NEET-PG 2015 Practice Questions

Q: Which is the largest nerve that exits the pelvis through the greater sciatic foramen?

Sciatic nerve. ***Sciatic nerve*** - The **sciatic nerve** is the largest nerve in the human body, formed from the sacral plexus, and it is indeed the largest structure that passes through the **greater sciatic foramen** as it descends into the posterior thigh. - It supplies motor and sensory innervation to the posterior thigh, lower leg, and foot. *Superior gluteal artery* - The superior gluteal artery exits the pelvis through the **greater sciatic foramen** above the piriformis muscle. - While significant, it is an artery and not a nerve, and it is not the largest structure passing through this foramen. *Inferior gluteal artery* - The inferior gluteal artery also exits the pelvis via the **greater sciatic foramen**, inferior to the piriformis muscle. - Like the superior gluteal artery, it is an arterial structure and not a nerve, and it is not the largest structure in the foramen. *Piriformis muscle* - The **piriformis muscle** originates inside the pelvis and passes through the **greater sciatic foramen** to insert on the greater trochanter of the femur. - Although it occupies a significant portion of the foramen, it is a muscle, not a nerve, and the sciatic nerve is the largest nerve exiting this aperture.

Q: Fibrous stroma of liver is derived from -

Mesoderm from the septum transversum. ***Mesoderm from the septum transversum*** - The **fibrous stroma of the liver**, which provides its structural framework, develops from the **mesoderm** of the **septum transversum** [1]. - The septum transversum is a thick mass of mesoderm that contributes to the formation of the **diaphragm** and the connective tissue elements of the liver [1]. *Endoderm from the foregut* - While the **parenchymal cells (hepatocytes)** of the liver are derived from the **endoderm of the foregut**, this tissue forms the functional units, not the fibrous supporting stroma. - The endoderm forms the glandular tissue, while the mesoderm forms the connective tissue [1]. *Endoderm from the midgut* - The midgut endoderm gives rise to structures like the **small intestine**, cecum, appendix, ascending colon, and part of the transverse colon, but not the liver's stroma [2]. - Its primary role is in forming the epithelial lining of these digestive organs. *Endoderm from the hindgut* - The hindgut endoderm develops into the distal third of the transverse colon, descending colon, sigmoid colon, rectum, and superior part of the anal canal, - It plays no role in the development of the liver's fibrous stroma.

Q: Inferior pancreaticoduodenal artery is a branch of which of the following arteries?

Superior mesenteric artery. ***Superior mesenteric artery*** - The **inferior pancreaticoduodenal artery** is a direct branch of the **superior mesenteric artery (SMA)**. - It supplies the **head of the pancreas** and the **duodenum**, anastomosing with branches from the gastroduodenal artery. *Splenic artery* - The splenic artery is a branch of the **celiac trunk** and primarily supplies the **spleen**, stomach, and pancreas (via pancreatic branches). - It does not give rise to the inferior pancreaticoduodenal artery. *Left gastric artery* - The left gastric artery is a branch of the **celiac trunk** and supplies the **lesser curvature of the stomach** and distal esophagus. - It has no direct connection to the inferior pancreaticoduodenal artery. *Gastroduodenal artery* - The gastroduodenal artery is a branch of the **common hepatic artery** (from the celiac trunk) and gives off the **anterior and posterior superior pancreaticoduodenal arteries**. - While it supplies the head of the pancreas and duodenum, it is not the origin of the inferior pancreaticoduodenal artery, which arises from the SMA.

Q: Nephron is derived from ?

Metanephros. ***Metanephros*** - The **metanephric mesenchyme**, also known as the **metanephros**, gives rise to the excretory units of the kidney, which are the nephrons. - This mesenchymal tissue differentiates to form the **glomerulus**, Bowman's capsule, proximal and distal convoluted tubules, and the loop of Henle. *Ureteric bud* - The **ureteric bud** originates from the mesonephric duct and forms the collecting system of the kidney, including the ureter, renal pelvis, calyces, and collecting ducts. - It induces the differentiation of the metanephric mesenchyme but does not directly form the nephron itself. *Mesonephric duct* - The **mesonephric duct** (Wolffian duct) is a primitive embryonic structure that gives rise to the ureteric bud and parts of the male reproductive system. - It does not directly form any part of the nephron. *Mesonephros* - The **mesonephros** is a transient embryonic kidney that functions briefly during fetal development. - It degenerates and does not contribute to the formation of the definitive nephrons in the mature kidney.

