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T. Koraz. University of Cincinnati.

In children up to the age of puberty purchase zestoretic 17.5 mg with visa arteriogram, those techniques assessing dental development are more accurate but more complex and time-consuming than those using eruption/emergence schedules generic zestoretic 17.5mg on line blood pressure lisinopril. From puberty to the time that growth and development have ceased generic zestoretic 17.5mg otc arteria radialis, around age twenty-one zestoretic 17.5mg line arterial narrowing, the most useful dental techniques involve analyzing the development or mineralization of the teeth, including the third molar. It is well known that third molar devel- opment variations are greater than for any other human tooth, but those are likely the only teeth still developing in the target age group. Tere is a need for more and larger population studies for specifc geographic and ethnic groups. For adults afer the age of around twenty-one years, the applicable dental tech- niques are those that look at gross, histological, biochemical, and trace ele- ment changes to teeth. In living adults these are limited to the radiological and visual examination techniques unless a valid clinical reason for removing 294 Forensic dentistry all or part of a tooth exists. In those cases, aspartic acid racemization analysis or 14C analysis may be performed. Te same radiographic and visual procedures used for living individuals can be used for the deceased. In addition to those methods, and with per- mission from coroners or medical examiners, teeth can be removed for age estimation studies. With proper con- sideration of the limitations of the technique, there is no reason that it could not be routinely used in human age estimation. Although work remains to be performed to validate the determination of the ratios in amino acid racemization, that method is a promising technique for improving dental age estimation in all age groups. Both tooth cementum annulation and aspartic acid racemization can be used, with associated limitations, for individuals of any age. Radioactive 14C analysis from tooth enamel is a new and promising technique, potentially ofering the most accurate and precise information on estimated date of birth for those individuals born afer 1943. Using human teeth for age estimation is well established in past and recent literature. Multiple studies have demonstrated varying accuracy, reli- ability, and precision. Reproducible and reliable results are possible when the appropriate techniques for a given situation are properly understood and applied. Specifc individuals within a population may live at either end of the range or fall outside the normal limits. Te limitations of current methods and the paucity of population data available mean those methods are not adequate to allow precise age estimation results for every case. Age estima- tion reports must clearly convey that the data reported are based on mean ages derived from the features studied for a specifc population and should include realistic ranges. Specifc casework may require combining methods to arrive at the most accurate conclusions. When possible, more than one dental technique or a combination of dental and skeletal or other techniques should be used. Since research into age estimation is ongoing, forensic dentists performing age estimation must age estimation from oral and dental structures 295 continually monitor the scientifc journals that report new developments and validate or challenge existing techniques. Multifactorial determination of skeletal age at death: A method and blind tests of its accuracy. Reliability of age at death in the Hamann-Todd collection: Validity of subselection procedures used in blind tests of the summary age technique. Test of the multifactorial aging method using skele- tons with known ages-at-death from the Grant Collection. A multivariate analysis of temporal change in Arikara craniometrics: A methodological approach. Tooth mineralization standards for blacks and whites from the middle southern United States. An example of regional variation in the tempos of tooth mineralization and hand-wrist ossifcation. Dental maturity of children in Perth, Western Australia, and its application in forensic age estimation. Dental maturity as an indicator of chrono- logical age: Radiographic evaluation of dental age in 6 to 13 years children of Belgaum using Demirjian methods. Relationship between the sequence of calci- fcation and the sequence of eruption of the mandibular molar and premolar teeth. Studies from the center for research in child health and devel- opment, School of Public Health, Harvard University. Sex diferences in the chronology of deciduous tooth emer- gence in white and black children. Comparison of the deciduous dentition in Negro and white infants: A preliminary study. Timing of exchange of the maxillary deciduous and permanent teeth in boys with three types of orofacial clefs. Te accuracy of three methods of age estimation using radiographic measurements of developing teeth. Negro-Caucasoid diferences in permanent tooth