Anatomy
2 questionsWhich of the following is the PRIMARY action of the superior oblique muscle?
Substantia nigra is connected to which part of the basal ganglia?
INI-CET 2024 - Anatomy INI-CET Practice Questions and MCQs
Question 71: Which of the following is the PRIMARY action of the superior oblique muscle?
- A. Adduction
- B. Intorsion (Correct Answer)
- C. Abduction
- D. Depression
Explanation: ***Intorsion*** - The **primary action** of the **superior oblique muscle** is **intorsion** (internal rotation), which means rotating the top of the eyeball medially (towards the nose). - This action helps to counteract the **extorsion** caused by the inferior oblique muscle and stabilize the visual field during head tilt. *Depression* - While the superior oblique muscle does contribute to **depression** (moving the eye downwards), this is a **secondary action**, particularly when the eye is in **abduction** [1]. - The **inferior rectus muscle** is the primary depressor of the eye [1]. *Abduction* - The superior oblique has a minor **tertiary action** of **abduction** (moving the eye away from the midline) [1]. - However, the **lateral rectus muscle** is the primary abductor of the eye [1]. *Adduction* - **Adduction** (moving the eye towards the midline) is primarily performed by the **medial rectus muscle** [1]. - The superior oblique muscle does **NOT** contribute to adduction; this is not one of its actions [1].
Question 72: Substantia nigra is connected to which part of the basal ganglia?
- A. Thalamus
- B. Pallidum
- C. Striatum (Correct Answer)
- D. Subthalamic nucleus
Explanation: ***Striatum*** - The **substantia nigra pars compacta (SNc)** provides **dopaminergic input** to the striatum via the **nigrostriatal pathway**, which is crucial for motor control [1]. - This connection establishes the direct and indirect pathways of the basal ganglia, modulating **movement initiation** and **inhibition** [1]. *Thalamus* - The thalamus acts as a **relay station** for information leaving the basal ganglia, but it is not directly connected to the substantia nigra as a primary input or output structure within the basal ganglia circuitry [1]. - The basal ganglia influence the thalamus, which then projects to the **motor cortex**, but the direct connection from substantia nigra is to the striatum. *Pallidum* - The **pallidum (globus pallidus)** receives input from the striatum and projects to the thalamus, but it is not directly connected to the substantia nigra as the **primary recipient** of nigral efferents [1]. - While it's part of the basal ganglia, the substantia nigra's main direct projection is to the **striatum**. *Subthalamic nucleus* - The **subthalamic nucleus (STN)** is an excitatory component of the basal ganglia that receives input from the cortex and projects to the globus pallidus. - While there are some indirect connections, the STN is not the primary target of the **nigrostriatal dopaminergic projections** from the substantia nigra [1].
Biochemistry
2 questionsCongenital lactic acidosis is due to the defect of:
Which gene defect causes familial hypercholesterolemia?
INI-CET 2024 - Biochemistry INI-CET Practice Questions and MCQs
Question 71: Congenital lactic acidosis is due to the defect of:
- A. Transaldolase
- B. Pyruvate dehydrogenase (Correct Answer)
- C. Alpha-ketoglutarate dehydrogenase
- D. Branched chain alpha-ketoacid dehydrogenase
Explanation: ***Pyruvate dehydrogenase*** - A defect in **pyruvate dehydrogenase (PDH)** is the most common cause of **congenital lactic acidosis** - PDH is a crucial enzyme complex that converts **pyruvate to acetyl-CoA**, linking glycolysis to the citric acid cycle - When PDH is deficient, **pyruvate accumulates** and is shunted to **lactate** via lactate dehydrogenase, causing persistent elevation of blood lactate levels - Clinical features include **neurological dysfunction, developmental delay, and metabolic acidosis** from birth or early infancy *Transaldolase* - **Transaldolase** is an enzyme in the **pentose phosphate pathway** - Its deficiency primarily affects **NADPH production and ribose-5-phosphate synthesis**, not lactate metabolism - Transaldolase deficiency causes hepatosplenomegaly and liver dysfunction, but is **not a direct cause of congenital lactic acidosis** *Alpha-ketoglutarate dehydrogenase* - **Alpha-ketoglutarate dehydrogenase** is part of the **citric acid cycle (TCA cycle)** - Its deficiency would impair energy production and lead to accumulation of **alpha-ketoglutarate**, not lactate - Defects cause **neurological dysfunction** but do not primarily present with **lactic acidosis** *Branched chain alpha-ketoacid dehydrogenase* - **Branched chain alpha-ketoacid dehydrogenase (BCKDH)** metabolizes **branched-chain amino acids** (leucine, isoleucine, valine) - Deficiency causes **maple syrup urine disease (MSUD)**, characterized by accumulation of **branched-chain keto acids** and their corresponding amino acids - Presents with characteristic maple syrup odor in urine, neurological symptoms, but **not lactic acidosis**
Question 72: Which gene defect causes familial hypercholesterolemia?
