NEET-PG 2012 Practice Questions

Q: Which of the following extraocular muscle has the longest tendon?

Superior oblique. ***Superior oblique*** - The superior oblique muscle has the **longest tendon** and overall length of all extraocular muscles because it passes through the **trochlea**, a cartilaginous pulley. - Its long course allows it to have a complex action, primarily **intorsion, depression, and abduction** of the eye [1]. *Superior rectus* - The superior rectus is one of the **straight muscles** (recti) and is not the longest. - Its primary actions are **elevation, adduction, and intorsion** of the eyeball [1]. *Medial rectus* - The medial rectus is another **straight muscle** and is generally considered the **strongest** but not the longest extraocular muscle. - Its main action is **adduction** (moving the eye inward) [1]. *Inferior oblique* - The inferior oblique is the **shortest** of all the extraocular muscles. - Its primary actions are **extorsion, elevation, and abduction** of the eyeball [1].

Q: After trauma, a person cannot move their eye outward beyond the midpoint. Which nerve is injured?

6th. ***6th*** - The **abducens nerve (CN VI)** innervates the **lateral rectus muscle**, which is responsible for moving the eye **outward (abduction)** [1]. - Injury to the abducens nerve would result in an inability to move the eye laterally, causing an **esotropia** (eye turned inward at rest) [1]. *2nd* - The **optic nerve (CN II)** is responsible for **vision**, not eye movement [2]. - Damage to this nerve would cause **visual field defects** or **blindness** [3]. *3rd* - The **oculomotor nerve (CN III)** controls most extraocular muscles, including the **medial, superior, and inferior rectus** and **inferior oblique muscles**, as well as the **levator palpebrae superioris** and **pupillary constriction** [2]. - Injury to CN III would lead to a **down and out deviation of the eye**, **ptosis**, and a **dilated pupil** [2]. *4th* - The **trochlear nerve (CN IV)** innervates the **superior oblique muscle**, which primarily causes **intorsion** (rotation downward and inward) [1]. - Damage to this nerve results in **vertical diplopia**, especially when looking down and in, and a characteristic **head tilt** to compensate [3].

Q: What is the daily requirement of vitamin K?

1-2 mcg/kg. ***1-2 mcg/kg*** - The daily requirement of **vitamin K** for adults is approximately **1-2 mcg/kg body weight** (or about 90-120 mcg/day for average adults). - This amount is sufficient for **γ-carboxylation** of clotting factors II, VII, IX, and X, as well as proteins C and S. - The **Adequate Intake (AI)** set by dietary guidelines supports normal coagulation and bone health at these levels. *0.5-1 mg/kg* - This represents a **500-1000 fold excess** over the actual requirement (mg instead of mcg). - This is a **unit error** - the requirement is in **micrograms (mcg)**, not milligrams (mg). - Such high doses would be **pharmacological** rather than physiological, though vitamin K has relatively low toxicity. *10-15 mcg/kg* - This is approximately **10 times higher** than the actual daily requirement. - While not toxic, this amount is **unnecessarily high** for maintaining normal hemostasis. - Typical dietary intake and physiological needs are much lower. *5-10 mg/kg* - This represents an extremely **excessive amount** (5000-10000 times the requirement). - Another example of a **unit confusion** (mg vs mcg). - Such doses have no physiological benefit and are not used clinically except in specific therapeutic situations (e.g., warfarin reversal).

Q: What is the recommended daily calcium intake for adult non-pregnant females?

1000 mg. ***1000 mg*** - The recommended daily calcium intake for adult non-pregnant females (ages 19-50) is **1000 mg** according to **WHO and international guidelines** (US RDA/NIH) to maintain bone health and prevent osteoporosis. - This is the **standard recommendation** used in most medical textbooks and international nutritional guidelines. - Adequate calcium intake supports various bodily functions, including **nerve transmission**, **muscle contraction**, and **hormone secretion**. *1200 mg* - While 1200 mg is the recommended intake for **older women (above 50-70 years)** or during **pregnancy/lactation** per some guidelines, it is generally higher than necessary for non-pregnant adult females aged 19-50. - While not harmful, this higher dose is not specifically indicated for the general non-pregnant adult female population. *600 mg* - This amount of calcium is **lower than the internationally recommended daily allowance** for adult women (though it aligns with some regional guidelines like ICMR for sedentary women). - For optimal bone health and prevention of osteoporosis, **1000 mg is the widely accepted standard** in medical education. *800 mg* - This value is **below the internationally recommended daily intake** for adult non-pregnant females, which could lead to long-term calcium deficiency. - Insufficient calcium intake can increase the risk of conditions like **osteopenia** and **osteoporosis**.

Q: What is the RDA (Recommended Dietary Allowance) for vitamin A in infants aged 0-6 months?

