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THORAX FORUM Diaphragm: What is the blood supply and innervation (sensory/motor) to the superior and inferior surface of the diaphragm? A: Motor innervation is from right and left phrenic nerves (C3, 4, 5 keep the diaphragm alive). Sensory innervation for the central surface (parietal pleura and peritoneum) is from the phrenic nerve. Peripheral sensory innervation is from the lower six intercostal nerves. Superior blood supply is pericardiacophrenic, superophrenic musculophrenic and inferior are inferior phrenic arteries. James Lamberg Thoracic Wall Case 1: During your third year rotations you observe a resident perform a thoracocentesis to sample pleural fluid. He inserts the needle near the lower border of the 8th rib at the right midaxillary line. The next day, during rounds, his patient is complaining of tingling and loss of sensation over the skin of his chest near the 8th rib and down toward his umbilicus on the same side as his thoracocentesis. Why did the resident select the 8th intercostal space for insertion? A: That is the location of the costodiaphragmatic recess; the gap between the costo pleura and the diaphragmatic pleura. Thus a needle can be inserter into this space to sample fluid without risk of direct damage to the lung. Why did the patient develop numbness and tingling (parasthesia)? A: Likely, the intercostal nerve was damaged as this lies just beneath the rib border. This nerve innervates the skin on the described dermatome. What structure was damaged resulting in the parasthesia? A: Intercostal nerve What other structures are associated with the damaged structure? How are they arranged? What two muscle layers are they between? A: Intercostal vein, artery, nerve from superior to inferior. The two muscles layers they are between are the internal intercostal and innermost intercostal. Where should the insertion have been made to avoid damage? A: Above the border of the 9th rib, within the 8th intercostal space Other than sampling fluid, thoracocentesis could be used to…? A: Relieve pus/fluid/air pressure such as for pleural effusions What structures, in order, would the needle pass through during a thoracocentesis?

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A: Skin, superficial fascia, serratus anterior, external intercostal, internal intercostal, innermost intercostal, endothoracic fascia, parietal pleura, into pleural cavity/space…stopping prior to the visceral pleura and lung. Lung Case A 20 month old boy was helping his mom clean up the morning after a party when he suddenly started to choke. The mother straddled him over her forearm and began to whack him on his back. Nothing was expelled from his mouth. He continued to have difficulty breathing (dyspnea) so she called the doctor and went to the ER. When asked what the child ate she said responded that she didn’t see him eat anything but maybe he got a peanut off of the floor. The child was in respiratory distress, with coughing and dyspnea. The doctor noted limited movement of the right side of his chest and reduced breath sounds on the right. A bronchoscopy revealed a peanut in the right middle lobe bronchus which was removed with forceps passed through the bronchoscope. Why had the peanut fallen down the right side? A: Because the right bronchus is wider and a more direct continuation of the trachea. What do you suppose would have eventually happened to the lobes blocked by the peanut? A: The gas would dissolve away and they would collapse How do collapsed lungs differ from aerated lungs on radiographs? A: Following the pleural edge outlined by air in the pleural space (thin white line) can show the reduced lung size. The pleural thin white line will not go to the edge of the thorax on the radiograph. The collapsed side may appear black or more black (radiolucent). Cardio Case 1: A 57 y.o. male is brought into the ER by his wife. The wife explains that her husband complains of a sharp, squeezing pain behind his sternum and has had such bouts repeatedly over several years. A diagnosis of an acute myocardial infarction (MI) is made. What is the most common site of occlusion responsible for MI? A: Anterior interventricular branch (left anterior descending) of left coronary artery. 4050% occur in the proximal portion of the LAD branch of the left coronary artery. What part of the cardiac conduction system might be affected by occlusion to this artery? A: The LAD lies on the anterior wall, which is septal (interventricular). This could affect the RBB and possibly the LBB of the conduction system or even a higher septal structure such as the Bundle of His.

