Airway Anatomy — MCQs
Kiesselbach's area does not involve _______.
Which of the following statements is false about the right bronchus?
What is Little's area, also known as Kiesselbach's plexus?
Which of the following changes in voice is not produced as a result of external laryngeal nerve injury post thyroidectomy?
What is the nerve supply of the larynx above the level of the vocal cords?
Angle of tracheal bifurcation is increased in which chamber of heart enlargement.
Which of the following muscles is responsible for abduction of the vocal cord?
What is the MOST clinically significant anatomical difference between pediatric and adult airways?
In correct positioning the tip of the instrument shown in the image should lie at:
What is the most reliable indicator to prevent esophageal intubation?
Airway Anatomy Indian Medical PG Practice Questions and MCQs
Question 1: Kiesselbach's area does not involve _______.
- A. Anterior ethmoidal artery
- B. Posterior ethmoidal artery (Correct Answer)
- C. Sphenopalatine artery
- D. Greater palatine artery
Explanation: ***Posterior ethmoidal artery*** - The **posterior ethmoidal artery** typically supplies the posterior and superior aspects of the nasal septum and sinuses, but it does not directly contribute to the vascular network in **Kiesselbach's area**. - Its high-arising origin from the ophthalmic artery and posterior distribution anatomically excludes it from the anterior septal region. *Anterior ethmoidal artery* - The **anterior ethmoidal artery** is a major artery contributing to **Kiesselbach's plexus**, supplying the anterosuperior part of the nasal septum. - It anastomoses with branches from the sphenopalatine and labial arteries in this region. *Sphenopalatine artery* - The **sphenopalatine artery** is a terminal branch of the maxillary artery and its septal branch significantly contributes to the posteroinferior part of **Kiesselbach's plexus**. - It forms anastomoses with the anterior ethmoidal and greater palatine arteries in this vascular hotspot. *Greater palatine artery* - The **greater palatine artery**, a branch of the descending palatine artery, contributes to **Kiesselbach's plexus** by supplying the anteroinferior aspect of the nasal septum. - Its septal branch ascends to anastomose with other arterial branches in the region, forming part of this highly vascularized area.
Question 2: Which of the following statements is false about the right bronchus?
- A. Shorter
- B. More horizontal (Correct Answer)
- C. In the line of trachea
- D. Wider
Explanation: ***More horizontal*** - The right bronchus is traditionally described as **more vertical** or **more directly in line with the trachea** compared to the left bronchus. - This anatomical orientation makes it more susceptible to the aspiration of foreign bodies. *Shorter* - The **right main bronchus** is indeed shorter than the left main bronchus. - Its length is typically 2-3 cm, while the left main bronchus is about 5 cm long. *Wider* - The **right main bronchus** has a larger diameter than the left main bronchus. - This wider lumen contributes to the ease with which foreign bodies can enter it. *In the line of trachea* - The right main bronchus diverges from the trachea at a **less acute angle** (approximately 25 degrees) compared to the left (approximately 45 degrees). - This makes it appear more as a **direct continuation of the trachea**, facilitating aspiration into the right lung.
Question 3: What is Little's area, also known as Kiesselbach's plexus?
- A. Anteroinferior lateral wall
- B. Anteroinferior nasal septum (Correct Answer)
- C. Posteroinferior lateral wall
- D. Posteroinferior nasal septum
Explanation: ***Anteroinferior nasal septum*** - **Little's area**, or **Kiesselbach's plexus**, is a well-vascularized region located on the **anteroinferior portion of the nasal septum**. - This area is a common site for **anterior epistaxis** (nosebleeds) due to its superficial position and rich anastomotic blood supply from several arteries. *Anteroinferior lateral wall* - While the lateral nasal wall also contributes to the nasal blood supply, the specific region of **Little's area** is on the **septum**, not the lateral wall. - The **lateral wall** contains structures like the turbinates and their associated vascular networks, which are distinct from Kiesselbach's plexus. *Posteroinferior lateral wall* - The **posterior and inferior aspects** of the nasal cavity are not where Kiesselbach's plexus is predominantly located. - Bleeding from this posterior region often indicates **posterior epistaxis**, which can be more severe and difficult to control. *Posteroinferior nasal septum* - The **posterior nasal septum** is supplied by different arteries, such as branches of the **sphenopalatine artery**. - Bleeding from this part of the septum is also considered **posterior epistaxis** and is not typically associated with Kiesselbach's plexus.