- A. LDL Receptor (Correct Answer)
- B. Apo E
- C. Apo CII
- D. Apo B48
Explanation: ***LDL Receptor*** - Familial hypercholesterolemia (FH) is primarily caused by mutations in the **LDL receptor (LDLR) gene**, which leads to impaired clearance of **low-density lipoprotein (LDL)** from the blood. - This defect results in significantly elevated levels of **LDL cholesterol** and an increased risk of premature cardiovascular disease. *Apo E* - Mutations in the **Apo E gene** are associated with **Type III hyperlipoproteinemia (dysbetalipoproteinemia)**, characterized by elevated **chylomicron remnants** and **VLDL remnants**. - This condition presents with xanthomas and premature atherosclerosis, but is distinct from the primary defect in FH. *Apo CII* - **Apo CII** is a cofactor for **lipoprotein lipase (LPL)**, an enzyme essential for the breakdown of **triglycerides** in chylomicrons and VLDL. - Deficiency in Apo CII or LPL causes **Type I hyperlipoproteinemia (familial chylomicronemia syndrome)**, leading to marked **hypertriglyceridemia**, not hypercholesterolemia. *Apo B48* - **Apo B48** is a structural component of **chylomicrons**, which are responsible for transporting dietary fats from the intestines. - It is not directly involved in the primary defect of **LDL clearing** that characterizes familial hypercholesterolemia.
Internal Medicine
1 questionsWhich of the following is typically not associated with upper motor neuron (UMN) lesions?
INI-CET 2024 - Internal Medicine INI-CET Practice Questions and MCQs
Question 71: Which of the following is typically not associated with upper motor neuron (UMN) lesions?
- A. DTR increased
- B. Atrophy (Correct Answer)
- C. Spasticity
- D. Rigidity
Explanation: ***Atrophy*** - **Severe atrophy** (significant muscle wasting) is a hallmark of **lower motor neuron (LMN) lesions**, where the direct innervation to the muscle is interrupted, leading to denervation and subsequent muscle mass loss [1]. - While some disuse atrophy can occur with UMN lesions due to **immobility**, it is typically not as pronounced or rapid as that seen with LMN lesions [1]. *DTR increased* - **Increased deep tendon reflexes (DTRs)**, also known as hyperreflexia, are a classic sign of **upper motor neuron (UMN) lesions** due to the loss of inhibitory control from higher centers on spinal reflex arcs [1]. - The stretch reflex arc becomes more excitable without descending modulation, leading to exaggerated responses. *Spasticity* - **Spasticity** is characterized by a **velocity-dependent increase in muscle tone** with increased resistance to passive stretch, often accompanied by hyperreflexia [1]. - This is a cardinal sign of **upper motor neuron (UMN) lesions**, resulting from the disinhibition of spinal reflex mechanisms. *Rigidity* - **Rigidity** is a form of hypertonia characterized by a **constant resistance to passive movement** throughout the entire range of motion, independent of the speed of movement [2]. - While it can be seen in some UMN conditions involving the basal ganglia (such as Parkinson's disease), it is **not a typical or direct consequence of UMN tract lesions** in the way spasticity is [2],[3].
