All of the following reflexes are monosynaptic except:

Correct Answer: D

Rationale: Monosynaptic reflexes involve a single synapse between the sensory neuron and motor neuron, typically seen in stretch reflexes like the knee jerk (A), biceps jerk (B), and triceps jerk (C), mediated by muscle spindles and alpha motor neurons. The abdominal reflex (D) is polysynaptic, involving multiple synapses in the spinal cord and interneurons, as it is a superficial reflex triggered by cutaneous stimulation.

Correct Answer: B

Rationale: Pyramidal (upper motor neuron) signs include hypertonia (A), upgoing toe (C, Babinski sign), and absent abdominal reflexes (D). 'Hyprflexion' (B, likely hyperreflexia typo) is not a standard term, but hyperreflexia fits; still, it’s less specific than others. B is the odd one out.

Correct Answer: C

Rationale: The knee jerk (A), ankle jerk (B), and supinator reflex (D) are monosynaptic stretch reflexes. The abdominal reflex (C) is polysynaptic, involving interneurons and cutaneous input. C is correct.

Correct Answer: C

Rationale: Pyramidal (upper motor neuron) disease causes weakness (C), spasticity, and hyperreflexia, not tremor (A, basal ganglia), wasting (B, lower motor), or hypotonia (D, cerebellar). C is correct.

Correct Answer: D

Rationale: This suggests a left hemispheric stroke (e.g., MCA), causing right-sided weakness and upper motor neuron signs: absent abdominal reflexes (D, correct), exaggerated reflexes on the right (not both, B), and possible left sensory loss (not both, C). Power isn’t lost bilaterally (A). D fits best.