Embryo gets implanted at what stage of development?
Traumatic optic neuropathy due to closed head trauma commonly affects which part of the optic nerve?
Cephalic index is calculated as
Anterior Mediastinal nodes are included in which level of lymph nodes?
Most common site for Cystic Hygroma is -
Transplanted kidney is relocated to which region in the recipient's body?
Food can commonly get obstructed in the esophagus at all of the following locations except
Which of the following statements about the bare area of the liver is false?
What is the shape of caecum in the newborn?
Which bones form the floor of the nasal cavity in children?
NEET-PG 2015 - Anatomy NEET-PG Practice Questions and MCQs
Question 151: Embryo gets implanted at what stage of development?
- A. Two cell stage
- B. Four cell stage
- C. Morula
- D. Blastocyst (Correct Answer)
Explanation: 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].
Question 152: Traumatic optic neuropathy due to closed head trauma commonly affects which part of the optic nerve?
- A. Optic canal (Correct Answer)
- B. Intraocular part
- C. Intracranial part
- D. Optic tract
Explanation: ***Optic canal*** - The **optic nerve** is highly susceptible to injury within the **optic canal** due to its tight anatomical confines and the close proximity of the optic nerve to rigid bone. - Trauma to this region can lead to direct compression, shearing injury, or ischemia from damage to surrounding vasculature, resulting in significant visual impairment. *Intra ocular part* - The intraocular part of the optic nerve, including the **optic disc**, is typically protected by the globe and orbit against blunt trauma. - Direct intraocular trauma, such as a penetrating injury, would be required to significantly affect this segment, which is not usually the cause in closed head trauma. *Intracranial part* - The intracranial part of the optic nerve is relatively mobile within the cerebrospinal fluid and is less prone to direct compression or shearing forces from closed head trauma compared to the optic canal. - While it can be affected by diffuse axonal injury or mass effects within the cranium, it is not the most commonly affected segment for traumatic optic neuropathy in closed head injuries. *Optic tract* - The **optic tract** lies posterior to the optic chiasm and is part of the central nervous system pathways for vision, not the optic nerve itself. - Injuries to the optic tract are more likely to cause homonymous hemianopia rather than the profound unilateral vision loss characteristic of traumatic optic neuropathy, and are generally less vulnerable to direct mechanical trauma from closed head injury.
Question 153: Cephalic index is calculated as
- A. Biparietal Diameter / Occipitofrontal Diameter (Correct Answer)
- B. Biparietal Diameter / Head Circumference
- C. Head Circumference / Femur Length
- D. Occipitofrontal Diameter / Biparietal Diameter
Explanation: ***Biparietal Diameter / Occipitofrontal Diameter*** - The **cephalic index** is a measure used in **craniometry** to describe the shape of the skull, calculated by dividing the maximum **biparietal diameter** (width) by the maximum **occipitofrontal diameter** (length) and multiplying by 100. [1] - This ratio helps classify head shapes into **brachycephalic** (short, wide), **mesocephalic** (medium), and **dolichocephalic** (long, narrow). *Biparietal Diameter / Head Circumference* - This ratio is not the standard definition for the **cephalic index**; head circumference is a measure of overall head size, not its proportional shape in terms of width to length. - While both parameters are used in fetal biometry, their ratio does not define the **cephalic index**. *Head Circumference / Femur Length* - This ratio is completely unrelated to the **cephalic index**. - **Head circumference** estimates head size, and **femur length** estimates fetal long bone growth, both used for gestational age assessment, but not for skull shape. *Occipitofrontal Diameter / Biparietal Diameter* - This formula represents the inverse of the **cephalic index**, which would yield a different and non-standard index for skull shape. - The traditional and medically recognized formula for the **cephalic index** places the **biparietal diameter** in the numerator.
Question 154: Anterior Mediastinal nodes are included in which level of lymph nodes?
- A. I
- B. V
- C. VI (Correct Answer)
- D. VII
Explanation: ***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.
Question 155: Most common site for Cystic Hygroma is -
- A. Lower third of neck (Correct Answer)
- B. Overlying the parotid gland
- C. Along the Zygomatic Prominence
- D. Post auricular
Explanation: ***Lower third of neck*** - **Cystic hygromas** (also known as **lymphatic malformations**) most commonly occur in the **posterior triangle of the neck**, which is located in the lower lateral aspect of the neck [1]. - Approximately **75-80%** of cystic hygromas are found in the neck region, with the **posterior triangle** being the predominant site. - The **posterior jugular lymph sac** fails to connect properly with the venous system during embryonic development, leading to these cystic malformations in this characteristic location [1]. - The posterior triangle encompasses the lower lateral neck, making "lower third of neck" an acceptable description of this most common site. *Overlying the parotid gland* - While lymphatic malformations can occur in the parotid region, this represents only about **10-15%** of cases. - This is a less common site compared to the posterior triangle of the neck. - Lesions in this area might raise concern for other parotid pathologies like **pleomorphic adenoma** or **hemangioma**. *Along the Zygomatic Prominence* - This is an unusual location for a cystic hygroma, as the lymphatic drainage and embryonic development in this area are not typically associated with these malformations. - Lesions here might suggest different developmental or neoplastic etiologies such as **dermoid cysts** or **vascular malformations**. *Post auricular* - The post-auricular region is not a common site for cystic hygromas. - Swelling in this area could be due to other conditions like **mastoiditis**, **lymphadenopathy**, or **sebaceous cysts**.
