Abdomen Complete 200L PDF

THE ABDOMINAL WALL  THE ABDOMINAL WALL The abdominal wall surrounds the abdominal cavity, providing it with flexible coverage and protecting the internal organs from damage Bounded superiorly by the xiphoid process and costal margins, posteriorly by the vertebral column...

THE ABDOMINAL WALL  THE ABDOMINAL WALL The abdominal wall surrounds the abdominal cavity, providing it with flexible coverage and protecting the internal organs from damage Bounded superiorly by the xiphoid process and costal margins, posteriorly by the vertebral column and inferiorly by the pelvic bones and inguinal ligament. It can be divided into two sections: anterolateral and posterior abdominal walls, which consists of numerous layers, from superficial to deep: skin, superficial fascia, muscles and their respective fasciae, and peritoneum.  The anterolateral abdominal wall Spans the anterior and lateral sides of the abdomen, can be divided into several topographical areas, which are used to describe the location of abdominal organs and the pain associated with them: Four quadrants, which are divided by the horizontal transumbilical and vertical median planes. The four resulting areas are called right upper, left upper, right lower and left lower quadrants. Nine abdominopelvic regions, which are divided horizontally by the superior subcostal plane, which passes right under the costal margins of the 10th ribs, and the inferior intertubercular plane, which connects the tubercules of the iliac crest. Vertically they are divided by the two midclavicular planes which pass through the midpoint of each clavicle and halfway between the pubic symphysis and the anterior superior iliac spine. The four planes create nine abdominal regions: hypochondriac (right, left) and epigastric regions superiorly, flanks (right, left) and umbilical region in the middle, groin (right, left) and hypogastric region inferiorly.  Fascia The skin is the most superficial layer of the anterior abdominal wall. In pregnant women, obese people and those with abdominal distention, it can contain elongated lines called stretch marks or striae distensae, usually situated in the umbilical and hypogastric regions. The superficial fascia is located just below the skin and consists of connective tissue. In the anterior abdominal wall, superior to the umbilicus, it is similar and continuous to the superficial fascia of the body and is made up mostly of one layer. However, inferior to the umbilicus, it is divided into two layers: Superficial Camper’s fascia, which is a thicker fatty layer that can have a variable degree of thickness. For example, it is greatly increased in obese individuals and very thin in people with low body fat.  Deep Scarpa's fascia, which is a thinner and denser membranous layer overlying the muscle layer of the abdominal wall. It is firmly attached to the linea alba and pubic symphysis and fuses with the fascia lata (deep fascia of the thigh) right below the inguinal ligament. In men, the Camper’s fascia continues over the penis and blends with the Scarpa’s fascia to form the superficial fascia of the penis. The latter extends further on into the scrotum, where it contains smooth muscle fibers and becomes the dartos fascia. Scarpa’s fascia continues into the perineum to form the superficial fascia of the perineum, called Colles’ fascia. In women it continues into the labia majora and anterior perineum.  Muscl The muscles of the anterolateral es abdominal wall are divided into two main groups: Lateral flat muscle group situated on either side of the abdomen, which includes three muscles: external oblique, internal oblique and transversus abdominis. Anterior vertical muscles situated bilaterally to the median fibrous structure called linea alba. They are called rectus abdominis and pyramidalis muscles. Lateral abdominal muscles Anterior abdominal wall muscles The anterior muscle group includes the rectus abdominis and pyramidalis muscles. These are almost completely enveloped by the thick rectus sheath formed by the aponeuroses of the lateral abdominal muscles. The rectus abdominis muscles are a pair of long, straight muscles which run vertically on either side of the anterior abdominal wall. They are separated by the linea alba. The term rectus abdominis means “straight abdominal” in Latin, indicating that the muscle fibers run in a straight vertical line through the abdominal region of the body Each muscle consists of a string of four fleshy muscular bodies connected by three narrow bands of tendon known as tendinous intersections. The shape of these segments is often visible through the superficial fascia and skin in those with low body fat, resulting in a ‘six-pack’ shape.  The pyramidalis muscle is a small triangular muscle lying anterior to the rectus abdominis muscle that can be absent in approximately 20% of the population. It is contained in the rectus sheath and originates from the bony pelvis, where it is attached to the pubic symphysis and pubic crest through tendinous fibers. The fibres run superiorly and medially to insert into the linea alba, tensing it during muscular contractions.  Neurovasculature The arteries of the anterolateral abdominal wall can be divided into superficial and deep layers. The superficial branches include: Musculophrenic artery, which is a branch from the internal thoracic artery. It supplies the superior part of the superficial anterolateral abdominal wall. Superficial epigastric artery and lateral to it the superficial circumflex iliac artery. They are branches of the femoral artery and supply the inferior part of the wall. The deep layers of the anterolateral abdominal wall are supplied by the following: Superior epigastric artery, a terminal branch of the internal thoracic artery. It runs in the rectus sheath behind the rectus muscle and supplies the superior part of the wall. Inferior epigastric artery and deep circumflex iliac artery, both branches from the external iliac artery, supply the inferior part of the wall. The inferior epigastric artery enters the rectus sheath after piercing the fascia transversalis and ends by anastomosing with the superior epigastric artery. The tenth and eleventh intercostal arteries and subcostal artery supply the lateral part of the abdominal wall. There is a network of superficial veins that radiate out from the umbilicus and a few small paraumbilical veins which interconnect the network. The deep veins follow the arteries of the same name. The skin and peritoneum of the anterolateral abdominal wall are innervated by the T7 to L1 spinal nerves, which run in an inferomedial direction. They give off lateral and anterior cutaneous branches along their course. Muscles of the anterior abdominal wall are supplied by lower six thoracic nerves, the iliohypogastric nerve and the ilioinguinal nerve  Posterior abdominal wall Fascia Thoracolumbar fascia, analogously to the anterolateral abdominal wall, the fascia of the posterior abdominal wall lies immediately below the skin and subcutaneous tissue. The thoracolumbar fascia is a large, roughly diamond-shaped area of connective tissue formed by the thoracic and lumbar parts of the deep fascia, it is continuous with the transversalis fascia of the anterolateral abdominal wall and it is divided into three layers: anterior, middle and posterior. The intrinsic deep back muscles are enclosed between the posterior and middle layers, while the quadratus lumborum muscles lay between the middle and anterior layers. More profound to the anterior layer runs the psoas major muscle with its psoas fascia.  Muscles The posterior abdominal wall is supported by 12th thoracic and all five lumbar vertebrae, along with their corresponding intervertebral discs. Three or four muscles are present in the posterior abdominal wall, depending on the individual: psoas major, iliacus, quadratus lumborum and psoas minor muscles. The latter is variable, being present in about 40% of the population. Psoas major is a triangular, bilaterally paired muscle that forms part of the floor of the paravertebral gutter. It joins the iliacus muscle to form the iliopsoas muscle, the strongest hip flexor of the human body. Iliopsoas is important for standing, walking and running. Quadratus lumborum muscle has medial attachments to the costal processes of L1-L4 and superior attachments to the inferior border of the 12th rib. The paired muscle acts by stabilizing the caudal connections of the diaphragm, while its unilateral contraction leads to lateral flexion of the trunk. Bilateral contraction depresses the thoracic rib cage during inspiration and extends the trunk. Psoas minor is a variable muscle present in only about 40% of the population. Its contraction leads to weak trunk lateral flexion of the trunk.  Vascular Structure Branches derived from the descending aorta supply the posterior abdominal wall. These include paired subcostal arteries, which run right below the 12th ribs and four pairs of lumbar arteries arising from the back of the aorta. A variable fifth pair of lumbar arteries arising from the median sacral artery can be present. Subcostal and lumbar arteries anastomose with one another and with the superior epigastric, lower intercostal and iliolumbar arteries, supplying the posterior abdominal wall and related structures. Venous drainage of the posterior abdominal wall is carried out mainly by the lumbar veins which empty into the inferior vena cava. There is a plethora of nerves and vessels coursing through the abdominal cavity which are closely related to the posterior abdominal wall. These include: abdominal aorta and its major branches, inferior vena cava with its tributaries, lumbar plexus, sympathetic ganglion chain and sympathetic plexus. The lumbar plexus is formed by the divisions from L1 – L4 spinal nerves with contribution of T12, which merge on the anterior surface of psoas major.  