Chart — Neurology
Upper vs Lower Motor Neuron Lesions Chart
One bedside pattern sorts a huge range of neuro problems: spastic and hyperreflexic points up (CNS), flaccid and areflexic points down (peripheral). Tone, reflexes, atrophy, fasciculations, and Babinski are the five tells. (ALS is the classic that hits both.)
Educational use only. A learning framework for localizing weakness; real findings can be mixed (e.g., ALS shows both UMN and LMN signs) and require clinical correlation. This material supports nursing education and exam review. It is not medical advice and is not a substitute for clinical judgment, institutional policy, or medical direction. Always follow facility protocols and current provider orders.
Side by Side
| Feature | Upper motor neuron (UMN) | Lower motor neuron (LMN) |
|---|---|---|
| Where | Brain or spinal cord (CNS), above the anterior horn cell | Anterior horn cell, peripheral nerve, NMJ, or muscle (PNS) |
| Tone | Increased — SPASTIC | Decreased — FLACCID |
| Deep tendon reflexes | Hyperreflexic (brisk) | Hyporeflexic or absent (areflexia) |
| Muscle bulk | Little atrophy (disuse only) | Marked atrophy |
| Fasciculations | Absent | Present |
| Babinski sign | Present (upgoing toe) | Absent (downgoing/normal) |
| Example diagnoses | Stroke, MS, spinal cord injury (below the lesion once spasticity sets in), cerebral palsy | Guillain-Barré, myasthenia gravis (NMJ), polio, peripheral neuropathy, lower SCI/cauda equina |
Exam Traps
- ✦UMN = spastic + hyperreflexic + Babinski present + little atrophy (CNS lesion).
- ✦LMN = flaccid + areflexic + atrophy + fasciculations (peripheral lesion).
- ✦Guillain-Barré is LMN (areflexia); stroke and MS are UMN (spasticity).
- ✦ALS is the classic mixed picture — BOTH upper and lower motor neuron signs together.
- ✦An upgoing toe (Babinski) is normal in infants but abnormal in adults — a UMN sign.
Related Resources
Standards & sources
Fact-checked Jun 21, 2026This page is written to align with American Heart Association / American Stroke Association (AHA/ASA) · American Association of Neuroscience Nurses (AANN). It is an educational summary, not a citation of any single document — always verify specific doses, values, and protocols against current guidelines and your facility policy. How we source content →