NEET-PG 2012 Practice Questions

Q: Which bone has the maximum anatomical contribution to the floor of the orbit?

Maxillary. ***Maxillary*** - The **maxilla** contributes the most significantly to the **orbital floor**, forming approximately **75%** of its surface area. - The orbital plate of the maxilla is a thin, triangular bone that also forms the roof of the **maxillary sinus**. *Zygomatic* - The **zygomatic bone** forms the **lateral wall** and the **lateral portion** of the **orbital floor**. - Its contribution to the overall floor is less extensive than that of the maxilla (approximately 20-25%). *Sphenoid* - The **sphenoid bone** does **NOT** contribute to the **orbital floor** at all. - It forms parts of the **posterior wall** and **lateral wall** (via greater and lesser wings) of the orbit, but has no anatomical contribution to the floor. *Palatine* - The **palatine bone** (via its orbital process) contributes a very small, **posterior-most part** of the **orbital floor**. - Its contribution is minimal (less than 5%) compared to the maxilla and zygomatic bone.

Q: From which ribs does the spleen extend?

9th to 11th rib. ***9th to 11th rib*** - The **spleen** is located in the **left upper quadrant** of the abdomen, deep to the 9th, 10th, and 11th ribs. - Its protected position beneath these ribs makes it vulnerable to injury from trauma to the left lower chest or upper abdomen. *5th to 9th rib* - This range primarily covers the location of the **heart** and the upper part of the **lungs**. - While the spleen is superior to other abdominal organs, it does not extend as high as the 5th rib. *2nd to 5th rib* - This region is mainly associated with the **upper lobes of the lungs** and the **superior mediastinum**. - The spleen is an abdominal organ and is situated much lower in the thoracic cavity. *11th to 12th rib* - This range is too low and posterior for the typical position of the spleen, especially for its superior border. - The 12th rib primarily overlies the **kidneys** and the more inferior aspects of the diaphragm.

Q: In bladder injury, pain is referred to which of the following areas?

Lower abdominal wall. ***Correct Option: Lower abdominal wall*** - **Referred pain** from the bladder is typically felt in the **suprapubic region** of the lower abdominal wall due to shared visceral and somatic afferent innervation. - The **parietal peritoneum** overlying the bladder is innervated by somatic nerves that also supply the abdominal wall. - This convergence of visceral afferents from the bladder and somatic afferents from the abdominal wall at the spinal cord level (particularly S2-S4) results in referred pain to the suprapubic area. *Incorrect Option: Upper part of thigh* - Pain in the upper thigh is more commonly associated with conditions affecting the **hip joint**, **femoral nerve**, or **inguinal region**. - Bladder innervation does not primarily refer pain to the upper thigh. *Incorrect Option: Flank* - Flank pain is typically associated with conditions of the **kidneys** or **ureters**, such as **nephrolithiasis** or **pyelonephritis**. - The bladder's referred pain pattern does not usually extend to the flank. *Incorrect Option: Penis* - While bladder irritation can sometimes cause sensations in the penis, it is more often associated with conditions like **urethritis**, **cystitis**, or **prostatitis**. - Direct referred pain from bladder injury to the penis is less common than to the lower abdominal wall.

Q: Inferior parathyroid develops from which pharyngeal pouch?

3rd. The inferior parathyroid glands develop from the dorsal wing of the third pharyngeal pouch. Due to their origin, they often migrate further caudally than the superior parathyroid glands, sometimes even locating within the thymus which also develops from the third pouch. *1st* - The first pharyngeal pouch contributes to the formation of the eustachian tube, tympanic cavity, and mastoid air cells. - It has no role in the development of the parathyroid glands. *2nd* - The second pharyngeal pouch mainly gives rise to the palatine tonsils and their crypts. - It is not involved in the development of parathyroid tissue. *4th* - The fourth pharyngeal pouch gives rise to the superior parathyroid glands and the parafollicular cells (C cells) of the thyroid, which produce calcitonin. - While it forms parathyroid tissue, it is for the superior glands, not the inferior ones.

Q: Which of the following is derived from endoderm?