Inguinal region The anterior abdominal wall has naturally occurring paired canals in the lateral lower regions known as inguinal canals. These oblique intramuscular tunnels may range from 3 to 5 cm long in an adult. They serve as a conduit that allows the passage of the male gonads from their intra-abdominal point of origin to their final destination in the scrotal sac. Each inguinal canal originates superolaterally at the deep inguinal ring located at the medial half of the inguinal ligament of Poupart. The canal then terminates at the superficial inguinal ring, which is found about 1 cm superolateral to the pubic tubercle. In females, the round ligament of the uterus passes through each canal. Male inguinal canals convey the spermatic cord, which contains the vas deferens, its related neurovasculature, lymphatics and connective tissue. Superficial and deep inguinal rings impose weak points in the abdominal wall, creating a predisposition to inguinal hernias.  Clinical relevance:Surgical Incisions in Abdominal Wall Midline: An incision that is made through the linea alba. It can be extended through the whole length of the abdomen by curving around the umbilicus The linea alba is poorly vascularised, so blood loss is minimal, a major nerves are avoided. It can be used in any procedure tr requires access to the abdominal cavity. Paramedian: Similar to the median incision, but is performed laterally to the lin alba, providing access to more lateral structures (kidney, sple and adrenals). This method ligates the bloodand nerve supply muscles medial to the incision resulting in their atrophy. Kocher: An Kocher incision begins inferior to the xiphoid process and extends inferolaterally in parallel to the right costal margin. It mainly used to gain access for gall bladder and/or biliary tree pathology. Two modifications and extensions of the Kocher incision a possible: Chevron/rooftop incision or modification-the extension of t incision to the other side of the abdomen. This may be used 1 loesophagectomy, gastrectomy, bilateral adrenalectomy, hepa resections, or liver trtransplantation Mercedes Benz incision or modification -the Chevron incisi lwith a vertical incision and break through the xiphisternum. It may be used for the same indications as the Chevron incisic however classically seen in liver transplantation. McBurney: A McBurney is a called a 'grid iron' incision, because it consists two perpendicular lines, splitting the fibres of the muscles withc cutting them-this allows for excellent healing. McBurney incision is performed at McBurney's point (1/3 of the distance between the ASIS and the umbilicus) and is used in an open appendicectomy ANTERIOR ABDOMINAL WALL FBA Borders of the Abdomen Superior: Costal cartilages 7-12. Xiphoid process: Level of 10th cartilage = L3 Inferior: Pubic bone and iliac crest: Level of L4. Umbilicus: Level of IV disc L3-4  Lines of the Anterior Abdominal Wall Linea alba: Located along the midline. = connective tissue raphe. Linea semilunaris: Along each lateral border of rectus abdominis. Linea transversa: Tendinous bands of rectus abdominis. Abdominal Quadrants Formed by two intersecting lines: Intersect at umbilicus. Quadrants: Upper left. Upper right. Lower left. Lower right. Abdominal Regions Divided into 9 regions by two pairs of planes: Vertical Planes: Left and right lateral planes = midclavicular planes Horizontal Planes: Transpyloric plane: Midway between jugular notch and pubic symphysis (between xiphoid and umbilicus). Intertubercular plane: Through tubercles of iliac crests. Abdominal Regions Right and left hypochondriac: Contain liver Epigastric: Contains: liver, stomach, pancreas Right and left lateral (lumbar): Right contains ascending colon. Left contains descending colon. Abdominal Regions Umbilical: Contains small intestine and transverse colon. Right and left inguinal: Right contains ileocecal junction and appendix. Left contains sigmoid colon. Hypogastric: Contains small intestine, urinary bladder (full), pregnant uterus. Cutaneous Nerves Derived from ventral rami of T7 through L1. Pass inferiorly and medially in plane between transverse and internal oblique muscles. Motor innervation: To abdominal muscles. Cutaneous innervation: Lateral cutaneous branches. Anterior cutaneous branches: Penetrate rectus sheath. Cutaneous Nerves Ventral rami of T7 through T11: = thoracoabdominal nerves. T7 to dermatome over xiphoid process. T10 at level of umbilicus. Subcostal nerve Ventral ramus of L1: Gives rise to: iliohypogastric nerve. ilioinguinal nerve. Fascia Superficial: Camper’s fascia Continuous with fascia over thorax and thigh. Fatty layer. Fascia Deep Superficial: Scarpa’s fascia Membranous layer. Continues into perineum as: Superficial perineal fascia = Colle’s fascia. Deep: Thin layer covering abdominal muscles. Arterial Supply Above Umbilicus Posterior intercostal arteries 10-11. Subcostal artery. Lumbar arteries 1-4. Musculophrenic arteries. Superior epigastric arteries. Inferior epigastric arteries. Arterial Supply Below Umbilicus Superficial epigastric arteries. Superficial circumflex iliac arteries. Superficial external pudendal arteries. Venous Drainage Superficial veins are paired with arteries. Above the umbilicus: Drain into the azygos venous system. Below the umbilicus: Drain into the femoral system (via great saphenous). Lymphatic Drainage Above the umbilicus: Drain into the axillary and sternal nodes. Below the umbilicus: Drain into the superficial inguinal nodes. Anterior Abdominal Wall Arteries Superior epigastric: Terminal branch of internal thoracic. Descends in rectus sheath posterior to muscle. Anastomoses with inferior epigastric. Anterior Abdominal Wall Arteries Inferior epigastric: Arises from external iliac artery. Enters rectus sheath at arcuate line. Branches: Cremasteric artery. Pubic branch. Anterior Abdominal Wall Arteries Deep circumflex iliac artery: Branch of external iliac. Superficial epigastric artery: Arises from femoral artery. Superficial circumflex iliac artery: Arises from femoral artery. Superficial external pudendal artery: Arises from femoral artery. Anterior Abdominal Wall Veins External iliac vein: Receives from epigastric and deep circumflex iliac veins. Femoral vein: Receives superficial circumflex iliac vein, Superficial epigastric vein, Superficial external pudendal vein. Superior epigastric vein: Drains to brachiocephalic vein. Muscle Layers General Characteristics: Three large flat sheets connecting rib cage to hip bone. Muscular posteriorly and laterally. Aponeurotic anteriorly and medially. Muscle Layers Include: External oblique. Internal oblique. Transversus abdominus. Rectus abdominus. Muscle Layers: Innervations Lower intercostal spinal nerve. Subcostal spinal nerve. First lumbar spinal nerve. Linea Alba Median raphe Extends from xiphoid to pubic symphysis. Lies between paired rectus abdominus muscles. = fusion of aponeuroses of transversus abdominus, internal oblique, and external oblique. Surface Features Linea semilunaris: Along lateral margin of rectus abdominus. Crosses costal margin near tip of 9th costal cartilage. Arcuate line: Lower free edge of posterior lamina. Lies midway between umbilicus and pubis. Inguinal Ligament Inguinal ligament: Thickened lower border of external oblique aponeurosis. From anterior superior iliac spine to pubic tubercle. Muscle Layers Rectus sheath: Encloses rectus abdominus. Formed by fusion of fascia of other three layers of abdominal muscles. Anterior and posterior laminae. (layers) Arcuate line is the lower free edge of the posterior lamina Lies midway between umbilicus and pubis. Inguinal Region Inguinal Canal: Oblique passage through lower abdominal wall. Site of potential weakness. Transmits: Spermatic cord in males. Round ligament of uterus in females. Extends between superficial and deep inguinal rings. Inguinal Region Inguinal Canal: Superficial inguinal ring: Triangular defect in the aponeurosis of the external oblique muscle layer. Superficial opening of the inguinal canal. Lies above and lateral to pubic tubercle. Larger in males: Transmits spermatic cord in males. Transmits round ligament of uterus in females. Inguinal Region Inguinal Canal: Deep inguinal ring: Opening of the evagination of the transversalis fascia. Lies above inguinal ligament midway between anterior iliac spine and pubic tubercle. Inguinal Region Inguinal Canal: Male: spermatic cord: Vas deferens. Ilioinguinal nerve. Genital branch of genitofemoral nerve. Testicular arteries and veins. Pampiniform plexus Lymph vessels. Cremaster muscle. Inguinal Region Inguinal Canal: Female: Round ligament. Ilioinguinal nerve. Lymph vessels. Inguinal Region Hernias: Direct inguinal: Occurs in older men (rarely women). Due to weakness in abdominal wall behind or lateral to superficial inguinal ring. Passes directly through abdominal wall to superficial inguinal ring. Does not extend into scrotum. Has sac formed by peritoneum. Inguinal Region Hernias: Indirect inguinal: Traverses deep and superficial inguinal rings and inguinal canal. Lies within coverings of spermatic cord. May descend into scrotum. More common than a direct inguinal hernia. More common in boys and young men. May be congenital. Inguinal Region Hernias: Femoral: Occurs within femoral canal. More common in females. Umbilical: Occurs at site where umbilical cord penetrates between muscles and fascia of anterior abdominal wall. Folds on Posterior Surface (of anterior wall) Median umbilical fold: Midline peritoneal fold on inner abdominal wall above bladder. Contains median umbilical ligament: Remnant of embryonic urachus. Medial umbilical fold: Paired peritoneal folds on either side of median fold. Contain medial umbilical ligaments: Remnants of umbilical arteries. Folds on Posterior Surface (of anterior wall) Lateral umbilical fold: Paired peritoneal folds lateral to medial folds. Contain inferior epigastric vessels: From deep inguinal ring to arcuate line. Folds on Posterior Surface (of anterior wall) Falciform ligament: Double layer of peritoneum. Attaches liver to anterior abdominal wall and to inferior surface of diaphragm. Contains ligamentum teres hepatis (round ligament of liver): Remnant of left umbilical vein.  