Question 156: Transplanted kidney is relocated to which region in the recipient's body?
- A. Lumbar region
- B. Epigastrium
- C. Beside the dysfunctional kidney
- D. Retroperitoneal region (Correct Answer)
Explanation: ***Retroperitoneal region*** - The transplanted kidney is typically placed in the **iliac fossa** within the **retroperitoneal space** of the recipient [2]. - This location provides adequate space and a convenient site for connecting the transplant's renal artery and vein to the recipient's **iliac vessels**, and the ureter to the bladder [2]. *Lumbar region* - The native kidneys are located in the lumbar region, but a transplanted kidney is not usually placed there due to the complexity of vascular anastomoses and limited access [1]. - Positioning in the lumbar region would require more extensive surgical dissection and potentially longer vascular connections. *Epigastrium* - The epigastrium is the upper central part of the abdomen, above the navel. - This location is not suitable for kidney transplantation due to anatomical constraints and the lack of readily accessible large blood vessels for connection. *Beside the dysfunctional Kidney* - The dysfunctional native kidneys are usually left in place unless they are causing severe complications like uncontrolled hypertension or infection. - Placing the transplanted kidney directly beside the native dysfunctional kidney is not the standard procedure due to space limitations and to avoid operating near potentially diseased native organs.
Question 157: Food can commonly get obstructed in the esophagus at all of the following locations except
- A. Crossing of left bronchus
- B. Crossing of arch of aorta
- C. Crossing of the hemiazygous vein (Correct Answer)
- D. Diaphragmatic aperture
Explanation: 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 158: Which of the following statements about the bare area of the liver is false?
- A. It is circular in shape (Correct Answer)
- B. It is not a site of portocaval anastomosis
- C. Formed by the reflections of coronary ligaments
- D. Infection can spread from the abdominal to thoracic cavity at this area
Explanation: ***It is circular in shape*** - The bare area of the liver is **triangular** in shape, bordered by the reflections of the **coronary ligaments** and the inferior vena cava. [1] - Its shape is dictated by the anatomical arrangement of these peritoneal folds, making it distinctly non-circular. *Infection can spread from the abdominal to thoracic cavity at this area* - This statement is true because the bare area is the only part of the liver not covered by **peritoneum**, allowing direct contact between the liver and the diaphragm. [1] - This anatomical arrangement facilitates the spread of infections, like **subphrenic abscesses**, from the abdominal cavity to the posterior mediastinum and pleural cavity. [2] *It is not a site of portocaval anastomosis* - This statement is true; there is **no direct portosystemic shunt** at the bare area of the liver that becomes significant in portal hypertension. - While small veins connect the liver capsule to the diaphragm, these do not represent major portocaval anastomoses like those found at the gastroesophageal junction or rectum. *Formed by the reflections of coronary ligaments* - This statement is true; the bare area is specifically demarcated by the points where the **anterior and posterior layers of the coronary ligament** diverge, leaving a triangular region of the liver directly apposed to the diaphragm. [1] - The **coronary ligaments** are reflections of the peritoneum from the diaphragm onto the superior surface of the liver.
Question 159: What is the shape of caecum in the newborn?
- A. Ovoid
- B. Trapezoid
- C. Globular
- D. Conical (Correct Answer)
Explanation: ***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**.
Question 160: Which bones form the floor of the nasal cavity in children?
- A. Nasal bone and maxilla
- B. Vomer and ethmoid
- C. Palatine process of the maxilla and horizontal plate of the palatine bone (Correct Answer)
- D. Nasal crest of maxilla and palatine process of maxilla
Explanation: ***Palatine process of the maxilla and horizontal plate of the palatine bone*** - These two bones form the **hard palate**, which also serves as the **floor of the nasal cavity**. - The **palatine process of the maxilla** forms the anterior two-thirds, while the **horizontal plate of the palatine bone** forms the posterior one-third of the hard palate. *Vomer and ethmoid* - The **vomer** and part of the **ethmoid bone** (specifically the perpendicular plate) contribute to the **nasal septum**, which divides the nasal cavity. - They do not form the floor of the nasal cavity. *Nasal bone and maxilla* - The **nasal bones** form the **bridge of the nose** and part of the roof of the nasal cavity anteriorly. - While the **maxilla** contributes to the floor via its palatine process, the nasal bones do not. *Nasal crest of maxilla and palatine process of maxilla* - The **palatine process of the maxilla** does form part of the floor of the nasal cavity. - However, the **nasal crest of the maxilla** is part of the vomer's articulation and is involved in the septum, not the primary floor structure.