of emptying of stomach contents into the duodenum. It has two surfaces: 1. Anterior and Posterior surfaces The stomach has two curvatures: 1. The concave medial border (the lesser curvature). 2. The convex lateral border (the greater curvature). Small Intestine It is the 1st part of the small intestine. It is the shortest, widest and most fixed part of small intestine. Contains numerous duodenal (Brunner’s) glands in submucosa. Duodenum It is C-shaped tube surrounds the head of the pancreas. Most of the duodenum is retroperitoneal. It is divided into four parts: 1st (superior), 2nd (descending), 3rd (transverse), and 4th (ascending) part Intraperitoneal. Jejunum Mainly lies in upper abdominal cavity. Has numerous elevated sub-mucosal circular folds, plicae circularis and abundant, long villi. Last part of small intestine. Mainly lies in lower abdominal and pelvic cavity. Ileum Has few plicae circularis and short villi. Submucosa contains aggregated lymphoid nodules, Payer’s patches. The ileocecal valve controls flow of material into cecum from ileum. Large Intestine It consists of the: cecum, vermiform appendix, colon, and rectum. The colon has ascending, transverse, descending and sigmoid parts. The ascending and descending parts are retroperitoneal and transverse colon is intraperitoneal. Special features of the colon: 1. Taeniae coli: Longitudinal muscles are thickened forming three bands. 2. The sacculations: Linear series of sac like structure, between taeniae coli. These sacs are called as haustra, haustrum (singular). 3. Omental appendages: Small pouches of peritoneum filled with fat. Rectum A continuation of the sigmoid colon. Last 15 cm of digestive tract It ends in front of the tip of the coccyx, pierces pelvic diaphragm (levator ani) and becomes continuous with the anal canal. It is expandable for temporary feces storage. The muscular coat is arranged in the usual outer longitudinal and inner circular layers of smooth muscle. The anal canal is about 4 cm long and passes downward and backward from the rectal ampulla to the anus. — Lecture 24 — Digestive System (Part-2) Four Abdominal quadrants Two planes, vertical median and a horizontal transumbilical, divide the whole abdomen into four quadrants. Nine Regions of the Abdomen Three regions on each side: The right and left hypochondrium: This region lies deep to the costal cartilages. The right and left lumbar/flank region: This region is on the side of the umbilical region below the hypochondrium. The right and left groin/iliac region: This region is inferior to the flank and lateral to the pubic region. The abdomen can be divided into nine regions by: 1. Midclavicular point (above) to midinguinal point (below), two vertical planes. 2. Subcostal and intertubercular (two horizontal planes). These planes separate the abdomen into nine regions. Three central regions: Epigastric regions: It is an upper central region inferior to the sternum. Umbilical regions: It is a middle central region around the umbilicus. Hypogastric (Pubic) regions: It is a lower central region superior to the pubic bones. Muscles of the Anterolateral Abdominal Wall Five muscles makeup the anterior abdominal wall. Three flat muscles pass anteriorly from the posterolateral abdominal wall. Muscle fibers are replaced anteriorly by aponeurosis towards midline. The three flat muscles are: 1. External oblique abdominis. 2. Internal oblique abdominis. Inferior 3. Transversus abdominis. Lateral Different directions of muscle fibers provide for the increase in tensile strength. Two vertical muscles, the Rectus abdominis and Pyramidalis are located in midline. These are enclosed in tendinous sheath, the Rectus sheath. Weakening/ defects/ trauma of these muscles causes bulging and result in hernias. Anterolateral Abdominal Wall The anterior abdominal wall consists of: (from superficial to deep). Skin Superficial fatty (Camper’s) fascia Deep membranous (Scarpa’s) fascia Three muscles Fascia transversalis Extraperitoneal fascia The umbilicus is a scar representing the site of attachment of the umbilical cord in the fetus; it is situated in the linea alba. The skin is loosely attached to the underlying structures except at the