- The gallbladder stores bile formed within the liver, releasing it for fat digestion.
- Bile travels through the intrahepatic ducts into the paired hepatic ducts; these merge into the common hepatic duct. Bile is then diverted via the cystic duct to the gallbladder for storage.
- When food is ingested and travels through the stomach to the duodenum, a hormone is released (cholecystokinin) which stimulates the gallbladder to contract and the sphincter of Oddi to relax. This allows bile to flow through the cystic duct and the common bile duct into the duodenum.
- The most common pathology in the extrahepatic biliary system is bile (gall) stones (concretions of bile salts, cholesterol, and minerals) which can block ducts, causing inflammation, pain, and jaundice.
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- The primary function of the upper abdominal organs is the breakdown of food for distribution by the small bowel. Chewed and macerated food travels through the esophagus to the stomach, where strong acids and muscular contractions break it down further.
- Proteolytic enzymes from the pancreas and bile from the liver and gallbladder drain into the duodenum to further the digestion and breakdown of food.
- The spleen functions as part of the hematopoietic system, controlling the distribution and eventual destruction of red blood cells. It also acts as a part of the immune system.
- Blood is supplied to most of these structures by branches of the celiac trunk, the first major aortic branch in the abdomen.
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- The contents of the abdomen are primarily associated with digestion and distribution of nutrients.
- The esophagus, a tube which carries food and fluid through the thorax, enters the abdomen through the diaphragm, where it widens into the stomach; the stomach empties into the small bowel (duodenum, jejunum, and ileum, in which food is absorbed into the blood stream), and from there into the large bowel, where waste material is compacted as fluid is reabsorbed into the system.
- The liver has multiple functions affecting a number of other body systems, including digestive, hematologic and endocrine/metabolic.
- The large and small bowels are supplied by branches off of the aorta carried within the mesentery, a double-layered sheetlike structure.
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- The external eye has upper and lower lids which close over the globe to protect it. The sclera is the white of the eye, the colored portion is the iris, and the black opening in the middle of the iris is a hole known as the pupil. This is the only window in the body through which the nervous system can be seen directly.
- The anterior transparent media consists of the cornea, anterior chamber and lens; the posterior elements of the globe are covered with specialized nerve tissue, the retina.
- The optic nerve enters the eye posteriorly along with its own blood supply; this area is known as the optic disc. The macular area is where visual acuity is greatest.
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- The stomach is a muscular sac derived from the simple fetal gastrointestinal tube. The mucosal lining has specialized cells which secrete strong acids and enzymes to break food down before it passes to the small bowel for absorption and distribution.
- The walls are folded into rugae which increase the surface area of the sac. The muscular walls contract to help break up food material.
- The greater omentum arises from the greater curvature of the stomach, and the lesser omentum from the lesser curvature; the hepatoduodenal ligament lies at the free edge and contains the extrahepatic biliary ducts.
- The stomach lies under the diaphragm and to the left of the liver. The strong pyloric sphincter divides the distal stomach from the duodenum or the first portion of the small intestine.
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- With the exception of a portion of the first part of the duodenum, the small bowel is supplied by the many branches of the superior mesenteric artery.
- The branches anastomose with each other in two layers of arcades or arches, and from these, small straight vessels pass to the bowel surface, traveling around and through the wall, dividing into smaller and smaller branches.
- The arcades and multiple straight vessels are an adaptation which protects the bowel. Damage can occur to a portion of the small bowel without loss of the entire organ. Clots and ischemia from atherosclerosis and other vascular pathologies can affect the small bowel, much like the brain, heart, kidney and other organs can be affected by such conditions.
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- The blood supply of the colon comes from three sources: the superior mesenteric arteries supplying the cecum, ascending (right) colon and half of the transverse colon; the inferior mesenteric arteries supplying the distal half of the transverse colon, the descending (left) colon, and the sigmoid colon; the rectal arteries supply the rectum.
- The arteries then divide into arcades, as they do to the small bowel, with straight arteries entering the bowel wall at the mesenteric border.
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- The portal system is a specialized venous drainage system of the large bowel. Instead of merely draining deoxygenated blood, the portal system drains metabolites and nutrients upward so that they detour through the liver instead of returning directly to the heart and lungs. The liver serves as a cleaning and metabolic sieve where drugs and other chemicals are further broken down and either used or removed from the system.
