Block 3 Thorax Quiz

The correct answer includes all the components of the conducting system of the heart, which are the sinuatrial node, the atrioventricular node, the A-V bundle, the right and left branches, and the Purkinje fibers network. These components work together to coordinate the electrical signals and ensure proper contraction and relaxation of the heart muscles, allowing for efficient pumping of blood throughout the body.

Type II pneumocytes are responsible for the secretion of pulmonary surfactant. Pulmonary surfactant is a substance that reduces surface tension in the alveoli, preventing them from collapsing during exhalation and promoting efficient gas exchange. Type II pneumocytes are specialized cells located in the alveoli of the lungs and are responsible for producing and secreting surfactant. This secretion helps to maintain the elasticity and stability of the alveoli, ensuring proper lung function.

A typical rib consists of a head, a neck, and a shaft with its costal groove. This means that a typical rib has these three distinct parts which are necessary for its structure and function. The head of the rib articulates with the corresponding vertebra, the neck is a narrow portion connecting the head to the shaft, and the shaft contains the costal groove which protects the intercostal nerves and blood vessels. This description accurately defines the components of a typical rib.

The septomarginal trabecula, also known as the moderator band, is a muscular structure located in the right ventricle of the heart. It extends from the interventricular septum to the base of the anterior papillary muscle. Its main function is to provide electrical conduction and mechanical support to the right ventricle during contraction. Therefore, the correct answer is right ventricle.

Coarctation of the aorta is a congenital condition characterized by a narrowing of the aorta. The ductus arteriosus, also known as the ligamentum arteriosum, is a small blood vessel that connects the pulmonary artery to the descending aorta in fetal circulation. This vessel normally closes shortly after birth. In cases of coarctation of the aorta, the narrowing often occurs near the site where the ductus arteriosus used to be. This can lead to restricted blood flow and increased pressure in the upper body, while blood flow to the lower body is reduced.

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A tumor in the posterior mediastinum is most likely to involve the thoracic duct. The thoracic duct is the main duct of the lymphatic system and it runs through the posterior mediastinum. Tumors in this area can compress or invade the thoracic duct, leading to obstruction of lymphatic flow and causing lymphatic fluid to accumulate in the body. This can result in symptoms such as swelling, pain, and difficulty breathing. Therefore, the thoracic duct is the most likely structure to be involved in a tumor in the posterior mediastinum.

In congenital coarctation of the aorta, the aortic blood flow is obstructed past the left subclavian artery. This obstruction leads to the development of collateral circulation, where alternate pathways are formed to carry the blood flow from the upper part to the lower part of the trunk. One of these pathways involves the anastomosis between the superior epigastric arteries and the inferior epigastric arteries. The superior epigastric artery arises from the internal thoracic artery, making it the correct answer.

The correct answer is the Heart. The middle mediastinum is the central compartment of the thoracic cavity, located between the two lungs. It contains the heart, which is a major organ responsible for pumping blood throughout the body.

The hoarseness in this patient is most likely due to the involvement of the left recurrent laryngeal nerve. The left recurrent laryngeal nerve innervates the muscles of the larynx, including the vocal cords. In this case, the cancer of the esophagus with obstruction and metastatic involvement of surrounding structures likely caused compression or invasion of the left recurrent laryngeal nerve, resulting in hoarseness. The other nerves listed are not directly involved in innervating the larynx and would not be expected to cause hoarseness in this scenario.

Premature infants may suffer from respiratory distress due to an inadequate number of terminal air sacs and surfactant deficiency in the lungs. The correct answer is 24 to 26 weeks after fertilization because at this stage of development, the number of terminal air sacs and the level of surfactant in the lungs are sufficient for survival.

After passing through the parietal pleura, a bullet would perforate the potential pleural cavity. The potential pleural cavity is the space between the parietal and visceral pleura, which are the two layers of the pleura that surround the lungs. The potential pleural cavity normally contains a small amount of fluid that allows the lungs to move smoothly during respiration. A bullet passing through the parietal pleura would enter this potential pleural cavity before reaching any other structures listed in the options.

The axillary lymph node chain is a group of lymph nodes located in the armpit region. It is responsible for draining lymphatic fluid from the upper limb, breast, and surrounding areas. The lateral nodes, apical nodes, central nodes, and pectoral nodes are all considered groups within the axillary lymph node chain. However, the deep cervical nodes are not part of the axillary lymph node chain. They are located in the neck region and are responsible for draining lymphatic fluid from the head and neck area.

The azygos vein is a large vein that drains blood from the thoracic wall and upper abdominal wall. It ascends on the right side of the vertebral column and typically drains into the superior vena cava. The superior vena cava is a major vein that receives blood from the upper body, including the head, neck, and upper limbs. Therefore, the correct answer is superior vena cava.

A knife wound in the heart at the level of the fifth left interspace near the sternum would penetrate all of the structures listed except the visceral and parietal pleura. The fibrous pericardium, serous visceral pericardium, serous parietal pericardium, and pericardial cavity are all layers or spaces within the pericardium, which surrounds the heart. However, the visceral and parietal pleura are layers of the pleural membrane that surround the lungs, not the heart. Therefore, they would not be affected by a knife wound to the heart.

Umbilical Artery become INTERNAL iliac artery

The superior mediastinum is located in the upper part of the chest, between the thoracic inlet and the lower border of the fourth thoracic vertebra. It contains various structures including the superior vena cava, trachea, esophagus, and the left recurrent laryngeal nerve. The right recurrent laryngeal nerve, however, does not pass through the superior mediastinum. It descends into the chest through the neck and loops around the right subclavian artery. Therefore, the right recurrent laryngeal nerve does not lie in the superior mediastinum.

The correct answer is the caudal part of the body of sternum and medial ends of left 4th and 5th costal cartilages. This is because the pericardial sac is located in the chest cavity, specifically between the sternum and the heart. The caudal part of the body of sternum refers to the lower part of the breastbone, while the medial ends of the left 4th and 5th costal cartilages refer to the lower ribs on the left side. By introducing a needle in this area, the straw-colored fluid in the pericardial sac can be safely removed.

The smooth muscle, cartilage, and connective tissues of the bronchial tubes and the pleural sacs of the lungs develop from mesenchyme (mesoderm).

The phrenic nerve is responsible for the sensory innervation of the mediastinal pleura. This nerve originates from the cervical spine (C3-C5) and supplies sensation to the diaphragm and the mediastinal pleura. In this case, the patient's complaint of pain at the root of the neck and over the shoulder suggests involvement of the phrenic nerve, as these areas are innervated by this nerve. Additionally, the fact that the patient is a heavy smoker may suggest a potential cause for the abnormal mass invading the mediastinal pleura.

The septum primum is responsible for the development of the atrial septum. In the case of an ostium secundum atrial septal defect, there is a failure of the septum primum to properly close the ostium secundum, resulting in a hole in the atrial septum. This allows blood to flow between the left and right atria, leading to pulmonary hypertension.