emer- gence at a constant income level. Efect of extraction of deciduous molars on the formation and eruption of their successors. Emergence of the permanent teeth in Pima Indian children: A critical analysis of method and an estimate of population parameters. An epidemiological survey of the time and sequence of eruption of permanent teeth in 4–15-year-olds in Tehran, Iran. Comparison of diferent methods for estimating human tooth-eruption time on one set of Danish national data. Parametric survival analysis in Bangladeshi, Guatemalan, Japanese, and Javanese children. Tooth-by-tooth survival analysis of the frst caries attack in diferent age cohorts and health centers in Finland. Development of the human jaws and surrounding structures from birth to the age of ffeen years. Structural and calcifcation patterns of the neonatal line in the enamel of human deciduous teeth. Deciduous tooth size and morpho- genetic felds in children from Christ Church, Spitalfelds. Formation of the permanent dentition in Arikara Indians: Timing diferences that afect dental age assessments. Growth, maturation, and body composition: Te Fels Longitudinal Study, 1929–1991, xiii. Te formation and the alveolar and clinical eruption of the permanent teeth: An orthopantomographic study. Tooth formation age estimated on a few selected teeth: A simple method for clinical use. Te validity of four methods for age determination by teeth in Swedish children: A multicentre study. Tooth formation and the mandibular sym- physis during the frst fve postnatal months. Abnormal odontogenesis in children treated with radiation and chemotherapy: Imaging fndings. Te dates of eruption of the permanent teeth in a group of Minneapolis children: A preliminary report.

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These were not medicinal interventions order 17.5 mg zestoretic amex blood pressure medication zanidip, compared with that in promulgated in isolation but after consultation the White male population order zestoretic 17.5mg otc hypertension treatment in pregnancy, have been only with academia and industry 17.5 mg zestoretic with visa blood pressure higher at night. In the United States purchase zestoretic 17.5 mg with visa hypertension risks, sporadically addressed by the research, academic, initially this was done under the auspices of the and industry pharmaceutical development American Society of Clinical Pharmacology and communities. Industry was allowed to participate In general, globally and especially in the United and was largely credited with aiding the process. This, often in the again involved the regulators and the regulated United States, caused the implementation of the and, for the first time, involved Japan as a Food, Drug and Cosmetic Act of 1906, which out- major contributor. As a result of pre-conference, lawed the practice of embalming meat for con- during-conference and post-conference discus- sumption. On occasion, ing chapters include the four major demographic these amendments have been due to political pres- segments: the elderly, women, children and major sure from special advocate groups rather than a ethnic groups; and although any smaller grouping specific therapeutic disaster. Second, the ever-present fear of litigation Each chapter will give a limited historical con- resulting from perceived exploitation, coercion text. These units have increased market what constitutes an orphan population and an penetration and retention of drugs for third-party ‘orphan drug’, the history of legislation, and the reimbursement and allowed niche dominance. Although it is part of most clinical programs (as a predictor of the latest, it will not be the last – the future impact drug pharmacokinetics in the elderly), it is of the genome project on each of these major included in this section as these volunteer patients demographic segments, and its influence on geno- are indeed special patients. For less-developed countries, this would still reach The elderly (over 64 years old) comprise 12% of 76 years. In the United States, by a decrease in fertility rate, now under way, from it is estimated that the elderly population will grow 1. Even in the least (Everitt and Avorn, 1986), contributed to accep- developed (Third World) countries, five births per tance by industry of additional requirements for woman would fall to two by 2050. Database (1996) (National Center for Health Sta- The social and healthcare impact of these demo- tistics, 1996) projected that, for the year 2020, the graphics in the United States and across the globe less-developedcountrieswouldcontainonly16. This elderly and that by 2020 the mean age of the population in population have more income than average per more developed countries would be 42 years, up capita income. In developed regions, the ‘baby-boomers’ are starting to retire to a total of elderlywouldoutnumberyoungchildrenby8:1,for 86. In addition, with survival rates, only 2% of the population would be more time on their hands to lobby, they are more five years or younger, but 40% would be 65 years likely to vote, and can be expected to use their and older. The governments will