THE PERITONEUM BY DARE, B.J ANATOMY DEPARTMENT, OSUN STATE UNIVERSITY, OSOGBO General features Serous membrane that line the walls of the abdominal and pelvic cavities and cover the organs Parietal peritoneum －lines the walls of the abdominal and pelvic cavities Visceral peritoneum －covers the organs Peritoneal cavity －the potential space between the parietal and visceral layer of peritoneum. In the male, is a closed sac, but in the female, there is a communication with the exterior through the uterine tubes, the uterus, and the vagina Function Secretes a lubricating serous fluid that continuously moistens the associated organs Absorb Support viscera   Interperitoneal viscera －most part of viscera surrounded by peritoneum, The relationship between viscera  example, liver, gallbladder, ascending and and peritoneum descending colon, upper part of rectum, urinary bladder and uterus Intraperitoneal viscera －viscera  Retroperitoneal viscera －some organs lie completely surrounded by on the posterior abdominal wall and are peritoneum covered by peritoneum on their anterior  Stomach, surfaces only, example, kidney, suprarenal  superior part of duodenum, gland, pancreas, descending and horizontal  jejunum, parts of duodenum, middle and lower parts  ileum, of rectum, and ureter  cecum, Intraperitoneal viscera  vermiform appendix,  transverse and Interperitoneal viscera  sigmoid colons, spleen and  ovary Retroperitoneal viscera  Folds on Posterior Surface (of anterior wall) Median umbilical fold: Midline peritoneal fold on inner abdominal wall above bladder. Contains median umbilical ligament: Remnant of embryonic urachus. Medial umbilical fold: Paired peritoneal folds on either side of median fold. Contain medial umbilical ligaments: Remnants of umbilical arteries. Lateral umbilical fold: Paired peritoneal folds lateral to medial folds. Contain inferior epigastric vessels: From deep inguinal ring to arcuate line.  Folds on Posterior Surface (of anterior wall) Falciform ligament: Double layer of peritoneum. Attaches liver to anterior abdominal wall and to inferior surface of diaphragm. Contains ligamentum teres hepatis (round ligament of liver): Remnant of left umbilical vein. Interperitoneal viscera  Structures which are formed by peritoneum Omentum －two-layered fold of peritoneum that extends from stomach to adjacent organs Lessor omentum －two-layered fold of peritoneum which extends from porta hepatis to lesser curvature of stomach and superior part of duodenum Hepatogastric ligament －extends from porta hepatis to lesser curvature of stomach Hepatoduodenal ligament Extends from porta hepatis to superior part of duodenum Contains common bile duct, proper hepatic a. and hepatic portal v. Omental foramen Behind the right border of hepatoduodenal ligament Superior－caudate lobe of liver Inferior－superior part of duodenum Anterior－hepatodudenal ligament Posterior－peritoneum covering the inferior vena cava Greater omentum  Four-layered fold of peritoneum Anterior two layers descend from the greater curvature of stomach and superior part of duodenum Hangs down like an apron in front of coils of small intestine, Turns upward and attaches to the transverse colon. During infection of the intestine, plasma cells formed in the lymph nodes combat the infection and help prevent it from spreading to the peritoneum.  Omental bursa Position－situated behind the lesser omentum and stomach Walls Superior－peritoneum which covers the caudate lobe of liver and diaphragm Anterior－formed by lesser omentum, peritoneum of posterior wall of stomach, and anterior two layers of greater omentum Inferior－conjunctive area of anterior and posterior two layers of greater omentum Posterior－formed by posterior two layers of greater omentum, transverse colon and transverse mesocolon, peritoneum covering pancreas, left kidney and suprarenal gland  Left－formed by the spleen, gastrosplenic ligament and splenorenal ligament Right－formed by omental foramen The Omental bursa (lesser sac) communicates with the greater sac through the omental foramen. Mesenteries or mesocolons－ two-layered fold of peritoneum that attach part of the intestines to the posterior abdominal wall Mesentery －suspends the small intestine from the posterior abdominal wall Broad and a fan-shaped Consists of two peritoneal layers Intestinal border－folded, 7 m long Radix of mesentery 15 cm long Directed obliquely from left side of L2 to in front of right sacroiliac joint Mesoappendix Triangular mesentery－ extends from terminal part of ileum to appendix Appendicular artery runs in free margin of the mesoappendix Transverse mesocolon －a double fold of peritoneum which connects the transverse colon to the posterior abdominal wall Sigmoid mesocolon － inverted V-shaped, with apex located in front of left ureter and division of common iliac artery Ligaments －two-layered folds of peritoneum that attached the lesser mobile solid visera to the abdominal wall Ligaments of liver Falciform ligament of liver Consists of double peritoneal layer Extends from anterior abdominal wall (umbilicus) to live Free border of ligament site of ligamentum teres  Coronary ligament － the area between upper and lower parts of the coronary ligament is the bare area of live, this area is devoid of peritoneum and lies in contract with the diaphragm Left and right triangular ligaments －formed by right extremity of coronary ligament and left leaf of falciform ligament, respectively  Hepatogastric ligament Hepatoduodenal ligament Ligamentum teres hepatis Ligaments of spleen Gastrosplenic ligament －a double layer of peritoneum that connects the fundus of stomach to hilum of spleen. In this double layer of peritoneum are the short gastric and left gastroepiploic vessels Splenorenal ligament －extends between the hilum of spleen and anterior aspect of left kidney. The splenic vessels lies within this ligament, as well as the tail of pancreas Phrenicosplenic ligament Splenocolic ligament Ligaments of stomach Hepatogastric ligament Gastrosplenic ligament Gastrophrenic ligament Gastrocolic ligament Gastropancrestic ligament Folds and recesses of posterior abdominal wall Superior duodenal fold and recess Inferior duodenal fold and recess Intersigmoid recess － formed by the inverted V attachment of sigmoid mesocolon  Retrocecal recess － in which the appendix frequenty lies Hepatorenal recess － lies between the right lobe of liver, right kidney, and right colic flexure, and is the lowest parts of the peritoneal cavity when the subject is supine Folds and fossas of anterior abdominal wall Medial umbilical fold － contain the remnant of urachus (median umbilical ligaments) Medial umbilical fold － contains remnants of the umbilical arteries (medial umbilical ligaments) Lateral umbilical fold － contains the inferior epigastric vessels Supravesical fossa Medial inguinal fossa Lateral inguinal fossa Pouches In male－rectovesical pouch In female Rectouterine pouch － between rectum and uterus Vesicouterine pouch － between bladder and uterus Peritoneal subdivisions The transverse colon and transverse mesocolon divides the greater sac into supracolic and infracolic compartments. Supracolic compartments (subphrenic space)－lies between diaphragm and transverse colon and transverse mesocolon Suprahepatic recess lies between the diaphragm and live－the falciform ligament divides it into right and left suprahepatic recesses  Left suprahepatic recesses left anterior suprahepatic spaces left posterior suprahepatic spaces Right suprahepatic recesses right anterior suprahepatic spaces right posterior suprahepatic spaces bare area of live (extraperitoneal space) Infrahepatic recess lies between the live and transverse colon and transverse mesocolon－the ligamentum teres hepatic divides it into right and left infrahepatic recesses Right infrahepatic recesses (hepatorenal recess) Left infrahepatic recesses left anterior infrahepatic space left posterior infrahepatic space Infracolic compartments － lies below the transverse colon and transverse mesocolon Right paracolic sulcus (gutter) －lies lateral to the ascending colon. It communicates with the hepatorenal recess and the pelvic cavity. It provides a route for the spread of infection between the pelvic and the upper abdominal region. Left paracolic sulcus (gutter) －lies lateral to the descending colon. It is separated from the area around the spleen by the phrenicocolic ligament, a fold of peritoneum that passes from the colic flexure to the diaphragm.  Right mesenteric sinus － triangular space, lies between root of mesentery, ascending colon, right 2/3 of transverse colon and transverse mesocolon Left mesenteric sinus －lies between root of mesentery, descending colon, right 1/3 of transverse colon and transverse mesocolon, its widens below where it is continuous with the cavity of the pelvis  Stomach and Intestine By DARE, B.J ANATOMY DEPARTMENT, COLLEGE OF HEALTH SCIENCES, OSUN STATE UNIVERSITY,OSOGBO  Stomach The stomach is a muscular bag that acts as reservoir of food and helps in digestion of carbohydrates, proteins and fats. It is connected above to the lower end of the oesophagus, and below to the duodenum. Occupying the epigastric, umbilical and left hypochondriac regions. Most  DIMENSIONS It is about 25 cm long, and Volume (30 ml) at birth, one litre (1000 ml) at puberty, and 2 J litres in adults. Two Orifices  The cardiac orifice is joined by the lower end of the oesophagus. It lies behind the left 7th costal cartilage 2.5 cm from its junction with the sternum, at the level of vertebra Tl2  The pyloric orifice opens into the duodenum. , it lies 1.2 cm from median plane Two Curvatures  The lesser curvature is concave and forms the right Two Surfaces border of the stomach. It provides attachment to the  The anterior or anterosuperior surface lesser omentum.  The greater curvature is convex and forms the left  The posterior or posteroinferior surface border of the stomach. It provides attachment to the Two Parts greater omentum, the gastrosplenic ligament and the Cardiac and gastrophrenic ligament. pyloric by a line drawn downwards and  At its upper end the greater curvature presents the to the left from the incisura angularis. cardiac notch which separates it from the oesophagus.  Cardiac part is comprised fundus and body Pyloric part is subdivided into the pyloric antrum and pyloric canal Fundus: This is dome-shaped and projects upward and to the left of the Figure 23.10a cardiac orifice. It is usually full of gas. Body: This extends from the level of the cardiac orifice to the level of the incisura angularis, a constant notch in the lower part of the lesser curvature Pylorus: This is the most tubular part of the stomach. The thick muscular wall is called the pyloric sphincter, and the cavity of the pylorus is the pyloric canal The pyloric antrum is separated The posterior surface (the stomach bed) and lesser from the pyloric canal by sulcus sac. intermedius present It is about 7.5  The diaphragm; cm long.  the left kidney; The pyloric canal is about 2.5 cm  the left suprarenal gland; long. It is narrow and tubular. At its right end it terminates at the  the pancreas; pylorus.  