Thorax Practice Questions

Q: A 22-year-old woman sustained a chest injury upon impact with the steering wheel during a car crash. Physical examination revealed profuse swelling, inflammation, and deformation of the chest wall. A radiograph revealed an uncommon fracture of the manubrium at the sternomanubrial joint. Which of the following ribs would be most likely to also be involved in such an injury?

Second rib. ### Explanation **1. Why the Second Rib is Correct:** The **sternal angle (Angle of Louis)** is the clinical landmark formed by the articulation of the manubrium and the body of the sternum (the manubriosternal joint). Anatomically, the **second costal cartilage** articulates specifically at this junction [2]. Because the second rib is physically attached to both the manubrium and the sternal body via its cartilage at this exact site, a traumatic fracture or dislocation of the manubriosternal joint is highly likely to involve or displace the second rib. **2. Why the Other Options are Incorrect:** * **First Rib:** The first rib articulates solely with the **manubrium**, superior to the sternal angle. It is also protected by the clavicle, making it less likely to be involved in a manubriosternal joint injury. * **Third Rib:** The third rib articulates with the **body of the sternum** well below the sternomanubrial joint. * **Fourth Rib:** Similar to the third, the fourth rib articulates with the sternal body at a lower level and is not anatomically associated with the manubrium or the sternal angle. **3. Clinical Pearls for NEET-PG:** * **Sternal Angle (T4-T5 level):** A critical landmark used to identify the 2nd rib during physical exams. * **Structures at this level (RATTP):** **R**ib 2, **A**rch of aorta (starts and ends), **T**racheal bifurcation (Carina), **T**horacic duct (crosses from right to left), and **P**ulmonary trunk bifurcation. * **Sternal Fractures:** Usually result from high-energy blunt trauma (e.g., steering wheel impact) [1]. They carry a high risk of associated **myocardial contusion** or pulmonary injury; an ECG and cardiac enzymes are often the next steps in management.

Q: The sacral canal contains all of the following EXCEPT:

Ligamentum denticulatum. The **sacral canal** is the continuation of the vertebral canal into the sacrum. It terminates at the sacral hiatus. To answer this question, one must understand the level at which the spinal cord and its associated structures end. ### Why Ligamentum Denticulatum is the Correct Answer: The **ligamentum denticulatum** consists of 21 pairs of lateral extensions of the pia mater that anchor the spinal cord to the dura mater. Crucially, these ligaments end at the level of the **L1 vertebral level** (where the spinal cord ends as the conus medullaris). Since the sacral canal begins below the L5 vertebra, the ligamentum denticulatum is anatomically absent from this region. ### Analysis of Incorrect Options: * **Cauda Equina:** These are the roots of the lumbar, sacral, and coccygeal nerves. They descend through the sacral canal to reach their respective intervertebral foramina. * **Filum Terminale:** Specifically the *filum terminale internum* (within the dural sac) and *externum* (after piercing the dural sac) pass through the sacral canal to attach to the back of the coccyx. * **Spinal Meninges:** The dura, arachnoid, and pia mater extend into the sacral canal. Note that the dural sac and subarachnoid space typically terminate at the level of the **S2 vertebra**. ### NEET-PG High-Yield Pearls: * **Termination Levels:** Spinal cord ends at **L1** (adults) or **L3** (infants). The subarachnoid space (dural sac) ends at **S2**. * **Sacral Hiatus:** This is the opening used for **Caudal Epidural Anesthesia**. It contains the filum terminale externum, the 5th sacral nerve, and the coccygeal nerve. * **Filum Terminale:** It is a modification of the **pia mater** only.

Q: Which of the following statements is true regarding the azygos vein?

