ANTR 510 W7 QBank

B: Left atrium. The left atrium forms most of the base (posterior aspect) of the heart. The esophagus passes immediately posterior to the left atrium, forming its major posterior relation. This relationship is readily seen in radiographs, especially following a barium swallow. Mitral valve stenosis restricts blood flow out of the left atrium, leading to dilation of this chamber. This dilation of the left atrium can compress the esophagus and impede swallow- ing. Heart valve damage is one possible outcome of rheu- matic fever and occurs more often in young girls. The given figure shows a barium swallow of a normal esophagus (right) demonstrating narrowing of the lumen at the sites of constriction, including the aortic arch, left main stem bron- chus, left atrium, and the diaphragmatic hiatus. Choice A (Right atrium) is incorrect. The right atrium contributes to a small portion of the base of the heart. However, it is not related to the esophagus. The right atrium forms the right border and right pulmonary surface of the heart. Choice C (Arch of the aorta) is incorrect. The esophagus passes posterior and to the right of the arch of the aorta. The aortic arch makes one of three normal thoracic impressions (con- strictions) on the thoracic part of the esophagus and may compress the esophagus. This close relationship is read- ily observed in PA chest radiographs following a barium swallow. However, this patient's mitral valve stenosis makes compression by the left atrium a more likely condition. Choice D (Pulmonary trunk) is incorrect. The pulmonary trunk arises from the right ventricle, on the anterior (ster- nocostal) surface of the heart. This vessel does not have a relation to the esophagus. Choice E (Superior vena cava) is incorrect. The superior vena cava lies immediately above the right border of the heart and empties into the right atrium. This large vessel does not have a relation to the esophagus.

A 14-year-old girl is having difficulty swallowing. Her case history reveals she has mitral valve stenosis related to rheu- matic fever. Which of the following structures is most likely compressing the esophagus? (A) Rightatrium (B) Left atrium (C) Arch of the aorta (D) Pulmonarytrunk (E) Superior vena cava

D: Right main bronchus. The main (primary) bronchi are the first branches of the trachea. They supply the right and left lungs. Because of the position of the heart, the main bronchi have different orientations in their routes to the lungs. The right main bronchus is shorter, wider, and more vertical. Thus, aspirated foreign bodies are more likely to drop into and become lodged in this tube. The given chest film shows air trapped within the right lung during expiration due to the presence of the peanut within the right main bron- chus. The right inferior lobar bronchus, a secondary bronchus that supplies the inferior lobe of the lung, is another common site for foreign objects to reside following accidental inhala- tion. Choice A (Larynx) is incorrect. The larynx is the com- pound chamber at the upper end of the lower respiratory tree, proximal to the trachea. Aspirated items may become lodged in the rima glottidis (the space between the true vocal folds). In such cases, the obstruction can usually be dislodged by using the Valsalva maneuver (i.e., by forcefully compressing the abdomen to rapidly expel air from the lungs). However, in this patient's case, the aspirated peanut is located in the thorax. If it were in the larynx, radiographs would show the peanut located in the neck. Choice B (Carina of the trachea) is incorrect. The carina is a small ridge at the inferior end of the trachea that separates the openings of the right and left main bronchi. Its mucosal covering is highly sensitive, and contact by an aspirated object stimulates the cough reflex. However, objects do not normally lodge at the carina of the trachea. Instead, they usually fall into the right main bron- chus. Choice C (Left main bronchus) is incorrect. Because the left main bronchus must extend past the heart, it is lon- ger, more narrow, and more horizontal than the right main bronchus. Thus, aspirated objects usually fall into the right main bronchus rather the left. Choice E (Right upper lobar bronchus) is incorrect. The right main bronchus divides into three lobar (secondary) bronchi, one to each lobe of the lung. The right superior lobar bronchus turns superiorly from the end of the main bronchus to enter the superior lobe. Thus, it is very difficult for an aspirated object to enter this tube. Instead, objects that pass beyond the main bronchus usually fall into the inferior lobar bronchus, which takes a more verti- cal descent.

A 2-year-old boy comes to the ER due to accidental inhalation of a peanut. Which of the following sites is the most likely location for the aspirated peanut in the thorax? (A) Larynx (B) Carina of the trachea (C) Left main bronchus (D) Right main bronchus (E) Right upper lobar bronchus

C Cervical cysts are located in the lateral neck, in the vicinity of the anterior border of the sternocleidomastoid muscle.

A 20-year-old female patient has a noticeable swelling in her neck that recently began increasing in size. The swelling was located beneath the anterior border of the sternocleidomastoid muscle, about two thirds up from its clavicular origin. What is your initial diagnosis? a Accessory thryoid tissue b Accessory tonsils c Cervical cyst d Thyroglossal duct cyst

E: Pericardium. Due to the location of the stab wound, the pericardial sac and the right ventricle of the heart (the most anterior chamber of the heart) are most likely dam- aged. The pericardium is a fibrous, unyielding sac that sur- rounds the heart. Lesion of the right ventricle would cause blood to spill out of the heart into the pericardial space, caus- ing a pericardial effusion (blood accumulation within the peri- cardial sac). Compression of the heart (cardiac tamponade) would result. These events make it impossible for the heart to fill completely, which limits the blood it can receive. Patients with cardiac tamponade present with engorged veins of the face and neck due the backup of blood. A pericardial effusion can be drained via a procedure known as pericardiocentesis, which temporarily relieves the patient's problem until theheart wall is repaired. However, time is critical because cardiac tamponade compresses the heart and may result in a quick death. Choice A (Left lung) is incorrect. The left lung, and the pleural sac in which it resides, are pushed laterally away from the sternum due to the position of the heart, which resides primarily on the left side of the body. Due to the location of the knife wound in this patient, the pericardium and right ven- tricle would be damaged, not the left lung. Choice B (Pulmo- nary trunk) is incorrect. The pulmonary trunk is the outflow tract of the right ventricle. The pulmonary trunk resides left of the sternum at approximately the 2nd intercostal space, which is located above the entry point of the knife in this patient. Choice C (Left bronchus) is incorrect. The bifurcation of the trachea occurs at the 4th thoracic vertebral level. The wound location is at the 7th or 8th thoracic vertebral level, or the 5th intercostal space of the anterior thoracic wall. Therefore, the left main stem bronchus is located above the damaged area. Furthermore, the left bronchus resides deep to the heart, and the depth of the stab wound (~4 cm) would not reach the left bronchus. Choice D (Stomach) is incorrect. The stomach resides inferior to the location of the knife wound. Also, due to its posterior positioning and the depth of the wound, the stomach would not be damaged in this patient.