respond in the usual United Nations International Population Division knee-jerk reaction – ‘more regulations and con- (1996). They projected life expectancy in the trols’ on industry – while increasing funding for Principles and Practice of Pharmaceutical Medicine, 2nd Edition Edited by L. It will is 1–4 months in general (1–18 months for be interesting to see whether a more extended life Alzheimer’s patients) and, even with what would expectancy, over and above the current projections, normally be an adequate pension, this burden can will reverse the depopulation trend. In the United States alone, Alzheimer’s disease will affect 16 million people by 2050 (Tauzin, 1995). This is already happening in Europe and in population aged 15–65 years will fall from 22% the United States. In the United States, 60 years ago, the and intestinal disease, endemic to many of their retirement age for Social Security ‘pension’ was home countries. In 1997, 39% of tuberculosis cases designed for an expected average lifespan of in the United States were in foreign-born parents; 65 years. Already this has been pushed back to in California, this rose to 67% (Satcher, 1999) and 67 years by year 2004, and additional legislation the annual cost of diagnosis and treatment of the will probably push the age requirements back to 70 1 million immigrants was $40 million (Muenning in 10 years’ time, when the ‘baby-boomers’ swell et al. To encourage the healthy older person to con- tinue working beyond 65 years, legislation was passed to remove the penalty (in workers 65–70 15. In 1999, it was proposed that, because of the high Studies of drug utilization in the elderly showed cost of medication and because the older people that older people receive disproportionate amounts were the greatest users, they be eligible for drug of medication (Rochon and Gurwitz, 1995). The elderly current situation is that the government will not use comprised 18% of the population but received 45% this volume to drive prices down. One in 10 admissions to acute geriatric units Of great concern is the social and financial was caused or partly caused by adverse drug reac- impact of Alzheimer’s disease, whose incidence tions. The drugs involved most commonly were per capita increases to 32% of the surviving popu- benzodiazepines, warfarin, digoxin and nonster- lation at ages 80–85 (and declines rapidly after age oid anti-inflammatories (Denham and Barnet, 85). This causes enormous cited reports of adverse events causing 5–23% of detriment to the surviving spouse and family and hospitalizations, nearly 2% of ambulatory visits to family finances, and must eventually impact and 1 in 1000 deaths in the general population. In perceived concerns of both investigators and phar- addition, 31% take alcohol frequently (Conn, 1992). There are very increase the bleeding tendency, and not just from fit 80-year-olds who climb mountains, and young the stomach. Antacids can decrease the excretion children dying from genetic advanced aging (pro- of antidepressant tricyclics, quinidine, pseudoe- geria). So many of the above concerns can be the absorption of digoxin and b-blocker hyperten- reduced by selecting ‘uncomplicated, healthy’ sive medication. These are only a few of the older patients in phase I studies, who are increas- multitude of interactive drug effects. This is ingly available due to the success of medicines and imposed on the reduced efficacy of hepatic meta- preventative medicine. For the elderly, of equal importance to life exten- sion and cure is improvement or preservation of their activities. Traditionally, elderly subjects were frequently excluded from clinical drug development (unless 15. The reasons given were that the By the 1980s, most of the new medicines still had elderly suffer from too many other diseases, little or no information on elderly dosing or con- require concomitant medicines, are more frail tained disclaimers. All that 30% of prescription drugs by then were con- these can cause ‘static’ in the interpretation of the sumed by just 12% of the population (those over data, and give undue weightage to adverse events 65 years), a new guideline was issued. The tripartite guidance, Studies in Support of Special patients must be in ‘steady state’. The agency followed up with specific requirements on content and format of labeling 6. Usually, differences in the therapeutic response or adverse events are too small to detect at an equivalent plasma level between ordinary adult 15. Studies should include patients 65 years and lized by the liver, the effect of drug enzyme older, and preferably patients aged 75 or older, inducers and inhibitors should be explored. Finally, other common the increasing importance of medicines for the drugs most likely to be used with the test drug graying population of United States. There is also a unique form called 1993) showed that, for 11 drugs recently approved isolated systolic hypertension, which affects 9% or awaiting approval of New Drug Applications, in of the geriatric population and is growing as the seven applications 30–36% of patients were aged population ages. In one application, a