Q: Fossa ovalis is a remnant of -

Septum primum. ***Septum primum*** - The **fossa ovalis** is a depression in the right atrium that represents the sealed-off foramen ovale [2]. - It is formed from the **septum primum**, which becomes the floor of the fossa ovalis. *Septum secundum* - The **septum secundum** forms the limbus or rim of the fossa ovalis, not the fossa itself. - This structure develops later than the septum primum and partially covers the foramen ovale during fetal development [2]. *Septum spurium* - The **septum spurium** is an embryonic ridge in the right atrium that typically regresses during development and does not contribute to the fossa ovalis. - It is a transient structure formed by the confluence of the right and left venous valves. *AV cushion* - The **atrioventricular (AV) cushions** contribute to the formation of the AV valves and the atrial and ventricular septa, but not directly to the fossa ovalis [1]. - They are crucial for separating the atria from the ventricles and forming the mitral and tricuspid valves.

Q: The internal anal sphincter is a part of which of the following?

Internal circular fibers. ***Internal circular fibers*** - The **internal anal sphincter** is an involuntary muscle formed by the thickening of the **circular smooth muscle layer** of the rectum. - This sphincter maintains **tonic contraction** and is responsible for about 80% of resting anal pressure [1]. *Puborectalis muscle* - The **puborectalis muscle** is a voluntary muscle, forming a sling around the anorectal junction to maintain the **anorectal angle** [1]. - It is part of the **levator ani muscles**, which are skeletal muscles, not smooth muscle [1]. *Deep perineal muscles* - The **deep perineal muscles** are a group of skeletal muscles located in the urogenital diaphragm. - They are involved in functions such as **urinary continence** and **erection**, but do not form the internal anal sphincter. *Internal longitudinal fibers* - The **longitudinal muscle layer** of the rectum continues downwards as the conjoined longitudinal muscle, which blends with the external anal sphincter. - These fibers contribute to the **anorectal ring** and support the anal canal but do not form the internal anal sphincter itself.

Q: Which artery passes through the anatomical snuffbox?

Radial artery. ***Radial artery*** - The **radial artery** is palpable within the **anatomical snuffbox**, as it courses over the scaphoid and trapezium bones towards the deep palmar arch. - This location is clinically significant for feeling the pulse and is vulnerable to injury, especially during **scaphoid fractures**. *Brachial artery* - The **brachial artery** is found in the **arm**, typically running in the cubital fossa, well proximal to the anatomical snuffbox. - It bifurcates into the radial and ulnar arteries at the level of the elbow, not within the wrist structures. *Ulnar artery* - The **ulnar artery** typically lies on the **medial side of the forearm** and wrist, contributing to the superficial palmar arch. - It does not pass through the anatomical snuffbox, which is located on the lateral aspect of the wrist. *Interosseus artery* - The **interosseus arteries** (anterior and posterior) run between the radius and ulna in the forearm, supplying muscles and bones. - These arteries are deep within the forearm compartments and do not traverse the superficial anatomical snuffbox at the wrist.

Q: Which of the following is not a recognized stage of prophase I in meiosis?

Arachytene. ***Arachytene*** - **Arachytene** is not a recognized stage of prophase I in meiosis. - The correct stages are leptotene, zygotene, pachytene, diplotene, and diakinesis. *Diakinesis* - **Diakinesis** is the final stage of prophase I, where homologous chromosomes condense further, and the nuclear envelope begins to break down. - Chiasmata terminalize, and the bivalents are ready for metaphase I. *Leptotene* - **Leptotene** is the first stage of prophase I, characterized by the condensation of chromatin into visible chromosomes. - Chromosomes appear as long, thin threads. *Zygotene* - **Zygotene** is the second stage of prophase I, where homologous chromosomes pair up in a process called **synapsis**, forming bivalents. - The synaptonemal complex begins to form between homologous chromosomes.

