Anatomy of the Nose and Paranasal Sinuses — MCQs
Which of the following statements is true regarding the anatomy of the external nose?
A 13-year-old boy presents with right-sided nasal obstruction and recurrent epistaxis for the past 6 months. What is the most likely diagnosis?
Which of the following parts of the nasal septum is the most common site for epistaxis?
Which of the following is not a complication of maxillary sinus lavage and insufflation?
Which radiographic view is best for visualizing the frontal sinus?
Which of the following arteries does NOT contribute to Little's area?
If posterior epistaxis cannot be controlled, which artery is ligated?
Which nerve is targeted in the nasociliary nerve block?
The following test is done for the evaluation of:
Which fungus is most commonly associated with orbital cellulitis in patients with diabetic ketoacidosis?
Anatomy of the Nose and Paranasal Sinuses Indian Medical PG Practice Questions and MCQs
Question 1: Which of the following statements is true regarding the anatomy of the external nose?
- A. The lower one-third is primarily cartilaginous. (Correct Answer)
- B. The upper two-thirds is entirely bony.
- C. The lateral aspect has only a single cartilage.
- D. The external nose is supported by two nasal bones.
Explanation: ***The lower one-third is primarily cartilaginous.*** - The **lower one-third** of the external nose, including the nasal tip and alae, is predominantly supported by **alar cartilages** (lower lateral cartilages) and other minor cartilages, giving it flexibility. - This cartilaginous structure allows for movement and shaping of the nostrils. - This statement is **anatomically accurate and complete**. *The upper two-thirds is entirely bony.* - This is **incorrect**. - The **upper one-third** is bony (nasal bones and frontal process of maxilla). - The **middle one-third** is primarily **cartilaginous** (upper lateral cartilages). - Therefore, the upper two-thirds consists of **both bone and cartilage**, not entirely bone. *The lateral aspect has only a single cartilage.* - This is **incorrect**. - The lateral aspect contains **multiple cartilages**: upper lateral cartilages, lower lateral (alar) cartilages, and accessory cartilages. - The presence of multiple cartilages provides structural support and flexibility. *The external nose is supported by two nasal bones.* - This is **incomplete and misleading**. - While two **nasal bones** do form the superior bony bridge (upper one-third), the external nose is also supported by: - Frontal process of the maxilla - Upper and lower lateral cartilages - Septal cartilage - Stating only the nasal bones ignores the majority of nasal support structures.
Question 2: A 13-year-old boy presents with right-sided nasal obstruction and recurrent epistaxis for the past 6 months. What is the most likely diagnosis?
- A. JNA (Correct Answer)
- B. Coagulation disorder
- C. Antrochoanal polyp
- D. Allergic rhinitis
Explanation: ***JNA (Juvenile Nasopharyngeal Angiofibroma)*** - **Classic presentation**: Adolescent male with **unilateral nasal obstruction** and **recurrent, often profuse epistaxis** - JNA is a **highly vascular benign tumor** that predominantly affects males aged 10-18 years - Though benign, it is **locally aggressive** and can extend into adjacent structures (orbit, skull base) - The combination of age, gender, unilateral symptoms, and recurrent epistaxis makes this the most likely diagnosis *Coagulation disorder* - Would cause **generalized bleeding tendencies**, not localized unilateral nasal obstruction - Epistaxis would typically be **bilateral** and associated with other bleeding manifestations (easy bruising, gum bleeding, prolonged bleeding from cuts) - No mass effect or persistent obstruction would be expected - Other systemic bleeding signs are absent in this presentation *Antrochoanal polyp* - **Benign inflammatory lesion** originating from maxillary sinus, extending through ostium into choana - Can cause nasal obstruction but epistaxis is **much less common and less severe** than in JNA - More commonly associated with **chronic sinusitis symptoms** (rhinorrhea, postnasal drip, facial pressure) - Less vascular than JNA, so recurrent profuse epistaxis would be unusual *Allergic rhinitis* - Characterized by **bilateral symptoms**: nasal obstruction, sneezing, rhinorrhea, and nasal itching - Often has **seasonal pattern** or clear allergen triggers - May cause minor epistaxis from mucosal irritation, but not the **severe recurrent epistaxis** seen here - **Unilateral** persistent obstruction would be atypical for allergic rhinitis
Question 3: Which of the following parts of the nasal septum is the most common site for epistaxis?
