USMLE PRACTICE QUESTION #51
TOPIC: Head & Neck Vascular Anatomy.
Today’s question will test your understanding of the basic head & neck vasculature.
I’m Paul Ciurysek, MD, and this is The USMLE Times: An independent, subscriber-supported newsletter designed to help you survive medical school, pass your USMLE exams, and match into your dream residency program.
A 51-year-old female presents to the walk-in clinic complaining of a persistent nosebleed for the past forty-five minutes. The patient reports that she has experienced recurrent episodes of nosebleeds over the past month and has also noticed the presence of blood in her mouth during the incidents. The patient has no prior personal or known familial history of bleeding disorders. Efforts to cease the bleeding, such as using nasal packing and tilting the head forward and backward, were unsuccessful. During the physical examination, continuous bleeding from the right nostril was observed, along with the presence of blood in the oropharynx. To bring about hemostasis, bilateral nasal packing was implemented. Despite this intervention, the bleeding persisted and required specialist support. Which of the following vessels most likely involves the patient's nosebleed?
A. Posterior ethmoid artery
B. Anterior ethmoidal artery
C. Anterior septal branches
D. Maxillary artery
E. Ophthalmic artery
F. Posterior septal branches
G. Sphenopalatine artery
H. Kiesselbach plexus
Detailed Breakdown of Answers + Correct Answer Below ⏬
ANSWER + QUESTION BREAKDOWN
The mental model used to answer this question comes from our detailed test-taking skills masterclass. Here’s how to think through this question:
Step 1. Determine what the question asks you to do: Identify the vessel responsible for this patient’s excessive nosebleed.
Step 2: Is this a first-, second-, or third-order question?
Answer: 2nd order (Figure out why the patient’s nosebleed is uncontrollable (Genetic, acquired, anatomical?); then name the most likely underlying cause (ie. The responsible vessel).
Step 3. Read the vignette to identify the underlying cause.
Step 4. With your diagnosis established, locate the vessel most likely responsible.
Step 5. Look at the answer choices and select the option most closely resembling your thoughts from “Step 4” above.
GENERAL ANALYSIS
This question describes a 51-year-old female with a persistent and recurrent nosebleed (epistaxis) that has not responded to typical first-aid measures like nasal packing. The bleeding is significant enough to require specialist intervention. The task is to identify the vessel most likely involved in this type of severe and persistent epistaxis.
ANSWER CHOICES:
ANSWER CHOICE A: Posterior ethmoid artery
The posterior ethmoid artery supplies the upper part of the nasal cavity. While it can be involved in posterior epistaxis, it is not the most likely cause.
ANSWER CHOICE B: Anterior ethmoidal artery
The anterior ethmoidal artery supplies the anterior and superior parts of the nasal cavity. It is more commonly involved in anterior epistaxis, which is usually less severe and more amenable to simple interventions.
ANSWER CHOICE C: Anterior septal branches
These branches supply the anterior part of the nasal septum. They are part of Kiesselbach's plexus, typically involved in anterior nosebleeds, which are usually less severe.
ANSWER CHOICE D: Maxillary artery
The maxillary artery is a major artery supplying the face and nasal cavity. While it gives rise to the sphenopalatine artery, it is not directly involved in nasal bleeding.
ANSWER CHOICE E: Ophthalmic artery
The ophthalmic artery supplies the orbit and parts of the nasal cavity. It is not typically involved in significant nasal bleeding.
ANSWER CHOICE F: Posterior septal branches
These branches supply the posterior part of the nasal septum. They are not the primary vessels involved in severe posterior epistaxis.
ANSWER CHOICE G: Sphenopalatine artery
The sphenopalatine artery is a branch of the maxillary artery supplying the posterior part of the nasal cavity. It is often involved in severe posterior epistaxis.
ANSWER CHOICE H: Kiesselbach plexus
Kiesselbach's plexus is a network of vessels located in the anterior part of the nasal septum, commonly involved in anterior nosebleeds. Anterior nosebleeds from Kiesselbach's plexus are usually less severe and easier to manage, unlike the persistent bleeding described in this case.
FINAL VERDICT…
The sphenopalatine artery is the primary vessel involved in posterior epistaxis, which is often more severe and difficult to control than anterior epistaxis. Posterior nosebleeds can lead to significant blood loss and may require specialist intervention, as simple measures like nasal packing are often ineffective. The sphenopalatine artery, a branch of the maxillary artery, supplies the posterior nasal cavity, and its involvement explains the persistent and severe nature of the bleeding in this patient. To achieve hemostasis, this condition requires more advanced treatment, such as posterior nasal packing, cauterization, or surgical intervention.
CORRECT ANSWER: G) Sphenopalatine artery
That’s all for today 👋
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