Pleura and Lungs — MCQs
Which of the following factors does not directly influence oxygen delivery to tissues?
At what level does the trachea bifurcate?
Which are the segments of the upper lobe of the right lung?
Which of the following structures is NOT innervated by the phrenic nerve?
The incidence of a foreign body being aspirated into the right lung is higher than into the left lung. All of the following statements support this, EXCEPT?
Angle of tracheal bifurcation is increased in which chamber of heart enlargement.
While performing drainage of fluid from the pleural cavity, the needle is introduced through all of the following structures except which one?
Arrange lung hilar structure from anterior to posterior:- 1. Primary bronchus 2. Bronchial artery 3. Pulmonary vein 4. Pulmonary artery
The sequestrated lobe of the lung is commonly supplied by what?
Which of the following statements about Sibson's fascia is correct?
Pleura and Lungs Indian Medical PG Practice Questions and MCQs
Question 1: Which of the following factors does not directly influence oxygen delivery to tissues?
- A. Type of fluid administered (Correct Answer)
- B. Cardiac output
- C. Oxygen saturation
- D. Hemoglobin concentration
Explanation: ***Type of fluid administered*** - While fluid administration can indirectly affect oxygen delivery by altering blood volume and cardiac output, the **type of fluid itself (e.g., crystalloid vs. colloid)** does not directly influence the oxygen-carrying capacity of the blood or its release to tissues. - The direct effect of fluid resuscitation is on **hemodynamic parameters**, which then influence delivery. *Oxygen saturation* - **Oxygen saturation** directly reflects the percentage of hemoglobin binding sites occupied by oxygen, thus determining the amount of oxygen carried by each unit of blood. - A decrease in oxygen saturation significantly reduces the **total oxygen content** available for tissue delivery. *Cardiac output* - **Cardiac output** (heart rate × stroke volume) is a primary determinant of blood flow to tissues, and therefore directly influences the rate at which oxygenated blood is delivered throughout the body. - A lower cardiac output leads to **reduced oxygen delivery** despite adequate oxygen content in the blood. *Hemoglobin concentration* - **Hemoglobin concentration** directly dictates the blood's capacity to carry oxygen, as hemoglobin is the main oxygen-carrying molecule in red blood cells. - A low hemoglobin concentration (anemia) results in **decreased oxygen-carrying capacity** and thus impaired oxygen delivery to tissues.
Question 2: At what level does the trachea bifurcate?
- A. Upper border of T4
- B. Lower border of T4 (Correct Answer)
- C. 27.5 cm from the incisors
- D. Lower border of T5
Explanation: ***Lower border of T4*** - The **tracheal bifurcation**, also known as the **carina**, typically occurs at the level of the **sternal angle** anteriorly and the **lower border of the fourth thoracic vertebra (T4)** posteriorly. - This anatomical landmark is crucial for understanding the division of the trachea into the **main bronchi**. *Upper border of T4* - While close to the correct level, the tracheal bifurcation is generally accepted to coincide with the **lower aspect of T4**, not its upper border. - This slight difference is important for precise anatomical localization. *27.5 cm from the incisors* - While the carina is approximately **25-27 cm from the incisors** in clinical bronchoscopy measurements, this is a **variable clinical measurement** rather than a fixed anatomical landmark. - The question asks for an anatomical level, and **vertebral landmarks** (T4) are the standard and more precise anatomical reference points. - Individual variation in body habitus makes distance measurements less reliable than bony landmarks. *Lower border of T5* - The bifurcation is almost consistently found at the level of **T4**, not T5. - Moving one vertebral level lower would be incorrect for locating this specific anatomical point.
Question 3: Which are the segments of the upper lobe of the right lung?
- A. Lateral, medial, superior
- B. Apical, anterior, posterior (Correct Answer)
- C. Basal, medial, lateral
- D. Anterior, posterior, medial
Explanation: ***Apical, anterior, posterior*** - The **right upper lobe** is consistently divided into three bronchopulmonary segments: **apical**, **anterior**, and **posterior** [1]. - These segments are named according to their anatomical position and the branching of the **tertiary bronchi** that supply them [1]. *Anterior, posterior, medial* - While **anterior** and **posterior** segments exist, the "medial" segment is not a standard division of the right upper lobe. - The term "medial" is typically associated with the **middle lobe** of the right lung (medial and lateral segments) [1]. *Lateral, medial, superior* - The segments **lateral** and **medial** are characteristic of the **right middle lobe** [1]. - "Superior" is a general directional term and not a specific segment name within the upper lobe in this context, although the apical segment is superiorly located. *Basal, medial, lateral* - **Basal** segments are found in the **lower lobes** of the lungs (e.g., anterior basal, medial basal, posterior basal, lateral basal). - **Medial** and **lateral** segments are typical of the **right middle lobe**, not the upper lobe [1].
