---

Assessing Motor Power — MRC (MMT) Grading Scale

---

The MRC Grades

---

How to Test Each Grade in Practice

• For grade 2 testing, the limb must be supported and moved in a plane where gravity is eliminated (e.g., hip abduction tested with the patient supine and the leg sliding sideways on the bed).
• For grades 3–5, gravity acts as the baseline resistance and examiner adds more.

1. Isokinetic (active resistance): Ask the patient to contract while you offer graded resistance throughout the range of motion.
2. Isometric ("break test"): Ask the patient to hold maximally and you try to "break" the contraction. If you can break it, the muscle is weak.

---

The Grade 4 Problem

• 4− (4 minus): moves against slight resistance only
• 4 : moves against moderate resistance
• 4+ (4 plus): moves against strong resistance but still less than normal

---

Important Practical Tips

• Squat and rise from squatting (tests proximal lower limb)
• Walk on heels and toes (tests tibialis anterior, gastrocnemius)
• Rise from a chair without using arms (proximal hip/thigh)
• Raise both arms overhead (shoulder girdle)

• Pain inhibition (algesic paresis): pain causes reflex reduction in power; test isometrically to avoid moving the painful part.
• Poor effort: hysteria, malingering, or low pain tolerance — experience and observation help distinguish.
• Infants/uncooperative patients: assess resistance to passive manipulation and observe natural movements.

• Proximal weakness → myopathy
• Distal weakness → peripheral neuropathy
• Segmental / dermatomal weakness → radiculopathy
• Upper vs. lower motor neuron pattern guides further localisation

---

Myotomal Localisation (Key Root Levels)

---

Upper vs. Lower Motor Neuron Weakness — Clinical Distinction

---

Quick motor power chart (MRC/MMT)

• 0 no contraction
• 1 flicker
• 2 movement with gravity eliminated
• 3 movement against gravity
• 4 movement against gravity + resistance
• 5 normal power

---

Upper limb MMT (key neuro muscles + roots)

• Shoulder abduction (Deltoid) - C5
• Elbow flexion (Biceps) - C5-C6
• Elbow extension (Triceps) - C7
• Wrist extension (ECRL/ECRB) - C6-C7
• Finger extension (Extensor digitorum) - C7
• Finger flexion/grip (FDP/FDS) - C8
• Finger abduction/adduction (Interossei) - T1
• Little finger abduction (ADM) - T1

UMN pattern in upper limb (typical weakness)

---

Lower limb MMT (key neuro muscles + roots)

• Hip flexion (Iliopsoas) - L1-L3 (mainly L2-L3)
• Hip abduction (Gluteus medius) - L5
• Knee extension (Quadriceps) - L3-L4
• Knee flexion (Hamstrings) - L5-S1
• Ankle dorsiflexion (Tibialis anterior) - L4-L5
• Great toe extension (EHL) - L5
• Ankle plantarflexion (Gastro-soleus) - S1
• Foot eversion (Peronei) - L5-S1

UMN pattern in lower limb (typical weakness)

---

How to document (example)

• RUE: Shoulder abd 4/5, elbow flex 5/5, elbow ext 4+/5, wrist ext 4/5, grip 5/5
• LUE: 5/5 throughout
• RLE: Hip flex 4-/5, knee ext 5/5, dorsiflex 3/5, plantarflex 4/5
• LLE: 5/5 throughout

---

MMT (MRC Scale) — Proper Assessment for Upper and Lower Limbs

---

MRC Grades (Recap)

Grade 4 is subdivided: 4− (slight resistance), 4 (moderate resistance), 4+ (strong resistance but not full)

---

Upper Limb MMT — Proper Method

---

1. Shoulder Abduction — Deltoid (C5)

• Position: Patient seated, arm at side
• Gravity eliminated (grade 2): Patient supine, arm slides laterally on a table
• Gravity present (grade 3+): Ask patient to abduct arm to 90°
• Resistance: Press down on the distal humerus (above elbow) — do NOT push on the forearm
• Grade 5: Holds full abduction against strong pressure
• UMN note: Deltoid weakness is the hallmark of UMN upper limb pattern

---

2. Elbow Flexion — Biceps/Brachialis (C5–C6)

• Position: Seated, forearm in supination (to isolate biceps)
• Command: "Bend your elbow, don't let me straighten it"
• Resistance: Apply force at the wrist trying to extend the elbow
• Gravity eliminated (grade 2): Arm abducted to 90°, flexion in horizontal plane
• Grade 5: Resists strong extension force fully

