3.2 Screening Body Functions & Motor Performance
Key Takeaways
- Goniometric range of motion (ROM) measurement requires precise alignment with anatomical landmarks: axis/fulcrum over the joint center, stationary arm along the proximal bone axis, and movable arm along the distal bone axis.
- Manual Muscle Testing (MMT) grades evaluate voluntary motor control: Grade 5 (Normal, max resistance against gravity), Grade 4 (Good, mod resistance), Grade 3 (Fair, full active ROM against gravity without resistance), Grade 2 (Poor, full ROM in gravity-eliminated plane), Grade 1 (Trace, contraction palpated without motion), and Grade 0 (Zero).
- Grip dynamometry is assessed using the Jamar dynamometer at Handle Position 2 (standardized average of 3 trials), where a bell-shaped curve across all 5 positions validates sincere maximal effort.
- Standardized motor screening batteries—including the Purdue Pegboard, Nine-Hole Peg Test, and Box and Blocks—quantify unilateral and bilateral finger dexterity and manual speed.
- Functional mobility and fall risk are efficiently screened using the Timed Up and Go (TUG, ≥12–14s indicates fall risk) and the Berg Balance Scale (<45/56 indicates fall risk).
Screening Body Functions & Motor Performance
Screening body functions and motor performance allows the Certified Occupational Therapy Assistant (COTA) to collect objective, quantifiable baseline data regarding a client's musculoskeletal integrity, neurological control, and movement efficiency.
Under the direction of the supervising OTR, the COTA administers standardized screening procedures including goniometry, manual muscle testing (MMT), grip/pinch dynamometry, standardized dexterity pegboards, and functional balance tools.
1. Goniometric Measurement of Joint Range of Motion (ROM)
Universal goniometry provides standardized angular measurements of Active Range of Motion (AROM) and Passive Range of Motion (PROM).
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| UNIVERSAL GONIOMETER ALIGNMENT PRINCIPLES |
| |
| [STATIONARY ARM] ---> Aligned parallel to the longitudinal axis of |
| the proximal skeletal segment. |
| |
| [AXIS / FULCRUM] ---> Placed precisely over the anatomical axis of |
| the target joint. |
| |
| [MOVABLE ARM] ---> Aligned along the longitudinal axis of the distal |
| skeletal segment moving through space. |
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Upper Extremity Normative Values & Goniometric Landmarks
| Joint & Motion | Normal Adult ROM | Goniometer Axis Placement | Stationary Arm Alignment | Movable Arm Alignment |
|---|---|---|---|---|
| Shoulder Flexion | $0–180^\circ$ | Lateral aspect of greater tubercle of humerus | Midaxillary line of thorax | Lateral midline of humerus (lateral epicondyle) |
| Shoulder Abduction | $0–180^\circ$ | Acromion process (posterior or anterior) | Parallel to sternum / midline spine | Anterior/lateral midline of humerus |
| Shoulder Internal Rot. | $0–70^\circ$ | Olecranon process of ulna | Perpendicular to floor / parallel to table | Dorsal midline of ulna (ulnar styloid) |
| Shoulder External Rot. | $0–90^\circ$ | Olecranon process of ulna | Perpendicular to floor / parallel to table | Dorsal midline of ulna (ulnar styloid) |
| Elbow Flexion / Ext. | $0–140/150^\circ$ | Lateral epicondyle of humerus | Lateral midline of humerus (acromion) | Lateral midline of radius (radial styloid) |
| Forearm Pronation | $0–80^\circ$ | Lateral to ulnar styloid (dorsal wrist) | Parallel to anterior midline of humerus | Across dorsal aspect of distal radius/ulna |
| Forearm Supination | $0–80^\circ$ | Medial to ulnar styloid (volar wrist) | Parallel to anterior midline of humerus | Across volar aspect of distal radius/ulna |
| Wrist Flexion | $0–80^\circ$ | Lateral wrist over triquetrum | Lateral midline of ulna (olecranon) | Lateral midline of 5th metacarpal |
| Wrist Extension | $0–70^\circ$ | Lateral wrist over triquetrum | Lateral midline of ulna (olecranon) | Lateral midline of 5th metacarpal |
| Radial / Ulnar Dev. | $0–20^\circ / 0–30^\circ$ | Dorsal aspect of capitate bone | Dorsal midline of forearm (lateral epicondyle) | Dorsal midline of 3rd metacarpal shaft |
2. Manual Muscle Testing (MMT) Principles & Grading Scale
Manual Muscle Testing (MMT) evaluates the strength of individual muscles or muscle groups based on gravity resistance, manual resistance, and range of motion.