umbilicus. Parietal peritoneum Anterolateral Abdominal Wall-Fascia Superficial fascia: The superficial fascia are of two types: Superficial fatty layer (Camper’s fascia): It is continuous with the superficial fat over the rest of the body and may be extremely thick in obese patients. Deep membranous layer (Scarpa's fascia): It is thin and fades out laterally and above. Deep Fascia: It lies deep to the membranous layer of superficial fascia, and It is a thin layer of connective tissue covering the muscles. The Liver The liver is the soft, pliable largest gland in the body. It lies under the diaphragm in the right hypochondrium and epigastric regions, extending into the left hypochondrium. It is an intraperitoneal organ Surfaces of the liver: Diaphragmatic smooth surface under the diaphragm. Irregular surface- molded to adjacent viscera. and is therefore in shape. Lobes of the liver (four lobes): Right lobe is separated from left lobe by the falciform ligament. Left lobe is smaller than right lobe. Caudate lobe is present between the left lobe and inferior vena cava. Quadrate lobe present between left lobe and gallbladder. Porta (gateway) hepatis, or hilum: it found on the posteroinferior (visceral) surfaceand lies between the caudate and quadrate lobes. The upper part of the free edg of the lesser omentum is attached to its margins Note: the lesser omentum is a ligament that ties the stomach and the liver. Porta hepatis is pierced by: 1. Right and left hepatic branches of the hepatic artery (entering) proper. 2. Right and left hepatic ducts (exiting) of common hepatic duct. 3. Portal vein (entering). Blood supply: The hepatic artery proper (branch of celiac trunk). The portal vein (from GIT). Gall Bladder Gallbladder is a pear-shaped sac attached to the under (visceral) surface of the liver. It has three regions: fundus, body and neck. It is drained by cystic duct. The cystic duct joins with common hepatic duct to form the common bile duct. It store and concentrate bile which is produced by the liver. Bile is released into duodenum when hepatopancreatic sphincter (of Oddi) is relaxed. Blood Supply: Cystic artery: a branch of the right hepatic artery supplies the gallbladder. Cystic vein drains directly into the portal vein. Pancreas The pancreas is an elongated structure that lies in the epigastrium and the left upper quadrant. It is soft and lobulated and is retroperitoneal structure. The pancreas is both an exocrine and an endocrine gland. The exocrine portion of the gland produces a secretion that contains enzymes capable of hydrolyzing proteins, fats, and carbohydrates. The pancreas is divided into a head, neck, body, and tail. The head of pancreas lies within the C-shaped concavity of the duodenum. A part of the head extends to the left behind the superior mesenteric vessels and is called the uncinate process. Pancreatic duct begins in the tail and runs the length of the gland. It opens into the second part of the duodenum with the bile duct on the major duodenal papilla. Accessory pancreatic duct occurs in 3%–10% of people, drains the upper part of the head. Blood Supply: Pancreatic (branched) artery from splenic artery. Superior and inferior pancreaticoduodenal arteries supply the head of pancreas. The corresponding veins drain into the portal system. — Lecture 25 — Digestive System (Part-3) Peritoneum The peritoneum is the largest serous membrane in the body. It consists of the parietal and visceral layers. Parietal Peritoneum lines the abdominal and pelvic walls and the inferior surface of the diaphragm. Visceral Peritoneum covers the viscera. The peritoneal cavity is space between the parietal and visceral layers. It contains serous fluid that lubricates the peritoneal surfaces and allows free movement of the viscera. The retroperitoneal space is behind the peritoneum on the posterior abdominal wall. Peritoneal Space Lesser Sac (Omental Bursa) is a peritoneal space that lies behind the stomach and the lesser omentum. It extends upward as far as the diaphragm and downward between the layers of the greater omentum. The greater sac is the main compartment of peritoneal cavity. It extends from the diaphragm down into the pelvis. The greater and lesser