A 23-year-old man is stabbed in a bar fight. The blade of the knife enters his chest in the left 5th intercostal space, just lateral to the sternum, and pierces to a depth of approximately 4 cm. What structure is most likely damaged? (A) Lef tlung (B) Pulmonary trunk (C) Left bronchus (D) Stomach (E) Pericardium

E. middle lobe of the lung.The right lung is composed of three lobes: superior, middle, and inferior. The lobes are separated by two fissures: oblique and horizontal. The oblique fissure extends from the level of approximately T2 posterior to the sixth costal cartilage anterior. The hori- zontal fissure runs anterior from the oblique fissure along the fourth rib and costal cartilage. This stab wound is located in the anterior chest wall between the oblique and horizontal fissures. Therefore the middle lobe of the lung is most likely pierced. Because of the angulations of the ribs and the fissures, the damaged lobe will vary depending on the longitude of the wound (e.g., depending on an entry point in the midclavicu- lar, midaxillary, or scapular line). Choice A (Superior lobe of the lung) is incorrect. The superior lobe extends down to the horizontal fissure, at approximately the 4th rib and costal car- tilage. Thus, it is above the wound in question. However, if this wound were on the left side, it would pierce the superior lobe because the left lung has only superior and inferior lobes. Choice B (Lingula of the lung) is incorrect. The lingula is a feature of only the left lung. It is a thin, tongue-like projec- tion of the anteroinferior margin of the superior lobe of the lung and is formed by the cardiac notch. Choice C (Inferior lobe of the lung) is incorrect. In the midclavicular line, the inferior lobe reaches as high as approximately the 6th rib and costal cartilage. Thus, it is below this wound point. Choice D (Apex of the lung) is incorrect. The apex is the rounded supe- rior end of the lung. It extends into the root of the neck, above the level of the first rib.

A 25-year-old man is brought to the emergency room after suffering a deep stab wound directly through the right 5th intercostal space in the midclavicular line. Which of the fol- lowing structures is most likely pierced? (A) Superior lobe of the lung (B) Lingula of the lung (C) Inferior lobe of the lung (D) Apex of the lung (E) Middle lobe of the lung

D The recurrent laryngeal nerve on the right is in close proximity to the inferior thyroid artery.

A 27-year-old female with goiter comes to the hospital for surgical treatment. The surgeon must ligate the inferior thyroid artery before surgically resecting the goiter, so care must be taken to avoid injury to which of the following nerves? a External laryngeal b Hypoglossal c Internal laryngeal d Recurrent laryngeal

B: Closed ductus arteriosus. Significant narrowing of the aorta distal to the origin of the left subcla- vian artery is termed a coarctation of the aorta. If the constric- tion of the aorta is proximal to the ductus arteriosus, which connects the pulmonary trunk to the arch of the aorta in fetal circulation, the condition is termed a preductal coarctation. If the constriction is distal to the ductus arteriosus, the con- dition is denoted as a postductal coarctation. In postductal coarctation (more common than the preductal form), the duc- tus arteriosus is normally closed and forms the ligamentum arteriosum. In this condition, blood flow into the descending aorta is blocked. However, arterial flow into the distal aorta is usually maintained via expansion of collateral circulation through the internal thoracic and intercostal arteries. The pressure dynamics in this situation account for the classic clinical signs of hypertension in the upper limbs (especially the right side) and diminished pulse and pressure in the lower limbs. Choice A (Patent ductus arteriosus) is incorrect. A pat- ent ductus arteriosus is characteristic of preductal coarctation of the aorta. In this case, the collateral circulatory expansions are not required because blood flows into the distal aorta through the patent ductus arteriosus. However, blood oxy- genation levels are altered due to persistence of this shunt. Interestingly, patients with preductal coarctation often appear healthy (asymptomatic). However, closure of the ductus arteriosus can be life threatening. Choice C (Patent ductus venosus) is incorrect. The ductus venosus is a fetal shunt between the umbilical vein and the inferior vena cava that allows blood from the placenta to mostly bypass the liver. It obliterates after birth and forms the ligamentum venosum. Because blood does not flow through this channel after birth, neither form of coarctation of the aorta affects this structure. Choice D (Patent foramen ovale) is incorrect. Arterial flow to the distal aorta is maintained in both forms of coarctation of the aorta. The pressure dynamics in each case are not suffi- cient to force persistence of a patent foramen ovale. If patency occurs, it is due to other factors. Choice E (Stenotic aortic valve) is incorrect. Formation of the aortic and pulmonary (semilunar) valves is related to septation of the conotruncal region. The mechanics behind constriction of the aorta are not the same as those related to failure of conotruncal septa- tion. Thus, stenosis of the semilunar valves is not a feature of coarctation of the aorta.

A 4-year-old boy presents with hypertension in the upper extremities and a diminished femoral pulse and pressure. Radiologic imaging reveals a postductal coarctation of the aorta. Which of the following is the most characteristic feature of this condition? (A) Patent ductus arteriosus (B) Closed ductus arteriosus (C) Patent ductus venosus (D) Patent foramen ovale (E) Stenotic aortic valve

B: Lymph nodes. Enlarged lymph nodes are the most likely cause of the widened mediastinum in this patient due to his inhalation of anthrax, which presents with the described flu-like symptoms. A widened mediastinum is seen in bacterial infections (as in this case), lymphoma, a soft tissue mass, and aortic aneurysm usually associated with trauma. Choice A (Aorta aneurysm rupture) is incor- rect. The patient came to the ER due to flu-like symptoms resulting from inhalation of anthrax, so a rupture of an aortic aneurysm is not likely because there was no reported trauma. During traumatic blows to the chest, the thoracic aorta can be ruptured, usually in the vicinity of the ligamentum arte- riosum. A widened mediastinum would be seen on X-ray in a patient experiencing this type of trauma due to the blood collecting in the mediastinum. Choice C (Thymus) is incor- rect. The thymus, a primary lymphatic organ, is located in the anterior mediastinum, and it reaches its height of growth in children approximately 8 years of age due to the matura- tion of the lymphatic system. After approximately age 12, the thymus regresses in size through a process known as accre- tion, in which the lymphatic tissue is slowly replaced with adipose fat. The thymus would not cause the abnormally wide space between the lungs seen in this patient because it rests in the anterior mediastinum. Choice D (Respiratory bronchioles) is incorrect. Respiratory bronchioles are located within the lungs and are continuous with alveolar ducts. Respiratory bronchioles can be identified by the presence of alveoli, which interrupt the epithelium. However, the lungs are located within the pulmonary cavity, so enlargement of the respiratory bronchioles would not cause a widened mediastinum. Choice E (Heart) is incorrect. An enlarged heart is often seen in patients with a history of heart disease, and this condition would cause an abnormally wide space between the lungs. However, there is no history of heart dis- ease. Thus, the mediastinum widening in this patient is most likely due to the inhalation anthrax diagnosis, which causes enlarged lymph nodes.

A 46-year-old postal worker was exposed unknowingly to the powdered form of bacteria Bacillus anthracis (anthrax). He comes to the ER with flu-like symptoms, including fever, chills, fatigue, headache, chest pain, and shortness of breath. A chest X-ray shows an abnormally wide space between the lungs. Enlargement of which of the following structures is the most likely cause of the widened mediastinum in this patient? (A) Aortic aneurysm rupture (B) Lymph nodes (C) Thymus (D) Respiratorybronchioles (E) Heart

B The ostium of the maxillary sinus is typically located in the semilunar hiatus of the middle meatus.

A 54-year-old man is admitted to the hospital with severe pain in his nasal cavity. Radiographic examination reveals a carcinoma in his nasal cavity. In which of the following locations would the carcinoma block the ostium of the maxillary sinus? a Inferior meatus b Middle meatus c Superior meatus d Sphenoethmoidal recess e Nasopharynx

D The circumflex artery is a branch of the left coronary artery; it travels to the posterior aspect of the heart in the coronary sulcus.

