NEET-PG 2015 - Anatomy Practice Questions

Q: Number of stem villi at term in human placenta is?

240. ***240*** - At term, the **human placenta** contains numerous **stem villi** which branch extensively to form the villous tree. - The approximate number of **stem villi** at term is around **240**, contributing to the large surface area for maternal-fetal exchange. *60* - This number is significantly **lower** than the actual count of **stem villi** found in a mature, term placenta. - Such a low number would result in an **insufficient surface area** for effective nutrient and gas exchange. *120* - While higher than 60, this number is still **underestimated** for the quantity of **stem villi** present in a full-term human placenta. - A placenta with only 120 stem villi might not be able to adequately support a fetus at term. *480* - This number is an **overestimation** of the typical count of **stem villi** in a human placenta at term. - While villi are extensive, 480 stem villi represent a significantly higher number than usually observed.

Q: What is the shape of caecum in the newborn?

Conical. ***Conical*** - In newborns, the **caecum** is typically described as having a **conical** shape. - This shape gradually changes as the individual grows and develops. *Ovoid* - The ovoid shape is more characteristic of the adult **caecum**, which tends to be broader and less pointed. - This shape is not typically observed in newborns. *Globular* - A globular shape implies a more rounded and spherical form, which is not accurate for the newborn **caecum**. - This term is sometimes used to describe the general appearance of some organs but not the specific shape of the neonatal caecum. *Trapezoid* - A trapezoid shape is defined by four sides with at least one pair of parallel sides, which does not accurately describe the normal anatomical configuration of the **caecum** at any age. - This shape is completely inconsistent with the morphology of the **caecum**.

Q: Which of the following structures is present in an XY child but absent in an XX child?

Prostate gland. ***Prostate gland*** - The **prostate gland** is the most characteristic male-specific accessory reproductive organ that is **definitively present in XY and absent in XX individuals**. - It develops from the **urogenital sinus** under the influence of **dihydrotestosterone (DHT)** during embryonic development. - The prostate is a **substantial glandular structure** that surrounds the urethra and produces approximately 30% of seminal fluid. - It has **no homologous structure in females**—there is no female equivalent organ. *Incorrect: Urethral glands (Cowper's glands)* - **Cowper's glands (bulbourethral glands)** are indeed male-specific structures present only in XY individuals. - However, they are **homologous to Bartholin's glands** in females—meaning both develop from similar embryonic tissue (urogenital sinus). - While the question technically could accept this answer, the **prostate gland is the more definitive answer** as it is larger, more clinically significant, and has no female homologue. - Cowper's glands are small pea-sized glands that contribute to pre-ejaculate fluid. *Incorrect: Ovaries* - **Ovaries** are the primary female gonads present in **XX individuals**, not XY individuals [1]. - They produce ova and female sex hormones (estrogen and progesterone) [1]. - In XY individuals, the **testes** develop instead under the influence of the SRY gene. *Incorrect: Vestibular glands (Bartholin's glands)* - **Bartholin's glands** are female-specific structures present in **XX individuals**, not XY individuals. - Located at the posterior vaginal opening, they secrete mucus for vaginal lubrication. - They are homologous to Cowper's glands in males but are distinct structures.

Q: Which part of the bone is considered the most vascular zone?

Metaphysis. ***Metaphysis*** - The metaphysis is the most **vascular** part of the bone, containing numerous blood vessels that supply the growing bone. - This high vascularity makes it a common site for **osteomyelitis** and bone tumors due to the abundant blood supply [1]. *Diaphysis* - The diaphysis is the **shaft** or central part of a long bone, primarily composed of **compact bone** [2]. - While it has blood supply through nutrient arteries, its vascularity is less dense compared to the metaphysis. *Epiphysis* - The epiphysis is the **end portion** of a long bone, typically covered by articular cartilage. - It receives its blood supply from periarticular vessels, but is less vascular than the metaphysis, especially in mature bone. *Medullary Cavity* - The medullary cavity is the central cavity of bone shafts where **bone marrow** is stored [2]. - While it contains hematopoietic stem cells and a rich blood supply, the surrounding bone tissue of the metaphysis itself is considered more vascular in terms of nutrient delivery and growth.

