Anatomical Variations and Anomalies Practice Questions

Q: Where is the fabella typically present?

Lateral head of gastrocnemius. ### Explanation **Correct Answer: B. Lateral head of gastrocnemius** The **fabella** is a small sesamoid bone (a bone embedded within a tendon) typically located in the **lateral head of the gastrocnemius muscle**. It is a common anatomical variation found in approximately 10% to 30% of the population. It articulates with the posterior surface of the lateral femoral condyle and is often bilateral. **Why the other options are incorrect:** * **Medial head of gastrocnemius:** While sesamoid bones can rarely occur here, the fabella is classically and most frequently associated with the lateral head. * **Adductor magnus & Adductor longus:** These are muscles of the medial compartment of the thigh. They do not typically contain sesamoid bones near the knee joint. The adductor magnus inserts into the adductor tubercle, but no "fabella" is associated with its tendon. **High-Yield Clinical Pearls for NEET-PG:** * **Radiological Significance:** On a lateral X-ray of the knee, the fabella can be mistaken for a **loose body** (joint mouse) or an avulsion fracture. Its smooth, rounded borders and specific location help distinguish it. * **Fabella Syndrome:** This is a clinical condition where the fabella causes posterolateral knee pain due to compression of the common peroneal nerve or friction against the femoral condyle. * **Evolutionary Note:** It is more common in Asian populations compared to Caucasians and is considered a "vestigial" structure that is actually increasing in prevalence globally over the last century. * **Other Sesamoids to Remember:** The **Patella** (largest sesamoid in the body, in the quadriceps tendon) and the **Pisiform** (in the flexor carpi ulnaris tendon).

Q: Which of the following statements about anodontia is false?

In false anodontia, the tooth undergoes full development. **Explanation:** **Anodontia** is a congenital anomaly characterized by the absence of teeth. Understanding the terminology is crucial for NEET-PG: 1. **Why Option B is False (The Correct Answer):** **False anodontia** (also known as pseudoanodontia) occurs when teeth are present in the jaw but fail to erupt into the oral cavity. This is typically due to impaction or systemic conditions like Cleidocranial Dysplasia. The statement in Option B is misleading because while the tooth germ exists, the clinical presentation is the absence of teeth. In contrast, **True anodontia** involves the complete failure of the tooth germ to develop (Agenesis). 2. **Analysis of Other Options:** * **Option A:** Anodontia can indeed affect both dentitions. If the primary (deciduous) tooth germ is absent, the permanent successor will also be absent. * **Option C:** Anodontia is a spectrum. **Hypodontia** refers to the absence of 1–5 teeth (most common: 3rd molars, followed by maxillary lateral incisors and mandibular 2nd premolars). **Oligodontia** is the absence of 6 or more teeth. * **Option D:** **Total anodontia** is the rare, complete absence of all teeth, often associated with hereditary **Ectodermal Dysplasia**. **Clinical Pearls for NEET-PG:** * **Most common missing tooth:** 3rd Molar (Wisdom tooth). * **Most common missing tooth (excluding 3rd molars):** Maxillary lateral incisor. * **Ectodermal Dysplasia:** Look for the triad of anodontia/hypodontia, hypotrichosis (sparse hair), and anhidrosis (lack of sweat glands). * **Hyperdontia:** The presence of extra teeth (e.g., **Mesiodens** – a supernumerary tooth between maxillary central incisors).

Q: What is the term for a tongue anomaly?