A 62 year-old female presents with a myocardial infarction. The infarction damaged the left atrium and left ventricle. Which coronary artery was most likely blocked leading to this infarction? a right coronary b posterior interventricular c anterior interventricular d circumflex

C Of the structures listed, only the azygos vein is located in the posterior mediastinum.

A 64-year-old male is found to have a tumor in the posterior mediastinum. Which of the following structures is most likely to be compressed by this tumor? a Thymus b Arch of the aorta c Azygos vein d Phrenic nerve e Brachiocephalic veins

C Pain sensation from thoracic viscera returns to the spinal cord via sympathetic outflow routes. Visceral pain from thoracic organs will therefore return to the T1-T5 regions of the spinal cord - the location of the preganglionic sympathetic cells involved in the innervation of all thoracic viscera.

A 65 year-old man is brought to the emergency department with substernal chest pain that radiates along the anteromedial aspect of his left arm. Auscultation reveals occasional arrhythmias and his ECG is abnormal. To which of the following regions of the spinal cord is the visceral pain associated with this condition being referred? a C3-C5 b C6-C8 c T1-T5 d T6-T10 e S2-S4

C The pulmonary (pulmonic) valve is auscultated in the 2nd intercostal space at the left sternal border.

A 65-year-old male checks into the office for a wellness exam. Physical exam reveals a heart murmur heard best over the 2nd intercostal space at the left sternal border. The murmur is most likely the result of a defect in which of the following valves. a Aortic b Bicuspid c Pulmonary d Tricuspid

C: Superior mediastinum. The superior mediastinum is the large interpleural space above the plane running from the sternal angle to the T4 intervertebral disc. The symptoms seen in this patient suggest obstructed venous return from the head and neck, upper limbs, and thoracic walls. Venous drainage from these regions flows through the brachiocephalic veins and the azygos vein to converge in the superior vena cava (SVC). The SVC enters the right atrium through the right aspect of the superior mediastinum. Thus, the tumor in the right lung is most likely located in the superior lobe of the lung and is compressing the SVC in the superior mediastinum. Choice A (Anterior mediastinum) is incorrect. The anterior mediastinum is the small interpleural space between the sternum and the pericardial sac. The right internal thoracic vein (which collects the small anterior inter- costal veins) lies along the parasternal line inside the thoracic wall and could be compressed by an anterior lung tumor. However, such a condition would obstruct only a small por- tion of the thoracic wall drainage and would not produce the neck and upper limb effects seen here. Choice B (Posterior mediastinum) is incorrect. The posterior mediastinum is the large interpleural space posterior to the pericardial sac. The azygos vein ascends through roughly the right aspect of the posterior mediastinum and then curls through the superior mediastinum to join the SVC. A right lung tumor could com- press the azygos vein and notably obstruct venous drainage from the thoracic walls. However, collateral connections with the anterior intercostal veins could help relieve such obstruction. Further, obstruction of the azygos vein would not influence the neck and upper limb drainage and would not account for the full condition in this patient. Choice D (Hilum of the lung) is incorrect. The hilum is the slight con- cavity on the medial aspect of the lung where the root of the lung is attached. The root of the lung is the pleura-in- vested bundle of structures that enter and leave the lung at the hilum. These structures include the bronchi, pulmonary and bronchial vessels, lymphatics, and nerves. Compression of the root of the lung at the hilum would obstruct pulmo- nary functions, but would not produce any of the conditions noted in this patient. Choice E (Vena caval foramen of the diaphragm) is incorrect. The inferior vena cava (IVC) passes through the venal caval foramen of the diaphragm and imme- diately enters the right atrium. Compression of the IVC at this, or any other, point would not produce the effects seen in this patient.

A 65-year-old man presents with a swollen neck, marked edema in both upper limbs, and engorged and prominent intercostal veins. Subsequent examination reveals a tumor in his right lung. The tumor is likely compressing structures in which of the following regions? (A) Anterior mediastinum (B) Posterior mediastinum (C) Superior mediastinum (D) Hilum of the lung (E) Vena caval foramen of the diaphragm

D: Right coronary. The right coronary artery gives off arterial branches that usually supply both the SA and AV nodes. The SA node is usually supplied by the SA nodal artery, which branches off the proximal aspect of the right coronary artery. The AV nodal branch, which usually branches off the posterior interventricular branch of the right coronary artery, supplies the AV node. Iatrogenic injury to the right coronary artery would compromise the conduction system of the heart and lead to a heart block, as seen in this patient. Choice A (Anterior interventricular) is incorrect. The anterior interventricular artery, which is often called the left anterior descending (LAD) artery by clinicians, arises off the left coro- nary artery to supply the anterior aspects of both ventricles as it runs within the interventricular groove. In rare cases, its branches supply the AV bundle of the conduction system. Choice B (Left marginal) is incorrect. The left marginal artery branches off the circumflex branch of the left coronary artery to supply the left ventricle. This artery follows the left margin of the heart; however, iatrogenic injury to this artery would not cause the heart block seen in this patient. Choice C (Left coronary) is incorrect. The left coronary artery supplies the left atrium, most of the left ventricle, and some of the right ventricle. In rare cases, its branches supply the AV node of the conduction system, but the AV node is usually supplied by branches of the right coronary artery. Choice E (Circumflex branch) is incorrect. The circumflex branch of the left coro- nary artery follows the coronary sulcus around the left border of the heart to reach its posterior surface. This artery usually does not supply the conduction system of the heart, though it occasionally supplies blood to the SA node. However, the SA node is more commonly supplied by the sinuatrial node artery of the right coronary artery.

A 7-year-old boy with Down syndrome underwent surgery to repair a congenital ventricular septal defect. During this pro- cedure, iatrogenic injury to the coronary artery supplying the conduction system of the heart, including the sinuatrial (SA) and atrioventricular (AV) nodes, occurred, resulting in a heart block. What artery was most likely damaged by the surgeon? (A) Anteriorinterventricular (B) Left marginal (C) Leftcoronary (D) Rightcoronary (E) Circumflex branch

C General sensation of the lateral and medial walls of the nasal cavity is provided by the ophthalmic and maxillary nerves (CNs V1 & V2)

A CT scan obtained from a 40-year-old female suffering from headaches, nausea and vomiting reveals a tumor centered at the jugular foramen and damaging the nerves traversing this foramen and the hypoglossal canal. In this patient, which of the following functions will remain intact? a Gag reflex b Control of the vocal ligaments c Sesnation of the lateral nasal wall d Symmetric protrustion of the tongue e Sensation in the tympanic cavity

B With transposition of the great vessels there is no mechanism for exchange between the systemic and pulmonary circulatory systems. In the absence of accompanying septal defects to permit some exchange the condition is usually lethal.

