NEET-PG 2013 Practice Questions

Q: Which of the following is NOT a content of the occipital triangle?

Suprascapular nerve. Suprascapular nerve - The **suprascapular nerve** originates from the brachial plexus and supplies the supraspinatus and infraspinatus muscles; it travels through the suprascapular notch and is not found within the occipital triangle. - Its primary course and innervation are associated with the shoulder, entirely separate from the neck region defining the occipital triangle. *Great auricular nerve* - The **great auricular nerve** emerges from the cervical plexus and supplies sensory innervation to the skin over the parotid gland, mastoid process, and auricle, courses superficially across the sternocleidomastoid in the region of the occipital triangle. - It is a recognized content of the posterior triangle of the neck, which encompasses the occipital triangle. *Lesser occipital nerve* - The **lesser occipital nerve** arises from the cervical plexus at C2 and C3, providing sensory innervation to the skin of the neck and scalp posterior to the auricle. - It ascends along the posterior border of the sternocleidomastoid muscle, placing it within the boundaries of the occipital triangle. *Occipital artery* - The **occipital artery** is a branch of the external carotid artery that supplies blood to the posterior scalp. - It traverses the apex of the posterior triangle (including the occipital triangle) as it ascends to the back of the head.

Q: Medulla oblongata arises from which of the following?

Myelencephalon. ***Myelencephalon*** - The **myelencephalon** is the most caudal of the three primary brain vesicles and is the developmental origin of the **medulla oblongata**. - It differentiates from the **rhombencephalon** (hindbrain) and is responsible for vital autonomic functions. *Rhombencephalon* - The **rhombencephalon** is the hindbrain and is a primary brain vesicle that further divides into the **metencephalon** and **myelencephalon**. - While it is the parent structure, it does not directly give rise to the medulla oblongata as a final differentiated structure without further division. *Mesencephalon* - The **mesencephalon** is the midbrain, a primary brain vesicle that develops into structures like the **tectum** and **tegmentum** [1]. - It is located rostral to the rhombencephalon and is not involved in the development of the medulla oblongata [1]. *None of the options* - This option is incorrect because the **myelencephalon** is the direct embryonic precursor of the medulla oblongata.

Q: All are infraclavicular branches of brachial plexus except ?

Long thoracic nerve. Long thoracic nerve - The long thoracic nerve originates directly from the roots (C5, C6, C7) of the brachial plexus, making it a supraclavicular branch. - It does not arise from the cords of the brachial plexus, which are located infraclavicularly. Ulnar nerve - The ulnar nerve arises from the medial cord of the brachial plexus, which is an infraclavicular structure. - It supplies many intrinsic hand muscles and the ulnar half of the flexor digitorum profundus. Axillary nerve - The axillary nerve is a branch of the posterior cord of the brachial plexus, classifying it as an infraclavicular branch. - It innervates the deltoid and teres minor muscles. Thoracodorsal nerve - The thoracodorsal nerve also originates from the posterior cord of the brachial plexus, making it an infraclavicular branch [1]. - It provides motor innervation to the latissimus dorsi muscle [1].

Q: Transamination of Aspartate forms which compound?

Oxaloacetate. ***Oxaloacetate*** - **Aspartate** is transaminated by **aspartate aminotransferase (AST)**, transferring its alpha-amino group to **alpha-ketoglutarate**. - This reaction converts aspartate into its corresponding alpha-keto acid, which is **oxaloacetate**. *Pyruvate* - **Pyruvate** is the alpha-keto acid corresponding to the amino acid **alanine**. - Transamination of **alanine** yields **pyruvate**, not aspartate. *Acetyl-CoA* - **Acetyl-CoA** is not a direct product of amino acid transamination; it is formed from **pyruvate** or fatty acid oxidation. - It functions as a key metabolic intermediate in energy production and biosynthesis. *Alanine* - **Alanine** is an amino acid, and therefore a reactant in transamination reactions to form pyruvate, rather than a product of aspartate transamination. - While it can be formed from pyruvate via transamination, it is not formed from aspartate.