350 mcg. ***350 mcg*** - The **Recommended Dietary Allowance (RDA)** for vitamin A in infants aged 0-6 months is specifically set at **350 micrograms (mcg)** of **retinol activity equivalents (RAE)**. - This level is based on the **average vitamin A intake from human milk** during this period, assuming adequate maternal nutrition. *600 mcg* - This value is higher than the recommended intake for infants aged 0-6 months and is closer to the RDA for **older infants** or **young children**. - Excessive vitamin A intake can be **toxic**, making adherence to age-specific RDAs crucial. *800 mcg* - This amount is significantly higher than the RDA for infants 0-6 months and approaches the RDA for **adults**. - Providing such a high dose to an infant could lead to **vitamin A toxicity**, with symptoms including irritability, increased intracranial pressure, and desquamation of the skin. *400 mcg* - While closer to the correct answer, **400 mcg** is still slightly above the established RDA of 350 mcg for this specific age group. - The precise RDA values are determined based on **extensive research** to ensure optimal health outcomes without risk of deficiency or toxicity.

Q: What is the most common cause of ophthalmoplegia in adults?

Cranial nerve palsy. ***Cranial nerve palsy*** - **Cranial nerve palsies**, particularly those affecting cranial nerves III, IV, or VI, are the most frequent causes of isolated ophthalmoplegia in adults [1]. - They can result from various etiologies like **ischemia**, **compression**, or **inflammation**, directly impairing the nerves responsible for eye movement [1]. *Myasthenia gravis* - While it frequently causes **ocular symptoms** (ptosis and diplopia), it typically presents with **fluctuating weakness** that worsens with sustained effort [1]. - It's a neuromuscular junction disorder, not a primary cranial nerve issue, and often affects other muscle groups beyond the eyes. *Diabetes mellitus* - **Diabetic ophthalmoplegia** is a specific type of cranial nerve palsy (often CN III or VI) caused by microvascular ischemia. - While common in diabetics, it is a *cause* of cranial nerve palsy, not the overarching most common cause of ophthalmoplegia itself. *Trauma* - **Trauma** can certainly cause ophthalmoplegia, often due to direct damage to **extraocular muscles**, **orbital fractures**, or **cranial nerve injury**. - However, in the general adult population, non-traumatic cranial nerve palsies are more frequently encountered as the cause of ophthalmoplegia.

Q: What is the term for the fusion of the palpebral and bulbar conjunctiva?

Symblepharon. ***Symblepharon*** - **Symblepharon** is the term for the adhesion between the **palpebral conjunctiva** (lining the eyelid) and the **bulbar conjunctiva** (covering the eyeball). - This condition can limit eye movement and cause chronic irritation, often resulting from severe conjunctival inflammation or injury. *Trichiasis (inward growth of eyelashes)* - **Trichiasis** refers to the misdirection of eyelashes such that they rub against the cornea or conjunctiva. - It causes irritation, foreign body sensation, and can lead to corneal abrasion, but it does not involve fusion of conjunctival layers. *Ectropion (outward turning of eyelid)* - **Ectropion** is a condition where the lower eyelid turns outward or sags away from the eyeball. - This exposes the conjunctiva, causing dryness, irritation, and epiphora (excessive tearing), but it is not a fusion of conjunctival tissues. *Tylosis (thickening of skin on palms and soles)* - **Tylosis** is a medical term referring to diffuse **hyperkeratosis** or thickening of the skin, typically observed on the palms and soles. - This condition is completely unrelated to the conjunctiva or eye structures.

Q: Which type of congenital cataract is commonly associated with significant visual defects?

Nuclear cataract. ***Nuclear cataract*** - It involves the **nucleus** of the lens, which is the central and most visually critical part. - This type of cataract can cause **significant visual impairment** due to its central location and density, impacting early visual development. *Punctate Cataract* - These are **small, dot-like opacities** that are usually clinically insignificant and do not typically cause significant visual defects. - They are often **peripheral** or very fine, thus not obstructing the central visual axis. *Blue dot cataract* - Also known as **cerulean cataract**, this type consists of small, bluish opacities in the lens cortex. - While congenital, it often has **minimal impact on vision** and is frequently observed incidentally. *Fusiform cataract* - This cataract forms in the shape of a **spindle or needle**, usually along the visual axis. - While it can sometimes cause minor visual compromise, its impact is generally **less severe** compared to a dense nuclear cataract.

Q: Which type of cataract is specifically associated with decreased reading ability?