study on a drug for this area increase with the age of patients admitted, prostate cancer, 76% of patients were, not surpris- which correlates with increased concomitant med- ingly, over 60 years old (Everitt and Avorn, 1986). A survey by the Pharmaceu- Coronary heart disease caused one in five deaths tical Research and Manufacturers of America in 2002 at average age of 65. Why did companies target Because of its severity, patients are on many these therapeutic areas in the geriatric population? However, point death), make these very challenging and the next most frequent studies were quality-of-life, expensive studies. The later studies reflect leading cause of death, killing 160 000 persons in the elderly and third-party payers’ influences the United States each year, 7 out of 10 victims are (Chaponis, 1998). Of those that survive, one-third reported that more than 600 medicines were then will be permanently disabled. As of follow-up visits are easier to achieve than with 1999, more than 20 new drugs were in development Alzheimer or depressed patients. Alzheimer’s disease is the eighth leading cause Arthritis causing inflammatory and degenerative of death in the elderly and already affects some 4 changes around joints affects 43 million in the million Americans. New small study of donezil showed that this treatment medications, such as the anti-tumor necrotic factor avoided the need for home nursing care by half a-blockers, raise fresh challenges to clinical study compared to those who did not receive the medi- methodology because of limitations on nonclinical cine (Small, 1998). As with hypertension, the large numbers of patients to show the often small numbers of patients required in the database will be improvement, as well as months of observation to large for product approval, especially for safety. These studies Depression is a frequently missed diagnosis in require large numbers of patients, and many are the elderly.

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However cheap zestoretic 17.5 mg with amex blood pressure chart enter numbers, injuries to the median and ulna nerves can also occur purchase 17.5 mg zestoretic with amex arteria jugular, and these may be isolated or in any combination purchase zestoretic 17.5 mg amex heart attack in 20s. The superficial branch of the radial nerve may be spared with others being damaged (6) zestoretic 17.5 mg low price arteria entupida 70. Resultant symptoms are reported as lasting up to 3 years in one case; pain may be severe and prolonged, although the most disturbing symptom to patients is paresthe- 198 Page sia (5). Nerve conduction studies may be used to distinguish between a com- pressive mononeuropathy and a radiculopathy. The majority of cases with sig- nificant nerve damage either involve detainees who are intoxicated or have a clear history of excessive pressure being applied by the officers (5). Intoxica- tion may cause problems through a decreased awareness of local pain, marked uncooperativeness, or poor memory for the restraining episode when a signifi- cant struggle occurred. It is possible to have nerve damage with no skin break- age, reflecting undue pressure. Although some of the quoted studies predate the introduction of rigid handcuffs, because of the similar ratchet mechanism, direct pressure problems are still possible. Sensory nerve damage causes loss of pain, touch, and temperature sen- sation over an area of skin that is smaller than the nerve’s sensory supply because of the considerable overlap between the sensory territories of adja- cent peripheral nerves. Lesser degrees of damage lead to tingling, pain, and numbness in the appropriate sensory distribution. In acute compression of the nerve, symptoms appear more or less abruptly, and relief of this acute com- pression should lead to resolution in the course of some weeks. Associated motor weakness can be demonstrated by the correct clinical test within the hand. It should be noted that compression of the radial nerve at the wrist does not result in weakness. There was little formal training with these, but actual use was not that common, either because they were not terribly effective or the situations faced at that time could be dealt with differently. In 1993, trials of both side-handled and numerous straight batons were introduced, because there was a rise in the number of officers injured on duty and the adequacy of their equipment was called into question. Weighing approx 600 g with a shaft of polycarbonate plastic or aluminium, it has a fixed grip at right angles to the shaft toward one end. The addition of the handle to the shaft makes it versatile, with more than 30 blocking and striking techniques available to the officer. Correct use in stressful and challenging situ- ations requires extensive and ongoing training. It is carried unobtrusively on the belt and does not impede the general movement of the officer. This gives more weight distally, but it is prone to becoming flattened and rough over time because the baton is closed by striking this end against the ground. The acrylic patrol baton has a solid or hollow nylon shaft with a ring