A breathing newborn exhibits severe cyanosis immediately after birth and dies. Autopsy results show that both ventricles were of normal size and there was no evidence of an atrial or ventricular septal defect. Moreover, the lungs were of normal size and well inflated. What is the most likely diagnosis? a Tetralogy of Fallot b Transposition of the great vessels c Aortic valvular stenosis d Patent ductus arteriosus

D: Pulmonary infundibular stenosis. An abnor- mally narrowed right ventricular outflow tract (pulmonary infundibular stenosis) is one of the four components of TOF. This syndrome is the most common malformation complex resulting from unequal division of the conus cordis and truncus arteriosus by the spiraling conotruncal septum. This septum contributes significantly to the formation of the ven- tricular outflow tracts and the proximal parts of the aorta and pulmonary trunk. Anterior displacement of the developing conotruncal septum results in a narrow right ventricular out- flow (pulmonary infundibular stenosis), plus an overriding aorta, ventricular septal defect (VSD), and hypertrophied right ventricle. The four classic characteristics of TOF are pictured in the given figure. Children with TOF are typically cyanotic due to the mixing of right and left side blood through the VSD and the overriding aorta. Also, the systolic heart mur- mur is typical due to the VSD. Choice A (Transposition of the great vessels) is incorrect. Failure of the conotruncal septum to follow its normal spiral course results in transposition of the great vessels. When the septum runs directly downward through the conotruncal region instead of spiraling, the aorta originates from the right ventricle and the pulmonary trunk arises from the left ventricle. Choice B (Hypertrophy of the left ventricle) is incorrect. In TOF, the combination of back- pressure from the infundibular stenosis and systemic pressure needs from the overriding aorta and VSD results in hyper- trophy of the right ventricle. Choice C (Interatrial septal defect) is incorrect. The conotruncal septum contributes to the formation of the upper (membranous) part of the inter- ventricular septum. Thus, malformation of the conus septum commonly results in a membranous VSD, not an atrial septal defect. Choice E (Aortic valvular atresia) is incorrect. In this condition, the valvular orifice into the aorta is absent, and the aorta and left side chambers are underdeveloped. In TOF, the conotruncal septum is displaced, resulting in an open, overriding aorta.

A child is born at home without difficulty. Two weeks later, the mother takes the infant to her doctor, reporting that he "turns blue" when he cries. Physical examination reveals the infant is cyanotic and has a distinct systolic heart murmur. The physician suspects the baby has a tetralogy of Fallot (TOF). Which of the following conditions is a component of this syndrome? (A) Transposition of the great vessels (B) Hypertrophy of the left ventricle (C) Interatrial septal defect (D) Pulmonary infundibular stenosis (E) Aortic valvular atresia

D The membranous portion of the interventricular septum is an outgrowth of the inferior surface of the endocardial cushions that closes the interventricular foramen - the space between the free edge of the muscular ventricular septum, the free edge of the aorticopulmonary septum and the inferior surface of the fused endocardial cushions. Faulty fusion of any of these elements of the ventricular septum will result in a membranous ventricular septal defect.

A faulty fusion of the right and left bulbar ridges and AV cushion will result in which of the following? a Persistent truncus arteriosus b Transposition of the great arteries c Common ventricle d Membranous ventricular septal defect

E The ductus arteriosus is derived from the left sixth aortic arch - the left fourth aortic arch gives rise to the arch of the aorta. The large lumen of the ductus arteriosus permits the flow of blood from the pulmonary trunk to the aorta. The ductus arteriosus constricts at birth.

A female infant with congestive heart failure and continuous systolic and diastolic murmurs was diagnosed as having a patent ductus arteriosus. Which of the following statements regarding the ductus arteriosus is CORRECT? a The ductus arteriosus is a remant of the left fourth aortic arch. b The ductus arteriosus is closed during fetal development. c The ductus arteriosus shunts blood from the umbilical vein to the inferior vena cava. d The ductus arteriosus closes just before birth. e In the fetus, most of the blood from the pulmonary trunk flows into the aorta.

B: Membranous ventricular septal defect (VSD). The developing endocardial cushions constitute a tissue mass in the center of the heart that can be envisioned sche- matically as a cross-like formation. The crossbar (horizontal part) forms the atrioventricular canals and valves. The post (vertical part) forms portions of the atrial and ventricular septa. The lower limb of the vertical part forms the mem- branous part of the ventricular septum. Thus, defects in outgrowth of this component result in membranous VSDs. VSDs as a whole are the most common congenital cardiac malformations. Choice A (Atrial septal defect) is incor- rect. The upper limb of the vertical part of the endocardial cushion cross contributes to formation of the septum pri- mum in the common atrium. Extensions of the endocardial cushions here help to close the foramen (ostium) primum. Defects in this component result in primum type atrial sep- tal defects. Choice C (Transposition of the great vessels) is incorrect. This malformation is the result of failure of normal partitioning of the conus cordis and truncus arterio- sus. When the conotruncal septum runs directly downward through the conotruncal region instead of spiraling, the aorta originates from the right ventricle and the pulmonary trunk arises from the left ventricle. Thus, these major arter- ies are transposed from their normal positions. Choice D (Tricuspid atresia) is incorrect. In tricuspid atresia, the tri- cuspid valve is absent or fused and the right atrioventricu- lar orifice is obliterated. The horizontal part of the endo- cardial cushion cross forms the atrioventricular canals and valves. Thus, defective formation of the right limb of the endocardial cushion crossbar may produce tricuspid atresia. Choice E (Muscular ventricular septal defect) is incorrect. The medial walls of the two primitive ventricles merge to form the muscular part of the ventricular septum. This fuses with the lower limb of the endocardial cushions to form the complete ventricular septum. Muscular VSDs are more common than membranous VSDs, and most of these defects resolve during normal growth.

A genetic coding defect in an early embryo results in absence of the lower part of the vertical portion of the cross of the endocardial cushions in the developing heart. Which of the following malformations is most likely present? (A) Atrial septal defect (B) Membranous ventricular septal defect (VSD) (C) Transposition of the great vessels (D) Tricuspidstenosis (E) Muscular ventricular septal defect

C: Septum primum and the fused endocardial cushions. Closure of the foramen primum (ostium pri- mum) occurs when the free edge of the septum primum fuses with the endocardial cushions. While foramen secun- dum defects constitute the majority of atrial septal defects, foramen primum defects (primum atrial septal defects) do occur and often result in more severe conditions. The ventricular septal defects, seen on the given echocardio- gram, are often associated with Down syndrome and fetal alcohol syndrome. Choice A (Septum secundum and the septum primum) is incorrect. Because the foramen pri- mum closes before the septum secundum appears, the septum secundum does not play any role in closure of the foramen primum. Choice B (Septum secundum and the fused endocardial cushions) is incorrect. During nor- mal development, the foramen primum closes via fusion of the septum primum with the endocardial cushions. This event occurs before the septum secundum appears. Thus, the septum secundum plays no role in closure of the fora- men primum. Choice D (Septum primum and the septum spurium) is incorrect. The septum spurium is a fold in the right atrium formed by the right venous valve. It plays no role in partitioning of the atria. Thus, it plays no role in closure of the foramen primum. Choice E (Left inferior and right superior truncus swellings) is incorrect. The aorti- copulmonary septum, which divides the truncus arteriosus into the ascending aorta and pulmonary trunk, is formed by these two truncus swellings. They play no role in atrial septation.