Q: Fructose intolerance is due to deficiency of which enzyme?

Aldolase B. ***Aldolase B*** - **Hereditary fructose intolerance** is a genetic disorder caused by a deficiency in the enzyme **aldolase B**. - This deficiency leads to an accumulation of **fructose-1-phosphate** in the liver, kidneys, and small intestine, causing **hypoglycemia**, **vomiting**, and **liver damage** upon exposure to fructose. *Fructokinase* - A deficiency in **fructokinase** causes **essential fructosuria**, a benign metabolic disorder. - This condition is asymptomatic because **fructose** simply accumulates in the blood and urine without causing significant clinical problems. *Triokinase* - **Triokinase**, also known as **glycerol kinase**, is involved in glycerol metabolism, converting glycerol to **glycerol-3-phosphate**. - Its deficiency is not directly linked to fructose intolerance and typically presents with **hyperglycerolemia**. *Aldolase A* - **Aldolase A** is one of the three aldolase isoenzymes (A, B, and C) and is primarily involved in **glycolysis**, specifically in the breakdown of **fructose-1,6-bisphosphate**. - A deficiency in aldolase A can lead to **hemolytic anemia** and **myopathy**, not directly fructose intolerance.

Q: Type 3 respiratory failure occurs due to ?

Post-operative atelectasis. ***Post-operative atelectasis*** - **Type 3 respiratory failure**, also known as **perioperative respiratory failure**, is characterized by hypoxemia occurring typically after surgery. - **Atelectasis**, the collapse of lung tissue, is a common cause of hypoxemia in the post-operative period due to shallow breathing, pain, and anesthesia affecting lung volumes. *Kyphoscoliosis* - This condition leads to a **restrictive lung disease** due to chest wall deformity, causing chronic respiratory failure. [1] - It more typically results in **Type 2 respiratory failure** (hypercapnic) due to impaired ventilation over time. [1] *Flail chest* - Flail chest is a severe chest wall injury causing paradoxical movement, leading to **acute respiratory failure**. - It is often associated with **Type 1 (hypoxemic)** or **Type 2 (hypercapnic)** respiratory failure due to trauma-induced lung injury and impaired mechanics. *Pulmonary fibrosis* - This is a progressive interstitial lung disease causing **restrictive ventilatory defect** and impaired gas exchange. - It leads to chronic **Type 1 respiratory failure** (hypoxemic) as the lung tissue becomes stiff and scarred.

Q: Which type of nerve fibers are responsible for carrying joint position and vibration sense?

A-beta fibers. ***A-beta fibers*** - **A-beta fibers** are **large-diameter, myelinated** sensory fibers that conduct impulses rapidly. - They are primarily responsible for transmitting **light touch, pressure, joint position (proprioception), and vibration sense**. - **This is the correct answer** because A-beta fibers carry **BOTH joint position AND vibration sense together**. *A-alpha fibers* - **A-alpha fibers** are the **largest and fastest** conducting nerve fibers. - They include **motor nerves to skeletal muscles** and **sensory fibers from muscle spindles (Ia) and Golgi tendon organs (Ib)**. - While Ia fibers (A-alpha) do carry **proprioception from muscle spindles**, they do **NOT carry vibration sense**. - The question asks for fibers carrying **BOTH** joint position **AND** vibration sense, making A-beta the correct answer. *C fibers* - **C fibers** are **small-diameter, unmyelinated** nerve fibers with **slow conduction velocities**. - They are responsible for transmitting **dull, aching pain, temperature, and crude touch**. *A-delta fibers* - **A-delta fibers** are **small-diameter, thinly myelinated** nerve fibers with an intermediate conduction velocity. - They primarily transmit **sharp, fast pain** and **cold temperature sensations**.

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: Which type of muscle fibers has fewer mitochondria?