the transverse mesocolon;  the splenic flexure of the colon; and RELATIONS  the splenic artery lesser omentum greater omentum gastrophrenic ligament The anterior surface the liver, the diaphragm, and the anterior abdominal wall Blood Supply The left gastric artery, a branch of the coeliac trunk; the right gastric artery, a branch of the common hepatic; the right gastroepiploic artery, a branch of the gastroduodenal;  the left gastroepiploic artery, a branch of the splenic; and 5 to 7 short gastric arteries, which are also branches of the splenic artery. The veins of the stomach drain into the portal, superior mesenteric and splenic veins   The left gastric artery arises Celiac trunk from the celiac artery  The right gastric artery Left branch Left gastric a. arises from the hepatic artery at the upper border Right branch Common Short gastric a.  The short gastric arteries hepatic a. arise from the splenic Cystic a. Splenic a. artery at the hilum of the Right gastric a. spleen Proper hepatic a.  The left gastroepiploic artery arises from the Gastroduodenal a. splenic artery at the hilum Splemic branches of the spleen  The right gastroepiploic Left gastrioeploic a. artery arises from the Right gastroepiploic a. gastroduodenal branch of Superior pancreaticoduodenal a. the hepatic artery Area a, drains into the Area c drains into the right gastroepiploic nodes pancreaticosplenic nodes lying Lymph drain into the subpyloric nodes along the splenic artery, Lymph From here the lymph is drained further into vessels from these nodes travel the hepatic nodes and finally into the along the splenic artery to reach coeliac nodes. the coeliac nodes. Area d drains in different directions into the pyloric, Area b drains into the left gastric hepatic, and left gastric nodes, and passes from all nodes lying along the artery of the these nodes to the coeliac nodes. same name. Lymph from these nodes drains into the coeliac nodes. Nerve Supply Sympathetic and thoracic six to ten segments of the spinal cord, via the greater splanchnic nerves, and the coeliac and hepatic plexuses vasomotor, motor to the pyloric sphincter, and inhibitory to the rest of the gastric musculature; and pain sensations from the stomach parasympathetic nerves Derived from the vagi,  The anterior vagal trunk, which is formed in the through the oesophageal thorax mainly from the left vagus nerveThe plexus and gastric nerves posterior vagal trunk, which is formed in the thorax mainly from the right vagus nerve,  THE SMALL INTESTINE It is about 6 m long, extends from the pylorus to the ileo- caecal junction The greater part of digestion and food absorption takes place in the small intestine. It is divided into three parts: the duodenum, the jejunum, and the ileum.  Characteristic of the Small Intestine Lymphatic follicles: Large surface area -The solitary lymphatic follicles are 1 -great length of the intestine to 2 mm in diameter -presence of circular folds of mucous -The aggregated lymphatic follicles or membrane, Peyer's patches form circular or oval -villi and microvilli patches, largest and most numerous Intestinal glands or crypts of Lieberkuhn: in the ileum, and are small, circular Simple tubular glands distributed over the entire mucous membrane of the and fewer in the distal jejunum. jejunum and ileum. The arterial supply to jejunum and ileum is They secrete digestive enzymes and derived from the jejunal and ileal branches mucus. of the superior mesenteric artery. The duodenal glands or Brunner's glands lie in the submucosa The vasa recta are distributed (Small, compound tubule-acinar glands alternately to the opposite surfaces which secrete mucus). of the gut.  Middle colic a. Superior Mesenteric v. Inf. pancresticodudenal a. Superior mesenteric a. Right colic a. Ileocolic a. Jejunal and ileal a. Appendicular a. The nerve supply of the small intestine is sympathetic (T9 to T12) as well as parasympathetic (vagus), both of which pass through the coeliac and superior mesenteric plexuses.  The nerves form the myenteric plexus of Auefbach, containing parasympathetic ganglia between the circular and longitudinal muscle coats.  Fibres from this plexus form the submucous plexus of Meissner which also contains parasympathetic ganglia. The function of the small intestine comprises digestion and absorption of the digested contents from the fluid  THE DUODENUM parts The duodenum is the shortest,  First or superior part, 5 cm long. widest and most fixed part of the  Second or descending part, 7.5 cm long. small intestine about 25 cm in  Third or horizontal part, 10 cm long. lenght.  Fourth or ascending part, 2.5 cm long. It extends from the pylorus to the duodenojejunal flexure. It is curved around the head of the pancreas in the form of the letter 'C. First Part , The first part begins at the pylorus, and meet the second part at the superior duodenal flexure. Peritoneal Relations The proximal 2.5 cm is movable. It is attached to the lesser omentum above, and to the greater omentum below. The distal 2.5 cm is fixed. It is retroperitoneal. It is covered with peritoneum only on its anterior aspect. Visceral Relations Anteriorly: Quadrate lobe of liver, and gall bladder. Posteriorly. Gastroduodenal artery, bile duct and portal vein Superiorly : Epiploic foramen Interiorly : Head and neck of the pancreas. Second Part About 7.5 cm long, It begins at the superior duodenal flexure, passes downwards to reach the lower border of the third lumbar vertebra, at the inferior duodenal flexure continuous with the third part. Peritoneal Relations It is retroperitoneal and fixed Visceral Relations Anteriorly : Right lobe of the liver; transverse colon, root of the transverse mesocolon, small intestine Posteriorly: Anterior surface of the right kidney near the medial border, right renal vessels, right edge of the inferior vena cava, right psoas major Medially : Head of the pancreas and the bile duct Laterally : Right colic flexure   The major duodenal papilla is an elevation present posteromedially, 8 to 10 cm distal to the pylorus.  The hepatopancreatic ampulla opens at the summit of the papilla. Figure 23.13a  The minor duodenal papilla is present 6 to 8 cm distal to the pylorus, and presents the opening of the accessory pancreatic duct  Visceral Relations THIRD PART Anteriorly : Superior mesenteric vessels and  This part is about 10 cm long. root of mesentery  It begins at the inferior duodenal flexure, on Posteriorly: the right side of the lower border of the third Right ureter, lumbar vertebra. right psoas major,  It passes almost horizontally and slightly right testicular or ovarian upwards in front of the inferior vena cava, vessels, and ends by joining the fourth part in front of inferior vena cava, and the abdominal aorta. abdominal aorta with origin Peritoneal Relations of inferior msenteric artery It is retroperitoneal and fixed. Superiorly : Head of the pancreas with uncinate process Inferiorly : Coils of jejunum Fourth Part To the right: This part is 2.5 cm long. Attachment of the upper part of It runs upwards on or immediately to the left of the root of the mesentery the aorta, To the left: up to the upper border of the second lumbar Left kidney and left ureter. vertebra, continuous with the jejunum at the Superiorly : duodenojejunal flexure. Body of pancreas Peritoneal Relations It is mostly retroperitoneal, Posterior relation of the 4th part The terminal part is suspended by the uppermost part of the mesentery, and is mobile. Visceral Relations Anteriorly : Transverse colon, transverse mesocolon, lesser sac and stomach. Posteriorly : Left sympathetic chain, left psoas major, left renal vessels, left testicular vessels, inferior mesenteric vein  Middle colic a. Superior Mesenteric v. Inf. pancresticodudenal a. Superior mesenteric a. Right colic a. Ileocolic a. Jejunal and ileal a. Appendicular a.  Inferior mesenteric v. Inferior mesenteric a. Left colic a. Sigmoid a. Superior rectal a. JEJUNUM AND ILEUM The jejunum and ileum measure about 20 ft (6 m) long The jejunum constitutes the upper two-fifths of the mobile part of the small intestine, The ileum constitutes the lower three-fifths. The jejunum begins at the duodenojejunal flexure. The ileum terminates at the ileocaecal junction. Root of Mesentery It is marked by two parallel lines close together, extending from the duodenojejunal flexure to the junction of the right lateral and transtubercular planes. The duodenojejunal flexure lies 1 cm below the transpyloric plane and 3 cm to the left of the median plane  Blood Supply  The superior mesenteric artery,  Lymph from lacteals drains into plexuses in the wall of the gut along Figure 23.16b the superior mesenteric artery, it ultimately drains into superior mesenteric nodes  Nerve Supply The nerves are derived from the sympathetic and parasympathetic (vagus) nerves from the superior mesenteric plexus. Distribution of the Superior Mesenteric Artery Meckel's diverticulum is the It is situated about 2 feet or persistent proximal part of the 60 cm proximal to I the vitello-intestinal duct which is ileocaecal valve, attached to present in the embryo, and which antimesenteric border of normally disappears during the« the ileum. 6th week of intrauterine life. Its calibre is equal to that of  It occurs in 2% subjects. the ileum. Usually it is 2 inches or 5 cm Its apex may be free or may long. be attached to the umbilicus, to the mesentery, or to any other abdominal structure by a fibrous hand  Clinical Implication  Meckel's diverticulum may cause intestinal obstruction.  Occasionally it may have small regions of gastric mucosa.  Acute inflammation of the diverticulum may produce symptoms that resemble Meckel's diverticulum those of appendicitis.  It may be involved in other diseases similar to those of the intestine. LARGE INTESTINE. BY DR. ADELEKE N.A. Introduction. Large intestine is made up of the followings. Cecum and projecting vermiform appendix. Colon. (Ascending, transverse, descending and sigmoid) Rectum. Anal canal. 