sacs are in free communication with one another through an oval window called the epiploic foramen. Peritoneal Folds Peritoneal folds support the viscera and provide pathways for the nerves and vessels which supply the viscera Greater Omentum: It is the largest peritoneal fold containing fat in its layers. It extends from the greater curvature of the stomach to the transverse colon. Lesser Omentum: It Is a double layer of peritoneum that extends from Porta hepatis and along ligamentum venosum on the undersurface of the liver to the lesser curvature of the stomach and the first part of the duodenum. Mesenteries Mesenteries are double-layer folds of peritoneum that connect the intestines to the posterior body wall, and provide pathways for blood vessels and nerves to these viscera. Transverse mesocolon Suspends the transverse colon Sigmoid mesocolon Suspends the sigmoid colon. The mesentery (proper) Suspends the small intestine; (jejunum and ileum). Mesoappendix Connects the appendix to the mesentery of the ileum. Intraperitoneal and Retroperitoneal Intraperitoneal organs have a mesentery or are covered by the peritoneum. Intraperitoneal organs Examples: stomach, small intestine (bowel), transverse colon, liver, gallbladder. Retroperitoneal organs without a mesentery and are present behind the peritoneum associated with posterior body wall. Examples: aorta, inferior vena cava, kidneys, suprarenal Retroperitoneal glands, ascending and descending colon. organs Blood Supply of the Stomach Branches from celiac trunk: 1- lesser curvature by left and right gastric arteries. 2- greater curvature by right and left gastroepiploic arteries. 3- fundus by short gastric arteries. Veins: The veins corresponding to the arteries drain into the portal vein. Blood Supply of GIT The GIT is divide into three parts: Fore gut, Mid gut and Hind gut From the esophagus to 2nd part of duodenum, including the liver, pancreas and spleen. It is supplied by Celiac trunk. 1. Fore gut It is very short and arises from the abdominal aorta at the level of the 12th thoracic vertebra. It has three terminal branches: 1. left gastric 2. splenic, and 3. hepatic arteries. Begins from 2nd part of duodenum to 2/3rd of the transverse colon. It is supplied by Superior mesenteric artery. 2. Mid gut Superior mesenteric artery arises from the front of the abdominal aorta just below the celiac artery. The superior mesenteric artery supplies the distal part of the duodenum, the jejunum, the ileum, the cecum, the appendix, the ascending colon, and most of the transverse colon (proximal 2/3 rd). Begins from the last 1/3rd of transverse colon to upper part of anal canal It is supplied by Inferior mesenteric artery. Inferior mesenteric artery arises from the abdominal aorta. Inferior mesenteric artery terminates as the superior rectal artery. 3. Hind gut The inferior mesenteric artery supplies the distal 1/3rd of the transverse colon, the left colic flexure, the descending colon, the sigmoid colon, the rectum, and the upper half of the anal canal. Note: Lower part of the rectum and anal canal is supplied by the middle and inferior rectal arteries. Venous Drainage of GIT The venous blood from the greater part of the GIT and its accessory organs drains to the liver by the portal venous system. Portal Vein: Drains blood from most of the GIT (from lower third of the esophagus to halfway down the anal canal). It also drains the spleen, pancreas, and gallbladder. The portal vein enters the liver and breaks up into sinusoids, from which blood passes into the hepatic veins that join the inferior vena cava. Tributaries of the Portal Vein: tributaries of the portal vein are the splenic vein, superior mesenteric vein, left gastric vein, right gastric vein, and cystic veins. Systemic Circulation: 1. Upper third 2/3 of the esophagus drains into the azygos veins (part of systemic circulation). 