Bifid tongue. The correct answer is **Bifid tongue (Option B)**. This condition, also known as a cleft tongue, is a rare developmental anomaly resulting from the **failure of the two lateral lingual swellings to fuse** in the midline during the fourth week of intrauterine life. These swellings normally merge over the tuberculum impar to form the anterior two-thirds of the tongue. **Analysis of Options:** * **Bifid Tongue (Correct):** It is a true structural anomaly of development. It is frequently associated with **Orofacial Digital Syndrome Type 1**. * **Fissured Tongue (Incorrect):** Also known as "scrotal tongue," this is characterized by deep grooves on the dorsal surface. While it can be congenital, it is often considered a **variation of normal anatomy** or an acquired condition rather than a primary developmental anomaly of tongue formation. It is a key feature of **Melkersson-Rosenthal syndrome**. * **Macroglossia (Incorrect):** This refers to an enlarged tongue. It is a **clinical sign** rather than a specific developmental anomaly of the tongue's structural formation. It is commonly associated with Down syndrome, hypothyroidism (cretinism), and amyloidosis. **High-Yield Clinical Pearls for NEET-PG:** * **Embryology:** The anterior 2/3 of the tongue develops from the **1st pharyngeal arch** (lateral lingual swellings and tuberculum impar), while the posterior 1/3 develops from the **3rd and 4th arches** (hypobranchial eminence). * **Ankyloglossia (Tongue-tie):** Another common anomaly where the lingual frenulum is abnormally short, tethering the tongue to the floor of the mouth. * **Thyroglossal Duct Cyst:** The most common developmental anomaly related to the tongue's descent, usually presenting as a midline neck swelling that moves with protrusion of the tongue.

Q: A dens in dente is usually caused by:

A deep invagination of the enamel organ during formation. ### Explanation **Dens in dente** (also known as *Dens invaginatus*) is a developmental malformation resulting from a **deep invagination of the enamel organ** into the dental papilla before calcification occurs. #### Why the Correct Answer is Right: During the morphodifferentiation stage of tooth development, a portion of the enamel organ (specifically the internal enamel epithelium) proliferates and invaginates into the underlying dental papilla. This creates a "tooth within a tooth" appearance on radiographs, where a pocket of enamel and sometimes dentin is lined within the pulp cavity. It most commonly affects the **maxillary lateral incisors**. #### Why Other Options are Wrong: * **Option A:** Abnormal proliferation of pulp tissue does not lead to the formation of enamel structures inside the tooth; pulp proliferation is typically a reactive process (e.g., chronic hyperplastic pulpitis). * **Option B:** **Denticles** (pulp stones) are calcified masses found within the pulp chamber, but they are separate entities and do not involve the invagination of the enamel organ. * **Option C:** A supernumerary tooth bud enclaved within another is a description of **fusion** or **gemination** anomalies, not the invagination characteristic of dens in dente. #### High-Yield Clinical Pearls for NEET-PG: * **Most Common Site:** Maxillary permanent lateral incisors (followed by central incisors). * **Radiographic Appearance:** A pear-shaped radiopacity (enamel) within the radiolucency of the pulp canal. * **Clinical Significance:** The invagination often communicates with the oral cavity via a small pit, making the tooth highly susceptible to **early dental caries, pulpitis, and periapical lesions**, even without visible decay. * **Classification:** The **Oehlers’ Classification** is used to categorize the severity based on how far the invagination extends toward the root apex.

Q: The CT scan of paranasal sinuses shows:

Haller cells. ***Haller cells*** - The image shows **pneumatized ethmoid air cells** located inferior to the orbit and lateral to the maxillary sinus ostium (arrows), which are characteristic of Haller cells. - These ethmoid cells, also known as **infraorbital ethmoid cells**, can narrow the maxillary sinus ostium, potentially contributing to **recurrent sinusitis**. *Agger nasi cells* - **Agger nasi cells** are the most anterior ethmoid cells, located in the lacrimal bone, anterior and lateral to the frontal recess. - They are typically situated at the level of the frontal sinus ostium, not inferior to the orbit. *Onodi cells* - **Onodi cells** are sphenoethmoidal air cells that extend posteriorly and laterally over the sphenoid sinus, in close proximity to the optic nerve. - Their location is **posterior and superior** to the structures shown in the image, making them incorrectly identified here. *Frontoethmoid cells* - **Frontoethmoid cells** can be a broad category, but specifically refer to ethmoid cells that extend into the frontal sinus or drain into the frontal recess. - While they are ethmoid cells, the specific location shown in the image (inferior to the orbit and maxillary sinus ostium) is more precisely described as Haller cells.

