Thorax Practice Questions

Q: During an emergency thoracotomy, an incision is made greater than 1 cm lateral to the sternal margin. This incision will preserve which of the following structures?

Internal mammary artery. **Explanation:** The **Internal Mammary Artery (IMA)**, also known as the Internal Thoracic Artery, is a branch of the first part of the subclavian artery. It descends vertically behind the costal cartilages, approximately **1 cm lateral to the sternal margin** on each side. During an emergency thoracotomy or the placement of a chest tube, incisions must be made carefully to avoid vascular injury. By making an incision **greater than 1 cm lateral** to the sternum, the surgeon ensures they stay lateral to the course of the IMA, thereby preserving it. **Analysis of Options:** * **Internal Mammary Artery (Correct):** Its anatomical location (1 cm lateral to the sternum) makes it the primary structure at risk during parasternal incisions. * **Intercostal Artery & Vein (Incorrect):** These vessels run along the **inferior margin** of each rib within the costal groove. They are avoided by making incisions or inserting needles at the **superior border** of the rib, regardless of the distance from the sternum. * **Superficial Epigastric Artery (Incorrect):** This is a branch of the femoral artery found in the inguinal region/lower abdomen; it is not relevant to the thoracic anatomy involved in a thoracotomy. **High-Yield Pearls for NEET-PG:** * **Safe Zone:** For needle thoracocentesis (tension pneumothorax), the needle is inserted in the 2nd intercostal space in the mid-clavicular line or 4th/5th in the mid-axillary line. * **IMA Usage:** The IMA is the "gold standard" conduit for Coronary Artery Bypass Grafting (CABG) due to its superior long-term patency. * **Anatomy:** The IMA terminates in the 6th intercostal space by dividing into the **musculophrenic** and **superior epigastric** arteries.

Q: Occlusion of the left anterior descending artery will lead to infarction of which area?

Anterior wall of the left ventricle. The **Left Anterior Descending (LAD) artery**, often called the "widow-maker," is a branch of the Left Main Coronary Artery. It travels in the anterior interventricular groove and is the most common site of coronary occlusion. **Why the correct answer is right:** The LAD provides the primary blood supply to the **anterior wall of the left ventricle** and the **apex** of the heart. Additionally, it supplies the **anterior 2/3rd of the interventricular septum** via its septal branches. Therefore, occlusion leads to an anteroseptal myocardial infarction (MI). **Analysis of Incorrect Options:** * **A. Posterior part of the interventricular septum:** This area (the posterior 1/3rd) is supplied by the **Posterior Interventricular Artery**, which usually arises from the Right Coronary Artery (RCA) in right-dominant hearts. * **C. Lateral part of the heart:** This region is primarily supplied by the **Left Circumflex Artery (LCX)**. * **D. Inferior surface of the right ventricle:** The inferior (diaphragmatic) surface of the heart is supplied by the **Right Coronary Artery (RCA)**. **NEET-PG High-Yield Pearls:** 1. **Artery of Sudden Death:** The LAD is the most frequently occluded artery in MI (approx. 40–50% of cases). 2. **ECG Correlation:** LAD occlusion typically shows ST-elevation in leads **V1 to V4** [1]. 3. **Conductive System:** The LAD supplies the **Right Bundle Branch** and the **Anterior Fascicle** of the Left Bundle Branch; occlusion can lead to bundle branch blocks. 4. **Coronary Dominance:** Determined by which artery gives rise to the Posterior Interventricular Artery (85% RCA = Right Dominant).

Q: A 30-year-old man came with choking episodes after ingestion of fish bone while eating. The fishbone got impacted at the level of T4 in the esophagus. Which is the most likely site of obstruction?

