NEET-PG 2013 Practice Questions

Q: Which is the primary muscle causing supination of the forearm?

Supinator. ***Supinator*** - The **supinator muscle** is the **primary muscle** responsible for **supination** of the forearm, rotating the palm anteriorly or superiorly. - It is a deep muscle of the **posterior compartment** of the forearm. - Its action is especially prominent when **supinating against resistance** or in very slow movements, as it works synergistically with the biceps brachii. *Biceps brachii* - While the **biceps brachii** is also a powerful **supinator** of the forearm, especially when the elbow is flexed, it is a **secondary supinator**. - It is primarily a major **flexor** of the elbow, whereas the supinator is dedicated specifically to supination. *Brachioradialis* - The **brachioradialis** is primarily a **flexor** of the forearm at the elbow joint. - It helps to bring the forearm into a **mid-prone or mid-supine position** from either full pronation or full supination, but does not actively supinate. *Anconeus* - The **anconeus** is a small muscle that assists the **triceps brachii** in **extension of the forearm** at the elbow. - It helps to **stabilize the elbow joint** and slightly abducts the ulna during pronation, but has no role in supination.

Q: Sacrotuberous ligament is pierced by

Perforating cutaneous nerve. ***Perforating cutaneous nerve*** - The **perforating cutaneous nerve** typically pierces the sacrotuberous ligament to innervate the skin over the medial part of the lower gluteal region. - This nerve originates from the **S2 and S3 anterior rami**. *Posterior femoral cutaneous* - The **posterior femoral cutaneous nerve** runs inferior to the piriformis muscle, superficial to the sacrotuberous ligament, but does not pierce it. - It supplies the skin on the posterior thigh and popliteal fossa. *Superior gluteal nerve* - The **superior gluteal nerve** exits the pelvis through the greater sciatic foramen, superior to the piriformis muscle, and does not interact with the sacrotuberous ligament in this manner. - It innervates the **gluteus medius, gluteus minimus**, and **tensor fasciae latae muscles**. *Sciatic nerve* - The **sciatic nerve** exits the pelvis via the greater sciatic foramen, inferior to the piriformis muscle, and passes superficial to the sacrotuberous ligament. - It does not pierce the ligament, but rather lies in close proximity to its inferior border.

Q: Which chamber of the heart forms the posterior surface?

Left Atrium (LA). ***Left Atrium (LA)*** - The **left atrium** forms the posterior surface of the heart, lying in front of the esophagus and thoracic aorta [1]. - Its posterior position makes it susceptible to enlargement, which can compress the **esophagus** and cause dysphagia [1]. *Right Atrium (RA)* - The **right atrium** primarily forms the right border of the heart and receives deoxygenated blood from the systemic circulation. - It lies anteriorly and to the right, behind the sternum and costal cartilages. *Left Ventricle (LV)* - The **left ventricle** forms the apex of the heart and part of the left border. - It is positioned *inferiorly* and *anteriorly*, contributing significantly to the *diaphragmatic surface* of the heart. *Right Ventricle (RV)* - The **right ventricle** forms the majority of the anterior surface of the heart, directly behind the sternum. - It also contributes to the *inferior surface* of the heart, resting on the diaphragm.

Q: Which chamber of the heart is located anterior to the sternum?

Right ventricle. ***Right ventricle*** - The **right ventricle** forms the majority of the **anterior surface of the heart** and is the chamber closest to the sternum [2]. - This anatomical position is important clinically, for instance, in cases of **pericardial effusion** or **chest trauma**. *Left atrium* - The **left atrium** is located most **posteriorly** in the heart, adjacent to the esophagus [1], [2]. - Due to its posterior position, an enlarged left atrium can compress the esophagus, causing **dysphagia**. *Left ventricle* - The **left ventricle** forms the **apex of the heart** and is located more on the left and posterior aspect compared to the right ventricle [2]. - While it contributes to the anterior surface, the **right ventricle** is more directly anterior to the sternum [2]. *Right atrium* - The **right atrium** is positioned to the right and slightly posterior to the right ventricle. - It receives venous blood from the body and forms the **right border of the heart**.

Q: Which of the following is a cerebellar nucleus?

