Differentiate decorticate posturing from decerebrate posturing.

• A. Decorticate: flexor posturing of the arms; decerebrate: extended, rigid limbs.
• B. Decorticate: extended, rigid limbs; decerebrate: flexed arms with fists.
• C. Decorticate: no movement; decerebrate: full range of motion.
• D. Decorticate: involves the legs only; decerebrate: involves the arms only.

Answer: (A)

This question tests recognizing two distinct posturing patterns that reflect different brain injury levels. In decorticate posturing, the arms flex (flexor posturing) while the legs are typically extended; this pattern usually points to damage above the red nucleus, involving the cerebral hemispheres and corticospinal pathways. In decerebrate posturing, the arms extend with rigidity, the wrists often pronate, and the legs extend, indicating injury at the brainstem (midbrain/upper pons) with loss of inhibitory control over extensor pathways. So the best description is that decorticate posturing involves flexion of the arms, whereas decerebrate posturing involves extended, rigid limbs. Other choices swap these patterns or describe movements that don’t fit these postures.