Q: Spermatogenesis begins at -

Puberty. ***Puberty*** - **Spermatogenesis**, the process of sperm production, is initiated and sustained by the surge of **gonadotropin-releasing hormone (GnRH)**, which begins at puberty. - This hormonal signal leads to the secretion of **luteinizing hormone (LH)** and **follicle-stimulating hormone (FSH)**, crucial for testicular function and sperm development. *Birth* - At birth, the male testes contain **spermatogonia**, but these cells remain dormant and do not begin active sperm production. - Hormonal levels at birth are not conducive to initiating spermatogenesis. *5 years* - While some hormonal changes occur in early childhood, they are not sufficient to trigger the full process of spermatogenesis. - The reproductive system is still in a quiescent state before puberty. *18 years* - By 18 years, spermatogenesis is typically well-established and has been ongoing for several years, having started at puberty. - This age marks a period of full reproductive maturity, not the initiation of sperm production.

Q: Which of the following statements is true about branchial cysts?

They mostly arise from the second branchial cleft.. ***They mostly arise from the second branchial cleft.*** - **Second branchial cleft cysts** are the most common type, accounting for approximately **95%** of all branchial anomalies. - They typically present as a smooth, fluctuant mass along the **anterior border of the sternocleidomastoid muscle** at the junction of the upper and middle third of the neck. - These cysts result from **incomplete obliteration** of the second branchial cleft during embryonic development. *Branchial cysts are more common in males than females.* - Branchial cysts have **no significant sex predilection**, affecting males and females with roughly equal frequency. - The overall incidence is relatively rare, with most cases presenting in late childhood or early adulthood. *Surgical intervention is not always necessary.* - **Complete surgical excision** is the **definitive treatment** and is strongly recommended for all branchial cysts. - Indications for surgery include: prevention of **recurrent infections**, risk of **abscess formation**, elimination of cosmetic concerns, and removal due to potential (though rare) **malignant transformation**. - While very small asymptomatic cysts may occasionally be observed, this carries significant risk of future complications, making surgery the standard of care in clinical practice. *They can cause dysphagia and hoarseness if infected.* - While an **infected branchial cyst** causes local inflammatory signs (pain, swelling, warmth, erythema), it **rarely causes dysphagia or hoarseness** unless exceptionally large. - These symptoms would require the cyst to compress the **pharynx** (dysphagia) or involve the **recurrent laryngeal nerve** (hoarseness), which is uncommon even with infection. - The primary presentation of infected cysts includes **tender neck mass** with overlying skin changes and possible **abscess formation**.

Question 1

Which is the largest nerve that exits the pelvis through the greater sciatic foramen?

Accepted Answer

Sciatic nerve

Answer

Superior gluteal artery

Answer

Inferior gluteal artery

Answer

Piriformis muscle

Question 2

Fibrous stroma of liver is derived from -

Accepted Answer

Mesoderm from the septum transversum

Answer

Endoderm from the foregut

Answer

Endoderm from the midgut

Answer

Endoderm from the hindgut

Question 3

Inferior pancreaticoduodenal artery is a branch of which of the following arteries?

Accepted Answer

Superior mesenteric artery

Answer

Splenic artery

Answer

Left gastric artery

Answer

Gastroduodenal artery

Question 4

Nephron is derived from ?

Accepted Answer

Metanephros

Answer

Ureteric bud

Answer

Mesonephric duct

Answer

Mesonephros

Question 5

Fossa ovalis is a remnant of -

Accepted Answer

Septum primum

Answer

Septum secundum

Answer

Septum spurium

Answer

AV cushion

Question 6

The internal anal sphincter is a part of which of the following?

Accepted Answer

Internal circular fibers

Answer

Puborectalis muscle

Answer

Deep perineal muscles

Answer

Internal longitudinal fibers

Question 7

Which artery passes through the anatomical snuffbox?

Accepted Answer

Radial artery

Answer

Brachial artery

Answer

Ulnar artery

Answer

Interosseus artery

Question 8

Which of the following is not a recognized stage of prophase I in meiosis?

Accepted Answer

Arachytene

Answer

Diakinesis

Answer

Leptotene

Answer

Zygotene

Question 9

Spermatogenesis begins at -

Accepted Answer

Puberty

Answer

Birth

Answer

5 years

Answer

18 years

Question 10

Which of the following statements is true about branchial cysts?

Accepted Answer

They mostly arise from the second branchial cleft.

Answer

Branchial cysts are more common in males than females.

Answer

Surgical intervention is not always necessary.

Answer

They can cause dysphagia and hoarseness if infected.

NEET-PG 2015

Anatomy

Physiology

Surgery