NEET-PG 2012 Practice Questions

Q: Which of the following is NOT a surface marking of the oblique fissure of the lung?

7th rib. ***7th rib*** - The **oblique fissure** typically extends from the spine at approximately the **T3 vertebral level** anteriorly to the **6th costal cartilage**. [1] - The **7th rib** is generally inferior to the typical anterior termination point of the oblique fissure. [1] *T3* - The **oblique fissure** begins posteriorly at the level of the **spinous process of T3**. [1] - This marks the superior-posterior extent of the fissure on the surface. *5th rib* - The **oblique fissure** crosses the **5th intercostal space** on the lateral chest wall. [1] - This point helps map the fissure's path between its posterior and anterior endpoints. *6th costal cartilage* - The **oblique fissure** terminates anteriorly near the **6th costal cartilage** in the midclavicular line. [1] - This represents the inferior-anterior most point of the fissure on the chest wall.

Q: Which of the following is NOT an anterior relation of the right kidney?

4th part of duodenum. ***4th part of duodenum*** - The **4th part of the duodenum** is located to the **left of the vertebral column** and is related to the **left kidney**, not the right kidney. - This segment passes superiorly along the left side of the aorta to become continuous with the jejunum at the duodenojejunal flexure. *Liver* - The **right kidney's superior part** is in direct contact with the **right lobe of the liver**, often separated only by the peritoneum [1]. - This is a significant anterior relation, explaining why liver enlargement can sometimes displace the right kidney. *Hepatic flexure* - The **hepatic flexure** (right colic flexure) of the colon lies immediately inferior to the liver and anterior to the **lower part of the right kidney**. - This anatomical relationship means that the right kidney can be affected by diseases of the colon in this region. *2nd part of duodenum* - The **descending (2nd) part of the duodenum** lies anterior to the **hilum and medial part of the right kidney** [1]. - Its retroperitoneal position places it in close proximity to the renal structures, making it a key anterior relation.

Q: Pancreas divisum indicates which of the following?

Failure of fusion of dorsal & ventral pancreatic buds. ***Failure of fusion of dorsal & ventral pancreatic buds*** - **Pancreas divisum** is a congenital anomaly where the **dorsal and ventral pancreatic buds fail to fuse** during embryonic development [1]. - This results in the **bulk of the pancreas (dorsal bud)** draining through the **accessory pancreatic duct** into the minor duodenal papilla, while the ventral bud drains via the main pancreatic duct [1]. *Duplication of the pancreas* - This condition involves the presence of **multiple, distinct pancreatic tissues**, which is different from pancreas divisum where the existing buds simply do not fuse. - Pancreas divisum is a failure of fusion of two normally formed buds, not the formation of extra pancreatic tissue. *Formation of more than two pancreatic buds* - Normal embryonic development typically involves two pancreatic buds (dorsal and ventral), not more than two [1]. - The issue in pancreas divisum is with the **fusion process**, not the number of initial buds [1]. *Formation of only one pancreatic bud* - Pancreatic development normally involves **two distinct buds (dorsal and ventral)** [1]. - The formation of only one bud would lead to pancreatic agenesis or severe hypoplasia, which is a different anomaly than pancreas divisum.

Q: During incision and drainage of ischiorectal abscess, which nerve is most likely to be injured?

Inferior rectal nerve. ***Inferior rectal nerve*** - The **inferior rectal nerve** innervates the **external anal sphincter** and the skin around the anus, making it vulnerable during an incision and drainage of an **ischiorectal abscess** due to its anatomical proximity. - Injury to this nerve can lead to **fecal incontinence** or altered sensation in the perianal region. *Superior rectal nerve* - The **superior rectal nerve** is primarily involved in the innervation of the **rectum** and is not directly located in the area of an **ischiorectal abscess**. - This nerve supplies the smooth muscle of the rectum and is not anatomically vulnerable during incision and drainage of an abscess in the ischiorectal fossa. *Superior gluteal nerve* - The **superior gluteal nerve** supplies the **gluteus medius**, **gluteus minimus**, and **tensor fasciae latae muscles**, which are typically located much more superior and lateral to an **ischiorectal abscess**. - Damage to this nerve causes a characteristic **Trendelenburg gait**, which is unrelated to perianal surgery. *Inferior gluteal nerve* - The **inferior gluteal nerve** innervates the **gluteus maximus muscle**, which is also located more superiorly and laterally relative to the **ischiorectal fossa**. - Injury to this nerve would primarily affect hip extension and is not a common complication of **ischiorectal abscess** drainage.

Q: Which structure is not seen at the L3 level?

