Thorax/Abdomen

Thorax/Abdomen US Medical PG Question 1: A 72-year-old man presents to the emergency department after a fall. The patient was found lying down on the floor in his room in his retirement community. The patient has a past medical history of Alzheimer dementia and a prosthetic valve. His current medications include donepezil and warfarin. His temperature is 97.7°F (36.5°C), blood pressure is 85/50 mmHg, pulse is 160/min, respirations are 13/min, and oxygen saturation is 97% on room air. The patient is started on IV fluids and a type and screen is performed. Laboratory values are ordered as seen below. Hemoglobin: 13 g/dL Hematocrit: 39% Leukocyte count: 5,500 cells/mm^3 with normal differential Platelet count: 225,000/mm^3 INR: 2.5 AST: 10 U/L ALT: 12 U/L A chest radiograph and EKG are performed and are within normal limits. A full physical exam is within normal limits. The patient's vitals are repeated. His temperature is 99.5°F (37.5°C), blood pressure is 110/70 mmHg, pulse is 90/min, respirations are 10/min, and oxygen saturation is 98% on room air. Which of the following is the best next step in management?

• A. CT scan (Correct Answer)
• B. Urgent blood transfusion
• C. Fresh frozen plasma
• D. Exploratory laparoscopy
• E. Exploratory laparotomy

Thorax/Abdomen Explanation: ***CT scan*** - A patient with a **prosthetic valve** on **warfarin** and a fall is at high risk for **intracranial hemorrhage**, even without focal neurological deficits. - While initial vitals improved after IV fluids, the mechanism of injury (fall) and medication profile warrant a **CT scan** of the head to rule out serious internal injury, especially given the history of dementia which might mask symptoms. *Urgent blood transfusion* - The patient's **hemoglobin (13 g/dL)** and **hematocrit (39%)** are within normal limits, indicating no acute need for blood transfusion due to hemorrhage. - Transfusions are typically reserved for patients with significant blood loss or severe symptomatic anemia. *Fresh frozen plasma* - The patient's **INR of 2.5** is within the therapeutic range for a patient with a prosthetic valve on warfarin. - There is no evidence of active bleeding or supratherapeutic anticoagulation that would necessitate the administration of **fresh frozen plasma (FFP)** to reverse anticoagulation. *Exploratory laparoscopy* - There are no clinical signs or symptoms, such as abdominal pain, distension, or evidence of intra-abdominal bleeding (e.g., declining hemoglobin, peritoneal signs), to suggest an indication for an **exploratory laparoscopy**. - The patient's physical exam was described as normal. *Exploratory laparotomy* - Similar to laparoscopy, there is no clinical evidence of acute abdominal injury or hemorrhage, which would necessitate an **exploratory laparotomy**. - This invasive procedure is reserved for cases with strong suspicion of significant intra-abdominal pathology or trauma.

Thorax/Abdomen US Medical PG Question 2: A 71-year-old man is admitted to the hospital one hour after he was found unconscious. His pulse is 80/min and systolic blood pressure is 98 mm Hg; diastolic blood pressure cannot be measured. He is intubated and mechanically ventilated with supplemental oxygen at a tidal volume of 450 mL and a respiratory rate of 10/min. Arterial blood gas analysis shows: PCO2 43 mm Hg O2 saturation 94% O2 content 169 mL/L Pulmonary artery catheterization shows a pulmonary artery pressure of 15 mm Hg and a pulmonary capillary wedge pressure of 7 mm Hg. Bedside indirect calorimetry shows a rate of O2 tissue consumption of 325 mL/min. Given this information, which of the following additional values is sufficient to calculate the cardiac output in this patient?