Question 4: Which of the following changes in voice is not produced as a result of external laryngeal nerve injury post thyroidectomy?
- A. Inability to sing at higher ranges
- B. Poor volume and projection
- C. Hoarseness (Correct Answer)
- D. Voice fatigue
Explanation: ***Hoarseness*** - **Hoarseness** is primarily caused by injury to the **recurrent laryngeal nerve (RLN)**, which innervates most intrinsic laryngeal muscles responsible for vocal cord adduction and abduction. - An external laryngeal nerve (ELN) injury affects the **cricothyroid muscle**, leading to less tension on the vocal cords, but typically not frank hoarseness. *Voice fatigue* - Injury to the external laryngeal nerve (ELN) weakens the **cricothyroid muscle**, which is responsible for tensing and elongating the vocal cords. - This weakness leads to greater effort required to maintain vocal quality, resulting in **voice fatigue**. *Inability to sing at higher ranges* - The **cricothyroid muscle**, innervated by the ELN, is crucial for increasing vocal cord tension. - Increased tension is necessary for adjusting vocal pitch and reaching **higher frequencies** or notes. *Poor volume and projection* - The cricothyroid muscle's role in vocal cord tension contributes to the efficiency of vocal fold vibration. - Reduced tension due to ELN injury can lead to decreased **vocal power and projection**.
Question 5: What is the nerve supply of the larynx above the level of the vocal cords?
- A. Superior laryngeal (Correct Answer)
- B. Recurrent laryngeal
- C. Glossopharyngeal
- D. External laryngeal nerve
Explanation: ***Superior laryngeal*** - The **superior laryngeal nerve** branches into the internal and external laryngeal nerves. The **internal laryngeal nerve** (a branch of the superior laryngeal nerve) provides all sensory innervation to the larynx **above the vocal cords**. - It also carries **parasympathetic fibers** to the laryngeal glands in this region. *Recurrent laryngeal* - The **recurrent laryngeal nerve** provides sensory innervation to the larynx **below the vocal cords** [1]. - It also innervates all of the intrinsic muscles of the larynx except for the cricothyroid muscle [1]. *Glossopharyngeal* - The **glossopharyngeal nerve (CN IX)** primarily provides sensory innervation to the **posterior one-third of the tongue**, tonsils, pharynx, and middle ear. - It does not directly provide sensory innervation to the larynx. *External laryngeal nerve* - The **external laryngeal nerve**, a branch of the superior laryngeal nerve, is primarily **motor** and innervates the **cricothyroid muscle**. - It provides **no sensory innervation** to any part of the larynx.
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: Which of the following muscles is responsible for abduction of the vocal cord?
- A. Posterior cricoarytenoid (Correct Answer)
- B. Transverse arytenoid
- C. Lateral cricoarytenoid
- D. Cricothyroid muscle
Explanation: ***Posterior cricoarytenoid*** - This is the **only intrinsic laryngeal muscle** responsible for **abduction** (opening) of the vocal cords. - Contraction of this muscle causes the **arytenoid cartilages** to rotate laterally, separating the vocal folds. *Lateral cricoarytenoid* - This muscle is responsible for **adduction** (closing) of the vocal cords, thereby narrowing the **rima glottidis**. - Its contraction rotates the arytenoid cartilages medially. *Cricothyroid muscle* - This muscle is the primary tensor of the vocal cords, responsible for **increasing the pitch of the voice**. - It stretches the vocal cords by tilting the **thyroid cartilage** forward and downward. *Transverse arytenoid* - This muscle is an **adductor** of the vocal cords, helping to close them by drawing the **arytenoid cartilages** together. - It works with the oblique arytenoid muscles to approximate the arytenoids.
Question 8: What is the MOST clinically significant anatomical difference between pediatric and adult airways?