Arch of aorta. ***Arch of aorta*** - The esophagus has three principal anatomic constrictions where foreign bodies, such as swallowed fish bones, commonly lodge; the second constriction occurs at the level of **T4/T5** where the **arch of the aorta** passes anteriorly. - This large anatomical structure compresses the esophagus against the vertebral column, creating a localized narrowing precisely matching the T4 level described for the obstruction [1]. *Left bronchus* - The **left main bronchus** also crosses anterior to the esophagus and contributes significantly to the formation of the **middle esophageal constriction** at the T4/T5 level. - However, in standard radiological and endoscopic visualization, the compression caused by the arch of the aorta is often considered the dominant landmark at this specific location [1]. *Cricopharyngeus* - This structure forms the initial and **uppermost esophageal constriction** (upper esophageal sphincter), located at the level of the **C6 vertebra** (cervical spine). - Obstruction at the cricopharyngeus would occur in the neck, which is anatomically much higher than the reported **T4 (thoracic spine)** impaction site. *Diaphragm* - The passage of the esophagus through the **esophageal hiatus** of the diaphragm forms the **third and lowest physiological constriction**, typically located at the vertebral level of **T10**. - This site of potential foreign body obstruction is significantly distal and caudal to the T4 level described in the clinical case. Management of such objects often involves careful endoscopy under general anesthesia to prevent perforation [2].

Q: A woman presents with a breast lump, associated with skin dimpling and nipple retraction. What is the most likely anatomical structure responsible for the skin dimpling?

Suspensory (Cooper’s) ligaments. ***Suspensory (Cooper’s) ligaments*** - These are fibrous septa that run from the deep pectoral fascia to the dermis of the skin, providing structural support to the breast [1]. - Invasion and shortening of these ligaments by a growing tumor pull on the overlying skin, causing the characteristic **skin dimpling** or peau d'orange appearance [1]. *Lactiferous ducts* - These are the milk ducts that converge and open at the nipple [1]. - Malignant infiltration of the lactiferous ducts is more commonly associated with **nipple retraction** and pathologic nipple discharge, rather than skin dimpling [2]. *Pectoral fascia* - This is a deep layer of connective tissue that covers the pectoralis major muscle, on which the breast lies [1]. - Tumor invasion into the pectoral fascia can cause the breast to become **fixed** to the chest wall, a sign of advanced disease, but does not directly cause superficial skin dimpling. *Subcutaneous fat* - This tissue makes up the bulk of the breast volume and surrounds the glandular components. - Subcutaneous fat itself lacks the tensile strength to pull the skin inward; it is the **fibrous ligaments** passing through the fat that cause retraction [1].

Q: While doing an endoscopy, constriction is felt at the oesophageal junction at 25 cm from the incisor. This is due to?

b. Arch of aorta. ***b. Arch of aorta*** - The esophagus has **three normal anatomical constrictions** that are clinically important - At **25 cm from the incisors**, the esophagus is compressed by the **arch of aorta** crossing anteriorly, creating the **middle constriction** - This is the second of three constrictions and corresponds to the level of the **T4-T5 vertebrae** - These constrictions are sites where **foreign bodies may lodge** and where **strictures are more likely to develop** [1] *a. Inferior vena cava* - The IVC runs on the right side of the vertebral column and does **not cross anterior to the esophagus** - It does not cause any constriction of the esophagus *c. Right bronchus* - The **left main bronchus** (not right) crosses the esophagus anteriorly at approximately the same level as the aortic arch - The right bronchus does not come into contact with the esophagus *d. Diaphragmatic opening* - This causes the **third (lower) constriction** at approximately **40 cm from the incisors** - This is at the level of the **esophageal hiatus** in the diaphragm (T10 level) - Not at 25 cm as mentioned in the question

Q: Which of the following structures passes through the foramen marked by the arrow? ![img-53.jpeg](img-53.jpeg)