• A. Left ventricular end-diastolic volume
• B. Partial pressure of inspired oxygen
• C. End-tidal carbon dioxide pressure
• D. Pulmonary artery oxygen content (Correct Answer)
• E. Total peripheral resistance

Thorax/Abdomen Explanation: ***Pulmonary artery oxygen content*** - Cardiac output can be calculated using the **Fick principle**, which states that **Cardiac Output = (Oxygen Consumption) / (Arteriovenous Oxygen Difference)**. - We are provided with **O2 tissue consumption (325 mL/min)** and **arterial O2 content (169 mL/L)**. To complete the Fick equation, we need the **mixed venous oxygen content**, which is represented by the **pulmonary artery oxygen content**. *Left ventricular end-diastolic volume* - While **left ventricular end-diastolic volume** is a determinant of stroke volume (and thus cardiac output), it alone is not sufficient to calculate cardiac output without knowing heart rate and ejection fraction. - This value is more relevant for assessing **preload** and ventricular function. *Partial pressure of inspired oxygen* - The **partial pressure of inspired oxygen** is used to calculate the **alveolar oxygen partial pressure** and is important for assessing oxygenation and respiratory function. - It is not directly used in the Fick principle for calculating cardiac output. *End-tidal carbon dioxide pressure* - **End-tidal carbon dioxide (ETCO2)** is a measure of the partial pressure of CO2 at the end of exhalation and reflects ventilation and pulmonary perfusion. - While it can be correlated with cardiac output in certain clinical contexts, it is not a direct input for the **Fick principle** calculation of cardiac output. *Total peripheral resistance* - **Total peripheral resistance (TPR)** can be calculated from cardiac output and mean arterial pressure using the formula: **(MAP - CVP) / CO**, but it cannot be used to calculate cardiac output directly without knowing the other variables. - TPR is a measure of the **resistance to blood flow** in the systemic circulation.

Thorax/Abdomen US Medical PG Question 3: A 32-year-old woman comes to the physician for a screening health examination that is required for scuba diving certification. The physician asks her to perform a breathing technique: following deep inspiration, she is instructed to forcefully exhale against a closed airway and contract her abdominal muscles while different cardiovascular parameters are evaluated. Which of the following effects is most likely after 10 seconds in this position?

• A. Decreased intra-abdominal pressure
• B. Decreased left ventricular stroke volume (Correct Answer)
• C. Decreased pulse rate
• D. Decreased systemic vascular resistance
• E. Increased venous return to left atrium

Thorax/Abdomen Explanation: ***Decreased left ventricular stroke volume*** - After 10 seconds of performing the **Valsalva maneuver**, the increased intrathoracic pressure significantly reduces **venous return** to the heart. - Reduced venous return leads to decreased **ventricular filling** (preload), which in turn diminishes **left ventricular stroke volume** and cardiac output. *Decreased intra-abdominal pressure* - The instruction to "contract her abdominal muscles" during forceful exhalation against a closed airway (Valsalva maneuver) directly leads to an **increase** in **intra-abdominal pressure**, not a decrease. - This increase in intra-abdominal pressure further impedes venous return from the lower extremities to the heart. *Decreased pulse rate* - In the initial phase of the Valsalva maneuver (first 5-10 seconds), the decrease in cardiac output triggers a **reflex tachycardia** to maintain blood pressure, leading to an **increased pulse rate**. - A decrease in pulse rate (bradycardia) is more characteristic of the release phase, not during the sustained strain. *Decreased systemic vascular resistance* - During the Valsalva maneuver, the body attempts to compensate for the drop in cardiac output and blood pressure by increasing **sympathetic tone**, which causes **vasoconstriction** and thus **increases systemic vascular resistance**. - A decrease in systemic vascular resistance would further drop blood pressure and is not the physiological response during this phase. *Increased venous return to left atrium* - The Valsalva maneuver dramatically **reduces venous return** to both the right and left atria due to the high intrathoracic pressure compressing the great veins. - This decreased venous return is the primary mechanism leading to the subsequent fall in cardiac output during the maneuver.

Thorax/Abdomen US Medical PG Question 4: A 28-year-old female comes to the emergency department complaining of heart palpitations. She has had multiple episodes of these in the past few months. She has found that if she wears tight clothing then sometimes these episodes will stop spontaneously. On presentation to the ED, she feels like her heart is pounding and reports feeling nauseous. She appears mildly diaphoretic. Her blood pressure is 125/75 mmHg, pulse is 180/min, and respirations are 22/min with an O2 saturation of 99% on room air. A neck maneuver is performed and her pulse returns to 90/min with improvement of her symptoms. Stimulation of afferent fibers from which nerve are most responsible for the resolution of her symptoms?

