Variations in Vascular Anatomy — MCQs

10 questions

What is the imaging modality of choice for determining the etiology of subarachnoid hemorrhage?

A 55-year-old male, known smoker, complains of calf pain while walking. He experiences calf pain while walking but can continue walking with effort. Which grade of claudication does this patient fall under?

Which of the following arteries is likely to be involved in a 3rd cranial nerve lesion?

Pressure difference of 5 mm Hg between the two upper limbs occurs in which congenital heart disease?

Which of the following arteries is a derivative of the second aortic arch?

Superior vena cava is derived from:

A patient comes with abdominal pain, jaundice, and portal hypertension. Anastomosis between which of the following veins is seen?

Onodi cells and Haller cells are associated with which anatomical structures, respectively?

Liver is divided into eight segments according to Couinaud's classification based upon

Q10

As shown in the figure, abnormal subclavian artery develops as a result of: (AIIMS May 2016)

Variations in Vascular Anatomy Indian Medical PG Practice Questions and MCQs

Question 1: What is the imaging modality of choice for determining the etiology of subarachnoid hemorrhage?

A. Non-contrast CT
B. CECT
C. Four vessel DSA (Correct Answer)
D. MRI

Explanation: ***Four vessel DSA*** - **Four-vessel Digital Subtraction Angiography (DSA)** is considered the gold standard for identifying the source of subarachnoid hemorrhage (SAH). - It provides high-resolution images of the **cerebral vasculature**, enabling the detection of small aneurysms, arteriovenous malformations, or other vascular lesions. *Non-contrast CT* - **Non-contrast CT** is the imaging modality of choice for the initial diagnosis of SAH itself. - However, it primarily identifies the presence of blood and its location, but is not as effective in determining the **underlying cause** of the hemorrhage in many cases. *CECT* - **Contrast-enhanced CT (CECT)** can help identify some vascular abnormalities by highlighting vessels, but its sensitivity for detecting small aneurysms or complex vascular lesions is lower than DSA. - It is often used as an alternative or supplementary study when DSA is not immediately available or contraindicated. *MRI* - **MRI** is highly sensitive for detecting intraparenchymal and subtle SAH in later stages but is less effective than CT for acute blood detection, especially within the first few hours. - While MRA (Magnetic Resonance Angiography) can identify vascular lesions, its resolution and ability to detect smaller aneurysms are generally inferior to DSA.

Question 2: A 55-year-old male, known smoker, complains of calf pain while walking. He experiences calf pain while walking but can continue walking with effort. Which grade of claudication does this patient fall under?

A. Grade I (Mild claudication)
B. Grade II (Moderate claudication) (Correct Answer)
C. Grade III (Severe claudication)
D. Grade IV (Ischemic rest pain)

Explanation: ***Grade II (Moderate claudication)*** - **Grade II claudication** is characterized by **intermittent claudication** where the patient experiences pain while walking but can **continue walking with effort**. - This level of claudication reflects a moderate degree of peripheral arterial disease, where blood flow is sufficiently compromised to cause pain with exertion but not severe enough to force immediate cessation of activity. - The patient in this scenario can continue ambulation despite discomfort, which is the defining feature of this grade. *Grade I (Mild claudication)* - **Grade I claudication** involves discomfort or pain that the patient can **tolerate without significantly altering their gait or pace**. - In this stage, the pain is minimal, and the patient may perceive it as a dull ache or mild fatigue rather than true pain. - Walking can continue without significant effort or limitation. *Grade III (Severe claudication)* - **Grade III claudication** is marked by pain that is **severe enough to stop the patient from walking within a short distance** (typically less than 200 meters). - The pain forces the patient to rest and recover before they can resume walking. - This represents significant functional limitation in daily activities. *Grade IV (Ischemic rest pain)* - **Grade IV**, also known as **critical limb ischemia**, involves **pain even at rest**, especially in the feet or toes, often worsening at night when the limb is elevated. - This stage indicates severe arterial obstruction and is frequently associated with **ulcers, non-healing wounds, or gangrene**. - This represents advanced peripheral arterial disease requiring urgent intervention. **Note:** This grading system is a simplified clinical classification. The standard medical classifications for peripheral arterial disease are the **Fontaine classification** (Stages I-IV) and **Rutherford classification** (Categories 0-6).