Thoracic duct. ***Thoracic duct*** - The arrow in the image points to the **aortic hiatus**, which is the most posterior of the three major openings in the diaphragm, located at the vertebral level of **T12**. - This hiatus provides passage for the **aorta**, the **thoracic duct**, and the **azygos vein** from the thorax into the abdomen. *Oesophagus* - The oesophagus passes through its own opening, the **oesophageal hiatus**, which is located more anteriorly and superiorly at the **T10** vertebral level within the muscular part of the diaphragm. - This opening is formed by the fibers of the **right crus** of the diaphragm and also transmits the **vagal trunks**. *Inferior vena cava* - The inferior vena cava traverses the diaphragm through the **caval opening**, the most anterior and superior opening, situated at the **T8** vertebral level. - This foramen is located within the **central tendon** of the diaphragm and also allows passage for branches of the **right phrenic nerve**. *Sympathetic trunk* - The sympathetic trunk does not pass through any of the major apertures but rather descends posterior to the diaphragm. - It typically passes behind the **medial arcuate ligament** or pierces the **crus of the diaphragm** to enter the abdomen.

Q: All of the following are superior mediastinal tumors except:

Parathyroid. ***Parathyroid*** - Parathyroid tumors are **not classic superior mediastinal tumors** - Ectopic parathyroid adenomas, when mediastinal, are typically located in the **anterior-inferior mediastinum**, not the superior mediastinum - They descend embryologically with the thymus from the 3rd pharyngeal pouch and are found in the **thymic tongue** or anterior mediastinum at lower levels - **Not part of the classic anterior/superior mediastinal mass differential** (the "4 Ts") *Thymus* - The thymus is the **primary organ** of the anterior and superior mediastinum - **Thymoma, thymic hyperplasia, and thymic carcinoma** are classic superior/anterior mediastinal tumors - Part of the "4 Ts" mnemonic: **Thymus**, Thyroid, Teratoma, Terrible lymphoma *Thyroid* - **Retrosternal (substernal) goiter** represents extension of cervical thyroid into the superior mediastinum - Common cause of superior mediastinal masses, especially in older patients - Can cause tracheal compression and superior vena cava syndrome - Part of the "4 Ts" of anterior mediastinal masses *Lymphoma* - **Lymphoma (especially Hodgkin lymphoma and T-cell lymphoblastic lymphoma)** is one of the most common anterior/superior mediastinal masses - Part of the "4 Ts": Thymus, Thyroid, Teratoma, and **"Terrible lymphoma"** - Typically presents as a large anterior mediastinal mass in young adults - May cause B symptoms (fever, night sweats, weight loss) and superior vena cava syndrome

Q: Match the cardiac anatomical features from Column I with their corresponding labels from Column II. Column I: 1. Receives oxygenated blood from pulmonary veins; 2. Lies anterior to ascending aorta; 3. Arises from LV; 4. Hypertrophy in pulmonary stenosis. Column II: A. Ascending aorta; B. Right ventricle; C. Pulmonary trunk; D. Left atrium.

1-D, 2-C, 3-A, 4-B. 1-D, 2-C, 3-A, 4-B - 1-D (Receives oxygenated blood): The left atrium receives four pulmonary veins carrying oxygenated blood from the lungs [1], making it the only chamber that receives oxygenated blood directly from pulmonary circulation. - 2-C (Lies anterior to ascending aorta): The pulmonary trunk is positioned anteriorly and slightly to the left of the ascending aorta as both vessels exit from the base of the heart. - 3-A (Arises from LV): The ascending aorta arises directly from the left ventricle through the aortic valve and is the major systemic artery carrying oxygenated blood to the body. - 4-B (Hypertrophy in pulmonary stenosis): Pulmonary stenosis increases resistance to right ventricular outflow, causing chronic pressure overload and subsequent right ventricular hypertrophy. 1-A, 2-B, 3-C, 4-D - This matching is incorrect because the ascending aorta (A) does not receive blood from pulmonary veins [1]; it arises from the LV and carries blood away from the heart. Additionally, the pulmonary trunk (C) arises from the right ventricle, not the left ventricle. 1-B, 2-D, 3-C, 4-A - This matching is incorrect because the right ventricle (B) receives deoxygenated blood from the right atrium via the vena cavae, not oxygenated blood from pulmonary veins [1]. The left atrium (D) is a posterior chamber and does not lie anterior to the ascending aorta. 1-C, 2-A, 3-D, 4-B - This matching is incorrect because the pulmonary trunk (C) carries deoxygenated blood to the lungs; it does not receive oxygenated blood from pulmonary veins [1]. The left atrium (D) is not a vessel that arises from the LV—the correct structure is the ascending aorta (A).