4-Layer characteristics of the alimentary canal are present. However, with several adaptations and distinctive features based on functional requirements. GROSS The large intestine may be identified by the presence of teniae coli which is 3- thickened equally spaced parts of the outer longitudinal layer in the muscularis externa but absent in the rectum, appendix and anal canal. Haustra: The external surface of the cecum and the colon exhibits sacculations between the tinae coli. Omenta appendices: Small fatty projection on the serosa outer surface. LARGE INTESTINE. LARGE INTESTINE. Fig. 1732. HISTOLOGY. Mucosal: Made up of Columnal epithelium. It also contains numerous straight tubular intestine glands (crypts of Lieberkuhn) that extends through the dept of the mucosa layer. Other cell types are enterocytes, Goblet cell, enteroendocrine and M cell. Plicae, villi, microvilli and glycocalyx are less prominent compare to small GI. There is high turnover of mucosal epithelia and glandular cells at about 4 to 6 days. The lamina propria and muscularis mucosae occurred as in the rest of the GI. However wt modifications. Lamina propria special features. The Collagen table: This is a sheet of collagen and proteoglycan that lies b/2 the basal laminal of the epithelium and that of the fenestrated absorptive venous capillaries. It is about 5micrometer in thickness it may increase 3 folds or more during polypoid hyperplasia. It regulates the absorption of water and electrolytes from ECF to ICF. Lamina propria. Well Developed GALT: Large lymphatic nodles is aboundant in L. bowel and extends into the sub-mucosal, distorting the glands arraignments. This is necessary to handle large loads of micro-organisms and noxious products of digestion immunologically. Weii Developed Pericryptal Fibroblast Sheath: A group of fibroblasts that divide beneath the glands, migrate toward the lumen, many of these cells differentiate to the Macrophages of the laminal propria. Absence of lymphatic vessle: Unlike the rest of the GI the laminal propria of Large intestine has no Lymphatic vessles. But it is present in the muscularis mucosae. One reason for delay in the spread of Cancers of the L. Bowel SUB-MUCOSAL. As in the other parts of GI the sub-mucosal of large intestine contains secreory glands, vascular capillaries as well as lymphatic vessles and nodles. MUSCULARIS EXTERNAL. Made of smooth muscles in 2-layers, inner circular and outer longitudinal layer, the later has Teniae coli and the saccules(Haustra) the later become prominent during colon contractions. Colon is capable of segmental contraction which does not affect the contents unlike peristalsis. SEROSAL: Made of simple squamous epithelium (mesothelium) and small amout of cnt. It is absent where intestine is attached to adjoining structure. Fig.1733 CECUM and APPENDIX. Cecum is the blind pouch distal to the ileocecal valves and appendix is the finger like projection of the cecum. Cecum has the same histologicy as the colon, the muscularis externa of the appendix has no inner circular layer only longitudinal which is smooth. There is abundance of lymphatic nodes that extend into the sub- mucosa. Cross section of Apendix. Rectum and Anal Canal. Rectum is the dilated distal portion of the alimentary canal. The upper part unlike the rest of the colon has folds called transverse rectal folds. The mucosa is like that of the distal colon having straight tubular intestinal glands with many Goblet cells. The other layers are typical of the colon. There is no Teniae coli in the rectum. Anal Canal is the most distal portion of the alimentary canal about 4cm long and extends from the upper part of the pelvic diaphgram to the anus. The upper parts has longitudinal folds called Colums, depressions b2 the colums are called anal sinuses. Anal canal is divided into 3 zones according to the characters of the epithelia lining. 1. The upper 3rd is the Colorectal zone it is lined by simple columinal epithelium as in the colon. 2. The middle 3rd the anal transitiona zone(ATZ) lined by combinations of Simple columinal, stratified columinal and Stratified squamous epithelium. 3. The lower 3rd the Squamous zone lined by stratified squamous epithelium and it merges with the anus skin the lowest part of the alimentary canal.  The glands in the anal canal extends through mucosal , sub- mucosal and into the muscularies externa. These branched, straight tubular structures secrete mucus to lubricate the rectal surface. Sometimes lymphatic vessel surround the glands and may lead to FISTULA formation b2 the anus and perianal skin. Large apocrine glands, the Circumanal glands are found in the skin surrounding the anal orifice. Hair follicles and sebaceous glands are also found at this site. The terminal branches of the superior rectal artery and rectal venous plexus are present in the sub-mucosal. Internal hemorrhoids results from engorgement of these veins usually from portal hypertension. The muscularis mucosae disappears at the level of ATZ, where the circular inner layers of the muscularis externa thicken to form the internal anal sphincter. The external anal sphincter is formed by the striated muscles of the pelvic floor. RECTUM AND ANUS. Fig. 1737 FUNCTIONS OF LARGE INTESTINE. Absorptions of Water and electrolytes. Secretions of mucous for lubrication. Reservoir for the fecal matters. Defecation. Homeostasis of Bacteria flura of the alimentary canal.  RECTUM AND ANA CANAL BY DARE, B.J ANATOMY DEPARTMENT, FACULTY OF BASIC MEDICAL SCIENCES, COLLEGE OF HEALTH SCIENCES, OSUN STATE UNIVERSITY,OSOGBO THE RECTUM  The rectum is the distal part of the large gut. It is placed between the sigmoid colon above and the anal canal below.  The rectum is curved in an anteroposterior direction and also from side to side.  The three cardinal features of the large intestine, sacculations, appendices epiploicae and taeniae are absent in the rectum. Dimensions Rectum  12 cm long, In the upper part Rectovesical pouch diameter of 4 cm as that of the Urinary sigmoid colon, but in the lower part it bladder is dilated to form the rectal ampulla  Its begins as a continuation of the Pieces of sacrum sigmoid colon at the level of third sacral vertebra. The rectosigmoid Anococcygeal ligament junction is indicated by the lower end Anus of the sigmoid mesocolon. Urogenital diaphragm  The rectum ends by becoming continuous with the anal canal at the anorectal junction. The junction lies 2 to 3 cm in front of and a little below the tip of the coccyx. Course and Direction  Two anteroposterior curves : rectum runs first downwards and -The sacral flexure of the rectum follows backwards, then downwards, and finally the concavity of the sacrum and coccyx downwards and forwards - the perineal flexure of the rectum is the backward bend at the anorectal junction Sacral flexure  Three lateral curves : Upper right curve -The upper lateral curve of rectum is convex to the right; Middle left curve -the middle lateral curve is convex to t he left and is most prominent; and Anal canal -the lower lateral curve is convex to the Perineal flexure right. Lower right curve Peritoneal Relations Visceral Relations  upper one-third of the rectum is covered  Anteriorly in males : with peritoneum in front and on the -upper two-thirds are related to the sides; recto-vesical pouch with coils of  middle one-third is covered only in front; intestine and sigmoid colon;  lower one-third, which is dilated to form -lower one-third of the rectum is related the ampulla, is devoid of peritoneum, and to the base of the lies below the rectovesical pouch in males urinary bladder, and below the rectouterine pouch in terminal parts of the ureters, females seminal vesicles,  distance between the anus and the floor deferent ducts and of the pouch is 7.5 cm in males but only prostate 5.5 cm in females.  Anteriorly in females : - upper two-thirds are related to the recto-uterine pouch with coils of intestine and sigmoid colon.   The pouch separates the rectum from the uterus, and from the upper part of the vagina;  lower one-third of the rectum is related to the lower part of the vagina  Posteriorly -Lower three pieces of the sacrum, the coccyx and the anococcygeal ligament; -piriformis, the coccygeus and the levator ani; -median sacral, superior rectal and lower lateral sacral vessels -sympathetic chain with the ganglion -anterior primary rami of S3, S4, S5, - -lymph nodes, lymphatics and fat  Venous Drainage Arterial Supply  Superior rectal vein :  Superior rectal artery from inferior -tributaries of this vein begin in the anal mesenteric artery. canal, internal rectal venous plexus in -It divides opposite the third sacral the rectal submucosa, pierce the vertebra (S3) into right and left branches muscular coat about 7.5 cm above the on each side of the rectum. anus drain to inferior mesenteric vein. -Each branch breaks up at the middle of  Middle rectal vein : the rectum into several small branches drain, chiefly, the muscular walls of the run in the anal columns up to the anal rectal ampulla, and open into the valves where they form looped internal iliac veins. anastomoses  Lymphatics Drainage  Middle rectal arteries arise from the anterior -upper half of the rectum pass along the division of the internal iliac artery, supply superior rectal vessels to the inferior lower part of the rectum mesenteric nodes.  Median sacral artery : small branch arising -lower half of the rectum pass along the from the back of the aorta supplies the middle rectal vessels to the internal iliac posterior wall of the anorectal junction nodes.  Nerve Supply The rectum is supplied by both  sympathetic (LI, L2) and parasympathetic (S2, S3, S4) nerves through superior rectal inferior mesenteric and inferior hypogastric plexuses.  Sympathetic nerves are vasoconstrictor, inhibitory to the rectal musculature and motor to the internal sphincter.  Parasympathetic nerves are motor to the musculature of the rectum and inhibitory to the internal sphincter.  Sensations of distension of the rectum pass through the parasympathetic nerves, while pain sensations are carried by both the sympathetic and parasympathetic nerves. Supports of Rectum  Pelvic floor formed by levator ani muscles  Fascia of Waldeyer: It attaches the lower part of the rectal ampulla to the sacrum. It is formed by condensation of the pelvic fascia behind the rectum. It encloses the superior rectal vessels and lymphatics.  