Q: Locking of the knee involves which of the following?

Internal rotation of the femur with the foot on the ground. ***Internal rotation of the femur with the foot on the ground*** - When the foot is on the ground (closed kinematic chain), the **femur rotates internally on the tibia** during the end stages of knee extension. This creates a more stable, "locked" position of the knee. - This **terminal rotation of the femur** increases the contact area and tension in the cruciate ligaments, enhancing joint stability for weight-bearing. *Internal rotation of the tibia with the foot on the ground* - This describes the action of the **popliteus muscle** when "unlocking" the knee from full extension, not the locking mechanism itself. - With the foot on the ground, the tibia is fixed, and internal rotation would typically be a movement for unlocking, not locking. *Contraction of the popliteus muscle* - The **popliteus muscle** is primarily responsible for **unlocking the knee** from full extension, by causing internal rotation of the tibia (or external rotation of the femur). - Its contraction would lead to initial flexion of the knee, releasing the locked position, not establishing it. *External rotation of femur with the foot off the ground* - With the foot off the ground (open kinematic chain), **external rotation of the tibia** occurs during the final degrees of extension to lock the knee, not external rotation of the femur. - The locking mechanism requires specific relative rotation between femur and tibia; external rotation of the femur alone would not achieve the screw-home mechanism necessary for knee locking.

Q: Embryo gets implanted at what stage of development?

Blastocyst. Blastocyst - Implantation into the uterine wall occurs when the embryo has developed into a blastocyst, typically around day 6 post-fertilization [1]. - The blastocyst consists of an inner cell mass (which forms the embryo) and an outer layer called the trophoblast (which contributes to the placenta) [1]. Two cell stage - This stage occurs very early in development, usually within the first 24-30 hours after fertilization [1]. - At this point, the embryo is still in the fallopian tube and has not yet reached the uterus for implantation [1]. Four cell stage - The four-cell stage is also an early cleavage stage, occurring around 2 days post-fertilization [1]. - Like the two-cell stage, the embryo is still in transport through the fallopian tube and is not ready for implantation [1]. Morula - The morula is a solid ball of cells formed by cleavage, typically around day 3-4 post-fertilization [1]. - While it has moved closer to the uterus, it has not yet formed the distinct inner cell mass and trophoblast necessary for successful implantation [1].

Q: Most common location of ectopic salivary gland is -

Cervical lymph nodes. Cervical lymph nodes - **Ectopic salivary gland tissue** is most frequently found within or adjacent to **cervical periparotid lymph nodes**. - This is thought to be due to inclusion of salivary gland anlage within lymph nodes during embryological development. *Anterior mediastinum* - While ectopic tissues can occur in the mediastinum, **salivary gland tissue** is not a common finding there. - The **mediastinum** is more commonly associated with ectopic **thymic** or **thyroid** tissue. *Posterior triangle* - The **posterior triangle of the neck** is a common site for various neck masses , but **ectopic salivary gland tissue** is rare in this location. - Masses here are more typically **lymphadenopathy**, **brachial cleft cysts**, or **fibromas**. *Parathyroid gland* - The **parathyroid glands** are endocrine glands located near or within the thyroid, and are not typically associated with containing **ectopic salivary gland tissue**. - Their embryological development is distinct from that of salivary glands.

Q: Anterior Mediastinal nodes are included in which level of lymph nodes?

VI. ***VI*** - Level VI lymph nodes are the **prevascular and retrotracheal nodes** located in the **anterior mediastinum** [1]. - According to the **IASLC (International Association for the Study of Lung Cancer)** lymph node mapping system, Level 6 nodes are specifically classified as anterior mediastinal nodes [1]. - These include nodes anterior to the superior vena cava and ascending aorta, and nodes between the trachea and esophagus [1]. *I* - Level I lymph nodes are located in the **low cervical, supraclavicular, and sternal notch** regions. - These are **extra-thoracic nodes** and not part of the mediastinal compartments. - They represent the highest mediastinal, supraclavicular, and sternal notch nodes [1]. *V* - Level V lymph nodes are the **subaortic (aortopulmonary window)** nodes [1]. - These are located in the space between the **aorta and pulmonary artery**, lateral to the ligamentum arteriosum [1]. - While mediastinal, they are specifically in the aortopulmonary window, not classified as anterior mediastinal. *VII* - Level VII lymph nodes are the **subcarinal nodes** located below the carina in the **middle mediastinum** [1]. - These nodes are positioned in the space beneath where the trachea bifurcates into the main bronchi [1]. - They are classified as middle mediastinal nodes, not anterior mediastinal nodes.