• A. Facial
• B. Hypoglossal
• C. Glossopharyngeal (Correct Answer)
• D. Trigeminal
• E. Vagus

Thorax/Abdomen Explanation: ***Glossopharyngeal*** - The question specifically asks about **afferent fibers** responsible for the resolution of symptoms during the neck maneuver (carotid sinus massage). - The **glossopharyngeal nerve (cranial nerve IX)** provides the **afferent (sensory) limb** of the baroreflex by carrying signals from **baroreceptors in the carotid sinus** to the nucleus tractus solitarius in the medulla. - When the carotid sinus is massaged, baroreceptors are stimulated → afferent signals travel via **CN IX** → medullary cardiovascular centers → efferent vagal output → heart rate slows. - This is the afferent pathway that initiates the reflex response to terminate **supraventricular tachycardia (SVT)**. *Vagus* - The **vagus nerve (cranial nerve X)** is crucial for treating SVT, but it provides the **efferent (motor) limb** of the baroreflex, not the afferent limb. - After afferent signals from CN IX reach the medulla, the vagus nerve carries parasympathetic output to the SA node to slow the heart rate. - If the question asked about efferent fibers, vagus would be correct, but it asks specifically about **afferent fibers**. *Facial* - The **facial nerve (cranial nerve VII)** primarily controls **facial expressions**, carries taste sensation from the anterior two-thirds of the tongue, and innervates salivary glands. - It has no role in the baroreflex or cardiac rhythm regulation via neck maneuvers. *Hypoglossal* - The **hypoglossal nerve (cranial nerve XII)** is responsible for **tongue movement**. - It has no involvement in cardiac rhythm regulation or the afferent pathways of the baroreflex. *Trigeminal* - The **trigeminal nerve (cranial nerve V)** mediates sensation from the face and controls the muscles of **mastication (chewing)**. - While trigeminal stimulation via the **diving reflex** (cold water on face) can cause bradycardia, this is not the mechanism involved in carotid sinus massage for SVT treatment.

Thorax/Abdomen US Medical PG Question 5: A 28-year-old man comes to the physician because of a 3-month history of pain in his left shoulder. He is physically active and plays baseball twice a week. The pain is reproduced when the shoulder is externally rotated against resistance. Injury of which of the following tendons is most likely in this patient?

• A. Infraspinatus (Correct Answer)
• B. Subscapularis
• C. Pectoralis major
• D. Supraspinatus
• E. Teres major

Thorax/Abdomen Explanation: ***Infraspinatus*** - Pain during **external rotation against resistance** is a classic sign of infraspinatus tendon injury, as it is a primary muscle for this action. - The patient's history of playing baseball and experiencing pain, especially with resistive external rotation, points to an injury of this **rotator cuff muscle**. *Subscapularis* - The subscapularis primarily causes **internal rotation** of the shoulder; injury would typically present with pain during resisted internal rotation, not external. - While it is a rotator cuff muscle, its function does not align with the specific maneuver causing pain described in the patient. *Pectoralis major* - The pectoralis major is a large chest muscle involved primarily in **adduction**, **internal rotation**, and **flexion of the humerus**, not external rotation. - Injury to this muscle would present with pain during these specific movements, not resisted external rotation. *Supraspinatus* - The supraspinatus is primarily involved in **initiation of abduction** and helps stabilize the shoulder joint, and pain would usually be elicited during these movements. - While a common site of rotator cuff injury, its function does not directly cause pain with resisted external rotation as described. *Teres major* - The teres major acts as an **adductor** and **internal rotator** of the humerus, similar to the latissimus dorsi. - Pain from a teres major injury would be associated with these actions, not with resisted external rotation.

Thorax/Abdomen US Medical PG Question 6: An 18-year-old man is brought to the emergency department 30 minutes after being stabbed in the chest during a fight. He has no other injuries. His pulse is 120/min, blood pressure is 90/60 mm Hg, and respirations are 22/min. Examination shows a 4-cm deep, straight stab wound in the 4th intercostal space 2 cm medial to the right midclavicular line. The knife most likely passed through which of the following structures?