Ophthalmology
1 questionsA 40-year-old male experiences flashes of light. Which of the following can likely be the reason?
INI-CET 2024 - Ophthalmology INI-CET Practice Questions and MCQs
Question 71: A 40-year-old male experiences flashes of light. Which of the following can likely be the reason?
- A. Retinal detachment (Correct Answer)
- B. CRAO
- C. SAH
- D. Branch retinal artery occlusion
Explanation: ***Retinal detachment*** - Flashes of light, or **photopsia**, are a classic symptom of **retinal detachment**, often caused by the retina pulling away from the underlying choroid. - This sensation occurs as the detached retina is mechanically stimulated, sending abnormal signals to the brain that are interpreted as light flashes. *CRAO* - **Central Retinal Artery Occlusion (CRAO)** typically presents with **sudden, painless, severe vision loss** in one eye, not flashes of light. - The primary pathology is a blockage of blood flow to the retina, leading to **ischemia** and vision impairment. *SAH* - **Subarachnoid Hemorrhage (SAH)** is a neurological emergency characterized by **sudden, severe headache** (thunderclap headache), stiff neck, and altered mental status. - While it can cause visual disturbances, these are usually **diplopia** or **visual field defects** due to cranial nerve involvement, not flashes of light related to retinal pathology. *Branch retinal artery occlusion* - **Branch Retinal Artery Occlusion** causes **sudden, painless vision loss** in a specific part of the visual field corresponding to the occluded branch. - Like CRAO, it is an ischemic event and does not typically present with flashes of light; instead, it results in a **scotoma** or partial vision loss.
Orthopaedics
2 questionsA 75-year-old man presents with a fracture of the intracapsular neck of the femur. What is the most common management option for this patient?
A 26-year-old male presented with proximal 1/3rd fracture shaft of the femur. What is the treatment of choice in this patient?
INI-CET 2024 - Orthopaedics INI-CET Practice Questions and MCQs
Question 71: A 75-year-old man presents with a fracture of the intracapsular neck of the femur. What is the most common management option for this patient?
- A. Hemiarthroplasty (Correct Answer)
- B. Total Hip Replacement
- C. Dynamic Hip Screw
- D. Conservative Management
Explanation: **Hemiarthroplasty** - **Hemiarthroplasty** is the most common management for **intracapsular neck of femur fractures** in elderly patients, especially those who are frail or have substantial comorbidities. - This procedure replaces the **femoral head** with a prosthesis, preserving the native acetabulum, which is sufficient given the higher risk of complications with a full replacement in this age group. *Total Hip Replacement* - **Total hip replacement (THR)** is typically reserved for more active elderly patients with **pre-existing osteoarthritis** or for those requiring revision surgery, due to better functional outcomes but higher surgical risks. - It involves replacing both the **femoral head** and the **acetabulum**, *Dynamic Hip Screw* - A **dynamic hip screw (DHS)** is primarily used for **extracapsular femur fractures** (e.g., trochanteric fractures), where the blood supply to the femoral head is largely preserved. - It involves fixation, which is not suitable for most **intracapsular fractures** due to the disruption of blood supply, increasing the risk of **avascular necrosis** and non-union. *Conservative Management* - **Conservative management** (e.g., bed rest, pain control) is generally not recommended for **intracapsular neck of femur fractures** in mobile elderly patients due to high rates of complications such as **deep vein thrombosis**, **pressure ulcers**, and **avascular necrosis**. - It may be considered only in patients who are **non-ambulatory** or have severe contraindications to surgery.
Question 72: A 26-year-old male presented with proximal 1/3rd fracture shaft of the femur. What is the treatment of choice in this patient?