- A. Anterosuperior part of nasal septum
- B. Posterosuperior part of nasal septum
- C. Anteroinferior part of nasal septum (Correct Answer)
- D. Posteroinferior part of nasal septum
Explanation: ***Anteroinferior part of nasal septum*** - This region contains **Kiesselbach's plexus** (also known as Little's area), a highly vascularized area located in the anteroinferior nasal septum where four major arteries anastomose (anterior ethmoidal, sphenopalatine, greater palatine, and superior labial arteries). - Due to its **superficial location** and **rich blood supply**, Kiesselbach's plexus is the most common site for **epistaxis** (nosebleeds), accounting for approximately 90% of anterior nosebleeds. - This area is easily accessible and prone to trauma from nose picking, dry air, and minor injuries. *Anterosuperior part of nasal septum* - While part of the anterior septum, this region does not contain the dense vascular network of Kiesselbach's plexus. - It is less commonly associated with epistaxis compared to the anteroinferior region. *Posterosuperior part of nasal septum* - This area is supplied by branches of the **sphenopalatine artery** (Woodruff's plexus) and is associated with **posterior epistaxis**, which is less common but potentially more severe. - Posterior nosebleeds account for only about 10% of all epistaxis cases and typically occur in elderly patients or those with hypertension. *Posteroinferior part of nasal septum* - This region has a relatively less dense vascular supply compared to the anteroinferior or posterosuperior parts. - It is not a primary site for epistaxis and is less clinically significant for nasal bleeding.
Question 4: Which of the following is not a complication of maxillary sinus lavage and insufflation?
- A. Orbital injury
- B. Epistaxis
- C. Facial nerve injury (Correct Answer)
- D. Air embolism
Explanation: ***Facial nerve injury*** - The **facial nerve (CN VII)** passes through the parotid gland and temporal bone, far from the maxillary sinus. - There is no anatomical proximity or procedural mechanism during maxillary sinus lavage and insufflation that would put the facial nerve at risk of injury. *Air embolism* - **Insufflation of air** into the maxillary sinus, especially under pressure, can lead to air entering the bloodstream if a blood vessel is inadvertently punctured. - This can result in a serious and potentially fatal **air embolism**, particularly if the air reaches the cerebral circulation. *Orbital injury* - The **medial wall of the maxillary sinus** is in close proximity to the orbit, separated by thin bone. - During lavage, excessive force or incorrect angulation of instruments can perforate this thin bone, leading to **orbital complications** such as periorbital hematoma or injury to orbital contents. *Epistaxis* - During the procedure, the **mucosa of the nasal cavity** or the sinus itself can be traumatized by the instruments used for lavage. - This local trauma to the rich blood supply of these areas can easily cause **nasal bleeding (epistaxis)**.
Question 5: Which radiographic view is best for visualizing the frontal sinus?
- A. Caldwell's view (Correct Answer)
- B. Towne's view
- C. Schuller's view
- D. Water's view
Explanation: ***Caldwell's view*** - This **posteroanterior (PA) radiographic projection** is optimized for visualizing the **frontal sinuses** and the **anterior ethmoid air cells**. - The OML (orbitomeatal line) is positioned perpendicular to the image receptor, directing the central ray 15 degrees caudal from the posterior aspect of the skull, projecting the petrous ridges below the orbits. *Towne's view* - The **AP axial projection**, or Towne's view, is primarily used to visualize the **occipital bone**, **foramen magnum**, and the **condyles of the mandible**. - It involves caudal angulation of the central ray to separate these structures. *Schuller's view* - Also known as the **lateral projection of the mastoid**, Schuller's view is primarily used to assess the **mastoid air cells** and the **external auditory canal**. - It helps in evaluating mastoiditis or cholesteatoma. *Water's view* - This **parietoacanthial projection**, or Water's view, is best for visualizing the **maxillary sinuses**, and also provides good visualization of the **orbits** and **zygomatic arches**. - The MML (mentomeatal line) is positioned perpendicular to the image receptor, projecting the petrous ridges below the maxillary sinuses.