2. Lower half of the anal canal is also drained by middle and inferior rectal veins (systemic circulation). Porto-Systemic Anastomoses In the portal circulation blood passes through two sets of capillaries before it reaches back to heart. First set of capillaries is formed in the wall of GIT and drain into the portal vein, that goes through the portal vein into the liver. Second set of capillaries is formed inside the liver and drain through the hepatic veins into the inferior vena cava which is a part of systemic circulation. Smaller communications (anastomoses) exist between the portal and systemic circulations and they become enlarged when the portal route becomes blocked by liver disease. Porto-Systemic Anastomoses The communications (anastomoses) exist between the portal and systemic circulations are as follows: A. Lower 1/3 of esophagus: The esophageal branches of the left gastric vein (tributary of portal vein) anastomose with the esophageal branch (which is draining the middle 1/3 of the esophagus) into the azygos vein (tributary of systemic vein). Enlarged esophageal veins cause development of esophageal varices. B. Anal canal The superior rectal veins (portal tributary) draining the upper half of the anal canal anastomose with the middle and inferior rectal veins (systemic tributaries), which drain the lower half of the anal canal. Enlarged rectal veins develop hemorrhoids. — Lecture 26 — Urinary System Part-1 Components of the Urinary System The urinary system comprises of: Two kidneys. Two ureters. Urinary bladder. Urethra. Position of the Kidneys Kidneys are retroperitoneal organs which lie obliquely in the superior lumbar region on posterior abdominal wall. Right kidney lies slightly lower than the left kidney. Right kidney may be palpated in thin individuals at the end of deep inspiration. The levels of the kidneys alter with respiration and posture. Relations of Kidneys Right Kidney Anterior relations Posterior relations Right suprarenal gland. Liver. 2nd part of the duodenum. Right colic flexure. Left Kidney Left suprarenal gland. Spleen. Stomach. Pancreas. Left colic flexure. Coils of jejunum. Diaphragm. Costodiaphragmatic recess of the pleura. Muscles (psoas, quadratus lumborum, and transversus abdominis). 3 nerves (subcostal, iliohypogastric, ilioinguinal) running downward and laterally. 12th rib (Rt. kidney), 11&12th ribs (Lt. kidney). Renal Coverings Fibrous capsule closely applied to the kidney. Peri-renal (peri-nephric) fat surrounds the capsule and acts as a shock absorber, holds the kidney in place. Renal fascia anchors the kidney to the abdominal wall. Pararenal fat external to the renal fascia, hold the kidneys in position on the posterior abdominal wall. External Features of the Kidney Size 12x6x3 cm. Weight about 130 gms. Shape Bean shaped. Surfaces Poles Borders Anterior & Posterior. Superior & Inferior. Lateral & Medial. Hilum of kidney It is area on the medial border where structures (vein, artery, renal pelvis) enter and leave kidney. Renal Sinus Renal sinus is space which contains the upper expanded end of the ureter, the renal pelvis. Internal Features of the Kidney Cortex is an outer peripheral zone that extends into the medulla between adjacent pyramids as the renal columns. Extending from the bases of the pyramids into the cortex are striations (lines) called medullary rays. Medulla is inner to cortex, composed of renal pyramids, the bases of which are towards the cortex, and the apices (renal papilla) connects to the minor calyxes. Renal pelvis is an expanded, funnel shaped, superior part of a ureter present in the renal sinus. It divides into 2-3 short tubes, the major calices. Each major calyx divides again into 7-14 minor calices. Each minor calyx receives the openings of collecting tubules on the papilla of the pyramid that projects into the minor calices. Nephron A nephron (Uriniferous tubules) is an structural and functional unit of a kidney. Each kidney has about 1 million nephrons. Each nephron consists of Proximal tubule, Intermediate tubule, Distal tubule, and Collecting duct. Renal corpuscle consists of a glomerulus (red capillaries) inside bowman’s capsule Glomerular (Bowman’s) capsule is a proximal cup shaped part of the renal tubule (nephron). Blood Supply of The kidneys About 20 to 25% of cardiac output goes to kidneys. Renal Arteries: Right and Left renal arteries arise from aorta at the level of L2 vertebra. Renal Arteries Renal artery divides into 5-6 segmental arteries, as it enters the hilum of the kidney. Segmental