Coeliac trunk. ***Coeliac trunk*** - The **coeliac trunk** typically arises from the abdominal **aorta** at the level of **T12-L1**, which is significantly higher than L3. - It then immediately branches into the **left gastric**, **splenic**, and **common hepatic arteries** to supply foregut structures. *Iliac vessels* - The **common iliac arteries** and veins typically bifurcate from the **aorta** and **IVC** around the L4-L5 level. - Their presence, or the start of their formation, can be observed near or just above **L3**, depending on individual anatomical variation and how "at the L3 level" is interpreted (e.g., within the L3 vertebral body's span). *Aorta* - The **abdominal aorta** descends along the posterior abdominal wall and is a prominent structure at the **L3 level**. - It typically bifurcates into the common iliac arteries at the level of **L4**, meaning it is still a large, undivided vessel at L3. *IVC* - The **inferior vena cava (IVC)** ascends through the abdomen and is a significant vascular structure at the **L3 level**. - It is formed by the union of the common iliac veins at the level of **L5** and continues superiorly.

Q: In which region of the human spine is the number of vertebrae usually constant?

Cervical. ***Cervical*** - The human cervical spine almost universally consists of **seven vertebrae (C1-C7)**, making it the most constant region in terms of vertebral number. - This consistent number is crucial for normal neck movement and protection of vital neurological structures. *Thoracic* - While typically having **12 vertebrae**, variations in the thoracic region can occur, with some individuals having 11 or 13 due to transitional vertebrae. - These variations are less common but indicate that the number is not as strictly constant as in the cervical spine. *Lumbar* - The lumbar spine commonly has **five vertebrae (L1-L5)**, but variations such as four or six lumbar vertebrae can be seen due to lumbarization or sacralization. - **Lumbarization** involves the first sacral segment detaching, while **sacralization** involves the fifth lumbar vertebra fusing with the sacrum. *Sacral* - The sacrum is formed by the fusion of **five sacral vertebrae (S1-S5)**, but the number of *individual identifiable* vertebrae before fusion, or in cases of incomplete fusion, can vary. - The sacral region itself is a fused structure, and while it originates from five segments, the concept of "number of vertebrae" can be ambiguous due to its characteristic fusion.

Q: Which cranial nerve is not associated with the nucleus ambiguus?

Cranial Nerve XII (Hypoglossal). ***Cranial Nerve XII (Hypoglossal)*** - The **hypoglossal nucleus** in the medulla is the origin for CN XII, which primarily controls **tongue movements** [1]. - It does not receive motor fibers from the nucleus ambiguus, as its function is unrelated to the pharyngeal or laryngeal musculature. *Cranial Nerve X (Vagus)* - Motor fibers for the muscles of the **pharynx** and **larynx** from the nucleus ambiguus contribute to the vagus nerve. - The vagus nerve also provides parasympathetic innervation to the **thoracic and abdominal viscera**. *Cranial Nerve XI (Accessory)* - Cranial root contributions from the nucleus ambiguus exit with the vagus nerve to innervate the **laryngeal muscles**. - The **spinal root** of the accessory nerve, originating from the cervical spinal cord, innervates the **sternocleidomastoid** and **trapezius muscles**. *Cranial Nerve IX (Glossopharyngeal)* - The nucleus ambiguus provides motor innervation for the **stylopharyngeus muscle** via the glossopharyngeal nerve. - This muscle plays a role in **swallowing** and elevates the pharynx.

Q: Nucleus gracilis and nucleus cuneatus are seen in?

Medulla. ***Medulla*** - The **nucleus gracilis** and **nucleus cuneatus** are located in the **dorsal medulla** and are crucial for processing **conscious proprioception**, **vibration**, and **fine touch**. - These nuclei receive input from the fasciculus gracilis and fasciculus cuneatus (dorsal column tracts) and are part of the dorsal column-medial lemniscus pathway. - They give rise to the **internal arcuate fibers** which decussate and form the **medial lemniscus**. *Pons* - The pons contains several important nuclei, including the **pontine nuclei** (involved in motor coordination), nuclei of cranial nerves V, VI, VII, and VIII, and the **locus coeruleus**. - The dorsal column nuclei are not located in the pons. *Temporal lobe* - The **temporal lobe** is part of the cerebral cortex and is primarily involved in **auditory processing**, memory formation, and language comprehension. - It contains structures like the hippocampus and amygdala, but not the dorsal column nuclei. *Midbrain* - The **midbrain** contains nuclei such as the **red nucleus**, **substantia nigra**, and nuclei of cranial nerves III and IV, involved in motor control and eye movements. - The nucleus gracilis and nucleus cuneatus are not found in the midbrain.