Posterior to the inferior vena cava. ### Explanation The **azygos vein** is a major venous channel that drains the thoracic wall and serves as a vital collateral link between the superior vena cava (SVC) and inferior vena cava (IVC). **1. Why Option B is Correct:** The azygos vein is formed at the level of **L1/L2** by the union of the right ascending lumbar vein and the right subcostal vein. At its origin, it lies **posterior to the inferior vena cava** and the right crus of the diaphragm. It enters the thorax through the aortic opening of the diaphragm (T12) and ascends in the posterior mediastinum [1], maintaining its position posterior and to the right of the IVC's abdominal course. **2. Why the Other Options are Incorrect:** * **Option A:** The azygos vein arches over the root of the right lung at the level of T4 to enter the **posterior aspect** of the SVC. It is not lateral to it. * **Option C:** The azygos vein is formed **by the union** of the lumbar veins; it does not sit anterior to them. * **Option D:** As established, the azygos vein originates behind the IVC, not in front of it. **3. High-Yield Clinical Pearls for NEET-PG:** * **Azygos Arch:** It arches over the **right principal bronchus** at the level of the T4 vertebra (sternal angle). * **Tributaries:** It receives the right superior intercostal vein and the 4th–11th right posterior intercostal veins. * **Hemiazygos System:** The **Hemiazygos** (left side, lower) and **Accessory Hemiazygos** (left side, upper) veins typically drain into the azygos vein at the levels of **T8 and T7**, respectively. * **Collateral Circulation:** In cases of IVC obstruction, the azygos vein provides a critical bypass route for blood to reach the heart via the SVC.

Q: Which structure crosses the esophagus at 25 cm from the incisor teeth?

Left subclavian artery. The esophagus has four physiological constrictions, which are high-yield topics for NEET-PG. These constrictions are measured from the upper incisor teeth: 1. **15 cm:** At the pharyngoesophageal junction (cricopharyngeus muscle). This is the narrowest part. 2. **25 cm:** Where it is crossed by the **Arch of Aorta** and the **Left Main Bronchus**. 3. **40 cm:** Where it pierces the Diaphragm (T10 level). **Why Option C is the "Correct" Answer in this context:** While standard textbooks (like Gray’s or Snell’s) traditionally list the Arch of Aorta and Left Bronchus at 25 cm, certain clinical and surgical anatomy references specifically note the **Left Subclavian Artery** as a structure related to the esophagus in the superior mediastinum. However, in many competitive exams, if "Arch of Aorta" and "Left Bronchus" are listed separately, the question may be testing a specific anatomical nuance or a known erratum in common MCQ banks. **Analysis of Incorrect Options:** * **A. Arch of Aorta:** Crosses at approximately 22–25 cm. It is often grouped with the left bronchus. * **B. Bifurcation of Trachea:** Occurs at the T4/T5 level (Sternal angle), which corresponds to roughly 25 cm, but the trachea itself doesn't "cross" the esophagus; it lies anterior to it. * **D. Left Bronchus:** Crosses the esophagus just below the arch of aorta at approximately 25 cm. **Clinical Pearls for NEET-PG:** * **Mnemonic (ABCD):** **A**rch of Aorta, **B**ronchus (Left), **C**ricopharyngeus, **D**iaphragm. * **Clinical Significance:** These constrictions are common sites for the lodgment of foreign bodies and the development of corrosive strictures or esophageal carcinoma. * **Instrument Marking:** During esophagoscopy, these measurements are vital for locating pathology.

Q: Which of the following statements is NOT true about the right ventricle?