Question 3: Which of the following arteries is likely to be involved in a 3rd cranial nerve lesion?

A. Anterior communicating
B. Posterior communicating (Correct Answer)
C. Posterior cerebral
D. Anterior cerebral

Explanation: ***Posterior communicating*** - The **posterior communicating artery (PCoA)** is anatomically juxtaposed to the **oculomotor nerve (CN III)** as it exits the midbrain. - An **aneurysm** of the PCoA can compress the CN III, leading to findings such as **ptosis**, **mydriasis**, and **"down and out" deviation** of the eye [1]. *Anterior communicating* - The **anterior communicating artery (AComA)** is located more anteriorly and inferiorly, primarily associated with the **optic chiasm** and **olfactory tracts**. - While aneurysms here can cause visual field defects or frontal lobe dysfunction, they are less likely to directly compress the **oculomotor nerve**. *Posterior cerebral* - The **posterior cerebral artery (PCA)** supplies regions like the **visual cortex** and midbrain. - PCA aneurysms or infarctions typically result in deficits such as **hemianopia**, **alexia**, or specific midbrain syndromes, not isolated CN III compression. *Anterior cerebral* - The **anterior cerebral artery (ACA)** supplies the medial aspects of the frontal and parietal lobes. - Aneurysms or strokes in the ACA territory commonly lead to **contralateral leg weakness** or behavioral changes, not cranial nerve palsies due to its anatomical location.

Question 4: Pressure difference of 5 mm Hg between the two upper limbs occurs in which congenital heart disease?

A. HOCM
B. Coarctation of Aorta
C. Supra-valvular aortic stenosis (Correct Answer)
D. TOF

Explanation: ***Supra-valvular aortic stenosis*** - **Supravalvular aortic stenosis** causes a **pressure gradient** across the aortic valve, leading to a significant **pressure difference** between the upper limbs, typically with a **higher pressure** in the right arm. - This is due to the **Coanda effect**, where the high-velocity jet of blood preferentially flows up the **right subclavian artery** as it exits the aorta. *HOCM (Hypertrophic Obstructive Cardiomyopathy)* - HOCM is characterized by hypertrophy of the **left ventricular septum** causing **outflow tract obstruction**, but it does not typically cause a significant **pressure difference** between the upper limbs. - The obstruction primarily affects **ventricular ejection** rather than differential flow to major arteries. *Coarctation of Aorta* - **Coarctation of the aorta** causes a significant **blood pressure difference** between the upper and lower extremities, with higher pressures in the arms [1]. - However, it does not typically cause a marked **pressure difference between the two upper limbs**, unless the coarctation is pre-ductal and affects the subclavian artery circulation asymmetrically, which is less common for a difference of just 5 mmHg. *TOF (Tetralogy of Fallot)* - **Tetralogy of Fallot** is a cyanotic heart disease involving **pulmonary stenosis**, ventricular septal defect, overriding aorta, and right ventricular hypertrophy [2]. - While it causes significant circulatory abnormalities and potential for **hypoxia**, it does not inherently lead to a measurable **pressure difference** between the upper limbs.

Question 5: Which of the following arteries is a derivative of the second aortic arch?

A. Maxillary artery
B. Middle meningeal artery
C. Stapedial artery (Correct Answer)
D. Anterior tympanic artery

Explanation: ***Stapedial artery*** - The **stapedial artery** is a key derivative of the **second aortic arch**, which transiently supplies the stapes and is mostly obliterated in humans but can rarely persist. - Its remnants typically form the **caroticotympanic artery** and contribute to the **middle meningeal artery**. *Maxillary artery* - The **maxillary artery** is primarily a branch of the **external carotid artery** and is derived from the **first aortic arch**, making it responsible for supplying deep structures of the face. - Its main derivatives from the first arch include the **maxillary** and **external carotid arteries**. *Middle meningeal artery* - The main trunk of the **middle meningeal artery** is primarily derived from the **first aortic arch** (via the maxillary artery), although some contributions can arise from persistent parts of the second arch. - It enters the skull through the **foramen spinosum** to supply the dura mater. *Anterior tympanic artery* - The **anterior tympanic artery** is a small branch of the **maxillary artery**, which itself derives from the **first aortic arch**. - It supplies the **tympanic membrane** and the lining of the middle ear.

