Anatomy
1 questionsAfter trauma, a person cannot move their eye outward beyond the midpoint. Which nerve is injured?
NEET-PG 2012 - Anatomy NEET-PG Practice Questions and MCQs
Question 441: After trauma, a person cannot move their eye outward beyond the midpoint. Which nerve is injured?
- A. 3rd
- B. 4th
- C. 6th (Correct Answer)
- D. 2nd
Explanation: ***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].
Internal Medicine
2 questionsWhich of the following is NOT typically seen in 3rd nerve palsy?
What is the most common cause of ophthalmoplegia in adults?
NEET-PG 2012 - Internal Medicine NEET-PG Practice Questions and MCQs
Question 441: Which of the following is NOT typically seen in 3rd nerve palsy?
- A. Mydriasis
- B. Ptosis
- C. Loss of abduction (Correct Answer)
- D. Loss of light reflex
Explanation: ***Loss of abduction*** - The **oculomotor nerve (CN III)** controls adduction, elevation, and depression of the eye, but **not abduction**. [2] - **Abduction** is primarily controlled by the **abducens nerve (CN VI)**, so its loss would indicate a CN VI palsy. *Mydriasis* - The **oculomotor nerve (CN III)** innervates the **parasympathetic fibers** to the pupillary constrictor muscles. [3] - Palsy of these fibers leads to unopposed action of the sympathetic dilator muscles, causing **mydriasis (pupil dilation)**. [4] *Ptosis* - The **oculomotor nerve (CN III)** innervates the **levator palpebrae superioris muscle**, which lifts the eyelid. - Dysfunction of this nerve leads to **ptosis (drooping of the eyelid)**. [1] *Loss of light reflex* - The **efferent pathway** for the **pupillary light reflex** travels via the **oculomotor nerve (CN III)** to constrict the pupil. [3] - A 3rd nerve palsy, particularly affecting the parasympathetic fibers, **impairs pupillary constriction**, resulting in a loss of the direct and consensual light reflex in the affected eye. [4]
Question 442: What is the most common cause of ophthalmoplegia in adults?
- A. Cranial nerve palsy (Correct Answer)
- B. Myasthenia gravis
- C. Diabetes mellitus
- D. Trauma
Explanation: ***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.
Ophthalmology
6 questionsWhich muscle is the earliest to be involved in thyroid ophthalmopathy?
What is the treatment of choice for amblyopia?
Most common orbital tumor has its origin from?
What is the most common cause of intermittent proptosis in adults?
What is the term for the fusion of the palpebral and bulbar conjunctiva?
What is the definition of the visual axis in relation to the eye?
NEET-PG 2012 - Ophthalmology NEET-PG Practice Questions and MCQs
Question 441: Which muscle is the earliest to be involved in thyroid ophthalmopathy?
- A. Medial Rectus (MR)
- B. Inferior Rectus (IR) (Correct Answer)
- C. Superior Rectus (SR)
- D. Lateral Rectus (LR)
Explanation: ***Inferior Rectus (IR)*** - The **inferior rectus muscle** is most commonly and earliest affected in **thyroid ophthalmopathy** due to its anatomical location and muscle fiber type, making it highly susceptible to inflammation and edema. - Involvement of the inferior rectus leads to restricted **upward gaze** and **diplopia**, which are characteristic early symptoms of thyroid eye disease. *Medial Rectus (MR)* - While the **medial rectus** is often involved in thyroid ophthalmopathy, it is typically affected *after* the inferior rectus. - Dysfunction of the medial rectus manifests as difficulty with **adduction** (moving the eye inwards). *Superior Rectus (SR)* - The **superior rectus** is less frequently and usually later involved compared to the inferior and medial rectus muscles. - Its involvement typically causes restricted **downward gaze**. *Lateral Rectus (LR)* - The **lateral rectus** muscle is the *least common* ocular muscle to be affected in thyroid ophthalmopathy. - When affected, it primarily causes difficulty with **abduction** (moving the eye outwards).
Question 442: What is the treatment of choice for amblyopia?
- A. Corrective spectacles
- B. Surgical intervention
- C. Occlusion therapy (Correct Answer)
- D. Convergent exercises for vision therapy
Explanation: ***Occlusion therapy*** - **Occlusion therapy** involves patching the stronger eye to force the weaker, amblyopic eye to work harder, thereby strengthening its neural connections. - This treatment is most effective when initiated during the **critical period of visual development** in childhood. *Corrective spectacles* - While essential for addressing **refractive errors** that may contribute to amblyopia, spectacles alone are often insufficient to resolve the amblyopia. - Spectacles primarily optimize the image quality on the retina, but don't directly address the **cortical suppression** of the amblyopic eye. *Surgical intervention* - **Surgical intervention** is typically reserved for correcting structural issues like **strabismus** (misalignment of the eyes) that contribute to amblyopia. - Surgery for strabismus aims to align the eyes, which can then be followed by occlusion therapy or other treatments to address the functional amblyopia. *Convergent exercises for vision therapy* - **Vision therapy exercises**, including convergent exercises, may be used as an adjunct to occlusion therapy or in cases of **convergence insufficiency**. - However, they are not the primary or solitary treatment of choice for amblyopia, which requires direct stimulation of the amblyopic eye.