• A. Serratus anterior muscle, pleura, inferior vena cava
• B. External oblique muscle, superior epigastric artery, azygos vein
• C. Pectoralis minor muscle, dome of the diaphragm, right lobe of the liver
• D. Intercostal muscles, internal thoracic artery, right heart
• E. Pectoral fascia, transversus thoracis muscle, right lung (Correct Answer)

Thorax/Abdomen Explanation: ***Pectoral fascia, transversus thoracis muscle, right lung*** * The stab wound is in the **4th intercostal space**, 2 cm medial to the right midclavicular line, placing it over the anterior chest wall. This trajectory would first penetrate the **pectoral fascia**. * Deeper structures in this region include the **transversus thoracis muscle** and, given the depth, the **right lung** as it extends superiorly behind the anterior chest wall. * *Serratus anterior muscle, pleura, inferior vena cava* * The **serratus anterior muscle** is more laterally positioned, typically covering the side of the rib cage. * The **inferior vena cava** is located more medially and posteriorly within the mediastinum, deep to the diaphragm, making it an unlikely target for an anterior 4th intercostal stab. * *External oblique muscle, superior epigastric artery, azygos vein* * The **external oblique muscle** is part of the abdominal wall and would not be penetrated in the 4th intercostal space. * The **superior epigastric artery** is lower, typically extending into the abdominal wall, and the **azygos vein** is in the posterior mediastinum, not in the path of this superficial anterior stab wound. * *Pectoralis minor muscle, dome of the diaphragm, right lobe of the liver* * The **pectoralis minor muscle** is located deep to the pectoralis major, which would be penetrated. However, a stab at the 4th intercostal space would be too high to directly involve the **dome of the diaphragm** or the **right lobe of the liver**, which are typically below the 5th intercostal space, especially in forced expiration. * *Intercostal muscles, internal thoracic artery, right heart* * The **intercostal muscles** would certainly be traversed. * However, the **internal thoracic artery** runs paramedially (about 1-2 cm from the sternum), and getting to the **right heart** would require a more medial and deeper trajectory, potentially causing immediate tamponade or severe hemorrhage.

Thorax/Abdomen US Medical PG Question 7: A 23-year-old man is brought to the emergency department by a coworker for an injury sustained at work. He works in construction and accidentally shot himself in the chest with a nail gun. Physical examination shows a bleeding wound in the left hemithorax at the level of the 4th intercostal space at the midclavicular line. Which of the following structures is most likely injured in this patient?

• A. Right atrium of the heart
• B. Inferior vena cava
• C. Left upper lobe of the lung (Correct Answer)
• D. Left atrium of the heart
• E. Superior vena cava

Thorax/Abdomen Explanation: ***Left upper lobe of the lung*** - The **left upper lobe of the lung** extends to the 4th intercostal space at the midclavicular line, making it the most probable structure to be traversed by a penetrating injury at this location. - The **pleural cavity** and lung tissue are superficially located in this region, making them highly susceptible to injury from a nail gun. *Right atrium of the heart* - The **right atrium** is located predominantly on the right side of the sternum, more centrally, and slightly to the right of the midclavicular line. - An injury at the **left 4th intercostal space at the midclavicular line** would typically be too lateral and superior to directly injure the right atrium. *Inferior vena cava* - The **inferior vena cava (IVC)** enters the right atrium from below, primarily located within the abdomen and passing through the diaphragm at the level of T8. - Its position is far too **inferior and posterior** relative to the 4th intercostal space to be directly injured by this wound. *Left atrium of the heart* - The **left atrium** is the most posterior chamber of the heart and is largely covered by the left ventricle. - Although part of the heart is on the left, an injury at the **4th intercostal space, midclavicular line**, would likely impact the left ventricle or lung tissue before reaching the left atrium, which is located more posteriorly and medially. *Superior vena cava* - The **superior vena cava (SVC)** is located to the right of the midline, formed by the brachiocephalic veins behind the right first costal cartilage. - Its position is too **medial and superior**, on the right side, to be directly injured by a nail penetrating the left 4th intercostal space at the midclavicular line.