Question 4: Which of the following structures is NOT innervated by the phrenic nerve?
- A. Diaphragm
- B. Mediastinal pleura
- C. Serratus anterior (Correct Answer)
- D. Pericardium
Explanation: ***Serratus anterior*** - The **serratus anterior** muscle is innervated by the **long thoracic nerve (roots C5, C6, C7)**, not the phrenic nerve. - Its primary actions are to protract and rotate the scapula, and it is crucial for overhead arm movements. *Diaphragm* - The **diaphragm** is primarily innervated by the **phrenic nerve (C3, C4, C5)**, which is essential for its role in respiration [1]. - Sensory fibers from the phrenic nerve also supply the central part of the diaphragm. *Mediastinal pleura* - The **mediastinal pleura**, which lines the mediastinum, receives sensory innervation from the **phrenic nerve**. - Irritation of this pleura can cause referred pain to the shoulder, due to shared innervation origins. *Pericardium* - The **fibrous pericardium** and the **parietal layer of the serous pericardium** are innervated by the **phrenic nerves**. - This innervation accounts for referred pain to the shoulder in conditions affecting the pericardium.
Question 5: The incidence of a foreign body being aspirated into the right lung is higher than into the left lung. All of the following statements support this, EXCEPT?
- A. Tracheal bifurcation directs the foreign body to the right lung
- B. Right lung is shorter and wider than left lung (Correct Answer)
- C. Right inferior lobar bronchus is in continuation with the right principal bronchus
- D. Right principal bronchus is more vertical than the left bronchus
Explanation: ***Right lung is shorter and wider than left lung*** - This statement, while anatomically true, does **NOT directly explain** why foreign bodies preferentially enter the right lung - The dimensions of the **lung parenchyma itself** (shorter due to the diaphragm being pushed up by the liver, and wider) are unrelated to aspiration patterns - What determines aspiration is the **bronchial tree geometry** (angle, diameter, verticality), not the overall lung size - This is the EXCEPTION - it's a true anatomical fact but doesn't support the aspiration phenomenon *Incorrect - Tracheal bifurcation directs the foreign body to the right lung* - This statement DOES support higher right aspiration, so it cannot be the answer - The **carina angle** and bifurcation geometry favor the right side, directing foreign bodies preferentially to the right main bronchus - This is a key anatomical reason for the higher incidence *Incorrect - Right inferior lobar bronchus is in continuation with the right principal bronchus* - This statement DOES support higher right aspiration - After the right superior lobar bronchus branches off, the **intermediate bronchus** continues more directly toward the inferior lobe - This creates a straighter pathway from trachea → right main bronchus → intermediate bronchus → inferior lobar bronchus - Foreign bodies follow this direct path, often lodging in the right inferior lobe *Incorrect - Right principal bronchus is more vertical than the left bronchus* - This statement DOES support higher right aspiration - The right main bronchus diverges at approximately **25 degrees** from vertical, while the left diverges at **45 degrees** - This more vertical orientation makes the right bronchus a more direct continuation of the trachea - Gravity and airflow naturally direct aspirated material down this straighter path
Question 6: Angle of tracheal bifurcation is increased in which chamber of heart enlargement.
- A. Left ventricle
- B. Right atrium
- C. Right ventricle
- D. Left atrium (Correct Answer)
Explanation: ***Left atrium*** - An enlarged **left atrium** can lift the **left main bronchus**, increasing the angle between the two main bronchi, known as the **carinal angle** (or angle of tracheal bifurcation), visible on a chest X-ray. - This is a common radiological sign seen in conditions causing left atrial enlargement, such as **mitral stenosis** [2]. *Left ventricle* - **Left ventricular enlargement** primarily causes the cardiac apex to shift downward and laterally, but it typically does not directly impinge on the main bronchi to increase the carinal angle [1]. - While it can indirectly affect lung fields due to **pulmonary congestion**, it doesn't cause this specific sign [1]. *Right atrium* - **Right atrial enlargement** causes a bulging of the right border of the heart on a chest X-ray [1]. - It does not directly interact with or displace the main bronchi in a way that would alter the **tracheal bifurcation angle**. *Right ventricle* - **Right ventricular enlargement** can cause the heart to push into the retrosternal space and elevate the apex, but it generally does not impinge upon the main bronchi to change the **carinal angle** [1]. - Its effects are more focused on the anterior and rightward aspects of the heart.
Question 7: While performing drainage of fluid from the pleural cavity, the needle is introduced through all of the following structures except which one?