A male baby is born with Down syndrome (trisomy 21) and associated cardiac defects. The given apical four-chamber view echocardiogram shows a complete atrioventricular canal defect that includes a primum atrial septal defect and a poste- rior inlet ventricular septal defect. What embryonic structures normally fuse to close the foramen primum? (A) Septum secundum and the septum primum (B) Septum secundum and the fused endocardial cushions (C) Septum primum and the fused endocardial cushions (D) Septum primum and the septum spurium (E) Left inferior and right superior truncus swellings

D: Septum secundum. The septum secundum is the second fold of tissue that forms across the common atrium. However, it never forms a complete wall between the right and left atria. The opening left by the incomplete septum secundum, through which blood flows from the right atrium to the left atrium, is the foramen ovale. Ultimately, the septum secundum fuses with the remnant of the septum primum (the valve of the foramen ovale) to close the foramen ovale and form a complete atrial septum. Thus, a patent foramen ovale is the result of failure of fusion (to greater or lesser degrees) of the septum secundum with the remnant of the septum primum. Choice A (Endocardial cushions) is incorrect. Four endocardial cushions form and fuse together in the atrioventricular and conotruncal regions. They contrib- ute to the formation of the atrial and ventricular septa, the atrioventricular canals and valves, and the ventricular outflow tracts. Extensions of the endocardial cushions do contribute somewhat to the septum primum. However, the cushions have marginal contributions to the septum secundum. Choice B (Valve of the coronary sinus) is incorrect. This structure is not related to the atrial septum. The coronary sinus is derived from the left horn of the sinus venosus. The tissue flap that forms the valve of the coronary sinus is a derivative of the right sinus horn. Choice C (Ostium primum) is incorrect. The ostium primum is the opening between the septum primum and the endocardial cushions. It closes completely and does not contribute to the foramen ovale. Choice E (Septum spu- rium) is incorrect. This structure is not related to the foramen ovale. The septum spurium is a tissue ridge that forms at the junction of the right horn of the sinus venosus with the primi- tive atrium.

A newborn baby is diagnosed with tricuspid atresia. The given echocardiographic apical four-chamber view shows the abnormal valve plus its typical associated defects: a widely patent foramen ovale (double arrows), ventricular septal defect (single arrow), hypoplastic right ventricle, and hyper- trophied left ventricle. The patent foramen ovale most likely reflects a developmental failure of which of the following structures? (A) Endocardial cushions (B) Valve of the coronary sinus (C) Ostium primum (D) Septum secundum (E) Septum spurium

B Cleft lip is due to failed fusion of the maxillary process with the intermaxillary segment.

A newborn is delivered with a cleft lip. What structures did not properly fuse? a Intermaxillary segment and lateral nasal process b Intermaxillary segment and maxillary process c Lateral nasal process and maxillary process d Mandibular process and maxillary process

B The esophagus is related to the left atrium of the heart.

A physician notices a posterior deviation of the esophagus on a lateral x-ray during a contrast study of the esophagus. If the shift is caused by the heart, the __ would be implicated a right atrium b left atrium c right ventricle d left ventricle

A: Opening of the coronary sinus. The coronary sinus is a large vein that receives most of the venous drainage of the heart. It empties into the right atrium, between the opening of the inferior vena cava and the right atrioventricular opening. The coronary sinus possesses a ridge-like valve at its aperture. Choice B (Openings of the pulmonary veins) is incorrect. The four pulmonary veins, carrying oxygenated blood from the lungs, open into the left atrium. The left atrium is the most posterior of the four heart chambers. Choice C (Septomarginal trabecula) is incorrect. The septomarginal trabecula (modera- tor band) is a segment of trabeculae carneae located in the right ventricle. It runs from the ventricular septum to the base of the anterior papillary muscle (located on the anterior mar- ginal wall of the ventricle). It prevents ("moderates") overd- istension of the right ventricle. Furthermore, it conveys the right limb of the atrioventricular bundle (Purkinje fibers) from the ventricular septum to the anterior wall of the ventricle. Choice D (Openings of the coronary arteries) is incorrect. The two coronary arteries arise from the ascending aorta, in the sinuses of the aortic valve. The right coronary arises from the right aortic sinus, whereas the left coronary arises from the left sinus. Choice E (Trabeculae carneae) is incorrect. These structures are located in both the right and left ventricles. They are a network of elevated ridges of myocardium that present a trabecular appearing surface within the ventricles.

A radiologist is examining a series of contrast-enhanced CT scans of a patient's thorax in evaluating findings of a hypertrophied right heart. Which of the following structures is located in the pathologically enlarged right atrium? (A) Opening of the coronary sinus (B) Openings of the pulmonary veins (C) Septomarginal trabecula (D) Openings of the coronary arteries (E) Trabeculae carneae

A: Diaphragm flattens. The diaphragm is the primary muscle of respiration. It contracts during inspiration and relaxes during expiration. When the diaphragm contracts, its two domes descend and flatten. Descent of the diaphragm increases the vertical dimension (height) of the thoracic cav- ity, resulting in increased intrathoracic volume, decreased intrathoracic pressure, and increased intra-abdominal pres- sure. These essential actions occur during both quiet and forced respiration. Choice B (Intercostal muscles relax) is incorrect. The actions of the individual intercostal muscles have been debated without clear resolution for many years. It appears that the external intercostals are most active during forced inspiration, whereas the internal and inner- most intercostals are most active during forced expiration. However, the main role of all the intercostals appears to be that of maintaining the spacing and rigidity of the intercos- tal spaces during all degrees (quiet and forced) and phases (inspiration and expiration) of respiration so that the rib cage moves as a complete unit in a coordinated fashion. Thus, we may consider the proposal that the external intercostals are most active in maintaining the intercostal spaces during inspiration, and the internal and innermost intercostals are most active in maintaining these spaces during expiration. Choice C (Ribs lower) is incorrect. The ribs are elevated dur- ing inspiration, especially in forced inspiration. Thus, the rib cage expands in upward and outward directions, resulting in increased anteroposterior and transverse dimensions, which, in turn, contributes to the increased intrathoracic volume and decreased intrathoracic pressure characteristic of inspiration. Choice D (Abdominal wall muscles contract) is incorrect. The three abdominal oblique muscles (external oblique, internal oblique, transversus abdominis) that form the anterolateral abdominal wall relax during inspiration and contract during expiration. Contraction of the diaphragm compresses the abdo- men and increases intra-abdominal pressure. Simultaneous relaxation of the abdominal muscles assists in accommodating these changes. Subsequent contraction of these muscles dur- ing expiration increases intra-abdominal pressure and elevates the relaxed diaphragm. Choice E (Horizontal dimension of the rib cage decreases) is incorrect. The ribs are elevated dur- ing inspiration, causing expansion of the rib cage in upward and outward directions. This expansion results in increased horizontal (transverse) and anteroposterior dimensions of the thoracic cavity.

A young medical student finds herself at a moment of great relaxation during her pre-exam meditation. Which of the following events is characteristic of the inspiratory phase of normal, quiet respiration? (A) Diaphragm flattens (B) Intercostal muscles relax (C) Ribslower (D) Abdominal wall muscles contract (E) Horizontal dimension of the rib cage decreases

D The endodermal lining of the second pharyngeal pouch will differentiate as the primordium of the palatine tonsil.

All of the following are involved in the development of the ear EXCEPT: a Pharyngeal arch 1 b Pharyngeal pouch 1 c Pharyngeal arch 2 d Pharyngeal pouch 2 e Otocyst

F The great and middle cardiac veins drain into the coronary sinus, then the coronary sinus drains to the right atrium.

All of the following features are related to the right atrium EXCEPT: a Fossal ovalis b Opening of the coronary sinus c Sinoatrial node d Opening of inferior vena cava e Atrioventricular node f Opening of the middle cardinal vein

B Neural crest cells within the frontonasal prominence also contribute to the bones of the face.

