DFT-19/09/2025-ANATOMY D5

 A 75-year-old cachectic male with a large, malignant right-sided pleural effusion undergoes a therapeutic thoracentesis. The resident, attempting to aspirate fluid, inserts the needle in the 8th intercostal space in the mid-axillary line, but directs it immediately adjacent to the inferior border of the 8th rib. Shortly after, the procedure is aborted due to aspiration of frank blood, and the patient becomes hemodynamically unstable. Which of the following structures was most likely iatrogenically injured?

• Main trunk of the posterior intercostal artery

• Collateral branch of the intercostal artery

•  Internal thoracic artery

• Azygos vein

Answer explanation

The neurovascular bundle (Vein, Artery, Nerve) runs in the costal groove along the inferior border of the rib. Directing the needle here makes the artery the most vulnerable structure to significant injury, leading to hemothorax.

A 68-year-old male with a history of chronic obstructive pulmonary disease presents with a 4-day history of productive cough, pleuritic chest pain, and fever. Physical examination reveals crackles over the right lower lung field. A chest radiograph demonstrates multifocal, patchy consolidations. Given the radiological findings consistent with bronchopneumonia, which of the following structures is the initial and primary site of the inflammatory process?

• Terminal and respiratory bronchioles

  
  

• Alveolar sacs and inter-alveolar septa

• Segmental and lobar bronchi

• Trachea and primary bronchi

Answer explanation

 Bronchopneumonia is characterized by inflammation that begins in the terminal and respiratory bronchioles and then spreads to adjacent alveoli, resulting in the classic patchy pattern of consolidation seen on imaging.

A 68-year-old male with a history of heavy smoking is undergoing a right upper lobectomy for a centrally located adenocarcinoma. During the dissection of the hilar structures, the surgeon must carefully isolate the eparterial bronchus. Incorrect identification and clamping of an adjacent vessel, mistaken for a branch to the upper lobe, would most likely involve which structure?

• Right main pulmonary artery

  
  

• Azygos vein

  
  

• Superior pulmonary vein

  
  

• Bronchial artery

Answer explanation

The eparterial bronchus lies directly superior to the right main pulmonary artery. This intimate anatomical relationship makes the artery highly vulnerable to injury during dissection or clamping of the eparterial bronchus if not properly identified.

A 62-year-old male with a centrally located squamous cell carcinoma undergoes a left pneumonectomy. During the dissection of the hilum from a posterior approach, after incising the pleura, which structure would the thoracic surgeon typically encounter first and most posteriorly within the root of the lung?

• Left principal bronchus

•  Left pulmonary artery

•  Superior pulmonary vein

• Left phrenic nerve

Answer explanation

n the left lung hilum, the principal bronchus is the most posterior structure. Approaching the hilum from behind, the surgeon would encounter the thick-walled bronchus first after pleural incision.

A pathology intern is examining a gross specimen of a left lung resected for adenocarcinoma. To properly orient the specimen and identify the hilar lymph node stations, they recall the anatomical arrangement. Which of the following describes the most superiorly positioned major structure within the left lung hilum?

• Left pulmonary artery

  
  

•  Azygos vein

• Superior pulmonary vein

  
  

• Left subclavian artery

Answer explanation

The left pulmonary artery courses over the superior aspect of the left principal bronchus, making it the most superior structure within the hilum itself.

A 55-year-old male presents with facial plethora, jugular venous distention, and bilateral upper limb edema. He also complains of progressive proximal muscle weakness and ptosis, which worsens with activity. A large mass identified on imaging is most likely originating from which mediastinal compartment?

• Anterior mediastinum

• Superior mediastinum

• Middle mediastinum

  
  

• Posterior mediastinum

Answer explanation

The combination of Superior Vena Cava (SVC) syndrome and myasthenia gravis symptoms strongly points to a thymoma, the most common primary tumor of the anterior mediastinum, which contains the thymus gland.

A 68-year-old male with a history of hypertension and hyperlipidemia presents to the emergency department with severe, crushing substernal chest pain for the past hour. An electrocardiogram (ECG) reveals 3 mm ST-segment elevation in leads V2-V4. He is emergently taken for coronary angiography, which is expected to show an occlusion. Based on the provided anatomical diagram, which vessel is the most likely culprit responsible for these findings?

• Left Anterior Descending Artery (LADA)

• Right Coronary Artery (RCA)

• Circumflex branch of the Left Coronary Artery (LCX)

•  Main Pulmonary Artery

Answer explanation

The Left Anterior Descending Artery (LADA) supplies the anterior two-thirds of the interventricular septum and the anterior wall of the left ventricle. Occlusion here classically results in ST-elevation in the anteroseptal leads (V1-V4).

During a cadaveric dissection for first-year medical students, the prosector highlights the large venous channel located in the posterior part of the coronary sulcus, identified as the coronary sinus in the provided diagram. This structure is the main venous drainage conduit for the myocardium. From which embryonic structure is the coronary sinus primarily derived?

• Left horn of the sinus venosus

  
  

• Right horn of the sinus venosus

• Truncus arteriosus

• Primitive atrium

Answer explanation

The coronary sinus, the principal vein of the heart, is embryologically derived from the left horn of the sinus venosus and the left common cardinal vein.

During a pre-operative coronary angiography for a patient with severe aortic stenosis, the cardiologist notes a critical ostial lesion of the left main coronary artery. However, there is robust collateral circulation demonstrated by retrograde filling of the entire LAD system from a large, separate vessel originating from the right sinus of Valsalva. This well-defined collateral pathway is best identified as the:

• Annulus of Vieussens

• Artery of Kugel

•  Sinuatrial nodal artery

• Vasa vasorum of the pulmonary artery

Answer explanation

The Annulus of Vieussens is a critical preformed collateral pathway. It is an anastomotic ring between the conus artery (arising from the RCA or a separate ostium) and the LAD artery.

A 72-year-old male with a history of metastatic esophageal carcinoma develops a massive, milky-white pleural effusion on the right side. A thoracentesis confirms chylothorax. To manage this surgically, the thoracic duct must be ligated as it enters the thorax. Which anatomical landmark and vertebral level is the most reliable for locating this structure's entry point?

•  Posterior to the aorta, passing through the aortic hiatus at T12

• Alongside the esophagus, passing through the esophageal hiatus at T10

• Anteriorly, within the caval opening for the inferior vena cava at T8

• Piercing the central tendon independently, superior to the aortic bifurcation at L4

Answer explanation

The thoracic duct enters the posterior mediastinum from the abdomen by passing through the aortic hiatus, which is located at the T12 vertebral level. It typically lies posterior and to the right of the aorta at this point