Injury to which segment of the spine results in damage to the chest and abdominal muscles?

Correct Answer: B

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.

Correct Answer: B

Rationale: Posterior horns of the spinal cord are the correct answer because they are involved in processing sensory information, including pain and temperature. Damage to this area disrupts the transmission of these sensory signals, leading to a loss of temperature and pinprick sensation while preserving other sensory modalities.

Correct Answer: A

Rationale: Frontal lobe is the correct answer because Broca's area, which is responsible for speech production and language processing, is located in the posterior part of the frontal lobe, typically in the left hemisphere. Damage to this area results in Broca's aphasia, characterized by non-fluent speech and difficulty forming sentences.

Correct Answer: C

Rationale: Tremor is the correct answer because it is one of the earliest and most characteristic symptoms of Parkinson's disease. The tremor is typically a resting tremor, which decreases with voluntary movement and is often described as ‘pill-rolling' due to its appearance. It results from the degeneration of dopaminergic neurons in the substantia nigra.

Correct Answer: B

Rationale: The action potential is initiated by the influx of Na+ through voltage-gated sodium channels, causing depolarization. It is terminated by the efflux of K+ through voltage-gated potassium channels, leading to repolarization. The action potential does not decline in amplitude as it propagates along the axon (all-or-none principle), and there is a net movement of Na+ and K+ across the membrane during the process.