All of the following statements regarding development of the face are correct EXCEPT: a The face develops from five swellings that surround the stomodeum. b All of the bones of the face are derived from first arch neural crest cells. c All of the muscles of the face are derived from the first arch paraxial mesoderm. d The ectodermal lining of the five facial swellings is innervated by branches of the trigeminal nerve. e The adult palate is derived from both frontonasal prominence and maxillary processes.

C: Splanchnic mesoderm. Cardiac progenitor cells migrate from the epiblast into the cranial portion of the splanchnic layer of the lateral plate mesoderm. In the meso- derm, the progenitor cells ultimately form paired cardiac pri- mordia, that is, the endocardial tubes. Subsequent lateral and cephalocaudal folding of the embryo causes merging of the paired endocardial tubes plus caudal shifting of the primitive heart tube and pericardial cavity. Choice A (Paraxial meso- derm) is incorrect. The paraxial mesoderm segments into somites along the long axis of the body wall. Each somite ultimately differentiates into three portions: sclerotome, myo- tome, and dermatome. Choice B (Intermediate mesoderm) is incorrect. The intermediate mesoderm is the small por- tion of mesoderm that connects the paraxial and lateral plate mesodermal areas. It differentiates into urogenital organs. Choice D (Parietal mesoderm) is incorrect. The lateral plate mesoderm splits into parietal (somatic) and visceral (splanch- nic) parts, separated by the intraembryonic body cavity. The parietal layer becomes associated with the overlying ectoderm to form the lateral body wall folds. Choice E (Extraembryonic mesoderm) is incorrect. This cell population appears outside the embryonic body proper. It forms a loose connective tissue zone that eventually results in the chorionic cavity.

An early term embryo spontaneously aborts due to incomplete lateral body wall folding and failure of the primitive paired endocardial tubes to merge and form the primitive heart tube. The endocardial tubes are derived from which of the following embryonic sources? (A) Paraxial mesoderm (B) Intermediate mesoderm (C) Splanchnic mesoderm (D) Parietal mesoderm A (E) Extraembryonic mesoderm

C: Sinus venosus. The right horn of the embry- onic sinus venosus gives rise to the smooth part of the right atrium (the sinus venarum). In addition, it forms the roots of the superior and inferior vena cavae. Most of the left sinus horn is obliterated during development. Its major remnant forms the coronary sinus. Choice A (Pulmonary trunk) is incorrect. The pulmonary trunk and the ascending aorta are formed via the internal spiral septation of the truncus arteriosus. Thus, the pulmonary trunk is a derivative of an embryonic component rather than a source of other structures. Choice B (Conus cordis) is incorrect. The conus cordis is a derivative of the bulbus cordis. The conus cordis undergoes a complex spiral septation in close coordination with the septation of the ventricle and the truncus arteriosus. Ultimately, the conus cordis forms the right and left ventricular outflow channels. Choice D (Truncus arteriosus) is incorrect. The truncus arte- riosus is the cranial third of the bulbus cordis. It undergoes a spiral septation and forms the proximal parts of the pulmonary trunk and the aorta. Choice E (Ascending aorta) is incorrect. As noted previously, the ascending aorta and the pulmonary trunk are formed via the internal spiral septation of the trun- cus arteriosus. Neither gives rise to the left or right atrium.

An infant is born with an abnormally thin wall in the smooth part of the right atrium. This condition may be related to underdevelopment of which of the following embryonic structures? (A) Pulmonarytrunk (B) Conus cordis (C) Sinusvenosus (D) Truncusarteriosus (E) Ascending aorta

A The atrioventricular node is located on the right side of the interatrial septum, superior to the opening of the coronary sinus.

An infarct within which of the following structures of the right atrium could seriously affect the ability of the atrioventricular node to propagate action potentials? a posterior-inferior interatrial septum b auricle c anterior-lateral wall, near the opening of the superior vena cava d fossa ovalis

E: Increase heart rate. Stimulation of para- sympathetic neurons normally results in deceleration of the heart rate. However, by blocking parasympathetic stimulation, atropine negates normal parasympathetic function and allows the sympathetic system to exert its functional effects (such as increasing heart rate) without balanced regulation. Choice A (Paralyze the diaphragm) is incorrect. The diaphragm is com- posed of skeletal muscle. Autonomic neurons act on smooth and cardiac muscle and glands. Thus, the diaphragm is not affected by parasympathetic action or lack thereof. Choice B (Stimulate bronchoconstriction) is incorrect. Parasympathetic activity normally stimulates bronchoconstriction. However, blocking parasympathetic input allows unopposed sym- pathetic action to cause the bronchi to dilate beyond their normal caliber, resulting in bronchodilatation. Choice C (Increase sweat gland secretions) is incorrect. Sweat glands do not receive parasympathetic supply. Thus, they are not affected by blocking parasympathetic stimulation. Choice D (Paralyze the intercostal muscles) is incorrect. All the inter- costal muscles are composed of skeletal muscle. They are not affected by parasympathetic action or lack thereof.

Atropine is a drug that acts to block stimulation of the receptors targeted by postsynaptic parasympathetic neu- rons. When it takes effect, atropine acts to do which of the following? (A) Paralyze the diaphragm (B) Stimulate bronchoconstriction (C) Increase sweat gland secretions (D) Paralyze the intercostal muscles (E) Increase heart rate

A In the 4-week-old embryo blood enters the heart at its caudal end. Cranially blood passes from the heart through the arteries of the pharyngeal arches (aortic arch system) to reach the dorsally-located, paired dorsal aortae.

Blood flowing from the ventrally-located heart tube reach the dorsal aortae by passing through which of the following structures? a Aortic arches b Vitelline arteries c Umbilical arteries

A a single umbilical vein carries oxygenated blood to the embryo; right and left umbilical arteries return de-oxygenated blood to the placenta.

De-oxygenated blood is returned to the placenta via with of the following vessels? a Umbilical arteries b Umbilican vein c Cardinal arteries d Cardinal veins e Vitelline arteries f Vitelline veins

D: Vagus nerves. The vagus nerves provide parasympathetic input to the thoracic viscera and to the abdominal viscera as far as the left colic (splenic) flexure. Car- diac branches of the vagi arise in the neck and descend into the thorax to supply the heart. Multiple additional branches arise in the thorax and supply the other thoracic viscera. Thus, parasympathetic input to the thorax is widespread from a great extent of the vagus nerves. Choice A (Cervical paraver- tebral ganglia) is incorrect. The paravertebral ganglia are the sympathetic ganglia. The cervical ganglia give rise to cardiac branches that provide much of the sympathetic supply to the thoracic viscera. Choice B (Greater splanchnic nerves) is incor- rect. These nerves are branches of the thoracic sympathetic trunk ganglia. They convey sympathetic fibers to the upper abdomen. Choice C (Gray rami communicantes) is incorrect. Gray and white rami communicantes are short connections between individual spinal nerves and the sympathetic trunk. The gray rami carry mainly postsynaptic sympathetic fibers. The white rami convey mainly presynaptic fibers. Choice E (Intercostal nerves) is incorrect. There is no parasympathetic innervation in the body wall and limbs. Thus, the intercostal nerves (supplying the thoracic and abdominal walls) do not carry parasympathetic fibers.