Question 1

During an emergency thoracotomy, an incision is made greater than 1 cm lateral to the sternal margin. This incision will preserve which of the following structures?

Accepted Answer

Internal mammary artery

Answer

Intercostal artery

Answer

Superficial epigastric artery

Answer

Intercostal vein

Question 2

Occlusion of the left anterior descending artery will lead to infarction of which area?

Accepted Answer

Anterior wall of the left ventricle

Answer

Posterior part of the interventricular septum

Answer

Lateral part of the heart

Answer

Inferior surface of the right ventricle

Question 3

At the level of the arch of the aorta, what is the anatomical relationship between the left vagus nerve and the left phrenic nerve?

Accepted Answer

Left phrenic nerve is anterior and the left vagus nerve is posterior.

Answer

Left phrenic nerve is posterior and the left vagus nerve is anterior.

Answer

Both nerves are in the same plane anteroposteriorly.

Answer

The relationship between the nerves is variable.

Question 4

In postductal coarctation of the aorta, collaterals may be formed by all of the following, except?

Accepted Answer

Vertebral artery

Answer

Suprascapular artery

Answer

Subscapular artery

Answer

Posterior intercostal arteries

Question 5

A 30-year-old man came with choking episodes after ingestion of fish bone while eating. The fishbone got impacted at the level of T4 in the esophagus. Which is the most likely site of obstruction?

Accepted Answer

Arch of aorta

Answer

Diaphragm

Answer

Left bronchus

Answer

Cricopharyngeus

Question 6

A woman presents with a breast lump, associated with skin dimpling and nipple retraction. What is the most likely anatomical structure responsible for the skin dimpling?

Accepted Answer

Suspensory (Cooper’s) ligaments

Answer

Lactiferous ducts

Answer

Subcutaneous fat

Answer

Pectoral fascia

Question 7

While doing an endoscopy, constriction is felt at the oesophageal junction at 25 cm from the incisor. This is due to?

Accepted Answer

b. Arch of aorta

Answer

d. Diaphragmatic opening

Answer

c. Right bronchus

Answer

a. Inferior vena cava

Question 8

Which of the following structures passes through the foramen marked by the arrow? ![img-53.jpeg](img-53.jpeg)

Accepted Answer

Thoracic duct

Answer

Oesophagus

Answer

Sympathetic trunk

Answer

Inferior vena cava

Question 9

All of the following are superior mediastinal tumors except:

Accepted Answer

Parathyroid

Answer

Thyroid

Answer

Thymus

Answer

Lymphoma

Question 10

Match the cardiac anatomical features from Column I with their corresponding labels from Column II. Column I: 1. Receives oxygenated blood from pulmonary veins; 2. Lies anterior to ascending aorta; 3. Arises from LV; 4. Hypertrophy in pulmonary stenosis. Column II: A. Ascending aorta; B. Right ventricle; C. Pulmonary trunk; D. Left atrium.

Accepted Answer

1-D, 2-C, 3-A, 4-B

Answer

1-A, 2-B, 3-C, 4-D

Answer

1-B, 2-D, 3-C, 4-A

Answer

1-C, 2-A, 3-D, 4-B

Thorax — MCQs

Thorax — MCQs

On this page

Practice by Chapter

Want unlimited practice?