Thorax/Abdomen US Medical PG Question 8: A 55-year-old man comes to the emergency department because of left-sided chest pain and difficulty breathing for the past 30 minutes. His pulse is 88/min. He is pale and anxious. Serum studies show increased cardiac enzymes. An ECG shows ST-elevations in leads I, aVL, and V5-V6. A percutaneous coronary intervention is performed. In order to localize the site of the lesion, the catheter must pass through which of the following structures?

• A. Left coronary artery → left circumflex artery (Correct Answer)
• B. Right coronary artery → posterior descending artery
• C. Left coronary artery → left anterior descending artery
• D. Right coronary artery → right marginal artery
• E. Left coronary artery → posterior descending artery

Thorax/Abdomen Explanation: ***Left coronary artery → left circumflex artery*** - **ST-elevations** in leads I, aVL, and V5-V6 are indicative of a **lateral myocardial infarction**. - The **left circumflex artery** primarily supplies the lateral wall of the left ventricle. *Right coronary artery → posterior descending artery* - The **posterior descending artery** (PDA) typically supplies the inferior wall and posterior interventricular septum. - An occlusion here would cause **ST-elevations** in leads II, III, and aVF, which is not seen in this case. *Left coronary artery → left anterior descending artery* - The **left anterior descending** (LAD) artery supplies the anterior wall and apex of the left ventricle. - Occlusion of the LAD would typically cause **ST-elevations** in leads V1-V4, indicating an anterior MI. *Right coronary artery → right marginal artery* - The **right marginal artery** is a branch of the right coronary artery and supplies part of the right ventricle. - Occlusion here would primarily affect the **right ventricle**, and is not typically associated with the given ECG changes. *Left coronary artery → posterior descending artery* - While the **posterior descending artery** can sometimes originate from the left circumflex artery (**left dominant circulation**), it primarily supplies the inferior wall. - The observed ECG changes in leads I, aVL, and V5-V6 are characteristic of a **lateral wall infarct**, which is supplied by the left circumflex artery.

Thorax/Abdomen US Medical PG Question 9: A 40-year-old woman is brought to the emergency department by a paramedic team from the scene of a motor vehicle accident where she was the driver. The patient was restrained by a seat belt and was unconscious at the scene. On physical examination, the patient appears to have multiple injuries involving the trunk and extremities. There are no penetrating injuries to the chest. As part of her trauma workup, a CT scan of the chest is ordered. At what vertebral level of the thorax is this image from?

• A. T1
• B. T6
• C. T4
• D. T5
• E. T8 (Correct Answer)

Thorax/Abdomen Explanation: ***T8*** - The CT image shows the **inferior vena cava (IVC)** located anterior and to the right of the aorta, and the **esophagus** located posterior to the aorta and slightly to the left. The **azygos vein** is seen to the right of the vertebral body and posterior to the esophagus. - The **mainstem bronchi** are no longer visible, indicating a level below the carina. The presence of the IVC, aorta, esophagus, and azygos vein with the absence of mainstem bronchi is characteristic of the **T8 vertebral level**. *T1* - At the T1 level, the structures would primarily be the **trachea** anterior to the esophagus, with the main great vessels (e.g., brachiocephalic veins and arteries) visible, not the IVC. - The mainstem bronchi would not yet be visualized at this higher level. *T6* - At the T6 level, the **trachea would have already bifurcated into the mainstem bronchi**, which would be prominent structures visible on the CT scan. - While the aorta and esophagus would be present, the specific arrangement relative to the mainstem bronchi would differentiate it from T8. *T4* - The T4 level is typically associated with the **carina**, where the trachea bifurcates into the mainstem bronchi. - The great vessels would be prominent, but the IVC in its more inferior course would not be as distinctly visualized in this configuration compared to T8. *T5* - At the T5 level, the **mainstem bronchi** would still be clearly visible, having just diverged from the trachea. - While vessels like the aorta are present, the key differentiating factor from T8 is the presence of the mainstem bronchi.