- A. Hip Spica
- B. Above knee Cast
- C. Above knee Slab
- D. Interlocking Nail (Correct Answer)
Explanation: ***Interlocking Nail*** - **Interlocking nailing** is the treatment of choice for **femur shaft fractures** in adults, providing stable fixation and allowing early mobilization. - It involves inserting a **metal rod** into the medullary canal of the bone across the fracture site, with screws locking it in place at both ends. *Hip Spica* - A **hip spica cast** is typically used for **femur fractures in young children** (under 6 years old) as non-operative management. - It is **not suitable for adults** due to weight, discomfort, and the inability to maintain adequate reduction and stability for an adult-sized femur. *Above knee Cast* - An **above-knee cast** is generally insufficient for **femur shaft fractures** as it does not provide adequate immobilization of the hip joint. - It is more commonly used for **tibial fractures** or injuries to the knee/lower leg, not for a fracture as high as the proximal femoral shaft. *Above knee Slab* - An **above-knee slab** offers even less stability than a full cast and is usually a temporary measure for initial immobilization before definitive treatment or for less severe injuries. - It would be **inadequate to stabilize a femoral shaft fracture** and prevent displacement.
Pharmacology
1 questionsWhich of the following is not a polysaccharide vaccine?
INI-CET 2024 - Pharmacology INI-CET Practice Questions and MCQs
Question 71: Which of the following is not a polysaccharide vaccine?
- A. Pneumococcal vaccine
- B. Meningococcal vaccine
- C. H. Influenzae B vaccine
- D. Hepatitis B vaccine (Correct Answer)
Explanation: ***Hepatitis B vaccine (recombinant protein vaccine)*** - This is a **recombinant protein vaccine** which contains **HBsAg** (Hepatitis B surface antigen) produced in yeast. - As it uses a protein antigen, it is not a polysaccharide vaccine. *Pneumococcal vaccine (includes polysaccharide forms)* - There are two types: **Pneumococcal Polysaccharide Vaccine (PPSV23)** which is a pure polysaccharide vaccine, and **Pneumococcal Conjugate Vaccine (PCV13, PCV15, PCV20)** which contains polysaccharides conjugated to a protein carrier. - Both types utilize **polysaccharide antigens** from *Streptococcus pneumoniae* to elicit an immune response. *Meningococcal vaccine (includes polysaccharide forms)* - Similar to pneumococcal vaccines, there are **meningococcal polysaccharide vaccines (MPSV4)** and **meningococcal conjugate vaccines (MCV4)**. - These vaccines use **polysaccharides** from the capsule of *Neisseria meningitidis* as their immunogenic component, either alone or conjugated. *H. Influenza B vaccine (conjugate vaccine derived from polysaccharides)* - This is a **conjugate vaccine** that uses a **polysaccharide capsule antigen** from *Haemophilus influenzae type B* (Hib) chemically linked to a protein carrier. - Conjugation improves immunogenicity, especially in infants, by converting the T-independent polysaccharide antigen into a T-dependent one.
Physiology
1 questionsSpinal sensory nucleus of the trigeminal has 2nd order neurons to carry which sensation?
INI-CET 2024 - Physiology INI-CET Practice Questions and MCQs
Question 71: Spinal sensory nucleus of the trigeminal has 2nd order neurons to carry which sensation?
- A. Pain (Correct Answer)
- B. Proprioception
- C. Touch
- D. Vibration
Explanation: ***Pain*** - The **spinal trigeminal nucleus** receives nociceptive (pain) and thermal sensations from the face - Its **second-order neurons** relay these signals to higher centers for pain perception - This is the primary function of the spinal (descending) trigeminal nucleus *Proprioception* - **Proprioception** from the face and masticatory muscles is primarily processed by the **mesencephalic trigeminal nucleus** - This nucleus contains the **first-order neurons** for proprioception, which is unique among sensory nuclei *Touch* - **Discriminative touch** and pressure sensations from the face are primarily processed by the **principal (chief) sensory trigeminal nucleus** - This nucleus is distinct from the spinal trigeminal nucleus *Vibration* - **Vibration** sense is a type of mechanoreception, falling under the broader category of discriminative touch - Like other fine touch sensations, it is primarily processed by the **principal sensory trigeminal nucleus**