Question 6: Superior vena cava is derived from:

A. Aortic arch
B. Pharyngeal arch
C. Vitelline vein
D. Cardinal vein (Correct Answer)

Explanation: ***Cardinal vein*** - The **superior vena cava (SVC)** develops primarily from the **right anterior cardinal vein** and the common cardinal veins. [1] - The cardinal veins are the main venous drainage system in the early embryo, eventually forming the major veins of the adult. *Aortic arch* - The **aortic arches** are embryonic structures that contribute to the formation of the **major arteries**, such as the aorta, carotid arteries, and subclavian arteries. - They are involved in the arterial system, not the venous drainage of the superior vena cava. *Pharyngeal arch* - **Pharyngeal arches** are embryonic structures that give rise to various components of the **head and neck**, including skeletal structures, muscles, and nerves. - They are not directly involved in the formation of major blood vessels like the superior vena cava. *Vitelline vein* - The **vitelline veins** are embryonic vessels that drain blood from the **yolk sac** and contribute to the formation of the **portal system**, including the hepatic portal vein and sinusoids. - They are not involved in the development of the systemic veins like the superior vena cava, which drains the upper body.

Question 7: A patient comes with abdominal pain, jaundice, and portal hypertension. Anastomosis between which of the following veins is seen?

A. Left colic vein and middle colic veins
B. Superior rectal and phrenic veins
C. Sigmoid and superior rectal veins
D. Esophageal veins and left gastric veins (Correct Answer)

Explanation: ***Esophageal veins and left gastric veins*** - This anastomosis is crucial in **portal hypertension**, as increased pressure in the **portal venous system** (e.g., due to liver cirrhosis) causes blood to back up into the **systemic venous circulation** through these collateral vessels. - This shunting creates **esophageal varices**, which can rupture and lead to life-threatening **upper gastrointestinal bleeding**, commonly presenting with **jaundice** and **abdominal pain** in liver disease. *Left colic vein and middle colic veins* - Both the left colic and middle colic veins are tributaries of the **inferior mesenteric vein** and **superior mesenteric vein**, respectively, and are part of the **portal system**. - While they form an anastomosis (via the **marginal artery of Drummond**), this connection is within the portal system and does not typically serve as a portosystemic shunt to decompress portal hypertension in the way esophageal varices do. *Superior rectal and phrenic veins* - The **superior rectal vein** drains into the **inferior mesenteric vein** (part of the portal system), and the **phrenic veins** drain into the **inferior vena cava** (part of the systemic system). - There is no direct significant portosystemic anastomosis between these two veins that would be clinically relevant in portal hypertension. *Sigmoid and superior rectal veins* - Both the **sigmoid veins** and the **superior rectal vein** are part of the **inferior mesenteric venous system**, which drains into the **portal circulation**. - While there are anastomoses between these veins within the mesenteric circulation, they are not a direct portosystemic shunt used to relieve pressure in portal hypertension causing the described symptoms.

Question 8: Onodi cells and Haller cells are associated with which anatomical structures, respectively?

A. Optic nerve and orbital floor (Correct Answer)
B. Optic nerve and internal carotid artery
C. Optic nerve and nasolacrimal duct
D. Orbital floor and nasolacrimal duct