Q: A 28 -year-old male was found to have a condition shown in the image below. At which level is the fused part seen usually?

L4-L5 vertebral level. ***L4-L5 vertebral level (due to inferior mesenteric artery)*** - The image depicts a **horseshoe kidney**, a congenital condition where the lower poles of the kidneys are fused. - The fused portion, or **isthmus**, is typically located at the **L4-L5 vertebral level** because its ascent is blocked by the **inferior mesenteric artery**. *L1 - L2 vertebral level* - This level is usually where the **renal arteries** originate and corresponds to the normal position of the majority of the kidney mass, not typically the fused inferior pole. - The kidneys normally ascend during development to this level, but in a horseshoe kidney, the fusion prevents this full ascent. *T12 - L1 vertebral level* - This vertebral level is too high for the fused portion of a horseshoe kidney. - The kidneys initially develop in the pelvis and ascend; T12-L1 would be the upper extent of normal kidney position. *S1 - S2 vertebral level* - This level is too low for the fused portion of a horseshoe kidney, which typically is found in the lumbar region. - S1-S2 is more associated with pelvic structures, indicating the kidneys would have barely ascended at all.

Question 1

The accessory obturator artery most commonly arises from which of the following arteries?

Accepted Answer

Inferior epigastric artery

Answer

Femoral artery

Answer

Obturator artery

Answer

Profunda femoris artery

Question 2

Where is the fabella typically present?

Accepted Answer

Lateral head of gastrocnemius

Answer

Medial head of gastrocnemius

Answer

Adductor magnus

Answer

Adductor longus

Question 3

Which of the following statements about anodontia is false?

Accepted Answer

In false anodontia, the tooth undergoes full development

Answer

May involve both the deciduous and the permanent dentition

Answer

May involve a single tooth

Answer

In total anodontia, all teeth are missing

Question 4

Dysphagia lusoria means dysphagia:

Accepted Answer

Due to abnormal origin and course of right subclavian artery

Answer

For very cold items

Answer

Atresia of esophagus

Answer

Benign stricture of esophagus

Question 5

What is the term for a tongue anomaly?

Accepted Answer

Bifid tongue

Answer

Fissured tongue

Answer

Macroglossia

Answer

All of the above

Question 6

A dens in dente is usually caused by:

Accepted Answer

A deep invagination of the enamel organ during formation

Answer

An abnormal proliferation of pulp tissue

Answer

Denticle formation within the pulp tissue

Answer

A supernumerary tooth bud enclaved within a normal tooth

Question 7

Which of the following is the most common renal vascular anomaly?

Accepted Answer

Supernumerary renal arteries

Answer

Supernumerary renal veins

Answer

Double renal arteries

Answer

Double renal veins

Question 8

The CT scan of paranasal sinuses shows:

Accepted Answer

Haller cells

Answer

Agger nasi cells

Answer

Onodi cells

Answer

Frontoethmoid cells

Question 9

The following arrow marked vessel can cause torrential hemorrhage during cholecystectomy. Which of the following is the correct description?

Accepted Answer

Moynihan's caterpillar hump due to bend of right hepatic artery

Answer

Moynihan's caterpillar hump due to bend of left hepatic artery

Answer

Moynihan's caterpillar hump due to bend of cystic artery

Answer

Moynihan's caterpillar hump due to bend of common hepatic artery

Question 10

A 28 -year-old male was found to have a condition shown in the image below. At which level is the fused part seen usually?

Accepted Answer

L4-L5 vertebral level

Answer

L1-L2 vertebral level

Answer

T12-L1 vertebral level

Answer

S1-S2 vertebral level

Anatomical Variations and Anomalies — MCQs

Anatomical Variations and Anomalies — MCQs

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