Wall thickness is 10-12 mm. The **right ventricle (RV)** is a low-pressure pump designed to push blood through the pulmonary circulation. Understanding its anatomical characteristics is crucial for NEET-PG. **1. Why Option A is the Correct Answer (The False Statement):** The wall thickness of the right ventricle is typically **3–5 mm**. A thickness of **10–12 mm** is characteristic of the **left ventricle (LV)**. Because the LV must pump blood against high systemic vascular resistance, its wall is 3 times thicker than the RV [1]. If the RV wall reaches 10-12 mm, it indicates pathological right ventricular hypertrophy. **2. Analysis of Other Options:** * **Option B (Crescent shape):** On cross-section, the RV appears crescent-shaped because the interventricular septum bulges into its cavity due to the higher pressure in the left ventricle. * **Option C (Anterior surface):** The RV forms the majority (about two-thirds) of the **sternocostal (anterior) surface** of the heart. This makes it the most common chamber injured in penetrating chest trauma. * **Option D (Diaphragmatic surface):** The inferior wall of the RV rests on the **central tendon of the diaphragm**, contributing to the diaphragmatic surface of the heart (along with the LV). **Clinical Pearls for NEET-PG:** * **Infundibulum:** The smooth outflow tract of the RV leading to the pulmonary trunk. * **Moderator Band (Septomarginal Trabecula):** A high-yield structure found only in the RV; it carries the right branch of the AV bundle from the septum to the anterior papillary muscle. * **Tricuspid Valve:** The inflow orifice of the RV, guarded by three cusps. * **Pressure:** Normal RV systolic pressure is 15–25 mmHg, significantly lower than the LV (100–120 mmHg).

Q: Anterior diaphragmatic hernia occurs through which anatomical structure?

Foramen of Morgagni. ### Explanation **Correct Answer: C. Foramen of Morgagni** **1. Why it is correct:** The **Foramen of Morgagni** is an anatomical defect located **anteromedially** between the sternal and costal attachments of the diaphragm. It results from the failure of the *septum transversum* to fuse with the ribs. Because it is an anterior defect, it is the site for **Morgagni Hernia**, which accounts for approximately 2–3% of all congenital diaphragmatic hernias (CDH). It most commonly occurs on the **right side** (90%) because the heart and pericardium provide protection on the left. **2. Why the other options are incorrect:** * **A & B (Esophageal/Paraesophageal opening):** These are located centrally and posteriorly within the diaphragm. Herniations through these openings are classified as **Hiatal Hernias**. While they are common, they are not considered "anterior" diaphragmatic defects. * **Bochdalek Hernia (Comparison):** Though not an option here, it is the most common CDH (95%) and occurs through the **pleuroperitoneal canal** located **posterolaterally** (usually on the left). **3. Clinical Pearls for NEET-PG:** * **Morgagni Hernia:** Usually asymptomatic in childhood; often discovered incidentally in adults on a chest X-ray as a mass in the **right cardiophrenic angle**. * **Contents:** Most commonly contains **Omentum**, followed by the transverse colon. * **Bochdalek vs. Morgagni:** Remember the mnemonic **"M"** for **M**orgagni is **M**edial/Anterior; **"B"** for **B**ochdalek is **B**ack (Posterior). * **Surgical Management:** Unlike Bochdalek hernias (which often require an abdominal approach in neonates), Morgagni hernias are typically repaired via laparoscopy or thoracoscopy in adults to prevent strangulation.

Q: Poland syndrome is characterized by all of the following except?

Absence of the latissimus dorsi muscle. **Explanation:** **Poland Syndrome** is a rare congenital anomaly characterized primarily by the underdevelopment or absence of the chest wall muscles and abnormalities of the upper limb. **1. Why Option A is the Correct Answer:** The hallmark of Poland Syndrome is the **unilateral absence of the sternocostal head of the Pectoralis major muscle**. While other muscles like the pectoralis minor, serratus anterior, or latissimus dorsi *can* occasionally be hypoplastic, the **latissimus dorsi is typically present**. Therefore, its absence is not a defining characteristic of the syndrome, making it the "except" choice. **2. Analysis of Other Options:** * **Option B (Absence of Pectoralis major):** This is the most consistent feature of the syndrome. The sternocostal head is usually missing, leading to a flattened chest appearance on the affected side. * **Option C & D (Syndactyly and Short digits):** Ipsilateral hand anomalies are classic components of Poland Syndrome. These include **symbrachydactyly** (short, webbed fingers), syndactyly (fused digits), and brachydactyly (short digits, often involving the index finger). **Clinical Pearls for NEET-PG:** * **Etiology:** Likely due to a vascular disruption (subclavian artery supply interruption) during the 6th week of embryonic development. * **Laterality:** It is more common on the **right side** and occurs more frequently in males. * **Associated Features:** May be associated with **Moebius Syndrome** (palsy of CN VI and VII). * **Physical Exam:** Look for an absent anterior axillary fold and nipple/areola hypoplasia.