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What neural structure carries visceral pain fibers from the heart and results in referred pain over the T1-T5 dermatome? A: The visceral pain fibers (GVAs), which originate from T1-T5 and arise from the cervical portion of the sympathetic chain and track back via dorsal root. Superior Mediastinum Case 1: An 18 y.o. student has high blood pressure (b.p.) during a physical exam. His b.p. is significantly higher in both upper limbs than it is in his lower limbs. What condition covered in lecture could result in higher b.p. in upper vs. lower limbs? A: Coarction of the aorta What osteological effects, if any, would help in the diagnosis? A: Rib notching due to enlarged intercostal collateral vessels What would angiography reveal? A: A narrow area on the aortic arch as well as enlarged collateral (anastamosing) vessels Superior Mediastinum Case 2: Examining a 12 y.o. boy on a routine physical to play school soccer, the physician noticed a heart murmur. The mother recalled that he had bouts of cyanosis and breathlessness as an infant, but his pediatrician was not concerned. The boy also admits that he tires easily. Radiographs revealed left ventricular hypertrophy, and ultrasound revealed a patent ductus arteriosus. Surgery was performed to ligate his ductus arteriosus. The surgery was successful, but he experienced hoarseness when speaking following the procedure. What is the ductus arteriosus? Where is it found? What is its function? A: In the developing fetus, it connects the pulmonary artery to the aortic arch to bypass the lungs, since the lungs are not needed for oxygenation. What probably was the cause of the boy’s hoarseness? A: Damage to the left recurrent laryngeal nerve, which is wrapped underneath the ductus arteriosus from fetal development of the aortic arches, specifically IV and VI. Superior Mediastinum Case 3: While inserting a central line into his patient’s subclavian vein, a surgical resident had a difficult time and had three attempts before he was successful. Examination of a chest radiograph revealed a collapsed lung. Why had the lung probably collapsed?

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A: The subclavian vein runs right over the top of the lung. If the needle was angled too inferiorly instead of medially (along the line of the clavicle), it may be directed into the apex (cupula) of the lung. Breast Case/Lymphatics: A 54 y.o. woman presents to her physician complaining of chest and back pain following a fall. On physical examination, the physician finds a mass in her breast. The woman admits that she does not perform self breast exams and has not had them examined for several years. A mammogram shows a large mass consistent with cancer in her breast. Is breast tissue confined to the “breast”? A: No, it extends into the “tail” region as well, into the axilla What lymph nodes might show cancer cells? A: Anterior axillary lymph nodes and possibly parasternal lymph nodes What is responsible for the dimpling, orange-peel appearance of some cancerous breasts? A: Suspensory ligaments (of Cooper) Thoracic ANS Case 1: An 80 y.o. patient who has smoked since the age of 16 presents to your office with hoarseness of his voice and a constricted pupil in his right eye. Where is his lung tumor located? A: Right apically (Pancoast) with symptoms due to pressure on sympathetic chain. Thorax General Case 1: After a surgery to his upper chest, a patient has lost innervation to the right side of his diaphragm. What nerve supplies the diaphragm and was injured? A: Right phrenic nerve (C3, 4, 5) On inspiration, the right side of his diaphragm moves upward. Why? A: The left side of the diaphragm is innervated so it will be pulled down into the abdominal cavity upon inspiration. The abdominal contents will push on the left side of the diaphragm from below, forcing it upward. There may also be some involvement of intrathoracic pressure differences from the right to left. The diaphragm has three large hiatuses. What major structure passes through them and at what vertebral level?

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A: Caval hiatus has IVC (T8). Esophageal hiatus has esophagus (T10). Aortic hiatus has aorta (T12). Other things that pass through are the right phrenic nerve (caval hiatus), vagal trunks, esophageal branches to left gatric artery (esophageal hiatus), and thoracic duct, azygos vein (aortic hiatus). Obstruction of the esophagus could restrict the thoracic duct. Thorax General Case 2: After a 24 hour plane flight in cramped conditions, a 45 y.o. woman suffers a DVT which leads to a stroke (blockage of brain arteries). How could the thrombus end up in her brain? A: The DVTs could end up in her brain if they passed through foramen in the heart, such as a patent fossa ovallis (atrial septal defect, e.g. probe patency) or possibly a ventricular septal defect Thorax General Case 3: A 65 y.o. woman is admitted to the hospital complaining of shortness of breath and difficulty swallowing. She coughs up blood during the exam and speaks with a hoarse voice. Diagnosis is made of an esophageal carcinoma that commonly occurs at a site of constriction of the esophagus where it is indented by the left main bronchus. What other structures constrict/indent the esophagus? A: Aortic arch and diaphgram Why would the patient have a hoarse voice? A: Constriction of the left recurrent laryngeal nerve, which runs under the aortic arch and between the esophagus and left main bronchus (and trachea). If her carcinoma expands anteriorly into the middle mediastinum, what structure might initially become compressed? A: The left atrium Thorax General questions: 1. A doctor is prescribing medicine for his patient with Asthma, where the bronchioles become constricted. Using your knowledge of the function of the autonomic system on the lungs would you suggest he prescribe drugs that act like the sympathetic or parasympathetic nervous system? A: Sympathetic as this would inhibit bronchial smooth muscle (broncho-relaxation) Explain why regional referred pain is found in predictable areas based on the organ experiencing pain. What dermatomal levels does heart pain refer to?