arteries branch into lobar arteries which reaches the lobes. lobar arteries runs to reach the lobes present inside each segments, they divide and runs between the lobules as Interlobar arteries. Interlobar arteries gives a branch that runs over the bases of the pyramids and anastomose with another one to form an arch. They run at the bases and called as arcuate arteries. Arcuate arteries send interlobular arteries into cortex. Interlobular (straight) arteries give rise to afferent glomerular arterioles. Venous Drainage of the Kidney Interlobular veins to Arcuate veins to Interlobar veins to lobar vein to the renal vein which drains into inferior vena cava (IVC). The renal vein emerges from the hilum in front of the renal arteries and drains into IVC. Lymph Drainage: Lymph drains to lateral aortic lymph nodes around renal artery origin. Because 25% of the cardiac outflow passes through the kidneys, renal injury can result in rapid blood loss. — Lecture 27 — Urinary System (Part-2) Renal Pain Renal pain can result from stretching of the renal capsule or spasm of the smooth muscle in the pelvis. Pain can vary from a dull ache to a severe pain in the flank that radiates downward to the lower abdomen. Pain is usually referred along the distribution of the subcostal (T12) nerve. The Ureters The ureters are about 25 cm long tubes that leave each renal pelvis and carry urine to the bladder. The ureters descend behind the peritoneum and cross pelvic brim. The ureters enter obliquely on the posterolateral corners of bladder. This oblique entry acts as a valve and helps prevent backflow of urine. Constrictions of the Ureters There are 3 constrictions of the ureter along its course where kidney stones may be arrested. 1. Pelviureteral junction: Where the renal pelvis joins the ureter. 2. Pelvic brim: Where it is kinked as it crosses the pelvic brim. 3. Bladder: Where it pierces the bladder wall obliquely. Urinary Bladder It is distensible muscular sac that stores and expels urine. Lies on pelvic floor posterior to pubic symphysis; In males anterior to rectum and In females anterior to the vagina and uterus. It has an apex, a base (inferoposterior), a superior surface, and two inferolateral surfaces. The apex is directed toward the top of the pubic symphysis. The base is shaped like an inverted triangle and faces inferoposterior. The two ureters enter the bladder at each of the upper corners of the base, and the urethra drains from the lower corner of the base. Blood Supply of Ureters & Urinary Bladder Ureters Arteries: 1. Upper end is supplied by the renal artery 2. Middle portion is supplied by the testicular or ovarian artery. 3. Lower end (pelvic portion) is supplied by the superior vesical artery. Veins: veins correspond to the arteries. Urinary Bladder Arteries: Superior & Inferior Vesical arteries from the internal iliac artery. Veins: Communicates with vesical venous plexus. The prostatic plexus, drain into the internal iliac vein. Male Urethra The male urethra is about 20 cm long and extends from the neck of the bladder to the external meatus. It is divided into three parts: 1. Prostatic urethra is about 3 cm long and passes through the prostate gland. It is the widest and most dilatable portion of the urethra. 2. Membranous urethra is about 1.25 cm long and lies within the urogenital diaphragm. It is the least dilatable portion. 3. Penile (spongy) urethra is about 15.75 cm long traversing through the bulb and the corpus spongiosum of the penis. The bulbourethral glands open into the penile urethra below the urogenital diaphragm. The external urethral meatus is the narrowest part of the entire urethra. The navicular fossa is the part of the urethra that lies within the glans penis. In males the urethra provides a common passage for urine (urinary system) and semen (reproductive system). Female Urethra It is about 3.8cm long tube which extends from the neck of the urinary bladder and exits the body between the clitoris and the vagina. At the sides of the external urethral sphincter are the small openings of the ducts of the paraurethral glands. In females the urethra provides a passage only for urine (urinary system). — Lecture 28 — Male Reproductive