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| THE MMT TESTING SEQUENCE & DECISION TREE |
| |
| [STEP 1: POSITION AGAINST GRAVITY] |
| Place client in standardized anti-gravity testing position. |
| Ask client to perform active movement through full ROM. |
| | |
| +--------+--------+ |
| | | |
| v (Full ROM) v (Incomplete ROM / No Motion) |
| [ANTI-GRAVITY >= 3/5] [RE-POSITION TO GRAVITY-ELIMINATED] |
| Apply manual resistance Place client in horizontal plane. |
| at end-range (break test): • Full ROM (no resist) = Grade 2 (Poor) |
| • Max resist = 5/5 (Normal)• Partial ROM = Grade 2- (Poor Minus) |
| • Mod resist = 4/5 (Good) • Palpable flicker = Grade 1 (Trace) |
| • Breaks immediately = 3/5 • No contraction = Grade 0 (Zero) |
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Comprehensive MMT 0–5 Grading Scale
| Numerical Grade | Qualitative Term | Operational Definition & Resistance Criteria |
|---|---|---|
| Grade 5 | Normal (N) | Completes full available active ROM against gravity and holds firmly against maximal manual resistance without breaking. |
| Grade 4 | Good (G) | Completes full available active ROM against gravity and holds against moderate manual resistance; gives slightly under maximal load. |
| Grade 3+ | Fair Plus (F+) | Completes full available active ROM against gravity and holds against minimal manual resistance before breaking. |
| Grade 3 | Fair (F) | Completes full available active ROM against gravity, but cannot hold against any added manual resistance. |
| Grade 3- | Fair Minus (F-) | Moves through more than 50% but less than full active ROM against gravity; cannot tolerate resistance. |
| Grade 2+ | Poor Plus (P+) | Completes full active ROM in gravity-eliminated plane and holds against minimal resistance, OR completes less than 50% ROM against gravity. |
| Grade 2 | Poor (P) | Completes full active ROM in a gravity-eliminated (horizontal) plane with zero added resistance. |
| Grade 2- | Poor Minus (P-) | Completes partial active ROM in a gravity-eliminated plane with zero resistance. |
| Grade 1 | Trace (T) | Tendon tension or faint muscle flicker is palpated during attempted voluntary contraction, but no joint movement occurs. |
| Grade 0 | Zero (0) | Complete absence of muscle contraction; no palpable or visible flicker on palpation. |
3. Grip & Pinch Dynamometry Protocols
Standardized hand strength assessment is conducted using a calibrated hydraulic dynamometer (Jamar) and pinch gauge.
1. Jamar Grip Dynamometer Protocol (ASSH Standards)
- Client Posture: Seated comfortably, shoulder adducted, elbow flexed to $90^\circ$, forearm in neutral, wrist in $0–30^\circ$ extension and $0–15^\circ$ ulnar deviation.
- Standard Testing Position: Handle Position 2 is the standard position for establishing normative comparisons.
- Trials: Administer 3 trials per hand; record the mean score in pounds (lbs) or kilograms (kg).
- The 5-Position Bell Curve Test: To detect submaximal voluntary effort or symptom magnification, test all 5 handle positions. Sincere effort produces a distinct bell-shaped curve (peaking at handle positions 2 or 3); a flat line indicates submaximal effort.