Gall bladder. ***Gall bladder*** - The **gallbladder**, along with other organs of the **gastrointestinal tract** such as the liver, pancreas, and epithelial lining of the digestive and respiratory systems, originates from the **endoderm** [1]. - The endoderm forms the primitive gut tube, from which these accessory digestive organs bud off. *Lens* - The **lens of the eye** is derived from the **surface ectoderm**, which invaginates to form the lens vesicle. - This contrasts with the neural ectoderm, which forms the neural tube and retina. *Spleen* - The **spleen** is derived from the **mesoderm**, specifically from mesenchymal cells in the dorsal mesentery of the stomach. - It is involved in blood filtration and immune responses, making it a lymphoid organ. *Lymph nodes* - **Lymph nodes** are primarily derived from the **mesoderm**, specifically from specialized mesenchymal cells that form their connective tissue capsule and stroma. - The immune cells within the lymph nodes, such as lymphocytes, originate from hematopoietic stem cells that migrate into these developing structures.

Q: Which of the following is not a boundary of Koch's triangle?

Limbus fossa ovalis. ***Limbus fossa ovalis*** - The **limbus fossa ovalis** is a prominent oval ridge on the **interatrial septum** that surrounds the fossa ovalis. - It is **not involved** in forming the boundaries of Koch's triangle, which is located in the **right atrium** near the AV node [1]. *Tricuspid valve ring* - The **tricuspid valve ring** (or annulus) forms one of the key anatomical boundaries of **Koch's triangle**, specifically its base [1]. - This **fibrous ring** anchors the tricuspid valve leaflets and marks the inferior aspect of the triangle [1]. *Coronary sinus* - The **coronary sinus ostium** (opening) forms another crucial boundary of **Koch's triangle** [1]. - It is located at the **inferior-posterior aspect** of the interatrial septum, opening into the right atrium [1]. *Tendon of todaro* - The **Tendon of Todaro** is a fibrous structure that forms the superior boundary of **Koch's triangle** [1]. - It extends from the **Eustachian valve** (of the inferior vena cava) towards the central fibrous body, playing a role in **AV nodal localization** [1].

Q: What is the anatomical significance of the Rhinion in relation to the osseocartilaginous junction?

Rhinion. ***Correct Answer: Rhinion*** - The **rhinion** is the **most prominent anterior point of the nasal bone**, often palpable as a slight bump or angulation on the dorsum of the nose. - It marks the anatomical location of the **osseocartilaginous junction** of the nasal dorsum, where the bony nasal framework transitions to the cartilaginous framework. - This is the key anatomical landmark that defines the transition from bone to cartilage in the external nose. *Incorrect: Nasion* - The **nasion** is located at the **root of the nose**, specifically at the most anterior and superior point of the nasofrontal suture. - It is a bony landmark and does not directly relate to the osseocartilaginous junction of the nasal dorsum. *Incorrect: Radix* - The **radix** (or nasal root) refers to the **uppermost part of the nose**, corresponding to the nasion. - It defines the point where the nose begins to project from the forehead and is a bony landmark, not directly related to the osseocartilaginous junction. *Incorrect: Columella* - The **columella** is the **fleshy, narrow strip of tissue that separates the nostrils**. - It forms the inferior segment of the nasal septum and is composed of skin, soft tissue, and the medial crura of the alar cartilages, thus having no direct relation to the osseocartilaginous junction of the nasal dorsum.

Q: In starvation, nitrogen is primarily carried from muscle to liver and kidney by which amino acid?

Alanine. ***Alanine*** - During starvation, muscles break down proteins, and the amino groups from these proteins are transferred to **pyruvate** to form **alanine** via the **glucose-alanine cycle (Cahill cycle)**. - **Alanine** is then released into the bloodstream and transported primarily to the **liver**, where its carbon skeleton can be used for **gluconeogenesis** and the amino group enters the urea cycle. - Note: While alanine is the primary carrier to the liver, **glutamine** is the main nitrogen carrier to the kidney. However, among the given options, alanine is unequivocally the correct answer. *Aspartic acid* - While aspartate is involved in amino group transfer and is a crucial component of the **urea cycle**, it is not the primary carrier for inter-organ nitrogen transport from muscle to liver during starvation. - Its role is more localized within the liver for the urea cycle rather than as a transport amino acid. *Glycine* - Glycine plays roles in various metabolic pathways, including synthesis of heme, purines, and conjugation reactions, but it is not the primary amino acid for carrying nitrogen from muscle to liver during starvation. - Its small size and simple structure make it less suitable for efficient nitrogen transport compared to alanine. *Asparagine* - Asparagine has a minor role in nitrogen transport but is not the primary carrier during starvation. - It is synthesized from **aspartate** and ammonia and is typically involved in protein synthesis and nitrogen storage in some tissues.