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- Performed during surgery for gallbladder removal, this is an effective intraoperative radiographic test to look for either blockage or leakage in the biliary tree.
- This test may be performed prior to removing the gallbladder, or at any time a problem is suspected. A tiny catheter is threaded through a small incision in the cystic duct. Dye is injected into the biliary tract and x-rays are taken, allowing the surgeon to see which ducts are patent. Voids represent stones or tumors, and extravasation represents a leak in the system.
- While this test is very reliable in the case of a retained stone or suspected damage, the outcome in patients having routine intraoperative cholangiography without apparent complication is the same as those in whom the test was not performed.
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- After placement of the trocars, the gallbladder is grasped and retracted upward and outward. Adhesions, connective tissue, and the lesser omentum are divided from the neck of the gallbladder in a medial direction, to reveal a portion of the cystic duct.
- Clips are placed on the exposed cystic duct and an incision is made between the clips.
- The cystic artery is then located within the Triangle of Calot (formed by the planes of the lower border of the liver, the cystic duct, and the common hepatic duct), ligated and divided.
- The gallbladder is removed through one of the ports.
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- Cholecystitis, or inflammation of the gallbladder, is usually caused by gallstones blocking the cystic duct. Removal is usually performed via a laparoscopic approach, using an endoscope for visualization and hollow trocars holding the small instruments used for the surgery.
- The view through the laparoscope is transmitted to a video monitor, and the physician controls the progress by either looking directly through the scope or at the video display, depending on his or her preference and training.
- The overall complication rate for the laparoscopic procedure is about half that of the open procedure, although converting a laparoscopic procedure to an open one occurs approximately 4% of the time, usually because of difficulty in visualization.
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- Most of the abdominal contents lie within the peritoneum, a sac made up of a sheet of dense connective tissue. Some structures lie behind the peritoneum (retroperitoneal). Others go in and out of it, although edges are sealed and there is little or no direct connection between the intra- and retroperitoneal regions.
- The liver has a “bare area” at its top where it lies directly against the lower surface of the diaphragm, but the rest of it is intraperitoneal. The ascending and descending colons are both retroperitoneal, while the transverse colon and part of the sigmoid are intraperitoneal; the duodenum, or first portion of the small intestine, is retroperitoneal.
- True retroperitoneal structures include the pancreas, the kidneys, ureters and adrenals, the great vessels and the pelvic structures.
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- Adhesions are fibrous scars which can form after any disturbance within body cavities and spaces. Inciting events can include surgery, trauma, and inflammation.
- Within hours of disturbance, thin, filmy strands form between bowel loops and between bowel and peritoneum and/or body wall. These continue to form for a period of time and mature over a period of weeks.
- Mature adhesions are dense, white fibrous tissues which have merged with the outer layer of the tissues; they eventually develop their own blood supply and may become severe enough to cause chronic pain and pose a chronic risk of small bowel obstruction or volvulus.
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- Normal small bowel function is in the form of peristalsis, regular wave-like contractions of the smooth muscle within the wall of the bowel. Digested food materials (chyme) move through the small bowel, where intestinal villi absorb nutrients. These raw materials enter the bloodstream and are distributed throughout the body for growth and maintenance.
- Ileus is a temporary reduction or cessation of peristalsis, allowing fluid, chyme, and gases to accumulate. It is characterized by abdominal distension and discomfort; on x-ray, distended bowel loops with air/fluid levels can be seen. Bowel sounds are reduced or absent, and gas and stool are not passed.
- Ileus is a common sequela of abdominal or pelvic surgery, lasting hours to days. Symptoms are relieved by nasogastric suction to reduce pressure.
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- Gastric bypass is performed to reduce the volume of food which the stomach can hold, and to reduce the amount of bowel available to absorb nutrients.
- There are several surgical variations; in this version, the stomach is divided and the small bowel is surgically joined to the small stomach remnant, bypassing the rest of the stomach. A second surgical anastomosis is made further down the length of the small bowel. No tissue is removed.
- The procedure can be performed either through a large abdominal incision or laparoscopically, using “band-aid” incisions. A lighted scope is inserted into the abdomen, as are several slender tubes. Instrumentation is then placed into the tubes and the procedure is performed under direct vision through the scope.