System Male Reproductive Organs Components of male genital system: Scrotum: A pouch of skin which encloses and protects the testes. Testis: The male primary sex organ. Ducts: The main ducts are: 1. Epididymis 2. Ductus deferens (vas deferens) 3. Ejaculatory ducts 4. Urethra Accessory reproductive glands are: 1. The prostate gland 2. The seminal vesicles 3. The bulbourethral glands The penis: Erectile organ. Scrotum The scrotum is a fibro-muscular sac covered by skin. It contains: 1. testis 2. epididymis and 3. lower part of the spermatic cord. It is situated inferior to the pubic symphysis. On the outer skin there is a midline scrotal raphe, that is continuous as central line on the ventral surface of the penis. Along the scrotal raphe deep inside there is scrotal septum that divides the inside region into two compartments, one for each sided testis. The wall of the scrotum has the following layers: 1. Skin. 2. Superficial fascia (Dartos muscle in scrotum). 3. External spermatic fascia. 4. Cremasteric muscle and fascia. 5. Internal spermatic fascia. 6. Tunica vaginalis- a closed sac around each testis. The Testes They are paired, ovoid and mobile organs located in the scrotum. Produces: sperm and secretes hormones Surrounded by two coverings: Tunica vaginalis – (peritoneal origin) has inner visceral and outer parietal layers Tunica albuginea –(dense fibrous capsule) forming the outer wall with series of septa passing inwards to divide the testis into 250-300 lobules. Each lobule contains 1 to 3 tightly coiled seminiferous tubules. Blood Supply of the Testes and Epididymis 1. The testicular arteries to the testes arise from the abdominal aorta. 2. The venous drainage of the testis and epididymis is through the pampiniform venous plexus. – At the upper pole of the testis, it forms the testicular vein. – The right testicular vein drains into the inferior vena cava, and the left testicular vein joins the left renal vein. Epididymis It is a 7m long, single, tortious, comma shaped tube. Lies superior and posterior to the testis. Efferent ductules from testis open into epididymis. It extends from the upper pole of testis and continues in ductus deferens and consists of: – Head. – Body. – Tail: leads to ductus deferens. Functions of the epididymis: Stores sperm and facilitates their maturation. Sperm are ejaculated from the epididymis. Vas Deferens Ductus (Vas) deferens is 18 inches long fibromuscular tube. It begins as a continuation of the tail of epididymis. It conveys mature sperm from the epididymis to the ejaculatory duct and the urethra. It passes within the spermatic cord, then through the inguinal canal into the pelvic cavity. At the lateral pelvic wall, it crosses the obturator vessels and the ureter to reach the posterior surface of urinary bladder. Vas Deferens and Ejaculatory duct Its terminal part is dilated to form the ampulla, that joins the duct of the seminal vesicle to form the ejaculatory duct. The ejaculatory duct pierces the prostate gland and opens in the prostatic urethra. Penis The penis is an erectile organ composed mainly of the two corpora cavernosa and the single corpus spongiosum, which contains the urethra. They are covered by their respective muscles called as ischiocavernosus and bulbospongiosus. The corpus spongiosum expands to become the head of penis (glans penis). Spermatic Cord 1. It is a collection of structures that pass through the inguinal canal to the testis. 2. Extends from the superior extremity of testis to the deep inguinal ring of the inguinal canal. Coverings of the spermatic cord 1. External spermatic fascia – From external oblique. 2. Cremaster muscle and fascia – From internal oblique. 3. Internal spermatic fascia – From fascia transversalis. Contents of the spermatic cord 1. Ductus deferens. 2. Arteries: – Testicular artery. – Artery of the ductus deferens. – Cremasteric artery. 3. Veins: – Pampiniform plexus. 