Which layer of the meninges surrounds and supports the sinuses that form the route through which blood drains from the CNS?

Correct Answer: A

Rationale: The dura mater (A) forms and supports venous sinuses (e.g., superior sagittal) for CNS blood drainage. The arachnoid mater (B) and subarachnoid space (C) handle CSF, and pia mater (D) adheres to the brain. A is correct.

Correct Answer: B

Rationale: The soma, or cell body, of a neuron contains the nucleus, which houses the cell’s genetic material. Dendrites receive signals, axons transmit them, and the synaptic end bulb releases neurotransmitters, but only the soma contains the nucleus.

Correct Answer: B

Rationale: Upper motor neurons (UMNs) in the CNS target lower motor neurons (LMNs) in the spinal cord or brainstem, which then innervate skeletal muscles. UMNs don’t directly target muscles or other brain regions like the cortex or thalamus.

Correct Answer: B

Rationale: From a resting potential of -70 mV, the membrane must depolarize to the threshold (around -55 mV), a change of about +15 mV, to trigger an action potential via summation.

Correct Answer: A

Rationale: The brainstem includes the midbrain, pons, and medulla oblongata. The diencephalon (thalamus, hypothalamus) is part of the forebrain, not the brainstem.