Lateral ligaments of the rectum: They are formed by condensation of the pelvic fascia on each side of the rectum. They enclose the middle rectal vessels, and branches of the pelvic plexuses, and attach the  The pelvic peritoneum and the related rectum to the posterolateral walls of the lesser vascular pedicles also help in keeping pelvis. the rectum in position.  Rectovesical fascia of Denonvilliers : extends from  Perineal body with its muscles. the rectum behind to the seminal vesicles and prostate in front.  Mucosal Folds  The mucous membrane of an empty rectum shows two types of folds, -The longitudinal folds present in the lower part of an empty rectum, and are obliterated by distension. -The transverse or horizontal folds or Houston's valves or plicae transversales are permanent The upper fold lies near the upper end of the rectum, and projects from the right or the left wall. The middle fold, the largest and most constant, lies at the upper end of the rectal ampulla, and projects from the anterior and right walls. The lowest fold inconstant lies 2.5 cm below the middle fold, and projects from the left wall  The anal canal  terminal part of the large intestine  situated below the level of the pelvic diaphragm in the anal triangle of perineum in between the right and left ischiorectal fossae, which allow its expansion during passage of the faeces.  sacculations and taeniae are absent.  Anorectal junction is marked by the forward convexity of the perineal flexure of the rectum and lies 2-3 cm in front of and slightly below the tip of the coccyx.  ampulla of the rectum narrows and pierces the pelvic diaphragm  FEATURES Interior of the Anal Canal  surrounded by inner involuntary and outer  Divided into three parts: voluntary sphincters which keep the lumen upper part, about 15 mm long; closed in the form of an anteroposterior slit. middle part, about 15 mm long; and  The anus is the surface opening of the anal lower part about 8 mm long. canal, situated about 4 cm below and in Upper Mucous Part front of the tip of the coccyx in the cleft It is lined by mucous membrane, and is of between the two buttocks. endodermal origin.  The surrounding skin is pigmented and - 6 to 10 vertical folds called the anal columns thrown into radiating folds, and contains a of Morgagni. ring of large apocrine glands. - lower ends of the anal columns are united to each other by short transverse folds of mucous membrane; these folds are called the anal valves, - Above each valve there is a depression in the mucosa which is called the anal sinus,  Anal valve  The anal valves together form a transverse line that runs all round the anal canal called Anal column Pectinate line pectinate line.  It is situated opposite the middle of internal anal sphincter, the junction of ectodermal and endodermal parts. Occasionally the anal valves show epithelial projections called anal papillae.  Middle Part  anal columns are not present.  There is dense venous plexus that lies betweem it and the muscle coat.  The mucosa is less mobile than in the upper part of the anal canal referred to as the pecten or transitional zone.  The lower limit of the pecten often has a whitish appearance because of which it is referred to as the white line of Hilton.  Hilton's line is situated at the level of the interval between the subcutaneous part of external anal sphincter and the lower border of internal anal sphincter.  It marks the lower limit of pecten or stratified squamous epithelium which is devoid of sweat glands Lower Cutaneous Part  It surrounds the lower part of the anal canal.  lined by true skin containing sweat and It is in the form of a flat band about 15 mm sebaceous glands. broad.  The epithelium made up of sebaceous and  It has no bony attachment. sweat glands are present.  The superficial part is elliptical in shape and Anal Sphincters arises from the posterior surface of the  internal anal sphincter is involuntary. terminal segment of the coccyx and the  formed by the thickened circular muscle coat anococcygeal ligament or raphe. of this part of the gut.  The fibres surround the lower part of the  It surrounds the upper three-fourths, 30 internal sphincter and are inserted into the mm of the anal canal extending from the perineal body. upper end of the canal to the white line of  The deep part surrounds the upper part of Hilton. the internal sphincter and is fused with the  external anal sphincter is under voluntary puborectalis. control. It is made up of a striated muscle  It also has no bony attachment like the and is supplied by the inferior rectal nerve subcutaneous part. and the perineal branch of the fourth sacral nerve.  Circular muscle Puborectalis Internal anal sphincter External anal sphincter Conjoint longitudinal coat Pecten - Intersphincteric groove White line  Conjoint Longitudinal Coat  It is formed by fusion of the puborectalis with  some strands pass obliquely through the the longitudinal muscle coat of the rectum at internal sphincter and end in the the anorectal junction. submucosa below the anal valves  It lies between the external and internal sphincters. Anorectal Ring  becomes fibro-elastic and at the level of the  This is a muscular ring present at the white line it breaks up into a number of anorectal junction. fibroelastic septa which spread out fanwise,  It is formed by the fusion of the pierce the subcutaneous part of the external -puborectalis, sphincter, and are attached to the skin around -deep external sphincter and the anus. -internal sphincter.  The most lateral of these septa forms the perianal fascia.  The most medial septum forms, the anal intermuscular septum, which is attached to the white line. Blood Supply  Veins present in the three anal columns  The part of the anal canal above the situated at 3, 7 and 11 O'clock positions as pectinate line is supplied by the superior seen in the lithotomy position are large and rectal artery. constitute potential sites for the formation of  The part below the pectinate line is primary internal piles. supplied by the inferior rectal artery.  The external rectal venous plexus lies Venous Drainage outside the muscular coat of the rectum and  The internal rectal venous plexus or anal canal haemorrhoidal plexus lies in the -lower part of the external plexus is submucosa of the anal canal. It drains drained by the inferior rectal vein into mainly into the superior rectal vein, but the internal Pudendal vein; communicates freely with the external - middle part by the middle rectal plexus and thus with the middle and vein into the internal iliac vein and inferior rectal veins. -upper part by the superior rectal vein  The internal plexus is site of which continues as the inferior communication between the portal and mesenteric vein. systemic veins.  Nerve Supply  The anal veins are arranged radially around  Above the pectinate line, the anal canal is the anal margin. supplied by autonomic nerves, both  communicate with the internal rectal plexus sympathetic and with the inferior rectal veins. -inferior hypogastric plexus (LI, L2) and  Excessive straining during the defecation -parasympathetic (pelvic splanchnic, may rupture one of these veins, forming a S2,S3, S4). subcutaneous perianal haematoma known Pain sensations are carried by both of them. as external piles.  Below the pectinate line, it is supplied by Lymphatic Drainage somatic (inferior rectal, S2, S3, S4) nerves.  Lymph vessels from the part above the  Sphincters: The internal sphincter is caused pectinate line, drain with those of the to contract by sympathetic nerves and is rectum into the internal iliac nodes. relaxed by parasympathetic nerves.  Vessels from the part below the pectinate  The external sphincter is supplied by the line drain into the medial group of the inferior rectal nerve and by the perineal superficial inguinal nodes. branch of the fourth sacral nerve.  Department of Anatomy, Faculty of Basic Medical Sciences, College of Health Sciences, Osun State University, Osogbo, Osun State. ANA 204 (Gross Anatomy of the Abdomen) (2 Units) ADELEKE Opeyemi Samson. Surface and Radiological Anatomy of the Abdomen FIFTH (5TH) WEEK LECTURE  INTRODUCTION  Surface Anatomy can be define as the study of the structural relationships of the external features of the body to the internal organs and parts.  Surface anatomy provide knowledge of what lies under the skin and what structures are perceptible to touch (palpable) in the living body at rest and in action.  For instance someone that has stab wounds, Physician with the knowledge of Surface Anatomy must be able to visualize the deep structures that might be injured.  Surface Anatomy of the Abdomen  Visualization of the position of abdominal viscera is fundamental to a physical examination.  Some of these viscera or their parts can be felt by palpating through the abdominal wall.  Dividing anterior abdominal surface into regions and Quadrants can help to establish the positions of deep structures and locate any pathological structures.  By means of two vertical (Right & Left Midclavicular planes) and two horizontal (Transpyloric plane & Transtubercular plane) lines, abdomen will be divided into Nine regions.  Surface Anatomy of the Abdomen  By means of one vertical (Median plane) and one horizontal lines (Transumbilical plane), abdomen will be divided into Four Quadrants.  The 9 Abdominal regions are:  Right & Left Hypochondria  Right & Left Lumbar  Right & Left Inguinal (Iliac Fossa)  Epigastrum  Umbilical  Hypogastrium  The 4 Abdominal Quadrants are:  Right Upper Quadrant  Right Lower Quadrant  Left Upper Quadrant  Left Lower Quadrant  Surface Anatomy of the Abdomen  The lines/planes that divide the abdomen into regions and quadrants can be define in relation to the vertebral column L1,L2,L3,L4 and L5  The Transpyloric plane: Is an imaginary horizontal line, located halfway between the suprasternal notch of the manubrium and the upper border of the pubis symphysis. It lies roughly a hand's breadth beneath the xiphisternum  Transpyloric plane passes through the pylorus, body of the L1 Vertebra, pancreatic neck, the duodenojejunal flexure, the fundus of the gall-bladder, the tip of the 9th costal cartilage, Hila of the kidneys, level of termination of the spinal cord portal vein and root of the transverse mesocolon.  