4. Nerves: – Genital branch of the genitofemoral. – Sympathetic nerve fibres. Accessory Glands Provide 95% of the seminal fluid 1. Prostate Gland 2. Seminal Vesicles 3. Bulbourethral glands Prostate It is located inferior to the bladder and anterior to the rectum. It encircles the urethra as it leaves the urinary bladder. It It is perforated by the urethra and the ejaculatory ducts. Prostate is a firm, fibro-muscular gland. It consists of numerous glands embedded in the fibro-muscular tissue. Its ducts open into the prostatic urethra. Enclosed by a thin inner fibrous capsule (true capsule) and a strong outer covering of pelvic fascia. It can be palpated through the rectum when enlarged. Seminal Vesicles Seminal vesicles are 2 lobulated coiled glands located on the posterior surface of bladder, lateral to the ampulla of vas deferens. The duct of each seminal vesicle joins the vas deferens to form the ejaculatory duct. The seminal vesicles produce a fluid that provides sperm with a source of energy and helps with the sperm's motility (ability to move) The fluid of the seminal vesicles makes up most of the volume of the seminal fluid, or ejaculate Bulbourethral Glands Bulbourethral (Cowper’s) glands are two pea-sized glands, located lateral to the membranous part of the urethra. The ducts of the glands open into the penile portion of the urethra. Produce about 10% of seminal fluid. This fluid serves to lubricate the urethra and to neutralize the acidity of the residual drops of urine in the urethra. — Lecture 29-30 — Female Reproductive System Female Reproductive Organs The reproductive tract in women is contained mainly in the pelvic cavity and perineum. The female reproductive organs consists of: Ovaries: Produces ova and sex hormones. Reproductive ducts: 1. Fallopian tubes: Transmit and nourish sperms and ova, site of fertilization. 2. Uterus: Reception, retention and nourishment of fertilized ovum, foetal development. 3. Vagina: Organ of copulation. Accessory glands: Greater vestibular glands: Homologous to bulbo-urethral (Cowper’s) glands in males. External genitalia: Female pudendum (external genitalia). Ovaries Ovaries are located on the lateral wall of pelvis, in the ovarian fossa. Ovaries lie in the angle between external and internal iliac vessels. Each ovary is connected to the posterior aspect of the broad ligament by the mesovarium. The surface (or germinal) epithelium is the same mesothelial layer that forms the peritoneum. Underneath the germinal epithelium, the ovary is surrounded by a dense connective tissue capsule called the tunica albuginea. Ovaries Function Functions: 1. Produce eggs (ova). 2. Produce hormones ( Estrogen & Progesterone). During childhood ovaries are small and the surfaces are smooth. After puberty ovaries surface becomes scarred due to ovulation. After menopause: ovaries shrink and atrophy gradually due to lack of hormones and surface is more scarred. Ovaries Surfaces & Borders Surfaces: 1. Medial (facing uterus). 2. Lateral (attached to the lateral pelvic wall). Borders: 1. Posterior free border 2. Anterior (mesovarian), attached to broad ligament. Poles: 1. Superior pole/tubal extremity, close to the fimbria of oviduct. 2. Inferior pole/uterine extremity, connected to the uterus by the ovarian ligament. Ovareis Structure & Ligaments Structure: Cortex: contain ovarian follicles in different stages of the development. Medulla: central connective tissue containing blood vessels and nerves. Supporting Ligaments: The ovaries are not attached to the fallopian tubes but are suspended nearby from several ligaments. 1. Ovarian ligament: Connects the ovary to the uterus just below the uterine tube entrance. 2. Suspensory ligament of ovary: Contains the ovarian vessels 3. Mesovarium: The anterior border of ovary is attached to the posterior layer of the broad ligament by the mesovarium. Blood Supply of Ovaries Arteries: Ovarian artery (a branch of the abdominal aorta) enters the suspensory ligament of the ovary, runs medially in the mesovarium, and supplies the ovary. Anastomosis with uterine artery (a branch of internal iliac artery). Veins: The ovarian vein drains into inferior vena cava on the right side. Left renal vein on the left side. Fallopian Tubes/Uterine Tubes/Oviducts Location: lies in the upper border of broad ligament, between its two layers. Functions: 1. Transport the ovum from the ovary to the uterus. 2. Connect the peritoneal cavity with the uterine cavity. 