Q: Which of the following processes does not occur in mitochondria?

Glycogenolysis. ***Glycogenolysis*** - **Glycogenolysis** is the breakdown of **glycogen** into glucose, which primarily occurs in the **cytosol** of cells, mainly in the liver and muscles. - This process is crucial for maintaining blood glucose levels and providing energy during periods of fasting or increased demand, and it does not take place within the mitochondria. *Fatty acid oxidation* - **Fatty acid oxidation**, also known as beta-oxidation, is a mitochondrial process that breaks down fatty acids into **acetyl-CoA** for energy production. - This occurs extensively within the mitochondrial matrix, producing ATP. *Electron transport chain* - The **electron transport chain** is located in the **inner mitochondrial membrane** and is the final stage of aerobic respiration, producing the majority of ATP. - It involves a series of protein complexes that transfer electrons to oxygen, creating a proton gradient for ATP synthesis. *Citric acid cycle (Kreb's cycle)* - The **citric acid cycle**, or **Krebs cycle**, is a central metabolic pathway that occurs in the **mitochondrial matrix**. - It oxidizes acetyl-CoA, derived from carbohydrates, fats, and proteins, to produce ATP, NADH, and FADH2.

Q: What is the coenzyme form of pyridoxine?

PLP. ***PLP*** - **Pyridoxal phosphate (PLP)** is the active coenzyme form of **pyridoxine (vitamin B6)**. - It plays a crucial role in numerous metabolic reactions, particularly those involving **amino acid metabolism**. *ADP* - **Adenosine diphosphate (ADP)** is an important molecule in energy transfer, particularly in the formation of **ATP (adenosine triphosphate)**. - It is not a coenzyme form of any vitamin, but rather a **nucleotide**. *NAD* - **Nicotinamide adenine dinucleotide (NAD)** is a coenzyme derived from **niacin (vitamin B3)**. - It functions as an electron carrier in **redox reactions** and is vital for cellular respiration. *FAD* - **Flavin adenine dinucleotide (FAD)** is a coenzyme derived from **riboflavin (vitamin B2)**. - It also serves as an electron carrier in **redox reactions**, particularly in the electron transport chain.

Question 1

Which bone has the maximum anatomical contribution to the floor of the orbit?

Accepted Answer

Maxillary

Answer

Zygomatic

Answer

Sphenoid

Answer

Palatine

Question 2

From which ribs does the spleen extend?

Accepted Answer

9th to 11th rib

Answer

5th to 9th rib

Answer

2nd to 5th rib

Answer

11th to 12th rib

Question 3

In bladder injury, pain is referred to which of the following areas?

Accepted Answer

Lower abdominal wall

Answer

Flank

Answer

Upper part of thigh

Answer

Penis

Question 4

Inferior parathyroid develops from which pharyngeal pouch?

Accepted Answer

3rd

Answer

1st

Answer

2nd

Answer

4th

Question 5

Which of the following is derived from endoderm?

Accepted Answer

Gall bladder

Answer

Lens

Answer

Spleen

Answer

Lymph nodes

Question 6

Which of the following is not a boundary of Koch's triangle?

Accepted Answer

Limbus fossa ovalis

Answer

Tricuspid valve ring

Answer

Coronary sinus

Answer

Tendon of Todaro

Question 7

What is the anatomical significance of the Rhinion in relation to the osseocartilaginous junction?

Accepted Answer

Rhinion

Answer

Nasion

Answer

Radix

Answer

Columella

Question 8

In starvation, nitrogen is primarily carried from muscle to liver and kidney by which amino acid?

Accepted Answer

Alanine

Answer

Glycine

Answer

Aspartic acid

Answer

Asparagine

Question 9

Which of the following processes does not occur in mitochondria?

Accepted Answer

Glycogenolysis

Answer

Fatty acid oxidation

Answer

Electron transport chain

Answer

Citric acid cycle (Kreb's cycle)

Question 10

What is the coenzyme form of pyridoxine?

Accepted Answer

PLP

Answer

ADP

Answer

NAD

Answer

FAD

NEET-PG 2012

Anatomy

Biochemistry