of rubber separating the shaft and handle. It is broader than the friction lock type and, therefore, less likely to cause injury because the imparted energy is spread over a larger area. The heavier weights of these types of batons are used in public order disturbances. In the United States, a 26-in hickory (wooden) straight baton is used (similar to group 3 in the previous list). The situation throughout the Austra- lian states is variable, with intrastate differences relating to specific police staff; for example, plain clothes staff may use an Asp-type baton, whereas uniformed officers are equipped with straight or side-handled batons. Strikes are made from an officer’s strong (dominant) or weak (nondominant) side, and clearly the potential for injury varies with the baton mass and velocity at impact, the target area, and to how much of the surface area the force is applied. Although no body area is absolutely forbidden to strike, an officer must use a proportionate response to the situation he or she faces knowing the potential to injure. Although target areas are divided into low-, medium-, and high-risk areas, maintaining a distinction between them can be difficult because strikes are made in dynamic situations where an initial target area may change as the potential detainee moves. Target areas with a low injury potential are the areas of the common peroneal, femoral, and tibial nerves on the legs and those of the radial and median nerves on the arms. There is a low probability of permanent injury, with the main effects being seen as short-lived motor nerve dysfunction, as in a “dead leg” and bruising. The medium injury potential areas involve bones and joints, including the knees and ankles, wrist, elbow, hands, upper arms, and clavicle. In these cases fractures, dislocations, and more extensive soft tissue injuries would be expected. Finally, those areas with the highest risk of injury include the head, neck and throat, spine, kidneys, and solar plexus. The most common injury is bruising, and this is often in the pattern of so-called “tramline bruising,” where two parallel lines of bruising are sepa- rated by a paler area. This is not unique to a baton injury but reflects an injury caused by any cylindrical hard object. The absence of bruising or other find- 200 Page ings does not mean that a baton was not used because, for example, a degree of cushioning can occur from clothing. It is possible for a detainee to have signs but minimal symptoms or even be unaware of being struck. Fractures need to be considered where there are the traditional clinical signs of local pain, swelling, and loss of function. Considering the forces that can be applied when necessary, there is the potential for significant injury with bruising and rupture of internal organs, including the heart, liver, spleen, or kidneys or a head injury. The forensic physician should refer suspected cases for hospital review without delay, es- pecially if a confirmatory history for events is unavailable. Particular care is needed in those who are intoxicated because they are difficult to assess. Because they cannot be released them- selves, snips to cut them are always available at the same time. Although quick and easy to apply, they have no way of being locked in position, so they can tighten in an uncontrolled manner, resulting in direct compression injuries. At least two ties are used on each detainee; one is placed on each wrist and then interlocked with the other. These plastic constraints are used in preplanned operations, where numerous arrests are expected or in special- ized operations. Excessive force, either directly applied by the officer or from a detainee continuing to move, can result in strains to joints, such as the wrist, elbow, and shoulder. Officers in the United Kingdom are not trained in any neck holds because of the high risk of serious injury or death as a result of large blood vessel or airway compression. Fatalities can occur quickly, and if a detainee complains of such holds being used, the neck should be examined carefully. Petechial bruising should be looked for in the face, particularly in and around the eyes, on the cheeks, and behind the ears. It is common for clothing to be held in a struggle to restrain, which may tighten it around the neck. Linear bruising Medical Issues of Restraint 201 may be seen at the site of tightening, as well as petechial bruising on the neck and above on the face. Clearly, the tactical firearms units are often required in these situations, but there is an increasing trend to look for other “nonlethal” options, which will incapacitate with a lower risk of serious injury. In the United Kingdom, the investigation of firearm inci- dents under the auspices of the Police Complaints Authority with its attendant recommendations is a major influence when looking at developments in this area (7). Different countries use different restraint equipment, such as water cannon or the firing of different projectiles (e. They were first introduced in Northern Ireland in 1970; 125,000 rounds have been fired, and 17 fatalities have resulted, the last one occurring in 1989.