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A: Referred pain occurs because visceral nerves (organ pain) and somatic nerves (skin innervation) both synapse in the dorsal horn of the spinal cord so they are interpreted the same (GVAs). The heart affects the dermatomal levels of T1-T5. 2. You see a patient who you diagnose with pleurisy. One of her complaints is pain in the dermatomal area of C3-C5. Why is her pain occurring in this region? What does this tell you about the region of her pleura that is affected? A: The pain occurs do to compression of the phrenic nerve (C3, 4, 5). The referred pain would be due to pressure along the path of the phrenic nerve, so along the lateral sides of the pericardium (in the mediastinum) as well as the diaphragm. An 18 year old male patient presents to your office complaining of dyspnea and exhaustion even with minimal exertion. You run a complete physical and notice that his lower limbs have a lower blood pressure than that of his upper limbs. Angiography reveals a stenosis of the aortic arch just distal to the ligamentum arteriosum. What is the ligamentum arteriosum? What is a stenosis? A: The remnants of the embryonic connection between the aorta and the pulmonary artery. Stenosis is a narrowing of the vessels. What congenital condition does your patient suffer from? A: Coarctation of the aorta Why is he experiencing dyspnea? A: He is also not getting good perfusion due to the reduced circulation with backup into the left side of the heart. What chamber of his heart is having to work harder? A: The left ventricle What division of the NS is commanding his heart to increase its work? A: Sympathetic ANS Where do they originate from? Levels? Region? A: The cardiac nerves arise from levels T1-T5 within the IML. They arise from the cervical portion of the sympathetic chain. Where do their pre/post synaptic neurons synapse? A: Pre-synaptic neurons synapse in the sympathetic chain ganglia (IML) and postsynaptic neurons synapse in the cervical sympathetic chain. How do they get to the heart? Version: 09Apr2009

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A: They leave the sympathetic chain in the cervical region and travel down to the cardiac plexus, and then innervate the heart via the cervical cardiac sympathetic nerves (GVE). What chamber of his heart is having a back-up of fluid? A: The left atrium via left ventricle What valve may have leakage due to this overload? A: Left atrial mitral (bicuspid) What vessels are backing up? A: Pulmonary veins. Also, internal thoracic to anterior intercostal to posterior intercostal and retrograde to descending aorta. If this condition worsens or continues what other vessels and chambers will become involved? A: Right ventricle may become backed up and possibly the right atrium. The coronary vessels will become involved and possibly the pulmonary vessels. What will be the result of their involvement? A: They will become enlarged and possibly rupture If his heart tissue begins to infarct, how will pain fibers enter the spinal cord? A: They will enter the sympathetic chain, descend to the T1-T5(L2) level, and enter the spinal cord via a GVA fiber to dorsal root with cell body in dorsal root ganglion. At what levels will these pain fibers enter the spinal cord? A: T1-T5 Where will this pain be felt by the patient? A: Chest, anterior shoulder, medial arm and forearm Your patient eventually develops pleural effusion…you decide to drain this fluid. What procedure would you perform? A: Thoracocentesis (thoracentesis) If you wanted to do this from behind with the patient bent over a chair where would you perform the procedure? A: In the 10th intercostal space as this is between the visceral pleura (lung ending at T10) and parietal pleura (ending at T12). What structures do you want to avoid?

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A: The intercostal vein, artery, and nerve which lie in that order from superior to inferior just below each rib. What layers will you penetrate? A: Skin, superficial fascia, serratus anterior, external intercostal, internal intercostal, innermost intercostal, parietal pleura, into pleural cavity/space…stopping prior to the visceral pleura and lung.

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