Question 443: Most common orbital tumor has its origin from?
- A. Blood vessels (Correct Answer)
- B. Nerves
- C. Muscle
- D. Lymph node
Explanation: ***Blood vessels*** - The most common orbital tumor in childhood is a **capillary hemangioma**, which originates from blood vessels. - In adults, the most common primary orbital tumor is an orbital varix, also a **vascular lesion**. *Nerves* - Tumors of neural origin, such as **optic nerve gliomas** or **meningiomas**, are less common than vascular tumors. - While significant, they do not represent the *most* common overall origin for orbital tumors. *Muscle* - Tumors originating from muscle, such as **rhabdomyosarcoma** in children (a malignant tumor), are relatively rare. - **Pseudotumor** (idiopathic orbital inflammation), though common, is an inflammatory condition, not a true neoplasm of muscle origin. *Lymph node* - Tumors of lymphoid origin, such as **lymphomas**, are malignant and can occur in the orbit. - However, they are not the most common primary orbital tumor compared to those of vascular origin.
Question 444: What is the most common cause of intermittent proptosis in adults?
- A. Orbital varix (Correct Answer)
- B. Thyroid ophthalmopathy
- C. Neuroblastoma
- D. Retinoblastoma
Explanation: ***Orbital varix*** - An **orbital varix** is essentially a varicose vein within the orbit, which can cause intermittent proptosis. - Proptosis in an orbital varix is often exacerbated by activities that increase venous pressure, such as **Valsalva maneuvers**, crying, or bending over. *Thyroid ophthalmopathy* - This condition is characterized by **persistent proptosis**, lid retraction, and ophthalmoplegia, rather than intermittent symptoms. - While it can cause proptosis, it typically presents as **constant and progressive** rather than intermittent proptosis that varies with head position or straining. *Neuroblastoma* - This is a **malignant tumor** that primarily affects infants and young children, not typically adults. - Orbital metastasis from neuroblastoma would cause **progressive, constant proptosis** rather than intermittent proptosis. *Retinoblastoma* - **Retinoblastoma** is a malignant tumor of the retina that primarily affects young children, typically under the age of 5. - While it can cause proptosis in advanced stages, it presents as **constant and progressive proptosis** due to tumor growth, not intermittent proptosis.
Question 445: What is the term for the fusion of the palpebral and bulbar conjunctiva?
- A. Trichiasis (inward growth of eyelashes)
- B. Ectropion (outward turning of eyelid)
- C. Symblepharon (Correct Answer)
- D. Tylosis (thickening of skin on palms and soles)
Explanation: ***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.
Question 446: What is the definition of the visual axis in relation to the eye?
- A. Line from the object to the fovea (Correct Answer)
- B. Line from the center of the lens to the cornea
- C. Line from the center of the cornea to the center of the lens
- D. None of the options
Explanation: ***Line from the object to the fovea*** - The **visual axis** is the theoretical line connecting the **object of regard** in the external world to the **fovea centralis** (the area of sharpest vision) on the retina. - This axis passes through the **nodal points** of the eye, which are conceptual points within the lens system acting as optical centers. *Line from the center of the lens to the cornea* - This description does not correspond to any standard anatomical or optical axis of the eye. - The **cornea** and **lens** are parts of the eye's refracting system, but a line solely between their centers would not define visual perception. *Line from the center of the cornea to the center of the lens* - This line is generally referred to as the **optical axis**, which is an anatomical reference line. - The optical axis typically passes through the centers of curvature of the refractive surfaces, but it does not necessarily align with the actual line of sight or the path of light from an object to the fovea. *None of the options* - This option is incorrect because the first option accurately defines the visual axis.
Pharmacology
1 questionsWhich of the following is NOT caused by Prostaglandin E2 (PGE2)?
NEET-PG 2012 - Pharmacology NEET-PG Practice Questions and MCQs
Question 441: Which of the following is NOT caused by Prostaglandin E2 (PGE2)?
- A. None of the options (Correct Answer)
- B. Water retention
- C. Flushing
- D. Uterine contraction
Explanation: ***None of the options*** - All three listed effects (water retention, uterine contraction, and flushing) **ARE caused by Prostaglandin E2 (PGE2)**, making this the correct answer to the question asking what is NOT caused by PGE2. - Since PGE2 actually causes all the listed effects, "None of the options" is the accurate response. *Water retention* - PGE2 **stimulates ADH (vasopressin) release** from the posterior pituitary gland. - PGE2 also **enhances ADH action** on renal collecting ducts, promoting water reabsorption. - While PGE2 has complex renal effects including natriuresis, its net effect includes **promoting water retention** through the ADH mechanism. - This is an important effect of PGE2 on fluid balance. *Uterine contraction* - PGE2 is a **potent stimulator of uterine smooth muscle contraction**. - It is used clinically for **labor induction** and **cervical ripening** (dinoprostone). - PGE2 plays a crucial role in **parturition** and is involved in **dysmenorrhea**. *Flushing* - PGE2 causes **peripheral vasodilation**, particularly in cutaneous blood vessels. - This vasodilatory effect leads to **increased skin blood flow**, manifesting as **flushing** and warmth. - This is commonly seen as part of the **inflammatory response** and contributes to erythema.