You can rule out this answer option as false because a cuspid is a type of tooth discount zestoretic 17.5mg with mastercard blood pressure chart app, so it makes no sense that each tooth would have another type of tooth anchoring it discount 17.5mg zestoretic otc blood pressure medication nerve damage. Pharyngopalatine arch M Arch that starts at the buccal surface of the palate at the base of the uvula and ends alongside the back third of the tongue: d purchase zestoretic 17.5 mg with amex hypertension 14080. It facilitates swallowing generic zestoretic 17.5 mg otc blood pressure medication used for adhd, initiates the digestion of certain carbohydrates, and moistens and lubricates the mouth and lips. It lies below and in front of the ear, hence the Greek roots para–, meaning “beside,” and ot–, meaning “ear. Fungiform papillae S Large structures, each surrounded by a moat, that form a V-shaped furrow in the tongue: a. Cardiac sphincter 1 The sequential contraction of circular muscles as food moves through the esophagus is called d. A bit of Greek may help you remember this term, which comes from the word peristaltikos, which means “to wrap around. This question calls upon your knowledge of Greek prefixes and suffixes: pyl– means “gate,” and –orus means “guard. A silly but effective memory tool for this term is this: When food is ready to leave the stomach, it rings a chime. Chapter 9: Fueling the Functions: The Digestive System 161 8 The muscle that contracts to prevent gastric juices of the stomach from entering the esophagus is the b. To remember this one, keep in mind that the sphincter that serves this purpose is the closest digestive sphincter to the heart. Seeing as the food spends the most time there, it makes sense that it’s the site of a lot of digestion. It’s tricky to remember which of these enzymes is inactive until it combines with something else. You can either try to memorize the function of each enzyme, or you can pick apart the terms. What structure of the small intestine is composed of a network of capillaries with a central lymph vessel or lacteal, which contains a milky-white substance? Besides, all but one of the other answer options — rugae, islets of Langerhans, and plicae circularis — aren’t even in the small intestine. To help you answer this question, it may help to hark back to Chapter 8’s discussion of the nasal sinuses, which we defined as empty spaces. From a month after you’re con- ceived to the moment of your death, this phenomenal powerhouse pushes a liquid connec- tive tissue — blood — and its precious cargo of oxygen and nutrients to every nook and cranny of the body, and then it keeps things moving to bring carbon dioxide and waste products back out again. Do the math: How many pulses has your ticker clocked if the average heart keeps up a pace of 72 beats per minute, 100,000 per day, or roughly 36 million per year? Moving to the Beat of a Pump Also called the cardiovascular system, the circulatory system includes the heart, all blood vessels, and the blood that moves endlessly through it all (see Figure 10-1). It’s what’s referred to as a closed double system; the term “closed” is used for three reasons: because the blood is contained in the heart and its vessels; because the vessels specifically target the blood to the tissues; and because the heart critically regulates blood flow to the tissues. The system is called “double” because there are two distinct circuits and cavities within the heart separated by a wall of muscle called the septum. The double circuits are the following: The pulmonary circuit carries blood to and from the lungs for gaseous exchange. Centered in the right side of the heart, this circuit receives blood saturated with carbon dioxide from the veins and pumps it through the pulmonary artery (or trunk) to capillaries in the lungs, where the carbon dioxide departs the system. That same blood, freshly loaded with oxygen, then returns to the left side of the heart through the pulmonary veins where it enters the second circuit. The systemic circuit uses the oxygen-rich blood to maintain a constant internal environ- ment around the body’s tissues. From the left side of the heart, the blood moves through the aorta to a variety of systemic arteries for distribution throughout the body. Head & arms Jugular vein Carotid artery Right lung Left lung Aorta Pulmonary vein Pulmonary artery Descending aorta Hepatic artery Inferior vena cava Liver Mesenteric artery Hepatic portal vein Digestive tract Renal vein Renal artery Figure 10-1: The circula- Kidneys tory system Iliac vein Iliac artery is a closed double system. Trunk & legs Although cutely depicted