Type IIb fibers (Fast-twitch fibers). ***Type IIb fibers (Fast-twitch fibers)*** - These fibers rely primarily on **anaerobic glycolysis** for ATP production, which is a less efficient process than aerobic respiration and therefore requires fewer mitochondria. - Their primary function is rapid, powerful contractions over short durations, leading to quick fatigue. *Type IIa fibers* - These fibers are **fast-twitch oxidative-glycolytic** fibers, meaning they have a moderate number of mitochondria to support both aerobic and anaerobic metabolism. - They are capable of generating strong contractions and are more fatigue-resistant than Type IIb fibers but less so than Type I fibers. *Type I fibers (Red fibers)* - Known as **slow-twitch oxidative fibers**, they have a high density of mitochondria to support continuous **aerobic respiration** for sustained, low-intensity contractions. - Their rich blood supply and high myoglobin content give them their characteristic red color and make them highly fatigue-resistant. *Type IIx fibers (Intermediate fibers)* - These fibers are very similar to Type IIb fibers in their metabolic profile, often considered an intermediate or even functionally equivalent type depending on the species. - They also primarily utilize **anaerobic glycolysis** and have a relatively low mitochondrial content, making them prone to fatigue.

Q: What is the critical closing pressure in the context of capillary physiology?

Pressure below which capillaries close. ***Pressure below which capillaries close*** - The **critical closing pressure** is the lowest pressure at which blood can flow through a capillary. - When the luminal pressure falls below this threshold, the capillary collapses due to **extrinsic tissue pressure** and intrinsic vascular tone. *Arterial pressure minus venous pressure* - This calculation represents the **arteriovenous pressure gradient**, which drives blood flow through a vascular bed. - It does not directly define the point at which capillaries collapse. *Capillary pressure minus venous pressure* - This difference primarily influences filtration and reabsorption of fluids across the capillary wall. - It is not directly related to the **critical closing pressure** of the capillaries. *None of the options* - This is incorrect as one of the provided options accurately defines the **critical closing pressure**.

Question 1

Which of the following is NOT a content of the occipital triangle?

Accepted Answer

Suprascapular nerve

Answer

Lesser occipital nerve

Answer

Occipital artery

Answer

Great auricular nerve

Question 2

Medulla oblongata arises from which of the following?

Accepted Answer

Myelencephalon

Answer

Mesencephalon

Answer

Rhombencephalon

Answer

None of the options

Question 3

All are infraclavicular branches of brachial plexus except ?

Accepted Answer

Long thoracic nerve

Answer

Axillary nerve

Answer

Thoracodorsal nerve

Answer

Ulnar nerve

Question 4

Transamination of Aspartate forms which compound?

Accepted Answer

Oxaloacetate

Answer

Pyruvate

Answer

Acetyl-CoA

Answer

Alanine

Question 5

Fructose intolerance is due to deficiency of which enzyme?

Accepted Answer

Aldolase B

Answer

Aldolase A

Answer

Fructokinase

Answer

Triokinase

Question 6

Type 3 respiratory failure occurs due to ?

Accepted Answer

Post-operative atelectasis

Answer

Kyphoscoliosis

Answer

Flail chest

Answer

Pulmonary fibrosis

Question 7

Which type of nerve fibers are responsible for carrying joint position and vibration sense?

Accepted Answer

A-beta fibers

Answer

A-alpha fibers

Answer

C fibers

Answer

A-delta fibers

Question 8

Which of the following does not have sympathetic noradrenergic fibers?

Accepted Answer

Sweat gland

Answer

Heart

Answer

Eye

Answer

Blood vessels

Question 9

Which type of muscle fibers has fewer mitochondria?

Accepted Answer

Type IIb fibers (Fast-twitch fibers)

Answer

Type I fibers (Red fibers)

Answer

Type IIa fibers

Answer

Type IIx fibers (Intermediate fibers)

Question 10

What is the critical closing pressure in the context of capillary physiology?

Accepted Answer

Pressure below which capillaries close

Answer

Arterial pressure minus venous pressure

Answer

Capillary pressure minus venous pressure

Answer

None of the options

NEET-PG 2013

Anatomy

Biochemistry

Internal Medicine

Physiology