Mini 3 - Martin Questions:

The correct answer includes all the components of the conducting system of the heart, which are the sinuatrial node, atrioventricular node, bundle of His, right and left branches, and Purkinje fibers network. These components work together to coordinate the electrical signals that regulate the heartbeat. The sinuatrial node initiates the electrical impulse, which is then conducted through the atrioventricular node and bundle of His. The right and left branches further divide the impulse, and the Purkinje fibers distribute it throughout the ventricles, causing them to contract and pump blood.

Coarctation of the aorta is a congenital narrowing of the aorta, and it most often occurs near the ductus arteriosus (ligamentum arteriosum). The ductus arteriosus is a blood vessel that connects the pulmonary artery to the aorta in fetal circulation, allowing blood to bypass the lungs. After birth, the ductus arteriosus normally closes and becomes the ligamentum arteriosum. If the ductus arteriosus does not close properly, it can lead to coarctation of the aorta. Therefore, the correct answer is ductus arteriosus (ligamentum arteriosum).

A typical rib consists of all of the following: head, a neck, and a shaft with its costal groove. This means that a typical rib has a rounded head that articulates with the vertebrae, a narrow neck, and a long, curved shaft with a groove along its bottom surface where the intercostal blood vessels and nerves run. This description does not apply to the floating ribs (ribs 8-12) as they do not have a neck or costal groove.

The septomarginal trabecula, also known as the moderator band, is a muscular band that is found in the right ventricle of the heart. It extends from the interventricular septum to the base of the anterior papillary muscle. The primary function of the septomarginal trabecula is to provide additional support to the right ventricle and help facilitate the conduction of electrical signals during the contraction of the heart. Therefore, the correct answer is the right ventricle.

The hoarseness in this patient is 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 is causing compression or infiltration of the left recurrent laryngeal nerve, leading to hoarseness. The other options listed do not innervate the larynx and are not likely to cause hoarseness in this patient.

When a bullet passes through the parietal pleura, it would enter the potential pleural cavity. The potential pleural cavity is the space between the parietal and visceral pleura, which normally contains a small amount of fluid to reduce friction during breathing. The bullet would perforate this cavity before reaching any of the other structures listed.

A knife wound in the heart, at the level of the fifth left interspace, near the sternum, would penetrate the fibrous pericardium, serous visceral pericardium, serous parietal pericardium, and the pericardial cavity. However, it would not penetrate the visceral and parietal pleura, which are the membranes that surround the lungs.

The axillary lymph node chain is a group of lymph nodes located in the armpit area. It is responsible for draining lymph fluid from the upper limb, breast, and chest wall. 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 drain lymph fluid from the head and neck area.

The correct answer is the caudal part of the body of sternum and medial ends of left 5th and 6th costal cartilages. This is the location where the pericardial sac can be safely accessed to remove the straw-colored fluid.

The pulmonary cartilage, smooth muscle, and connective tissue are not derived from lung bud endoderm. Instead, they are derived from the surrounding mesoderm.

The superior mediastinum is located in the upper part of the thoracic cavity, between the thoracic inlet and the transverse thoracic plane. 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 lie in the superior mediastinum. It descends into the thorax on the right side, looping around the subclavian artery before ascending back up to innervate the larynx. Therefore, the right recurrent laryngeal nerve is not found in the superior mediastinum.

The correct pairings of fetal structures and adult derivatives associated with fetal circulation include the ductus venous/ligamentum venosum, the ductus arteriosus/ligamentum arteriosum, and the umbilical vein/ligamentum teres hepatis. The umbilical artery does not become the common iliac artery in adulthood. Instead, it becomes the medial umbilical ligament.

All of the mentioned structures (interventricular foramen, ductus arteriosus, ductus venous, and foramen ovale) are shunts that are present in the fetal circulation. These shunts allow blood to bypass certain areas of the developing fetus's circulatory system. Before birth, these shunts normally close or undergo structural changes to redirect blood flow once the baby starts breathing on its own and the lungs become functional. Therefore, all of the mentioned shunts normally close before birth.