Q: All the following are characteristics of the oculomotor nerve except:

Enters orbit through the inferior orbital fissure. ***Enters orbit through the inferior orbital fissure*** - The oculomotor nerve **does not** enter the orbit through the **inferior orbital fissure**; it enters via the **superior orbital fissure**. - The **inferior orbital fissure** transmits structures like the **maxillary nerve (V2)**, **zygomatic nerve**, and **inferior ophthalmic vein**. *Carries parasympathetic nerve fibres* - The oculomotor nerve contains **parasympathetic preganglionic fibers** that synapse in the **ciliary ganglion** [1]. - These fibers control **pupillary constriction** (via the **sphincter pupillae**) and **accommodation** (via the **ciliary muscle**) [1]. *Supplies inferior oblique muscle* - The **inferior oblique muscle** is one of the **extraocular muscles** innervated by the **oculomotor nerve (CN III)** [2]. - This muscle works to **elevate** and **externally rotate** the eye [2]. *Enters orbit through the superior orbital fissure* - The oculomotor nerve indeed passes through the **superior orbital fissure** to enter the orbit. - This fissure serves as the passage for several cranial nerves and vessels, including the **oculomotor (III)**, **trochlear (IV)**, **abducens (VI)**, and branches of the **ophthalmic nerve (V1)**.

Q: Peripheral and central chemoreceptors may both contribute to the increased ventilation that occurs as a result of which of the following?

An increase in arterial carbon dioxide tension. ***An increase in arterial carbon dioxide tension*** - An increase in **arterial PCO2** (hypercapnia) leads to a rapid decrease in the **pH of the cerebrospinal fluid (CSF)**, which strongly stimulates **central chemoreceptors** in the medulla. - While overwhelmingly driven by central chemoreceptors, a significant increase in **arterial PCO2** also causes a slight decrease in **arterial pH**, which can additionally stimulate **peripheral chemoreceptors** in the carotid and aortic bodies, leading to increased ventilation. *A decrease in arterial oxygen content* - A decrease in **arterial oxygen content** (e.g., due to anemia or carbon monoxide poisoning) without a significant drop in **arterial PO2** primarily affects oxygen delivery to tissues. - It does not directly stimulate peripheral chemoreceptors, which are sensitive to **PO2**, not content, nor does it affect central chemoreceptors directly to increase ventilation in this manner. *A decrease in arterial blood pressure* - A decrease in **arterial blood pressure** is sensed by **baroreceptors** and primarily triggers cardiovascular reflexes (e.g., increased heart rate and vasoconstriction) to restore blood pressure. - It does not directly stimulate peripheral or central chemoreceptors to significantly increase ventilation unless severe hypoperfusion leads to significant changes in arterial blood gases. *A decrease in arterial oxygen tension* - A decrease in **arterial oxygen tension (PO2)**, especially when it falls below approximately 60 mmHg, acts as a potent stimulus for **peripheral chemoreceptors**. - However, **central chemoreceptors** are primarily sensitive to **PCO2** and CSF pH, and a decrease in **arterial PO2** alone has little direct effect on their activity.

Question 1

Which of the following is NOT a surface marking of the oblique fissure of the lung?

Accepted Answer

7th rib

Answer

6th costal cartilage

Answer

T3

Answer

5th rib

Question 2

Which of the following is NOT an anterior relation of the right kidney?

Accepted Answer

4th part of duodenum

Answer

Hepatic flexure

Answer

Liver

Answer

2nd part of duodenum

Question 3

Pancreas divisum indicates which of the following?

Accepted Answer

Failure of fusion of dorsal & ventral pancreatic buds

Answer

Duplication of the pancreas

Answer

Formation of more than two pancreatic buds

Answer

Formation of only one pancreatic bud

Question 4

During incision and drainage of ischiorectal abscess, which nerve is most likely to be injured?

Accepted Answer

Inferior rectal nerve

Answer

Superior rectal nerve

Answer

Superior gluteal nerve

Answer

Inferior gluteal nerve

Question 5

Which structure is not seen at the L3 level?

Accepted Answer

Coeliac trunk

Answer

Iliac vessels

Answer

Aorta

Answer

IVC

Question 6

In which region of the human spine is the number of vertebrae usually constant?

Accepted Answer

Cervical

Answer

Thoracic

Answer

Lumbar

Answer

Sacral

Question 7

Which cranial nerve is not associated with the nucleus ambiguus?

Accepted Answer

Cranial Nerve XII (Hypoglossal)

Answer

Cranial Nerve X (Vagus)

Answer

Cranial Nerve XI (Accessory)

Answer

Cranial Nerve IX (Glossopharyngeal)

Question 8

Nucleus gracilis and nucleus cuneatus are seen in?

Accepted Answer

Medulla

Answer

Temporal lobe

Answer

Midbrain

Answer

Pons

Question 9

All the following are characteristics of the oculomotor nerve except:

Accepted Answer

Enters orbit through the inferior orbital fissure

Answer

Carries parasympathetic nerve fibres

Answer

Supplies inferior oblique muscle

Answer

Enters orbit through the superior orbital fissure

Question 10

Peripheral and central chemoreceptors may both contribute to the increased ventilation that occurs as a result of which of the following?

Accepted Answer

An increase in arterial carbon dioxide tension

Answer

A decrease in arterial oxygen content

Answer

A decrease in arterial blood pressure

Answer

A decrease in arterial oxygen tension

NEET-PG 2012

Anatomy

Physiology