---

3. Elbow Extension — Triceps (C7)

• Position: Arm abducted at shoulder, forearm hanging down (gravity assists extension) OR patient prone, arm hanging over table edge
• Gravity eliminated (grade 2): Arm abducted to 90°, test extension in horizontal plane
• Command: "Straighten your elbow, don't let me bend it"
• Resistance: Try to flex the elbow at the wrist

---

4. Wrist Extension — ECRL/ECRB (C6–C7)

• Position: Forearm pronated (palm down), wrist neutral
• Command: "Cock your wrist up"
• Resistance: Press down on dorsum of hand
• Grade 2: Forearm neutral (thumb up), extend wrist sideways

---

5. Finger Extension — Extensor Digitorum (C7)

• Position: Hand flat, fingers extended
• Command: "Lift your fingers up off the table"
• Resistance: Press down on dorsum of proximal phalanges

---

6. Finger Flexion / Grip — FDS/FDP (C8)

• Grip: Ask patient to squeeze two of your fingers as hard as possible
• Individual: Flex each finger at PIPJ/DIPJ against resistance
• Grade 2: Test with hand supported, gravity eliminated

---

7. Finger Abduction — Interossei / ADM (T1)

• Command: "Spread your fingers apart, don't let me push them together"
• Resistance: Squeeze 1st and 5th finger toward each other
• Little finger abduction (ADM): Ask to abduct little finger, resist at its tip

---

Lower Limb MMT — Proper Method

---

1. Hip Flexion — Iliopsoas (L1–L3)

• Position: Patient seated at edge of bed, thigh parallel to floor
• Command: "Lift your knee up, don't let me push it down"
• Resistance: Press down on distal thigh
• Gravity eliminated (grade 2): Patient supine, leg slides up the bed (flexion in bed plane)

---

2. Hip Abduction — Gluteus Medius (L5)

• Position: Patient supine
• Gravity eliminated (grade 2): Slide leg sideways on the bed
• Gravity present (grade 3): Side-lying, abduct leg upward
• Resistance (grade 4–5): Press down on lateral distal thigh while patient holds abducted position

---

3. Knee Extension — Quadriceps (L3–L4)

• Position: Seated at edge of bed, knee at 90°
• Command: "Kick your leg out straight, hold it there"
• Resistance: Press down on anterior shin (distal leg) — try to flex the knee
• Gravity eliminated (grade 2): Patient supine, support thigh, extend knee in air
• Reflex: Patellar (knee jerk) — L4

---

4. Knee Flexion — Hamstrings (L5–S1)

• Position: Patient prone OR supine with knee slightly bent
• Command: "Curl your heel toward your buttock"
• Resistance: Apply force at the heel trying to extend the knee
• Gravity eliminated (grade 2): Patient on side, flex knee in horizontal plane

---

5. Ankle Dorsiflexion — Tibialis Anterior (L4–L5)

• Position: Patient supine or seated
• Command: "Pull your foot up toward your nose"
• Resistance: Press down on dorsum of foot
• Grade 2: Foot supported, attempt dorsiflexion sideways
• Functional test: Walk on heels (grades 4–5 only)

---

6. Great Toe Extension — EHL (L5)

• Position: Foot neutral
• Command: "Pull your big toe up"
• Resistance: Press down on the dorsum of the great toe's proximal phalanx
• Clinically important: Pure L5 weakness marker

---

7. Ankle Plantarflexion — Gastrocnemius-Soleus (S1)

• Position: Patient supine, foot hanging off edge
• Command: "Push your foot down like pressing a pedal"
• Resistance: Against dorsum of foot
• Functional test: Single-leg heel raise — ask patient to stand on one leg and rise on tiptoe ×10; inability suggests grade 4 or less
• Reflex: Achilles (ankle jerk) — S1

---

8. Foot Eversion — Peronei (L5–S1)

• Command: "Turn your foot outward"
• Resistance: Against the lateral border of the foot

---

Summary Reference Card

---

---

Why You Start Testing from Grade 3 or 4

The Logic

• Grade 2 establishes: Can the muscle move the joint at all? (with gravity removed)
• Grade 3 establishes: Can it overcome gravity?
• Grade 4 establishes: Can it overcome gravity + examiner resistance?
• Grade 5 establishes: Is it fully normal?