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- There are normally 32 teeth, divided into 4 categories: molars, premolars, canines, and incisors.
- The teeth are embedded in the bones of the maxilla (upper jaw) and mandible (lower jaw) and are held in position by periodontal ligaments.
- The third molars (teeth #1, 16, 17, 32) are often vestigial and/or impacted. These are commonly known as “wisdom teeth”.
- The roots of the teeth are anchored within the bone and contain an artery, vein, and nerve which travel to the main portion of the tooth and divide within the pulp.
- Dentin covers the pulp and very hard enamel covers the dentin; the bone is covered with a mucosal tissue, the gingiva.
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- The mandible, or lower jaw, is the bone that hinges to the skull and, together with the maxilla, forms the mouth.
- The mandibular nerve, the third and largest branch of the trigeminal nerve, runs along the mandible.
- The mandibular nerve has both sensory and motor functions. It divides into trunks and smaller branches to innervate the teeth and gums of the mandible, the lower lip and lower part of the face, and the muscles of mastication.
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- The external ear acts as a collecting device for sound waves, focusing them into the canal.
- External sound waves cause vibration of the tympanic membrane (ear drum). The vibrating membrane moves the three ossicles of the middle ear (malleus, incus, and stapes) which transfer the vibration to branches of the vestibulocochlear nerve (cranial nerve VIII) within the cochlea.
- Motion and balance are detected by three fluid-filled canals in the temporal bone. Oriented in three perpendicular planes, the canals contain tiny hair cells that pick up fluid movement with motion of the head. This information is transmitted through the vestibular portions of the nerve to the appropriate portions of the brain.
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- Atherosclerotic plaque is fatty, cholesterol-laden material which accumulates within the inner layer of the major arteries, narrowing the diameter of the lumen or opening.
- It can occur in any artery in the body and is a direct cause of stroke when in the carotid arteries; myocardial infarction when in the coronary arteries; acute bowel ischemia when in the mesenteric vessels; peripheral vascular disease when in vessels to the legs, etc.
- Atherosclerosis can result in increased blood pressure in an effort to overcome the higher pressures caused by arterial stenosis throughout the body.
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- This procedure is a relatively non-invasive technique of opening stenotic blood vessels.
- A catheter is threaded through the arterial system from the arm or leg and into the diseased artery. The balloon is then positioned inside the stenotic area and gently inflated several times to crush the plaque and flatten it against the walls of the vessel.
- This procedure is commonly performed and is often accompanied by the deployment of a stent to hold the vessel open.
- Complications can include clot formation on the fractured plaque after the release of clotting factors and formation of a dissection (sometimes incorrectly called a “dissecting aneurysm”) in the vessel wall.
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- When coronary arteries are significantly blocked (>70% stenosis), pain symptoms often occur with exercise in the form of stable angina, or at rest in the form of unstable angina.
- Bypass vessels are harvested as free grafts from the saphenous veins of the legs. These are anastomosed to the aorta and then to the coronary arteries, literally bypassing the blocked regions.
- The internal mammary arteries, which lie on either side of the sternum within the rib cage, can also be harvested and anastomosed directly to the coronary arteries. These grafts are less likely to stenose than are vein grafts.
- The procedure can be performed either on or off cardiopulmonary bypass.
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- Heart muscle is supplied by the coronary arteries, not by the blood flowing through the heart.
- The major coronary vessels are the right coronary artery (RCA) and left main coronary artery (LCA), both of which come directly off of the aorta via the coronary ostia.
- The LCA divides into the left anterior descending artery(LAD) and circumflex artery.
- The RCA has no major branches and terminates as the posterior descending artery (PDA).
- There are may be variations in the anatomy.
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- These potentially lethal blood clots usually form in the deep veins of the leg or in the pelvis. Those in the legs are usually painful, whereas those in the pelvis may be asymptomatic.
- The clots usually form in the valves of the larger veins, propagating upward toward the heart.
- Clots of any size can break off and travel with the blood flow through the inferior vena cava to the right side of the heart and to the lungs; the pulmonary vasculature acts like a sieve and clots get caught in the vessels as the vessels get smaller, causing loss of blood flow in those areas. These clots are known as pulmonary emboli if they reach the lungs.