- A. Thoracic fascia
- B. Skin
- C. Pulmonary pleura (Correct Answer)
- D. Intercostal muscles
Explanation: ***Pulmonary pleura*** - The needle for pleural fluid drainage, or thoracentesis, passes through the **parietal pleura** [1] but not the **pulmonary (visceral) pleura**. - Puncturing the pulmonary pleura would indicate the needle has entered the lung parenchyma, which is an avoidable complication. *Skin* - The **skin** is the outermost layer and the first structure the needle penetrates during a thoracentesis. - It must be sterilized prior to the procedure. *Thoracic fascia* - The needle passes through the **superficial fascia** and then the **deep fascia** covering the intercostal muscles. - These fascial layers provide structural support and enclose the musculature of the thoracic wall. *Intercostal muscles* - The needle traverses the **external**, **internal**, and **innermost intercostal muscles** as it moves deeper into the thoracic cavity. - The neurovascular bundle runs between the internal and innermost intercostals, hence the needle is typically inserted over the superior border of the rib to avoid it [1].
Question 8: Arrange lung hilar structure from anterior to posterior:- 1. Primary bronchus 2. Bronchial artery 3. Pulmonary vein 4. Pulmonary artery
- A. 4,3,2,1
- B. 3,4,1,2 (Correct Answer)
- C. 1,2,3,4
- D. 2,3,4,1
Explanation: ***3,4,1,2*** - This order represents the typical arrangement of major structures in the **lung hilum** from anterior to posterior: **pulmonary vein (most anterior)**, **pulmonary artery**, **primary bronchus**, and finally the **bronchial artery (most posterior)**. - The **pulmonary vein** is usually the most anterior structure, while the **bronchial artery** often runs along the posterior aspect of the bronchus [1]. *4,3,2,1* - This order incorrectly places the **pulmonary artery** as the most anterior structure, which is generally not the case in the hilum. - The **primary bronchus** is usually more posterior than the main pulmonary artery. *1,2,3,4* - This order is incorrect as it places the **primary bronchus** as the most anterior structure, which is anatomically inaccurate for the lung hilum. - The **pulmonary veins** are typically the most anterior hilar structures. *2,3,4,1* - This order incorrectly positions the **bronchial artery** as the most anterior component, while it is usually the most posterior or associated closely with the posterior aspect of the bronchus. - The **pulmonary vein** should be anterior to the pulmonary artery and bronchus.
Question 9: The sequestrated lobe of the lung is commonly supplied by what?
- A. Pulmonary artery
- B. Intercostal artery
- C. Descending aorta (Correct Answer)
- D. Bronchial artery
Explanation: ***Descending aorta*** - The sequestrated lobe of the lung is typically supplied by branches from the **descending aorta**, a characteristic feature of pulmonary sequestration. - This condition occurs due to an **abnormality in the bronchial or pulmonary vascular supply**, leading to the lobe receiving systemic blood supply rather than standard pulmonary circulation. *Bronchial artery* - Although the **bronchial arteries** supply oxygenated blood to the lung tissues, they do not adequately supply a sequestrated lobe. - The sequestrated lobe is isolated from normal pulmonary circulation, making bronchial arteries insufficient as a primary supply. *Pulmonary artery* - The **pulmonary artery** carries deoxygenated blood to the lungs for oxygenation, but it does not typically supply sequestrated lung tissue. - In pulmonary sequestration, this lobe is not connected to the pulmonary artery, causing it to rely on systemic rather than pulmonary supply. *Intercostal artery* - Intercostal arteries provide blood to the **chest wall** and may have a minor contribution, but they do not primarily supply a sequestrated lung lobe. - Their main function is to supply the muscles and skin of the thoracic wall, rather than being a major source of blood for lung segments.
Question 10: Which of the following statements about Sibson's fascia is correct?
- A. Part of scalenus anterior muscle
- B. Vessel pass above the fascia
- C. Covers apical part of lung (Correct Answer)
- D. Attached to the inner border of 2nd rib
Explanation: ***Covers apical part of lung*** - **Sibson's fascia**, also known as the **suprapleural membrane**, is a dense fascial layer that covers and reinforces the **apex of the lung** and pleura. - It protects the lung apex and helps to support structures in the **root of the neck**. *Part of scalenus anterior muscle* - Sibson's fascia is a **separate fascial structure** extending from the first rib to the C7 transverse process, and is not a part of the scalenus anterior muscle. - The **scalenus anterior muscle** is one of the muscles of the neck, and while anatomically related by proximity to the fascia, it is not structurally part of it. *Vessel pass above the fascia* - Key neurovascular structures like the **subclavian artery** and the **brachial plexus** pass *below* Sibson's fascia, as the fascia protects the lung apex. - The fascia acts as a barrier, separating the lung apex from the more superficial structures of the neck. *Attached to the inner border of 2nd rib* - Sibson's fascia is primarily attached to the **inner border of the first rib** and the transverse process of the seventh cervical vertebra. - Its attachment to the first rib is crucial for its supportive role over the lung apex.
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