---

Practical Starting Rule

---

The Grade 3 Check — Most Important Step

• If they cannot hold it → grade 2 (gravity defeats them)
• If they can hold it → at least grade 3, then move on to resistance

---

The Grade 4 vs 5 Distinction — Where Most Clinical Grading Happens

• You break it easily with minimal force → 4− (mild weakness)
• You break it with moderate effort → 4 (moderate weakness)
• You can break it but only with significant force → 4+ (nearly normal)
• You cannot break it even with full effort → 5 (normal)

---

Why Grade 4 Is the Hardest to Assess

1. Always compare to the contralateral side — asymmetry is more meaningful than absolute grade
2. Use functional tasks to unmask grade 4− weakness that the break test misses:
   • Heel walking (tibialis anterior)
   • Single-leg heel raise ×10 (gastrocnemius — S1)
   • Single-leg squat (quadriceps — L3/L4)
   • Grip dynamometry (hand)

---

Bottom Line

In a conscious, cooperative patient with an intact-looking limb, you start at grade 3 (hold against gravity), confirm it, then apply resistance to distinguish 4− / 4 / 4+ / 5. You only go down to test grades 0–2 when the limb is clearly paretic or the patient cannot lift against gravity.

---

Complete Joint-by-Joint MMT

---

UPPER LIMB

---

🔵 SHOULDER JOINT

Tip for abduction: Supraspinatus initiates first 15°; Deltoid takes over 15–90°. Test at 90° for pure deltoid (C5).

---

🔵 ELBOW JOINT

Tip: To isolate Biceps → supinate forearm. To isolate Brachioradialis → forearm mid-prone (thumb up).

---

🔵 FOREARM

---

🔵 WRIST JOINT

Gravity eliminated position for wrist: Forearm vertical (thumb pointing up) — then flex/extend sideways, neither gravity-assisted nor gravity-resisted.

---

🔵 FINGERS (MCP/PIP/DIP)

---

🔵 THUMB

Quick test for T1 (ulnar): "Hold a paper between thumb and index finger" — Froment's sign if they flex the IP joint (FPL compensating for weak adductor pollicis).

---

---

LOWER LIMB

---

🔵 HIP JOINT

Gravity eliminated for hip: Patient supine, leg on a smooth surface (or examiner supports limb weight) and slides in a horizontal plane.

---

🔵 KNEE JOINT

Functional test for Quad (L3/L4): Single-leg sit-to-stand or squat. For Hamstrings (L5/S1): prone leg curl test.

---

🔵 ANKLE JOINT

Functional test: Heel walking = tib anterior (L4/L5); Single-leg toe raise ×10 = gastrocnemius (S1). These are more sensitive than break test for grade 4 weakness.

---

🔵 TOES

---

CERVICAL SPINE (Neck)

---

Quick Summary Table — Key Roots to Remember

---

Grade 3 — Elbow (Flexion & Extension)

---

Grade 3 means:

Moves the joint through full range against gravity — but cannot take any added resistance.

---

Elbow Flexion — Grade 3

• Patient seated or standing
• Arm hanging at the side in anatomical position (forearm supinated)
• Gravity is now the resistance (pulling the forearm down)

"Bend your elbow and bring your hand up to your shoulder — all the way."

• Do not touch the patient
• Watch if they can bring the forearm from full extension → full flexion against gravity (lifting the weight of the forearm)

• If they complete the arc but stop midway → still grade 2 (did not complete range against gravity)
• Full arc completed, no resistance applied → grade 3
• Then apply resistance at distal forearm → if they hold → grade 4

---

Elbow Extension — Grade 3

• Patient prone (face down) on the bed
• Shoulder abducted to 90°, upper arm resting on table
• Forearm hanging vertically downward off the edge of the table
• Now gravity assists extension — so this position does NOT test against gravity

• Patient prone, shoulder abducted 90°, forearm hanging down
• Ask patient to lift the forearm up (extend elbow) → this is now against gravity

"Straighten your elbow — lift your hand up toward the ceiling."

• Patient seated, arm at side, elbow flexed to 90°
• Ask to extend elbow forward against gravity (pushing hand forward)

---

Key Point — Why Positioning Matters for Grade 3

---

Clinically

• Grade 3 elbow flexion is seen in C5/C6 root lesions or musculocutaneous nerve injury — patient can lift the forearm but you can easily break the contraction
• Grade 3 elbow extension is seen in C7 radiculopathy or radial nerve injury — patient can extend against gravity but no resistance
• In UMN lesions, elbow extension is typically weaker than flexion (flexors spared, extensors weak)

---

The Rule for Positions in MMT

---

Corrected Positions — Elbow

---

Elbow Flexion

---

Elbow Extension

---

Corrected Positions — Shoulder

---

Shoulder Abduction

---

Shoulder Flexion

---

Shoulder Extension

---

Corrected Positions — Hip

---

Hip Flexion

---

Hip Extension

---

Hip Abduction

---

Hip Adduction

---

Corrected Positions — Knee

Knee Flexion

Knee Extension

---

Summary Rule

Grade 2 → Side-lying (horizontal plane, gravity eliminated) Grade 3–5 → The position where movement directly fights gravity (prone, supine, seated, or standing depending on the muscle)