- Conditions associated with DVT and PE include a history of leg trauma, cancer, surgery, venous stasis from illness, lack of exercise, clotting defects and others.
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- Sometimes called “dissecting aneurysm”, this is not an aneurysm, but a separation of the aortic wall layers.
- Blood enters the aortic wall through a small tear in the intima or inner lining of the artery. Under pressure, it then dissects through the wall, creating a false lumen or false channel. Sometimes there is a second tear through which the blood re-enters the true aortic lumen; sometimes the blood breaks through the wall to the thorax or retroperitoneal spaces.
- Dissections are usually associated with hypertension and atherosclerosis, although certain genetic conditions (Marfan’s syndrome) can predispose to dissection.
- Symptoms include a severe tearing pain in the back as the dissection travels distally, changes in blood pressure and distal pulses, and loss of various physiologic functions if the dissection blocks the blood supply to major organs.
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- The anterior 2/3 of the brain is supplied by branches of the internal carotid artery, whose terminal branches form the anterior and middle cerebral arteries.
- The vertebral arteries branch off the subclavian arteries and through small openings in the transverse processes of the cervical vertebrae. They merge to form the basilar artery supplying the cerebellum, brain stem, and the posterior cerebrum via the posterior cerebral arteries.
- The Circle of Willis has small connecting vessels between the three major cerebral vessels. Blood can change direction within the circle for collateral blood flow if needed. There can be significant variation in the form of the Circle of Willis from one individual to another.
- Tissues supplied by the tiny terminal branches of vessels are known as watershed regions and are vulnerable to damage during periods of low perfusion or oxygenation.
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- Cancer tends to spread by two mechanisms: infiltration, in which the tumor pushes against and enters contiguous tissue; and metastasis, when cancer cells enter lymphatic channels and/or small blood vessels and eventually travel to distant locations and organs in the body.
- Certain tumors have a predilection for specific sites. Colon cancer frequently spreads to the liver, and breast cancer to the brain and spine.
- When there is lymphatic spread, the local and regional lymph nodes are the first line of defense; when the nodes fill up with dividing tumor cells, the cells then break free and travel toward the heart for distribution throughout the body.
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- A common assumption is that a cancer may not have been diagnosed early enough to make a difference, with the assumption being that early diagnosis is always better.
- In reality, cancers are present for very long periods of time before they are diagnosable, and many have metastasized prior to the period in which they can be detected.
- The life span of more than 60% of cancer patients is essentially predetermined by the characteristics of the cancer itself. While a patient diagnosed earlier may live “longer” than one diagnosed later, both patients actually survive about the same length of time from the first cancer cell.
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- The breast in a premenopausal woman is composed of glandular tissue, fat, connective tissue and ducts; the axillary tail of breast tissue is tucked upward in the axilla. The breast lies on the pectoralis muscles of the thorax.
- The breast is divided by irregular fibrous septa which prevent masses from migrating from one area of the breast to another; malignant tumors may eventually erode through these septa.
- Lymphatic channels travel throughout the breast, with all but the most medial portions draining to the axillary lymph nodes. The “sentinel” node—the first node to receive drainage from the breast—can be determined with testing and evaluated for metastatic spread.
- Post-menopausal women have little glandular tissue since most of it has been replaced by fat.
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- Like in the arm, the deep, muscular arteries of the leg travel together, but the superficial veins are unpaired and variable in course.
- The legs receive blood from the terminal branches of the aorta, the iliac arteries. Branches supply the muscles of the thigh, and the name of the artery changes as it passes certain landmarks.
- The major vessels trifurcate behind the knee, dividing into the anterior and posterior tibial arteries and the peroneal artery, all of which travel toward the feet supplying the muscles and other tissues along the way.
- As in the arm, there are connective vascular arches in the foot supplying collateral circulation.
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- Mammography is an imaging technique which allows visualization of breast tissue. Fat, glandular tissue and ductal tissue have characteristic densities and patterns.
- Solid tumors are generally easier to see in older patients with larger amounts of fat within the breasts, but can be difficult to see in patients with “dense” breasts (young women and women with fibrocystic breasts).
- Approximately 75% of breast cancers can be seen on mammography, with the patient’s breast characteristics being the largest determining factor.