The Subcostal plane: Imaginary line joining the lowest point of the thoracic cage on each side, usually the inferior margin of the 10th rib  Subcostal plane It passes via body of the L3 Vertebra, the origin of the inferior rd  Surface Anatomy of the Abdomen  Transtubercular plane: Imaginary line uniting the 2 tubercles of the iliac crests.  Transtubercular plane passes through the upper border of the L5 vertebra and the confluence of the common iliac veins (IVC).  The Transumbilical plane: Imaginary line drawn through the umbilicus and passes via the intervertebral [IV] disc between the L3 and L4 vertebrae.  The Median plane: Imaginary line drawn longitudinally at the middle of the body, dividing the body into right and left halves.  The Midclavicular planes: Imaginary lines drawn from the midpoint of the clavicles to the midinguinal points.  Midclavicular planes roughly corresponds to the lateral border of the rectus abdominis muscle.  Surface Anatomy of the Abdomen Structures located in each quadrant Abdomino-thorax. Organs and their locations.  Surface Marking of some Abdominal organs  Liver: The lower border of the liver extends along a line from the tip of the right 10th rib to the left 5th intercostal space in the mid clavicular line.  The upper border follows a line passing through the 5th intercostal space on each side and It maybe palpable during deep inspiration.  Spleen: Spleen underlies the 9th, 10th and 11th ribs posteriorly on the left side 5 cm from the midline (median plane).  Gall-bladder: The fundus of the gall-bladder corresponds to the point where the lateral border of the rectus abdominis cuts the costal margin.  It can also be located at the tip of the 9th costal cartilage, easily detected as a distinct ‘step’ when the fingers are run along the costal margin.  Surface Marking of some Abdominal organs  Aorta Bifurcation: Terminates just to the left of the midline at the level of the iliac crest at L4 vertebra.  Pulsatile swelling below this level may thus be an iliac, but cannot be an aortic, aneurysm.  Pancreas: The transpyloric plane defines the level of the neck of the pancreas which overlies the vertebral column.  From this landmark, the head can be imagined passing downward and to the right, the body and tail passing upwards and to the left.  Kidneys: The lower pole of the normal right kidney may sometimes be felt in the thin human on deep inspiration.  Anteriorly, the hilum of the kidney lies on the transpyloric plane four finger breadths from the midline.  Posteriorly, the upper pole of the kidney lies deep to the 12th rib.  The right kidney normally extends about 2.5 cm lower than the left.  Surface Marking of some Abdominal organs Development of the spinal cord  Appendix: Appendix can be located by drawn imaginary line from right ASIS to the Umbilicus and locate a point(called McBurney’s point) which is one-third 1/3rd of the imaginary line from ASIS. Plain x-ray of abdomen. Gross Anatomy of the Spleen and Pancreas SIXTH (6TH) WEEK LECTURE  INTRODUCTION  The spleen is an ovoid, usually purplish, pulpy, soft, vascular, lymphatic organ which is about the size and shape of one's fist.  The spleen is 1inch thick, 3inches wide, 5inches long, and weighs 7ounces.  The Primary function of the Spleen is to help in the body's defense system and also in immune surveillance and response.  Prenatally, Spleen is a hematopoietic (blood-forming) organ, but after birth is involved primarily in identifying, removing, and destroying expended red blood cells and broken-down platelets, and in recycling iron and globin.  It serves as a blood reservoir and, to a limited degree, can provide a sort of self-transfusion in response to the stress imposed by hemorrhage.  Location of Spleen Spleen is located in the left hypochondrium, lies just beneath the left half of the diaphragm close to the 9th, 10th, and 11th ribs. The long axis lies along the shaft of the 10th rib, and extends forward only as far as the midaxillary line. Coverings of Spleen The spleen is covered by fibroelastic capsule and is surrounded by peritoneum except at the splenic hilum. Important relations of Spleen Anteriorly: The stomach, and tail of pancreas Posteriorly: The left part of the diaphragm which separates it from the pleura, lung, and ribs 9th, 10th and 11th. Inferiorly: The left colic flexure. Medially: The left kidney.  Presenting parts of Spleen Spleen has two Surfaces (Diaphragmatic and Visceral surface) Two borders (Superior and Inferior border) Two ends (Anterior or lateral and Posterior or medial end) The diaphragmatic surface of the spleen is convexly curved to fit the concavity of the diaphragm. The anterior and superior borders of the spleen are sharp and often notched Posterior (medial) end and inferior border are rounded   Spleen Ligaments  Gastrosplenic ligament: It is the fold of peritoneum that connects spleen at the hilum with greater curvature of stomach.  Splenorenal/lienorenal ligament: It is the fold of peritoneum that connects spleen at the hilum to the left kidney. This Ligament carries splenic vessels and sometimes tail of pancreas  Phrenicocolic ligament: It is attached to the left colic flexure (colon) and diaphragm. This ligament supports the spleen from below.  Arteries of Spleen  The large splenic artery convey blood out of the spleen.  Splenic artery is the largest branch of the celiac artery.  It has a tortuous course as it runs along the upper border of the pancreas.  The splenic artery then divides into about six branches, which enter the spleen at the hilum. Veins of Spleen  The splenic vein leaves the hilum and runs behind the tail and the body of the pancreas.  Behind the neck of the pancreas, the splenic vein joins the superior mesenteric vein to form the portal vein. Lymph Drainage of Spleen  The lymph vessels emerge from the hilum and pass through a few lymph nodes along the course of the splenic artery and then drain into the celiac nodes Nerve Supply of Spleen  The nerves accompany the splenic artery and are derived from the celiac plexus PANCREAS  Pancreas  The pancreas is an oblong-shaped abdominal glandular organ with both digestive (exocrine) and hormonal (endocrine) functions.  Pancreas is positioned at the level of the transpyloric plane  It is a retroperitoneal organ, located deep within the upper abdomen in the epigastrium and left hypochodrium regions with the exception of the tail of the pancreas which is intraperitoneal. Important Relations of the Pancreas Anterioly: Stomach (Separated from the pancreas by the lesser sac); First part of the Duodenum; Transverse mesocolon Posterioly: Common bile duct, aorta and inferior vena cava (Descends behind the head of the pancreas); Spleen (Connects to tail of the pancreas by Lienorenal Ligament); Superior mesenteric artery, the splenic and superior mesenteric veins (Descends behind the neck of the pancreas). Laterally: Second part of the Duodenum and Spleen  Pancreas parts  Head: This is the widest part of the pancreas. It lies within the C-shaped curve created by the duodenum, and is connected to it by connective tissue.  Uncinate process: It’s a projection arising from the lower part of the head and extending medially to lie beneath the body of the pancreas. It lies posterior to the superior mesenteric vessels.  Neck: Located between the head and the body of the pancreas. It overlies the superior mesenteric vessels which form a groove in its posterior aspect.  Body: Centrally located, crossing the midline of the human body to lie behind the stomach and to the left of the superior mesenteric vessels.  Tail: The left end of the pancreas that lies within close proximity to the hilum of the spleen. It’s lie within the splenorenal ligament and the splenic vessels and it’s the only part of the pancreas that is intraperitoneal.  Pancreatic Ducts  Histologically; Pancreas composed of clusters of cells called acini, connected by short intercalated ducts.  The intercalated ducts unite with one another and drain into a network of intralobular collecting ducts, which in turn drain into the main pancreatic duct.  The pancreatic duct runs through the length of the pancreas and unites with the common bile duct of the Liver to form the hepatopancreatic ampulla of Vater.  Hepatopancreatic ampulla of Vater then opens into the duodenum via the major duodenal papilla  Muscular valve called Sphincter of Oddi that surrounds the ampulla of Vater controls secretions via ampulla of vater into the duodenum.  Pancreas Vasculature  The pancreas is supplied by the pancreatic branches of the splenic artery.  The head is additionally supplied by the superior and inferior pancreaticoduodenal arteries which are branches of the gastroduodenal and superior mesenteric arteries respectively.  Venous drainage of the head of the pancreas is into the superior mesenteric branches of the hepatic portal vein.  The pancreatic veins draining the rest of the pancreas do so via the splenic vein. Lymphatics Drainage  The pancreas is drained by lymphatic vessels that follow the arterial supply.  They empty into the pancreaticosplenal nodes and the pyloric nodes, which in turn drain into the superior mesenteric and coeliac lymph nodes.  Clinical Significance Pancreatitis: Pancreatitis refers to inflammation of the pancreas which can be acute or persist over an extended period (chronic pancreatitis). The causes of pancreatitis can be Gall stones, Alcohol, Trauma, Steroids, Mumps, Autoimmune etc. Gross Anatomy of the Liver, gall bladder and bile ducts SEVENTH (7TH) WEEK LECTURE  INTRODUCTION  The liver is the largest wedge shaped of the abdominal gland and occupies a substantial portion of the upper abdominal cavity.  It weighs approximately 1500 g and accounts for approximately 2.5% of adult body weight.  It is an essential organ that performs a wide range of metabolic activities required for homeostasis, nutrition and immunity.  The functional unit of liver is called hepatocytes which originate from the endoderm of primitive foregut. Location of the Liver  The greater part of the liver is situated undercover of the right costal margin and also extends to the left to reach the left hemidiaphragm. Location of the Liver Contd..  