Thorax/Abdomen US Medical PG Question 10: A 24-year-old woman comes to the physician for an annual routine examination. Menses occur at regular 28-day intervals and last for 4 days with normal flow. Her last menstrual period was 3 weeks ago. She is sexually active with one male partner and they use condoms consistently. The patient is 160 cm (5 ft 3 in) tall and weighs 72 kg (150 lb); BMI is 28.1 kg/m2. She feels well. Pelvic examination shows a smooth, mobile right adnexal mass. A subsequent ultrasound of the pelvis shows a single, 2-cm large, round, hypoechoic mass with a thin, smooth wall in the right ovary. The mass has posterior wall enhancement, and there are no signs of blood flow or septae within the mass. Which of the following is the most appropriate next step in management?

• A. Diagnostic laparoscopy
• B. CT scan of the pelvis
• C. Oral contraceptive
• D. CA-125 level
• E. Follow-up examination (Correct Answer)

Thorax/Abdomen Explanation: ***Follow-up examination*** - The ultrasound findings of a **small (2-cm)**, **simple (hypoechoic, thin-walled, no septations, no blood flow)** adnexal cyst in a **premenopausal woman** are characteristic of a functional ovarian cyst. - Functional cysts are typically benign and resolve spontaneously, making **expectant management with follow-up** the most appropriate initial step. *Diagnostic laparoscopy* - This is an **invasive surgical procedure** indicated for suspicious or persistent ovarian masses that require histological evaluation or removal. - It is **not warranted for a small, simple cyst** with benign features found incidentally in an asymptomatic, premenopausal woman. *CT scan of the pelvis* - A CT scan provides additional imaging but exposes the patient to **radiation** and is generally reserved for masses with **complex features** or when evaluating for metastasis. - It is **not necessary for a simple cyst** that has already been well-characterized by ultrasound. *Oral contraceptive* - While oral contraceptives can **suppress ovulation** and potentially prevent the formation of new functional cysts, they generally do **not hasten the resolution of existing cysts**. - They are sometimes used in cases of recurrent functional cysts but are not the primary management for an initial, asymptomatic simple cyst. *CA-125 level* - **CA-125** is a tumor marker primarily used for monitoring ovarian cancer, especially in **postmenopausal women** or those with highly suspicious masses. - Its levels can be elevated in various benign conditions, and it is **not indicated for a small, simple cyst** in a premenopausal woman, where the risk of malignancy is very low.

Thorax/Abdomen Flashcard 1 of 10

Question: Which lymph node cluster drains the trachea and esophagus? _____

Answer: Mediastinal

Thorax/Abdomen Flashcard 2 of 10

Question: The _____ node is located in the wall of the right atrium near the orifice of the superior vena cava

Answer: SA

Thorax/Abdomen Flashcard 3 of 10

Question: In the right lung, the pulmonary artery is _____ to the bronchus

Answer: anterior

Thorax/Abdomen Flashcard 4 of 10

Question: Depending on heart size, the point of maximal apical impulse can be felt at the _____ left ICS

Answer: 5th

Thorax/Abdomen Flashcard 5 of 10

Question: Which sympathetics (2) innervate the regions of the foregut and midgut? _____

Answer: Greater and lesser splanchnics (T5 - T12)

Thorax/Abdomen Flashcard 6 of 10

Question: ID Artery: _____

Answer: Splenic

Thorax/Abdomen Flashcard 7 of 10

Question: Where in the respiratory tract do cilia terminate? _____

Answer: End of Terminal bronchioles

Thorax/Abdomen Flashcard 8 of 10

Question: How many thoracic spinal nerves are there?

Answer: 12

Thorax/Abdomen Flashcard 9 of 10

Question: List the retroperitoneal structures.

Answer: Suprarenal glands Aorta and IVC Duodenum Pancreas Ureters Colon Kidneys Esophagus Rectum mnemonic: SAD PUCKER

Thorax/Abdomen Flashcard 10 of 10

Question: In the right lung, the pulmonary artery is _____ to the bronchus

Answer: anterior

Extra Information:  Watch associated Bootcamp video [https://app.bootcamp.com/med-school/gross-anatomy/videos/lungs?index=3] https://onlinemeded.org/spa/pulmonology?ref=anki