- A. Funnel-shaped vs cylindrical airway shape
- B. Proportionally larger tongue
- C. Larynx in higher position
- D. Narrowest part is cricoid cartilage (Correct Answer)
Explanation: ***Narrowest part is cricoid cartilage*** - In **pediatric airways**, the **cricoid cartilage** is the narrowest point, making it the **most critical consideration** for endotracheal tube sizing and intubation. - This contrasts with adults where the **glottic opening** (vocal cords) is typically the narrowest. - This difference is **clinically crucial** as it determines tube selection, risk of subglottic stenosis, and why uncuffed tubes were traditionally preferred in children. *Proportionally larger tongue* - Pediatric patients indeed have a **proportionally larger tongue** relative to their oral cavity, which can contribute to airway obstruction [1]. - While this is a true anatomical difference, it is **less critical** for intubation decisions than the cricoid narrowing. *Funnel-shaped vs cylindrical airway shape* - Pediatric airways are **funnel-shaped** with narrowing at the cricoid, whereas adult airways are more **cylindrical**. - This morphological difference is a **consequence** of the cricoid being the narrowest point, not a separate primary consideration. *Larynx in higher position* - The **larynx** in infants and young children is positioned more **superiorly** (C3-C4 vs C4-C6 in adults). - While this affects intubation technique and angle, it is **less directly relevant** to airway sizing than the cricoid narrowing.
Question 9: In correct positioning the tip of the instrument shown in the image should lie at:
- A. Thyroid cartilage
- B. Above esophagus
- C. Vocal cords
- D. Epiglottis (Correct Answer)
Explanation: ***Epiglottis*** - The image shows a **Laryngeal Mask Airway (LMA)**, which is designed to sit in the hypopharynx, with its tip resting at the **epiglottis**. - This positioning allows the LMA to create a seal around the laryngeal inlet, facilitating effective ventilation without entering the trachea. *Vocal cords* - The LMA is designed to provide a seal *above* the vocal cords, ensuring ventilation of the trachea without direct intubation of the vocal cords themselves. - Positioning the tip *at* the vocal cords would hinder proper airway sealing and could cause trauma. *Thyroid cartilage* - The thyroid cartilage is an anterior neck structure and is not the anatomical landmark for the tip of a properly placed LMA. - The LMA sits deeper in the pharynx, above the glottic opening, making the epiglottis the relevant landmark. *Above esophagus* - While the LMA sits **above the esophageal inlet**, diverting air primarily into the trachea, its *tip* specifically rests at the epiglottis, covering the laryngeal opening. - Stating "above the esophagus" is too general; the precise anatomical placement for the tip is at the epiglottis.
Question 10: What is the most reliable indicator to prevent esophageal intubation?
- A. Oxygen saturation on pulse oximeter
- B. Direct visualization of passing tube beneath vocal cords
- C. Auscultation over chest
- D. Measurement of CO2 in exhaled air (EtCO2). (Correct Answer)
Explanation: ***Measurement of CO2 in exhaled air (EtCO2)*** - The presence of **carbon dioxide** in exhaled air confirms tracheal intubation as the esophagus does not contain CO2. - This method provides a **real-time**, objective assessment of tube placement that is highly reliable because even small amounts of CO2 are detected. *Oxygen saturation on pulse oximeter* - This indicator measures **oxygenation**, which can remain adequate for several minutes after esophageal intubation due to pre-oxygenation. - A **delayed drop in saturation** might indicate esophageal intubation, but it's not immediate and therefore not the most reliable early indicator. *Direct visualization of passing tube beneath vocal cords* - While helpful, **direct visualization** can sometimes be misleading due to difficult airways or poor visibility, where the tube might appear to pass correctly but enter the esophagus. - This method is **operator-dependent** and its reliability can vary based on the intubator's experience and the patient's anatomy. *Auscultation over chest* - **Auscultation** can detect breath sounds; however, sounds can be transmitted from the stomach or surrounding tissues, leading to false positives. - It is also very difficult to reliably distinguish between **esophageal and tracheal sounds**, especially in noisy environments or with inexperienced personnel, making it less reliable than EtCO2.
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