The meninx in contact with the brain and spinal cord is the:

Correct Answer: A

Rationale: The pia mater is the innermost meninx, directly adhering to the brain and spinal cord. The dura mater is outermost, arachnoid is middle, and 'perineural mater' is not a standard term.

Correct Answer: D

Rationale: All listed are involved: substance P transmits pain signals, thalamus relays them, enkephalins modulate pain, and posterior horns (spinal cord) receive sensory input. 'None of the above' is incorrect.

Correct Answer: B

Rationale: Dendrites in motor neurons receive signals from other neurons, forming synapses (B) to integrate incoming information. They do not act as sensory organs (A) or receptors (C)—those roles belong to sensory neurons. 'None of the above' (D) is incorrect as dendrites have a clear synaptic role.

Correct Answer: B

Rationale: The frontal lobe, particularly the prefrontal cortex, is critical for intelligence, executive function, and decision-making (B). Gait control involves motor areas and basal ganglia (A is partial), memory is more hippocampal (C), and smell sensation is primarily olfactory bulb and temporal lobe (D). B is the most accurate.

Correct Answer: A

Rationale: Medullary postural reflexes include tonic labyrinthine (B) and neck reflexes (C, D), adjusting posture via vestibular input. The optical righting reflex (A) is a midbrain/cortical reflex using visual cues, not medullary. A is the exception.