Question 6: Which of the following arteries does NOT contribute to Little's area?
- A. Sphenopalatine artery
- B. Posterior Ethmoidal artery (Correct Answer)
- C. Greater palatine artery
- D. Anterior Ethmoidal artery
Explanation: Posterior Ethmoidal artery - The posterior ethmoidal artery primarily supplies the posterior ethmoidal cells and part of the sphenoid sinus, but it does not contribute to the vascular plexus in Little's area. - Little's area, also known as Kiesselbach's plexus, is formed by anastomoses of several arteries on the anterior nasal septum. Sphenopalatine artery - The sphenopalatine artery, a terminal branch of the maxillary artery, is a major contributor to Little's area through its septal branch. - It supplies a significant portion of the nasal septum and is frequently involved in posterior epistaxis. Greater palatine artery - The greater palatine artery, a branch of the descending palatine artery (from the maxillary artery), enters the nasal cavity through the incisive canal and contributes to Little's area on the nasal septum. - It primarily supplies the hard palate and then anastomoses with other vessels in the anterior nasal septum. Anterior Ethmoidal artery - The anterior ethmoidal artery, a branch of the ophthalmic artery, is a key contributor to Little's area. - It supplies the anterior and middle ethmoidal cells and also contributes to the blood supply of the dura mater.
Question 7: If posterior epistaxis cannot be controlled, which artery is ligated?
- A. Sphenopalatine artery (Correct Answer)
- B. External carotid artery
- C. Posterior ethmoidal artery
- D. Maxillary artery
Explanation: ***Sphenopalatine artery*** - The **sphenopalatine artery** is the primary blood supply to the posterior nasal cavity, making its ligation highly effective for persistent **posterior epistaxis**. - It is a terminal branch of the **maxillary artery** and enters the nasal cavity through the sphenopalatine foramen. *Maxillary artery* - While the **maxillary artery** is the parent vessel of the sphenopalatine artery, ligating it further upstream can be more invasive and carry higher risks. - Ligation of the **sphenopalatine artery** directly addresses the most common source of posterior bleeding with less morbidity. *External carotid artery* - The **external carotid artery** is the main source of blood for the internal maxillary artery which gives origin to the sphenopalatine artery. - Ligation at this level is a more proximal and generalized intervention that might not be specific enough for intractable posterior epistaxis and can affect other vascular territories. *Posterior ethmoidal artery* - The **posterior ethmoidal artery** supplies a smaller, more superior portion of the posterior nasal cavity and is less frequently the primary source of severe posterior epistaxis. - Ligation of the ethmoidal arteries is typically reserved for cases where anterior or superior bleeding is refractory, not standard posterior epistaxis.
Question 8: Which nerve is targeted in the nasociliary nerve block?
- A. Greater palatine nerve
- B. Sphenopalatine nerve
- C. Anterior ethmoidal nerve
- D. Nasociliary nerve (Correct Answer)
Explanation: ***Nasociliary nerve*** - A nasociliary nerve block specifically targets the **nasociliary nerve** itself. - This block is used to anesthetize the sensory innervation of structures supplied by the nasociliary nerve, such as parts of the **nasal cavity**, **eyeball**, and **skin of the nose**. *Greater palatine nerve* - The **greater palatine nerve** supplies sensation to the posterior hard palate and is targeted in a **greater palatine nerve block**. - This nerve is a branch of the **maxillary nerve** and is primarily involved in dental and palatal anesthesia. *Sphenopalatine nerve* - The **sphenopalatine nerve**, or pterygopalatine ganglion, contains sensory fibers for the nasal cavity, palate, and pharynx, and its block is distinct from a nasociliary block. - A **sphenopalatine ganglion block** is mainly used for conditions like cluster headaches and facial pain, not for direct eyeball sensation. *Anterior ethmoidal nerve* - The **anterior ethmoidal nerve** is a branch of the nasociliary nerve, but a nasociliary nerve block targets the main trunk, which includes all its branches. - While the anterior ethmoidal nerve supplies the anterior part of the nasal septum and lateral wall, it is a **component** of the nasociliary innervation rather than the sole target.