Disruption of parasympathetic input to the thorax may be related to damage to which of the following structures? (A) Cervical paravertebral ganglia (B) Greater splanchnic nerves (C) Gray rami communicantes (D) Vagus nerves (E) Intercostal nerves

D: It gives rise to the posterior interventricular (IV) artery. Coronary dominance refers to which coronary artery gives rise to the posterior IV artery, which is often termed the posterior descending artery by clinicians. When the right coronary artery gives rise to the posterior IV, the condition is right coronary dominance, which is the usual pattern in approximately 66% of the population. When the circumflex branch of the left coronary artery gives rise to the posterior IV, the condition is left coronary dominance, which occurs in approximately 15% of human hearts. Other patterns, including codominance, also occur. The posterior IV supplies neighboring aspects of both ventricles, including part of the ventricular septum. Thus, coronary dominance is important in determining the roles of each of the coronary arteries in supplying specific areas of the heart. Choice A (It gives rise to the anterior interventricular artery) is incorrect. The anterior IV and the circumflex branch are the terminal branches of the left coronary artery. The anterior IV supplies both ventricles and most of the ventricular septum. It usually anastomoses with the posterior IV across the inferior bor- der of the heart. Choice B (It is derived from the left 6th aortic arch) is incorrect. The coronary arteries are derived from both local epicardial tissue and migrating angioblasts. They are not related to the aortic arches. The left sixth aor- tic arch does give rise to the left pulmonary artery and the ductus arteriosus. Choice C (It supplies the right border of the heart) is incorrect. The right (acute) border of the heart is formed mainly by the right atrium, which is supplied by the right coronary artery. Coronary dominance is not related to supply to this area. Choice E (It supplies the margin of the heart) is incorrect. The margin (inferior border) of the heart is the nearly horizontal edge between the anterior (sternocostal) and inferior (diaphragmatic) surfaces of the heart. It is formed primarily by the right ventricle and is sup- plied largely by the marginal branch of the right coronary artery. Coronary dominance is not defined by the supply to this area.

During a surgery rotation, a 3rd year medical student is asked by a cardiovascular surgeon to explain what "left coronary dominance" means in relation to the left coronary artery. Which of the following explanations should be given by an astute student? (A) It gives rise to the anterior interventricular (IV) artery (B) It is derived from the left 6th aortic arch (C) It supplies the right border of the heart (D) It gives rise to the posterior interventricular artery (E) It supplies the margin of the heart

B, C, E, F, G

Identify the regions of the heart typically supplied by the right coronary artery and its branches. a Anterior 2/3rds of the interventricular septum b Sinoatrical node c Diaphragmatic surface of left ventricle d Atrioventricular bundle e Posterior 1/3 of interventricular septum f Atrioventricular node g Right atrium h Left atrium

A The fibrous pericardium is a somatic structure (derived from the pleuropericardial folds of the embryonic body wall). The phrenic nerve innervates the fibrous pericardium.

In a case of cardiac tamponade, pain sensations from the stretching fibrous pericardium would: a be carried by somatic afferent fibers in the phrenic nerves to the cervical spinal cord levels. b follow parasympathetic pathways in the vagus nerve. c be carried by somatic afferent fibers entering the T1-T4 posterior roots. d follow sympathetic pathways back to the upper thoracic spinal cord levels.

C The first blood cells and vessels to differentiate in the embryo are derived from the blood islands of the yolk sac. These blood islands are derived from the extraembryonic mesoderm that surrounds the yolk sac membrane.

In embryonic development, early blood cells and blood vessels differentiate from which of the following tissues? a Cytotrophoblast b Syncytiotrophoblast c Extraembryonic mesoderm dyolk sac endoderm e Uterine endometrium

C: Right vagus passes posterior to the root of the lung. The root of the lung is the pleura-invested bundle of structures that enter and leave the lung at the hilum, which includes the bronchi, pulmonary and bronchial vessels, lym- phatics, and nerves. Both the right and left vagus nerves descend in the thorax posterior to the root of each lung. At this depth, they are well positioned to contribute to the pulmonary and esophageal plexuses, and to follow the esophagus into the abdomen. Choice A (Right vagus passes onto the anterior aspect of the esophagus to become the ante- rior vagus) is incorrect. Due to the developmental clockwise rotation of the stomach, the lower esophagus also rotates, carrying the right vagus onto its posterior aspect, where the nerve becomes the posterior vagus. In the same way, the left vagus shifts to the anterior aspect of the esophagus and becomes the anterior vagus. Choice B (Left vagus passes through the anterior mediastinum) is incorrect. Both the left and right vagus nerves descend in the thorax posterior to the pericardial sac, that is, in the posterior mediastinum. Choice D (Left vagus passes across the posterior side of the aortic arch) is incorrect. The left vagus nerve crosses the ante- rolateral aspect of the aortic arch in passing from the superior to posterior mediastinum. The right vagus has no relation- ship to the aortic arch. Choice E (Right vagus passes through the middle mediastinum) is incorrect. Both the left and right vagus nerves descend in the thorax posterior to the peri- cardial sac, that is, in the posterior mediastinum. However, both the phrenic nerves and the pericardiacophrenic vessels are held in the pericardial sac and pass through the middle mediastinum.

In preparing for his Board Certification in thoracic surgery, a surgeon reviews the geographic relations of critical structures in the chest. Which of the following is correct regarding the relation- ships of the vagus nerves in their passage through the thorax? (A) Right vagus passes onto the anterior aspect of the esophagus to become the anterior vagus (B) Left vagus passes through the anterior mediastinum (C) Right vagus passes posterior to the root of the lung (D) Left vagus passes across the posterior side of the aortic arch (E) Right vagus passes through the middle mediastinum

A Treacher-Collins syndromes, like other "first arch syndromes", differentially afffects the first pharyngeal arch.

Mandibulofacial dysostosis (Treacher-Collins syndrome) is a developmental disorder characterized by craniofacial deformities, including malformed or absent ears, zygomatic and mandibular hypoplasia, and downward slanting eyes exhibiting ptosis of the lateral eyelids. This condition is a result of lack of migration of neural crest cells into which of the following pharyngeal arches? a First b Second c Third d Fourth e Sixth

B A C

Match the embryonic vein to the structure/tissue of origin: 1. umbillical vein 2. cardinal vein 3. vitelline vein A. body of embryo B. plcaenta C. yolksac

B A E D C

Match the structure on the left to the appropriate statement on the right: 1. Ductus venosus 2. Ligamentum arteriosum 3. Ductus arteriosus 4. Umbilical arteries 5. Umbilican vein A. ligaentous remnant of the ductus arteriosus B. shunts oxygenated blood from the umbilical vein to the inferior vena cava thus bypassing the liver C. carries oxygenated blood from the placenta to the fetus D. return oxygen-depleted fetal blood to the placenta E. shunts oxygenated blood from the pulmonary trunk to the aortic arch thus bypassing the lungs

C D A B

Place the following layers in order from superficial (top of list) to deep (bottom of list) A. pericardial cavity B. visceral pericardium C. fibrous pericardium D. parietal pericardium

G A I D B F C H E

Place the following layers of the thoracic wall in correct sequence from superficial (first) to deep (last). A. superficial fascia B. endothoracic fascia C. pleural cavity D. muscular layer ( each individual layer with its own investing fascia) E. lung F. parietal pleura G. skin H. visceral pleura I. deep fascia

D The SA node starts the conduction system and is referred to as the pacemaker of the heart. It begins the contraction in the atria. The signal then moves to the AV node, which delays the signal from moving too quickly to the ventricles. The AV Bundle moves the signal into the ventricles. The right and left bundle branches split the signal to move to the right and left ventricles, respectively. The Purkinje fibers cause the ventricles to contract.