3. Provide site for fertilization and nutrition for the sperm and the fertilized ovum. It is divided into 4 parts: 1. Uterine /Intramural part: Traverses the uterine musculature and opens into the uterine cavity 2. Isthmus: Thick walled, narrowest part. 3. Ampulla: Widest part of tube. Site of fertilization. 4. Infundibulum: Funnel shaped terminal part, formed of fimbriae which spread over the ovary. Opens into peritoneal cavity through abdominal ostium. Fallopian tube obstruction or narrowing may cause infertility. Inflammation of the fallopian tubes is called Salpingitis. It is most common site of ectopic pregnancy, Ligation and cutting of uterine tube is a method of permanent birth control. It is usually performed at the isthmus part of the uterine tube. Blood supply: Uterine and ovarian arteries. Uterine and ovarian veins. Uterus Uterus is a pear shaped muscular organ. Location and Positions: Lies in the pelvic cavity between the urinary bladder and the rectum. In the erect position when the bladder is empty, the uterus lies in an almost horizontal plane. The normal position of uterus is: Anteverted (forward bending); axis of (cervical canal of) uterus at 90° with that of vagina). Anteflexed (axis of body of uterus is bent forward (170°) with that of the cervix). In some women, the uterus is bent backward on the vagina. The uterus is then, said to be retroverted. It is divided into: Fundus Rounded part above the entrance of the uterine tube. Body Main part of uterus, inferior to the fundus and superior to the isthmus. Isthmus Narrow part between the cervix and the body, corresponds to internal os. Cavity of uterus It is triangular in coronal section. Relations: Anteriorly Urinary bladder Posteriorly The anterior surface of rectum Laterally The broad ligament Uterine wall is made up of: Perimetrium (surrounding womb) outer coat, serosal visceral peritoneum. Myometrium (muscle of womb) middle thick smooth muscle layer. Increases in size during pregnancy due to muscular hypertrophy. Endometrium glandular layer (mucosa) It undergoes changes every month as part of the menstrual cycle. Implantation of the blastocyst (future embryo) occurs in this layer. Supports of the Uterus Pelvic diaphragm Surrounding organs: vagina and bladder Ligaments: Broad ligament of uterus. Round ligament of uterus. Pubo-cervical ligament. Transverse cervical ligament (Cardinal ligament) of uterus. Pubo-cervical ligament. Supports of the Uterus Anteriorly Laterally Pubocervical ligaments: from the posterior surface of pubis to the cervix. Transverse cervical ligaments (Cardinal ligament of uterus): provide lateral support to the uterus? Uterosacral ligament of uterus: maintain body of uterus in ante flexed position. Posteriorly Round ligament of uterus: maintain ante-verted position of uterus. Broad Ligament Broad ligament is a sheet like fold of peritoneum that runs from the lateral pelvic wall to the uterus. It encloses the uterine tube in its superior margin and suspends the ovary to its posterior aspect. The broad ligament has three parts: 1. Mesometrium 2. Mesosalpinx 3. Mesovarium Cervix It is the inferior narrow part of the uterus that projects into the vagina and is divided into: 1. Internal os: the junction of the cervical canal with the uterine cavity. 2. Cervical canal: the cavity of the cervix between the internal and external ostia. 3. External os: the opening of the cervical canal into the vagina. Cervix Blood Supply: Uterine artery: (branch of internal iliac artery) supplies the uterus, cervix and vagina. Ovarian artery: (branch of abdominal aorta) Both ovarian and uterine arteries anastomose. (collateral blood supply) Veins: drain into internal iliac veins. Vagina It is a fibromuscular tube about 7-9 cm long. It extends from cervix to vestibule. It serves as a: 1.Passageway for menstrual fluid. 2.Birth canal. 3.Receptacle for intercourse. Its external orifice is covered by a fold of mucous membrane called hymen. Relations Anteriorly Laterally Posteriorly Fundus of bladder and urethra. Levator ani muscle, ureters. Anal canal, rectum and rectouterine pouch. Blood Supply Arterial supply Superior part by uterine and vaginal arteries. Venous drainage Vaginal venous plexus, drains into the internal iliac veins.