Question 9: The following test is done for the evaluation of:
- A. Cheek tenderness in maxillary sinusitis (Correct Answer)
- B. Abnormality of nasal valve
- C. Severity of proptosis
- D. Skin pinch for dehydration
Explanation: ***Cheek tenderness in maxillary sinusitis*** - The image shows a person palpating the area over the **maxillary sinus** with their fingers. This examination technique is used to elicit tenderness, a common sign of **maxillary sinusitis**. - **Tenderness on palpation** over the maxillary sinus is a key clinical finding indicating inflammation or infection within the sinus cavity. *Abnormality of nasal valve* - Evaluation of the nasal valve typically involves external observation, internal examination with a speculum, or specialized maneuvers like the **Cottle test**, which involves pulling the cheek laterally to open the valve; it does not involve pressing on the cheek as depicted. - The nasal valve is an internal structure, and its palpation for abnormality would not be performed by pressing on the outer cheekbone as shown. *Severity of proptosis* - Proptosis (exophthalmos) refers to the **abnormal protrusion of the eyeball**. It is typically measured using an **exophthalmometer**. - The action shown in the image, pressing on the cheek, is not a method used to assess or quantify the severity of proptosis. *Skin pinch for dehydration* - The **skin pinch test** (turgor test) for dehydration is usually performed by pinching the skin on the back of the hand, lower arm, or abdomen, not the cheek. - Delayed return of the pinched skin to its normal state, known as **poor skin turgor**, indicates dehydration. The image does not show this technique.
Question 10: Which fungus is most commonly associated with orbital cellulitis in patients with diabetic ketoacidosis?
- A. Candida
- B. Mucor
- C. Rhizopus (Correct Answer)
- D. Aspergillus
Explanation: ***Rhizopus*** - *Rhizopus* is the most common cause of **mucormycosis** (also called zygomycosis), an aggressive fungal infection that frequently affects immunocompromised patients, especially those with **diabetic ketoacidosis (DKA)**. - *Rhizopus arrhizus* (formerly *R. oryzae*) accounts for approximately **70% of all mucormycosis cases**, making it the single most common causative organism. - In DKA, the acidic environment and high glucose levels favor the growth of **Mucorales fungi**, leading to rapid progression from the sinuses to the orbit and brain (rhinoorbital-cerebral mucormycosis). *Candida* - While *Candida* is a common cause of fungal infections, it typically manifests as **candidemia**, **esophagitis**, or **vulvovaginitis**, and is rarely associated with orbital cellulitis in DKA. - *Candida* infections are more likely in patients with indwelling catheters or those on broad-spectrum antibiotics, rather than specifically linked to DKA-induced orbital cellulitis. *Mucor* - The genus *Mucor* is part of the **Mucorales order** and can cause **mucormycosis** with identical clinical presentations to *Rhizopus*. - However, *Mucor* species account for only **10-20% of mucormycosis cases**, making *Rhizopus* the **most commonly** associated genus as asked in the question. - While both are clinically grouped under "mucormycosis," *Rhizopus* is the more specific and statistically correct answer when identifying the most common causative fungus. *Aspergillus* - *Aspergillus* species are common environmental fungi that can cause invasive infections, particularly in immunocompromised patients, leading to conditions like **aspergilloma** or **invasive aspergillosis**. - While *Aspergillus* can cause sinus and orbital infections, it is less commonly associated with the rapid, aggressive form of orbital cellulitis seen in DKA compared to mucormycosis caused by *Rhizopus*.
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