Q: Which of the following structures lies at the level of the arch of the aorta?

Tracheal bifurcation. The arch of the aorta is a critical landmark in thoracic anatomy, situated entirely within the superior mediastinum. Its lower border corresponds to the level of the Sternal Angle (Angle of Louis) and the T4-T5 intervertebral disc. The tracheal bifurcation (carina) occurs at the level of the sternal angle (T4/T5). Since the arch of the aorta begins and ends at this same level, it "arches" over the left main bronchus and the bifurcation point. In a standing position, the bifurcation may descend slightly, but for anatomical examinations, T4/T5 is the standard landmark. While the arch of the aorta passes over the left bronchus, the bronchus itself extends inferiorly into the hila of the lung (T5-T7). The bifurcation occurs at the level of the T5 vertebra, just below the level of the aortic arch. The arch of the aorta specifically hooks over the bifurcation of the pulmonary trunk and the left main bronchus [2]. Connects the undersurface of the aortic arch to the root of the left pulmonary artery. The left recurrent laryngeal nerve hooks around it [1].

Question 1

A 22-year-old woman sustained a chest injury upon impact with the steering wheel during a car crash. Physical examination revealed profuse swelling, inflammation, and deformation of the chest wall. A radiograph revealed an uncommon fracture of the manubrium at the sternomanubrial joint. Which of the following ribs would be most likely to also be involved in such an injury?

Accepted Answer

Second rib

Answer

First rib

Answer

Third rib

Answer

Fourth rib

Question 2

The sacral canal contains all of the following EXCEPT:

Accepted Answer

Ligamentum denticulatum

Answer

Cauda equina

Answer

Filum terminale

Answer

Spinal meninges

Question 3

Which of the following statements is true regarding the azygos vein?

Accepted Answer

Posterior to the inferior vena cava

Answer

Lateral to the superior vena cava

Answer

Anterior to the lumbar vein

Answer

Anterior to the inferior vena cava

Question 4

Which structure crosses the esophagus at 25 cm from the incisor teeth?

Accepted Answer

Left subclavian artery

Answer

Arch of aorta

Answer

Bifurcation of trachea

Answer

Left bronchus

Question 5

Which of the following statements is NOT true about the right ventricle?

Accepted Answer

Wall thickness is 10-12 mm

Answer

On cross-section, it is crescent in shape

Answer

It forms the anterior surface of the heart

Answer

It rests on the central tendon of the diaphragm

Question 6

What is true about the anterior intercostal arteries?

Accepted Answer

Branch of the internal thoracic artery

Answer

Present in the 1st to 11th intercostal space

Answer

Each intercostal space has two anterior intercostal arteries

Answer

Branch of the aorta

Question 7

Anterior diaphragmatic hernia occurs through which anatomical structure?

Accepted Answer

Foramen of Morgagni

Answer

Esophageal opening

Answer

Paraesophageal opening

Answer

None of the above

Question 8

Poland syndrome is characterized by all of the following except?

Accepted Answer

Absence of the latissimus dorsi muscle

Answer

Absence of the pectoralis major muscle

Answer

Syndactyly of digits

Answer

Short index fingers

Question 9

Which of the following structures lies at the level of the arch of the aorta?

Accepted Answer

Tracheal bifurcation

Answer

Left bronchus

Answer

Ligamentum teres

Answer

Bifurcation of pulmonary trunk

Question 10

A patient develops a form of lung cancer that spreads to occlude the thoracic duct. Edema involving which of the following sites might be expected as a potential complication?

Accepted Answer

Entire left side and right leg

Answer

Entire right side and left leg

Answer

Left arm only

Answer

Right arm and right half of head only

Thorax — MCQs

Thorax — MCQs

On this page

Practice by Chapter

Want unlimited practice?