Fastigial nucleus. ***Fastigial nucleus*** - The **fastigial nucleus** is one of the four principal deep cerebellar nuclei, involved in regulating **balance** and **posture** [2]. - The deep cerebellar nuclei are crucial for the cerebellum's output, relaying processed information to other brain regions [2]. *Caudate nucleus* - The **caudate nucleus** is part of the **basal ganglia**, a group of subcortical nuclei in the forebrain [1]. - It plays a significant role in **motor control**, learning, memory, and reward processing. *Subthalamic nucleus* - The **subthalamic nucleus** is a small nucleus located in the **diencephalon**, below the thalamus and above the substantia nigra [1]. - It is also part of the **basal ganglia system** and is critical for modulating motor control [1]. *Putamen* - The **putamen** is another structure belonging to the **basal ganglia**, located in the forebrain [1]. - It is primarily involved in regulating various types of **motor behavior** and learning.

Q: Which of the following does not have sympathetic noradrenergic fibers?

Sweat gland. ***Sweat gland*** - While sweat glands are innervated by the **sympathetic nervous system**, their postganglionic fibers are **cholinergic**, releasing **acetylcholine** rather than noradrenaline. - This is an important exception where sympathetic stimulation leads to acetylcholine release, causing sweating. *Blood vessels* - Most blood vessels, particularly resistance vessels such as **arterioles**, receive substantial **sympathetic noradrenergic innervation** that causes vasoconstriction. - This sympathetic tone is crucial for regulating **blood pressure** and distributing blood flow. *Heart* - The heart is richly innervated by **sympathetic noradrenergic fibers** that increase **heart rate**, **contractility**, and **conduction velocity** via beta-1 adrenergic receptors. - This makes noradrenaline a key neurotransmitter in the sympathetic regulation of cardiac function. *Eye* - The eye receives sympathetic noradrenergic innervation primarily to the **dilator pupillae muscle**, causing **mydriasis** (pupil dilation) upon activation. - These fibers also contribute to the sympathetic control of the **tarsal muscle** (Müller's muscle) in the eyelid.

Q: All should be features of a substance to measure GFR, except?

Freely reabsorbed. ***Freely reabsorbed*** - A substance used to measure GFR should **not be reabsorbed** by the kidney tubules. If it were reabsorbed, the amount excreted in the urine would be less than the amount filtered, leading to an **underestimation of GFR**. - The ideal GFR marker is **neither reabsorbed nor secreted**, ensuring that its excretion rate directly reflects the filtration rate. *Freely filtered across the glomerulus membrane* - For a substance to accurately measure GFR, it must be **freely filtered** from the blood into the Bowman's capsule, without any restriction due to its size or charge. - This ensures that its concentration in the glomerular filtrate is the same as in the plasma, allowing for a direct calculation of the filtration rate. *Not secreted by kidney* - An ideal GFR marker should **not be secreted** by the renal tubules, as active secretion would add to the amount excreted in the urine, leading to an **overestimation of GFR**. - This property, along with not being reabsorbed, ensures that the amount of the substance appearing in the urine solely reflects the amount filtered. *None of the options* - This option is incorrect because there is a definitive feature listed among the choices that is *not* a characteristic of an ideal GFR marker. The ability to be "freely reabsorbed" is a disqualifying trait.

Q: Which of the following statements is true regarding post-ganglionic parasympathetic fibers?

They release acetylcholine at the target organs.. ***They release acetylcholine at the target organs.*** - Post-ganglionic parasympathetic fibers are **cholinergic**, meaning they release the neurotransmitter **acetylcholine** at their effector organs. - This action mediates the characteristic "rest and digest" responses of the parasympathetic nervous system. *They originate from the spinal cord.* - **Pre-ganglionic parasympathetic fibers** originate from the **brainstem** (cranial nerves III, VII, IX, X) and the **sacral spinal cord** (S2-S4). - Post-ganglionic fibers originate in ganglia located near or within their target organs, not the spinal cord directly. *They are part of the sympathetic nervous system.* - Post-ganglionic parasympathetic fibers are a component of the **parasympathetic nervous system**, not the sympathetic nervous system. - The sympathetic and parasympathetic systems are distinct divisions of the autonomic nervous system with generally opposing functions. *They are responsible for 'fight or flight' responses.* - The **'fight or flight' response** is characteristic of the **sympathetic nervous system**, which prepares the body for stressful situations. - The parasympathetic nervous system is responsible for **'rest and digest' functions**, promoting energy conservation and maintenance activities.

Q: What type of reflex is the righting reflex?