Nuclear cataract. ***Nuclear cataract*** - **Nuclear cataracts** cause progressive hardening and yellowing of the lens nucleus with increased refractive index - This produces a **myopic shift** that initially causes **"second sight"** (temporary improvement in near vision) - However, as the cataract progresses, the increasing opacity leads to **overall visual decline affecting both distance and near vision**, including reading ability - Among the given options, nuclear cataract is the most common age-related cataract that significantly impairs vision including reading *Blue dot cataract* - **Blue dot cataracts** (cerulean cataracts) are small, bluish peripheral opacities, usually congenital and stationary - They rarely cause significant visual impairment and do not affect reading ability *Fusiform cataract* - **Fusiform cataracts** are congenital spindle-shaped opacities along the visual axis - While they can affect vision if dense, they are rare and not typically associated with progressive reading difficulty *Punctate cataract* - **Punctate cataracts** are small, scattered dot-like opacities in the lens - They are often congenital or age-related and cause minimal visual disturbance - Not specifically associated with decreased reading ability

Q: What is the primary mechanism of pathogenesis in acute angle closure glaucoma?

Outflow obstruction due to anatomical factors. ***Outflow obstruction due to anatomical factors*** - **Acute angle-closure glaucoma (AACG)** occurs due to a sudden blockage of the **trabecular meshwork**, which is the primary drainage pathway for aqueous humor. - This blockage is caused by anatomical predispositions, such as a **narrow anterior chamber angle**, relatively large lens, and **pupillary block** leading to iris bombé with peripheral iris bowing forward. - The iridocorneal angle closure prevents aqueous humor drainage, causing **rapid IOP elevation**. *Increased secretion of aqueous humor* - While increased aqueous humor production can contribute to elevated intraocular pressure, it is **not the primary mechanism** in acute angle-closure glaucoma. - This mechanism is more relevant in **open-angle glaucoma** or conditions with ciliary body overactivity. - AACG's hallmark is **outflow obstruction**, not increased production. *Decreased ciliary body function* - Decreased ciliary body function would **reduce aqueous humor production**, leading to **hypotony** (low IOP), not elevated pressure. - This is the opposite of what occurs in AACG, where IOP rises dramatically due to impaired drainage. - Ciliary body dysfunction is seen in conditions like **uveitis** or post-surgical complications. *Increased absorption of aqueous humor* - **Increased absorption** of aqueous humor would **reduce intraocular pressure**, which is the opposite of what occurs in acute angle-closure glaucoma. - The disease is characterized by a **rapid and severe rise in intraocular pressure** due to impaired outflow, not enhanced absorption. - Normal aqueous absorption occurs via trabecular and uveoscleral pathways, both of which are blocked in AACG.

Question 1

Which of the following extraocular muscle has the longest tendon?

Accepted Answer

Superior oblique

Answer

Medial rectus

Answer

Superior rectus

Answer

Inferior oblique

Question 2

After trauma, a person cannot move their eye outward beyond the midpoint. Which nerve is injured?

Accepted Answer

6th

Answer

3rd

Answer

4th

Answer

2nd

Question 3

What is the daily requirement of vitamin K?

Accepted Answer

1-2 mcg/kg

Answer

5-10 mg/kg

Answer

0.5-1 mg/kg

Answer

10-15 mcg/kg

Question 4

What is the recommended daily calcium intake for adult non-pregnant females?

Accepted Answer

1000 mg

Answer

1200 mg

Answer

600 mg

Answer

800 mg

Question 5

What is the RDA (Recommended Dietary Allowance) for vitamin A in infants aged 0-6 months?

Accepted Answer

350 mcg

Answer

400 mcg

Answer

600 mcg

Answer

800 mcg

Question 6

What is the most common cause of ophthalmoplegia in adults?

Accepted Answer

Cranial nerve palsy

Answer

Myasthenia gravis

Answer

Diabetes mellitus

Answer

Trauma

Question 7

What is the term for the fusion of the palpebral and bulbar conjunctiva?

Accepted Answer

Symblepharon

Answer

Trichiasis (inward growth of eyelashes)

Answer

Ectropion (outward turning of eyelid)

Answer

Tylosis (thickening of skin on palms and soles)

Question 8

Which type of congenital cataract is commonly associated with significant visual defects?

Accepted Answer

Nuclear cataract

Answer

Punctate Cataract

Answer

Blue dot cataract

Answer

Fusiform cataract

Question 9

Which type of cataract is specifically associated with decreased reading ability?

Accepted Answer

Nuclear cataract

Answer

Blue dot cataract

Answer

Fusiform cataract

Answer

Punctate cataract

Question 10

What is the primary mechanism of pathogenesis in acute angle closure glaucoma?

Accepted Answer

Outflow obstruction due to anatomical factors

Answer

Increased secretion of aqueous humor

Answer

Increased absorption of aqueous humor

Answer

Decreased ciliary body function

NEET-PG 2012

Anatomy

Biochemistry

Community Medicine

Internal Medicine

Ophthalmology