Q: Food can commonly get obstructed in the esophagus at all of the following locations except

Crossing of the hemiazygous vein. Food can commonly get obstructed in the esophagus at all of the following locations except ***Crossing of the hemiazygous vein*** - The **hemiazygos vein crosses the vertebral column** at T7-T9 to drain into the azygos vein; however, this anatomical relationship does not typically create a constriction or point of obstruction for the esophagus. - While it is in proximity, its course does not physically compress or narrow the esophageal lumen in a manner that would commonly cause food impaction. *Crossing of left bronchus* - The **left main bronchus crosses anterior to the esophagus** at the level of the carina (T4-T5), causing a natural indentation and narrowing of the esophageal lumen. - This anatomical narrowing, coupled with the rigid structure of the bronchus, makes it a common site for food impaction, especially for larger boluses. *Crossing of arch of aorta* - The **arch of the aorta crosses anterior and to the left of the esophagus** at the level of T3-T4, creating another significant anatomical constriction. - This bending and compression by a large, typically pulsatile vessel forms a natural bottleneck where swallowed food can easily become lodged. *Diaphragmatic aperture* - The **esophageal hiatus of the diaphragm** (T10) is the most distal natural esophageal narrowing, where the esophagus passes through a muscular opening before joining the stomach. - This narrow opening, surrounded by the crura of the diaphragm, is a very common site for food impaction, particularly when the opening is physiologically or pathologically narrowed (e.g., in cases of hiatal hernia or tight diaphragmatic attachments).

Question 1

Number of stem villi at term in human placenta is?

Accepted Answer

240

Answer

60

Answer

120

Answer

480

Question 2

What is the shape of caecum in the newborn?

Accepted Answer

Conical

Answer

Ovoid

Answer

Trapezoid

Answer

Globular

Question 3

Which bones form the floor of the nasal cavity in children?

Accepted Answer

Palatine process of the maxilla and horizontal plate of the palatine bone

Answer

Nasal bone and maxilla

Answer

Vomer and ethmoid

Answer

Nasal crest of maxilla and palatine process of maxilla

Question 4

Which of the following structures is present in an XY child but absent in an XX child?

Accepted Answer

Prostate gland

Answer

Urethral glands (Cowper's glands)

Answer

Ovaries

Answer

Vestibular glands (Bartholin's glands)

Question 5

Which part of the bone is considered the most vascular zone?

Accepted Answer

Metaphysis

Answer

Diaphysis

Answer

Epiphysis

Answer

Medullary Cavity

Question 6

Locking of the knee involves which of the following?

Accepted Answer

Internal rotation of the femur with the foot on the ground

Answer

Internal rotation of the tibia with the foot on the ground

Answer

Contraction of the popliteus muscle

Answer

External rotation of femur with the foot off the ground

Question 7

Embryo gets implanted at what stage of development?

Accepted Answer

Blastocyst

Answer

Two cell stage

Answer

Four cell stage

Answer

Morula

Question 8

Most common location of ectopic salivary gland is -

Accepted Answer

Cervical lymph nodes

Answer

Posterior triangle

Answer

Parathyroid gland

Answer

Anterior mediastinum

Question 9

Anterior Mediastinal nodes are included in which level of lymph nodes?

Accepted Answer

VI

Answer

I

Answer

V

Answer

VII

Question 10

Food can commonly get obstructed in the esophagus at all of the following locations except

Accepted Answer

Crossing of the hemiazygous vein

Answer

Crossing of left bronchus

Answer

Crossing of arch of aorta

Answer

Diaphragmatic aperture

NEET-PG 2015 — Anatomy