Postural reflex. ***Postural reflex*** - The **righting reflex** is a mechanism that helps an animal or human maintain or regain their upright body position or head orientation in space, which is a key component of **postural control**. - It involves complex inputs from the **vestibular system**, visual system, and proprioceptors to adjust muscle tone and body position against gravity. - Examples include **neck righting reflex**, **body righting reflex**, and **labyrinthine righting reflex**. *Stretch reflex* - A **stretch reflex** is a monosynaptic reflex that causes a muscle to contract in response to being stretched, primarily to maintain muscle length and tone. - It does not encompass the complex, multi-sensory integration required for maintaining overall body orientation. *Spinal reflex* - A **spinal reflex** is any reflex arc whose neural circuit passes through the spinal cord, and it can be either monosynaptic or polysynaptic. - While the righting reflex involves spinal cord components, it is a broader, more integrated reflex that extends beyond a simple spinal cord circuit. *Ocular reflex* - **Ocular reflexes** are involuntary eye movements or responses, such as pupillary light reflex or vestibulo-ocular reflex, that primarily control eye position or pupil size. - They do not directly relate to the maintenance of the entire body's upright posture.

Q: Which of the following fiber types is classically categorized as Group B nerve fibers?

Sympathetic preganglionic. ***Sympathetic preganglionic*** - **Group B nerve fibers** are **myelinated preganglionic autonomic fibers** with intermediate diameter (3-15 μm) and moderate conduction velocity (3-15 m/s) - Both **sympathetic and parasympathetic preganglionic fibers** are classified as Group B fibers - **Sympathetic preganglionic** neurons are the classical example, originating from T1-L2 spinal segments and synapsing in paravertebral or prevertebral ganglia *Sympathetic postganglionic* - These are **unmyelinated Group C fibers** with slow conduction velocity (0.5-2 m/s) - They extend from ganglia to target organs *Parasympathetic preganglionic* - These are also **Group B fibers** (myelinated preganglionic) - However, **sympathetic preganglionic** is the more commonly cited classical example in standard classifications - They originate from cranial nerves (III, VII, IX, X) and sacral segments (S2-S4) *Parasympathetic postganglionic* - These are **unmyelinated Group C fibers** with the slowest conduction velocities - Short fibers extending from ganglia near or within target organs to effector cells

Question 1

Which is the primary muscle causing supination of the forearm?

Accepted Answer

Supinator

Answer

Brachioradialis

Answer

Anconeus

Answer

Biceps brachii

Question 2

Sacrotuberous ligament is pierced by

Accepted Answer

Perforating cutaneous nerve

Answer

Posterior femoral cutaneous nerve

Answer

Superior gluteal nerve

Answer

Sciatic nerve

Question 3

Which chamber of the heart forms the posterior surface?

Accepted Answer

Left Atrium (LA)

Answer

Right Atrium (RA)

Answer

Left Ventricle (LV)

Answer

Right Ventricle (RV)

Question 4

Which chamber of the heart is located anterior to the sternum?

Accepted Answer

Right ventricle

Answer

Left ventricle

Answer

Right atrium

Answer

Left atrium

Question 5

Which of the following is a cerebellar nucleus?

Accepted Answer

Fastigial nucleus

Answer

Putamen

Answer

Caudate nucleus

Answer

Subthalamic nucleus

Question 6

Which of the following does not have sympathetic noradrenergic fibers?

Accepted Answer

Sweat gland

Answer

Heart

Answer

Eye

Answer

Blood vessels

Question 7

All should be features of a substance to measure GFR, except?

Accepted Answer

Freely reabsorbed

Answer

Not secreted by kidney

Answer

Freely filtered across the glomerulus membrane

Answer

None of the options

Question 8

Which of the following statements is true regarding post-ganglionic parasympathetic fibers?

Accepted Answer

They release acetylcholine at the target organs.

Answer

They originate from the spinal cord.

Answer

They are part of the sympathetic nervous system.

Answer

They are responsible for 'fight or flight' responses.

Question 9

What type of reflex is the righting reflex?

Accepted Answer

Postural reflex

Answer

Spinal reflex

Answer

Ocular reflex

Answer

Stretch reflex

Question 10

Which of the following fiber types is classically categorized as Group B nerve fibers?

Accepted Answer

Sympathetic preganglionic

Answer

Sympathetic postganglionic

Answer

Parasympathetic preganglionic

Answer

Parasympathetic post ganglionic

NEET-PG 2013

Anatomy

Physiology