in popular culture as uniformly curvaceous, the heart actu- ally looks more like a blunt, muscular cone (roughly the size of a fist) resting on the diaphragm. A fluid-filled, fibrous sac called the pericardium (or heart sac) wraps loosely around the package; it’s attached to the large blood vessels emerging from the heart but not to the heart itself. The sternum (breastbone) and third to sixth costal cartilages of the ribs provide protection in front of (ventrally to) the heart. Two-thirds of the heart lies to the left of the body’s center, with its apex (cone) pointed down and to the left. At less than 5 inches long and a bit more than 3 inches wide, an adult human heart weighs around 10 ounces — a couple ounces shy of a can of soda. On the outside lies the epicardium (or visceral pericardium), which is composed of fibroelastic connective tissue dappled with adipose tissue (fat) that fills exter- nal grooves called sulci (the singular is sulcus). The larger coronary vessels and nerves are found in the adipose tissue that fills the sulci. Beneath the epicardium lies the myocardium, which is composed of layers and bundles of cardiac muscle tissue. The endocardium, the heart’s interior lining, is composed of simple squamous endothelial cells. Epi– is the Greek term for “upon” or “on” whereas endo– comes from the Greek endon mean- ing “within. The pericardium is made up of two parts — a tough inelastic sac called the fibrous peri- cardium on the outside and a serous (or lubricated) membrane nearer the heart called the parietal pericardium. Between the serous layers of the epicardium and the parietal pericardium is the small pericardial space and its tiny amount of lubricating pericardial fluid. This watery substance prevents irritation during systole (contraction of the heart) and diastole (relaxation of the heart). Yet the proper anatomical terms for their positions refer to the atria as being “superior” (above) and the ventricles “inferior” (below). The atria Sometimes referred to as “receiving chambers” because they receive blood returning to the heart through the veins, each atrium has two parts: a principal cavity with a smooth interior surface and an auricle, a smaller, dog-ear-shaped pouch with muscular ridges inside called pectinate muscles, or musculi pectinati, that resemble the teeth of a comb. The right atrium appears slightly larger than the left and has somewhat thinner walls than the left. Its principal cavity, the sinus venarum cavarum, is between the two vena cavae and the atrioventricular (between an atrium and a ventricle) openings. The point where the right atrium’s auricle joins with its principal cavity is marked externally by the sulcus terminalis and internally by the crista terminalis. Openings into the right atrium include the following: The superior vena cava, which has no valve and returns blood from the head, thorax, and upper extremities and directs it toward the atrioventricular opening The inferior vena cava, which returns blood from the trunk and lower extremities and directs it toward the fossa ovalis in the interatrial septum, which also has no valve The coronary sinus, which opens between the inferior vena cava and the atrio- ventricular opening, returns blood from the heart, and is covered by the ineffec- tive Thebesian valve An atrioventricular opening covered by the tricuspid valve Chapter 10: Spreading the Love: The Circulatory System 167 The fossa ovalis is an oval depression in the interatrial septum that corresponds to the foramen ovale of the fetal heart. If the foramen ovale does not close at birth, it causes a condition known as “blue baby. The ventricles The heart’s ventricles are sometimes called the pumping chambers because it’s their job to receive blood from the atria and pump it back to the lungs and out into the body’s network of arteries. More force is needed to move the blood great distances, so the myocardium of the ventricles is thicker than that of either atrium, and the myocardium of the left ventricle is thicker than that of the right. The right ventricle only has to move blood to the lungs, so its myocardium is only one- third as thick as that of its neighbor to the left. Roughly triangular in shape, the right ventricle occupies much of the sternocostal (front) surface of the heart and forms the conus arteriosus where it joins the pulmonary artery, or trunk. The right ventricle extends downward toward where the heart rests against the diaphragm. A circular opening into the pulmonary trunk is covered by the pulmonary semilunar valve, so- called because of its three crescent-shaped cusps.

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