Explanation: ***Optic nerve and orbital floor*** - An **Onodi cell** is a **sphenoethmoidal air cell** that extends laterally into the sphenoid sinus, closely abutting the **optic nerve** canal and internal carotid artery. - A **Haller cell** (infraorbital ethmoid cell) is an **ethmoid air cell** that extends inferolaterally into the maxillary sinus, thereby impacting the **orbital floor** and infundibulum. *Optic nerve and internal carotid artery* - While **Onodi cells** are indeed closely associated with the **optic nerve**, they can also abut the internal carotid artery, but Haller cells are not primarily associated with this structure. - This option incorrectly pairs Haller cells with the internal carotid artery. *Optic nerve and nasolacrimal duct* - The **optic nerve** is associated with Onodi cells, but the **nasolacrimal duct** is not typically associated with either Onodi cells or Haller cells. - The nasolacrimal duct drains tears into the nasal cavity, an area distinct from the typical locations of these accessory sinuses. *Orbital floor and nasolacrimal duct* - The **orbital floor** is associated with **Haller cells**, but the **nasolacrimal duct** is not the primary anatomical structure of concern regarding either Onodi or Haller cells. - This option misassociates Onodi cells and the nasolacrimal duct, and only partially correctly identifies the Haller cell association.

Question 9: Liver is divided into eight segments according to Couinaud's classification based upon

A. Portal vein (Correct Answer)
B. Hepatic artery
C. Hepatic vein
D. Bile Duct

Explanation: ***Portal vein*** - Couinaud's classification divides the liver into eight segments, each supplied by a single portal triad (a branch of the **portal vein**, **hepatic artery**, and drained by a branch of the bile duct) [1]. - The portal vein branches are central to the segmentation as they dictate the functional units based on their intrahepatic distribution [1]. *Hepatic artery* - While the hepatic artery provides arterial blood supply to each segment, it is the distribution of the **portal vein** that primarily defines the surgical segments in Couinaud's classification. - The hepatic arterial supply tends to run alongside the portal vein branches but doesn't alone dictate the segmentation boundaries. *Hepatic Vein* - The hepatic veins typically run **intersegmentally**, defining the boundaries between segments rather than actually supplying them [1]. - They are used as landmarks to identify the different segments but not as the basis for the segmental division itself. *Bile Duct* - The bile ducts run in parallel with the portal vein and hepatic artery branches within each segment. - Although crucial for drainage, their branching pattern does not independently form the basis for Couinaud's segmental classification.

Question 10: As shown in the figure, abnormal subclavian artery develops as a result of: (AIIMS May 2016)

A. Persistence of B
B. Persistence of A
C. Obliteration of A with persistence of B
D. Obliteration of B with persistence of A (Correct Answer)

Explanation: ***Obliteration of B with persistence of A*** - The image depicts the 7th intersegmental artery (labeled **A**) and the right dorsal aorta (labeled **B**). An **abnormal subclavian artery** (retroesophageal subclavian artery or arteria lusoria) results from the **obliteration of B** (the right dorsal aorta) distal to the 7th intersegmental artery (A). - When the right dorsal aorta (B) obliterates prematurely, the right subclavian artery (derived from A plus portions of the 4th aortic arch and right dorsal aorta) gets its distal blood supply from the left dorsal aorta, causing it to cross behind the esophagus to reach the right arm. *Persistence of B* - The normal development of the right subclavian artery involves the **regression** of a segment of the right dorsal aorta (part of **B**). If **B** (the right dorsal aorta) persists, it could lead to other malformations, but not typically an abnormal subclavian artery coursing behind the esophagus. - The persistence of the right dorsal aorta, usually proximal to the 7th intersegmental artery, would be part of a **double aortic arch** or other arch anomalies, rather than directly causing arteria lusoria. *Persistence of A* - **A** represents the **7th intersegmental artery**, which normally persists to form a crucial part of the subclavian artery. Persistence of **A** alone is a normal developmental event and does not lead to an abnormal subclavian artery. - An abnormal subclavian artery requires an alteration in the usual regression patterns of other embryological vessels, not merely the persistence of a normally persistent vessel. *Obliteration of A with persistence of B* - **Obliteration of A** (the 7th intersegmental artery) would prevent the formation of a normal subclavian artery altogether. This would lead to a severely underdeveloped or absent right subclavian artery, rather than one with an abnormal course. - If **A** obliterates, and **B** (right dorsal aorta) persists, the right arm would lack its primary arterial supply, which is a much more severe anomaly than a retroesophageal subclavian artery.

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