Liver occupies most of the right hypochondrium and epigastrium and also a small portion extends into the left hypochondrium.  The diaphragm separates liver from pleura, lungs, pericardium and heart. Presenting parts of Liver  The liver has a convex diaphragmatic surface (anterior, superior, and Right surfaces) and a relatively flat visceral surface (posteroinferior). (Diaphragmatic surface) Superior surface: Features and Relations  It is the largest surface, convex in shape and is molded to the undersurface of the domes of the diaphragm.  This surface is covered by peritoneum except for a small triangular area between the two diverging layers of falciform ligament.  Centrally there is a shallow cardiac impression corresponding to the position of the heart above the central tendon of the diaphragm and is related to the pericardium. (Diaphragmatic surface) Anterior surface: Features and Relations  Triangular and convex in shape, the anterior surface is covered by peritoneum except at the attachment of the falciform ligament.  The anterior surface is related on the right with the pleura and 6th to 10th ribs and their cartilages and with 7th and 8th costal cartilages on the left.  The midline area of the anterior surface lies behind the xiphoid process and the anterior abdominal wall in the infracostal angle. Right Surface: Features and Relations  The right surface lies adjacent to the right dome of the diaphragm which separates it from the right lung and pleura and the 7th to 11th ribs.  The right lung and basal pleura between the diaphragm and the 7th and 8th ribs lie above and lateral to upper third of this surface.  The diaphragm, the costodiaphragmatic recess, and the 9th and 10th ribs are related lateral to the middle third of the right surface.  In the lower third, the diaphragm and thoracic wall are in direct contact. Visceral surface: Features and Relations  Visceral surface of the liver consist of posterior and inferior surfaces which are together called posteroinferior surface.  Posterior surface  The posterior surface is convex, wide on the right, but narrow on the left.  Much of the posterior surface is attached to the diaphragm by loose connective tissue in the region of the 'bare area'.  Posterior surface over the left lobe presents a shallow oesophageal impression which is related to the abdominal part of the oesophagus.  The posterior surface of the left lobe to the left of this impression is related to part of the fundus of the stomach.  A deep median concavity near the attachment of ligamentum venosum is related to vertebral column.  Fissure for ligamentum venosusm separates the caudate lobe of liver from the left lobe. Posterior surface Contd…  The lips of the fissure give attachment to the two layers of the lesser omentum.  The floor of the fissure lodges the ligamentum venosum.  Groove for inferior vena-cava lies in the medial end of the ‘bare area’ and to the left it is related to the caudate lobe.  The ‘bare area’ of the liver is devoid of peritoneum and is connected to the diaphragm by loose areolar tissue.  Inferolateral angle of the 'bare area' presents suprarenal impression that is related with the upper pole of the right suprarenal gland. Inferior surface  The inferior surface is irregular and bounded separated from the anterior and right surface by inferior border.  Inferior surface of the left lobe of liver presents gastric impression which is related inferiorly with the fundus of stomach and upper lesser omentum. Inferior surface Contd…  Fissure for ligamentum teres lodges the ligamentum teres.  Quadrate lobe is related to pylorus, first part of duodenum and lower part of lesser omentum.  Fossa for gallbladder that lodges the gallbladder is located on the inferior surface.  To the right of the fossa for the gall bladder, inferior surface of liver is related with the first part of duodenum, the hepatic flexure of colon, the right kidney and right suprarenal gland. Liver Lobes  Liver has a larger right and smaller left lobes.  Falciform ligament, fissure for ligamentus venosum and fissure for ligamentum teres separate the two lobes. Right Lobe  The right lobe also presents quadrate lobe and caudate lobe.  Bulge of tissue seen at the inferior border of the right lobe, to the right of the gallbladder is referred to as Riedel's lobe. Quadrate lobe  Present in the inferior surface of the Liver  Anatomically is the part of right lobe and functionally belongs to left lobe Boundaries  Above - porta hepatis  Below – Inferior border of the liver  To the right – fossa for the gallbladder  To the left – fissure for ligamentum teres Relations:  Pylorus and first part of duodenum  Caudate lobe  Present in the posterior surface of the liver  Anatomically is the part of right lobe and functionally belongs to left lobe Boundaries  Above continuous with superior surface  Below porta hepatis  To the right groove for inferior vencava  To the left fissure for ligamentum venosum Caudate process  Below and to the right, caudate lobe present a narrow strip called the caudate process.  Caudate process bounds porta hepatis posteriorly and forms the upper boundary of epiploic foramen. Left lobe  The left lobe is smaller & ends in a thin apex pointing into the left upper quadrant.  Since it is substantially thinner than the right lobe it is more flexible.  Ligaments of the liver Falciform ligament o Falciform ligament is a two-layered fold of peritoneum that ascends from the umbilicus to attach the liver to the posterior surface of anterior abdominal wall. o At the superior surface of the liver, the ligament splits into right and left layers. o The right layer turns laterally and forms the upper layer of the coronary ligament (the extreme of which is called the right triangular ligament) o The left layer turns medially to form the anterior layer of left triangular ligament. o Falciform ligament has a sickle shaped free margin that contains ligamentum teres hepatis or round ligament of liver. Lesser Omentum  The lesser omentum is also the peritoneal fold that is attached on the margin of the porta hepatis and the fissure for the ligamentum venosum and passes down to the lesser curvature of the stomach and proximal part of duodenum.  Thus lesser omentum has two components- hepatogastric and hepatoduodenal.  Ligaments of the liver Coronary Ligament The coronary ligament attaches posterior surfaces of the right lobe of the liver to the diaphragm. It consists of the upper and lower layers. Between the two layers of this ligament bounded laterally by groove for inferior vena cava and also a large triangular area of liver devoid of peritoneum This triangular area in the liver is called the 'bare area' of the liver. This part of liver is attached to the diaphragm by areolar tissue. The two layers of coronary ligament meet on the right to form the right triangular ligament. Porta Hepatis The porta hepatis is hilum of the liver present in the inferior surface. It provides a passageway to the neurovascular and biliary structures, except the hepatic veins. It is anteriorly bounded by the quadrate lobe and the caudate process posteriorly Neurovascular supply of liver  The portal vein and hepatic artery ascend in the lesser omentum and enter the liver at the porta hepatis where each bifurcates into right and left branches.  The hepatic bile duct and lymphatic vessels leave the liver at porta hepatis and descend through lesser omentum.  The hepatic veins directly drain into the inferior vena cava after leaving the liver through it posterior surface. Hepatic Artery  It arises from the coeliac trunk of abdominal aorta.  The artery may be subdivided into the common hepatic artery (from the coeliac trunk to the origin of the gastroduodenal artery) and the hepatic artery proper  Major Hepatic Artery Branches are: (Right Gastric artery, Gastroduodenal artery and Cystic artery from right hepatic artery) Veins  The liver has two venous systems: 1. The portal venous system (Portal vein) that conveys venous blood from the majority of the gastrointestinal tract and its associated organs to the liver 2. The hepatic venous system that drains blood from the liver parenchyma into the inferior vena cava Hepatic Veins  The hepatic veins convey blood from the liver to the inferior vena cava.  Hepatic veins are arranged in upper and lower groups.  The veins in upper group are usually large and commonly referred to as the right, middle and left hepatic veins.  The lower groups vein vary in number and extent of distribution Nerve supply The liver parenchyma is supplied by hepatic nerves, which arise from the hepatic plexus and contain sympathetic and parasympathetic (vagal) fibres. Hepatic nerve enter the liver at the porta hepatis and largely accompany the hepatic arteries and bile ducts. The liver capsule is innervated by branches of the lower intercostal nerves.  Lymphatic drainage The lymphatic from the liver are arranged into two sets: 1. Superficial lymphatics run in subserous areolar tissue and drain into: i. Subdiaphragmatic lymph nodes (most of the posterior surface, surface of caudate lobe and posterior part of inferior surface) ii. Hepatic lymph nodes (most of inferior surface, anterior and most of the superior surface) iii. Coeliac lymph nodes (few lymphatics from right surface) iv. Paracardiac lymph nodes (few lymphatics from posterior surface of left lobe) 2. Deep lymphatics  Deep lymphatics vessels drain the liver parenchyma.  The lymph vessels partly accompany the hepatic veins and portal vein and drain into i. Supra-diaphragmatic lymphnodes ii. Hepatic lymph nodes.  Ducts of liver Bile ducts of the liver:  The ducts of the liver consist of right and left hepatic ducts, the common hepatic duct, the bile duct, the gall bladder and the cystic duct.  The Intrahepatic bile ducts at porta hepatis of the liver form the right and left hepatic ducts. Hepatic Duct  The right hepatic duct drains the right lobe of the liver whereas the left hepatic duct drains the left, caudate and quadrate lobe of the liver.  After the short course the right and left hepatic ducts unite to form common hepatic duct which is about 4cm long and descends within the free margin of lesser omentum.  Common hepatic duct joined on its right side by the cystic duct to form the common bile duct. Bile duct  The bile duct or Common bile duct is about 3 inches (8cm) long.