Place the following nodes in the correct order of the electrical conduction pathway through the heart: 1: AV bundle 2: AV node 3: SA node 4: Right and left bundle branches 5: Purkinje fibers a 1, 3, 4, 2, 5 b 2, 3, 1, 4, 5 c 3, 1, 2, 5, 4 d 3, 2, 1, 4, 5 e 3, 1, 2, 4, 5 f 5, 3, 1, 2, 4

B

The Eustachian (or auditory) tube connects the middle ear to the: a Nasal cavity b Nasopharynx c Oral cavity d Oropharynx e Larynx f Laryngopharynx

D

What is the correct flow of blood through the primitive heart tube? a Sinus venosus - bulbus cordis - ventricle - atrium - truncus arteriosus b Sinus venosus - ventricle - atrium - bulbus cordis - truncus arteriosus c Sinus venosus - atrium - ventricle - truncus arteriosus - bulbus cordis d Sinus venosus - atrium - ventricle - bulbus cordis - truncus arteriosus

C The secondary palate is that portion of the palate formed by the palatine shelves of the maxillary processes.

When the palatine processes (palatal shelves) fail to meet and fuse with each other and with the nasal septum, the resulting anomaly is a cleft of the a Uvula b Primary palate c Secondary palate d Primary and secondary palates e Intermaxillary segment

A As the choroid fissure closes, the hyaloid artery becomes enclosed within optic nerve, thus forming the central artery of the retina.

Where does one find the remnants of the hyaloid canal in the mature eye? a In the optic nerve b In the lens c In the choroid d In the vitreous body e In the aqueous humor

C The foramen secundum is formed by apoptosis within the septum primum as the latter fuses to the endocardial cushions.

Which of the following associations is INCORRECT? a Endocardial cushions - atrioventricular valves b Foramen primum - septum primum c Foramen secundum - septum secundum d Outflow tract - pulmonary trunk

B: Transposition of the great vessels. The conus cordis and truncus arteriosus normally undergo an internal spiral partitioning (septation) that results in forma- tion of the ventricular outflow tracts, pulmonary trunk, and ascending aorta. Failure of the conotruncal septum to follow its normal spiral course results in transposition of the great vessels. In this case, the septum runs directly downward through the conotruncal region instead of spiraling, caus- ing the aorta to originate from the right ventricle and the pulmonary trunk to arise from the left ventricle. Alternately, displacement of the developing spiral septum causes unequal division of the conotruncal region, resulting in a narrow right ventricular outflow plus an overriding aorta. This condition is different from transposition of the great vessels and forms the basis for tetralogy of Fallot. Choice A (Double aortic arch) is incorrect. A double aortic arch is the result of the persistent right dorsal aorta connecting with the seventh intersegmental artery and the left dorsal aorta. This arrangement produces a vascular ring that surrounds both the trachea and esopha- gus. Choice C (Patent foramen ovale) is incorrect. A patent foramen ovale is a persistent opening in the atrial septum, resulting from failure of fusion of the septum secundum with the remnant of the septum primum. This defect allows post- natal exchange of blood between the two atria. Choice D (Ventricular septal defect) is incorrect. VSDs are gaps in the ventricular septum resulting from failure of fusion of the mus- cular walls of the primitive ventricles and/or failure of growth of tissue from the endocardial cushions. In either case, blood may be exchanged between the ventricles. VSDs are com- monly closely associated with other defects that result from mistakes in partitioning of the conotruncal region. However, they are not directly derived from such defects. Choice E (Ectopia cordis) is incorrect. In this rare malformation, the heart lies on the surface of the chest, which results from failure of the lateral body wall folds to meet and fuse in the anterior midline of the thorax.

Which of the following congenital defects is the direct outcome of malformation of the spiral partitioning of the conus cordis and truncus arteriosus? (A) Double aortic arch (B) Transposition of the great vessels (C) Patent foramen ovale (D) Ventricular septal defect (VSD) (E) Ectopia cordis

A

Which of the following congenital defects is the direct outcome of malformation of the spiral partitioning of the truncus arteriosus? a Transposition of the great vessels b Patent foramen ovale cVentricular septal defect d Ectopia cardis

D, E Cyanosis is related to the presence of a significant shunt of oxygen-depleted blood from the right side of the heart to the systemic circulation on the left side of the heart.

Which of the following congenital heart defects are associated with cyanosis in the newborn? (select all that apply) a Atrioseptal defect b Interventricular septal defect c Patent ductus arteriosus d Tetraology of Fallot e Transposition of great vessels

A All but the atrial septal defect listed above are features of this malformation.

Which of the following heart defects is NOT a component of the tetralogy of Fallot? a Atrial septal defect b Ventricular septal defect c Pulmonary stenosis d Overriding aorta e Right ventricular hypertrophy

C Although located posterior to the left atrium of the heart, this is not a location where the esophagus is naturally constricted. The fourth location of natural constriction of the esophagus is at its origin from the pharynx (upper esophageal sphincter).

Which of the following is NOT a location of natural constriction of the esophagus in the thorax? a Posterior to the aortic arch b Esophageal hiatus c Posterior to the left atrium of the heart d Posterior to the left primary (main) bronchus

B Whereas the parietal pleura contains pain receptors, the visceral pleura does not. There is no need to anesthetize the visceral pleura.

Which of the following statements regarding procedures involving the thoracic wall is(are) INCORRECT? a In procedures meant to drain excess air or fluids from the pleural cavity the needle or chest tube should be introduced at the upper margin of a rib. b In all procedures care must be taken to assure the local anesthesia reaches the visceral pleura. c In an intercostal nerve block, the needle should be introduced at the inferior margin of a rib.

B The facial nerve is the nerve of the second pharyngeal arch.

Which of the following structures is NOT related to the first pharyngeal arch? a Malleus b Facial nerve c Meckel's cartilage d Mandibular process e Maxillary process

C: Left main bronchus. The trachea, bronchi, and lungs appear as radiolucent (black) structures because of their air content. Left and right are differentiated by remem- bering that the conventional view of CT scans is from below, as if standing at the foot of the patient's bed and looking to the supine person's head. Also, the left main (primary) bronchus is more horizontally aligned, whereas the right main bronchus is more vertically aligned. Thus, the left main bronchus offers a more oblong profile in cross-sectional (axial) scans, while the right main bronchus is more circu- lar. Choice A is incorrect. The ascending aorta is identified. Note the position of this structure relative to the left ventri- cle. Choice B is incorrect. The right main bronchus is iden- tified. Note the differentiating features outlined previously. Choice D is incorrect. The azygos vein is identified. Note the size and position of the azygos vein slightly offset to the right anterior aspect of the vertebral body. Choice E is incorrect. The descending aorta is identified. Note the size and position of the aorta slightly offset to the left anterior aspect of the vertebral body.

Which of the labeled structures in the given CT scan of the thorax indicates the left main bronchus?