2. Standardized Pinch Strength Measures
- Tip Pinch (Two-Point): Thumb tip to index fingertip (tests median/anterior interosseous nerve).
- Key / Lateral Pinch: Pad of thumb against the radial aspect of the index middle phalanx (tests ulnar nerve / adductor pollicis; strongest pinch).
- Three-Jaw Chuck (Palmar Pinch): Pad of thumb to pads of index and middle fingers (functional pinch for pen/pencil holding).
4. Standardized Motor & Balance Batteries
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| STANDARDIZED MOTOR & BALANCE SCREENS |
| |
| [PURDUE PEGBOARD] ---> Fine fingertip dexterity & assembly; |
| pins, collars, washers in 30 / 60 seconds.|
| |
| [NINE-HOLE PEG TEST] ---> Rapid finger dexterity & finger agility; |
| time to place & remove 9 pegs. |
| |
| [BOX AND BLOCKS TEST] ---> Gross manual dexterity & grasp/release; |
| number of 1-inch blocks moved in 60s. |
| |
| [TIMED UP AND GO (TUG)] ---> Dynamic mobility & fall risk; |
| stand, walk 3m, turn, sit; >=12-14s = Fall|
| |
| [BERG BALANCE SCALE] ---> Static & dynamic balance (14 tasks); |
| Max score 56; <45 indicates fall risk. |
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Clinical Scenario: COTA Musculoskeletal & Motor Screening
Clinical Case Vignette: A 64-year-old carpenter who sustained a right distal radius fracture (status-post open reduction internal fixation 8 weeks ago) is referred for outpatient OT. The client reports stiffness, weak grip, and difficulty using hand tools. The supervising OTR directs the COTA to perform goniometric ROM, MMT, grip/pinch dynamometry, and a TUG screening.
COTA Assessment Administration:
- Goniometry: The COTA aligns the goniometer axis over the triquetrum and records right wrist flexion at $45^\circ$ (normal $80^\circ$) and extension at $40^\circ$ (normal $70^\circ$) with a firm capsular end-feel.
- Manual Muscle Testing: The COTA isolates wrist extensors against gravity. The client completes full available active ROM ($40^\circ$) and holds against moderate manual resistance before breaking, graded as 4/5 (Good).
- Dynamometry: Using the Jamar dynamometer at Handle Position 2 with elbow at $90^\circ$, the client averages $38\text{ lbs}$ on the right hand versus $92\text{ lbs}$ on the left hand. Three-jaw chuck pinch is $8\text{ lbs}$ right versus $22\text{ lbs}$ left.
- TUG Screening: The client completes the 3-meter TUG in $8.4\text{ seconds}$, demonstrating intact dynamic balance and low fall risk.
- Documentation: The COTA enters the objective data into the electronic health record and meets with the OTR to review findings for therapeutic exercise progression.
A COTA is measuring right shoulder flexion range of motion using a universal goniometer. What are the correct anatomical landmarks for positioning the axis (fulcrum), stationary arm, and movable arm?
When performing Manual Muscle Testing (MMT) for elbow flexion, the client is unable to move the forearm against gravity. The COTA positions the client's upper extremity in a gravity-eliminated horizontal plane (arm supported on a tabletop in 90° shoulder abduction). In this position, the client moves the elbow through the entire available active flexion ROM without resistance. What MMT grade should the COTA assign?
A COTA conducts a 5-handle position grip test using a Jamar hydraulic dynamometer to evaluate a client complaining of total hand weakness following a minor workplace strain. The client's recorded grip strength is 18 lbs at Handle 1, 19 lbs at Handle 2, 18 lbs at Handle 3, 19 lbs at Handle 4, and 18 lbs at Handle 5. How should the COTA interpret this flat graphical curve?
A COTA is screening an 81-year-old community-dwelling older adult following a mild transient ischemic attack. The client scores 38 out of 56 on the Berg Balance Scale and takes 16.5 seconds to complete the Timed Up and Go (TUG) test. What is the primary clinical implication of these combined screening results?