A nurse is assessing a patient with suspected musculoskeletal injury. Which assessment finding would indicate normal muscle strength?
The nurse is performing a muscle strength assessment on a 60-year-old retired teacher who reports shoulder pain after gardening.
1The patient can move the joint through partial range of motion against gravity but cannot resist additional resistance.
2The patient can move the joint through full range of motion but cannot overcome gravity
3The patient can move the joint through full range of motion against gravity but cannot resist additional resistance.
4The patient can move the joint through full range of motion against gravity and can resist moderate to strong pressure.✓ 정답
해설
Normal muscle strength (grade 5) involves full range of motion against gravity with resistance to moderate pressure. Other options represent lower grades of muscle weakness.
Clinical Judgment
This question assesses your ability to understand the standard scale for muscle strength testing and apply the Core Concept that defines normal muscle strength (Grade 5). A patient is considered to have normal strength only if they can move through a full range of motion (Full ROM) against gravity and also withstand moderate to strong resistance applied by the examiner. Option 4 is the only choice that meets both of these conditions ("against gravity" and "resist moderate pressure").
Memory Tip:
An easy way to remember muscle strength grades is with Gravity and Resistance. Grade 3 can only oppose Gravity, while Grade 5 can oppose both Gravity and Resistance. The key is "Full ROM + against gravity + against resistance."
KR vs US:
Both Korea and the US use the standardized 0-5 scale for muscle strength testing. The difference is that US clinical settings more strictly follow a structured protocol called "Manual Muscle Testing (MMT)," which is especially important in fields like Physical Medicine and Occupational Therapy. In Korea, nurses perform basic muscle strength assessments, whereas in the US, it is more common for nurses to conduct initial screenings, with detailed MMT being performed by a Physical Therapist (PT) or Occupational Therapist (OT).
Clinical Practice Guide
When assessing muscle strength, place the patient in a stable position and support the proximal part of the joint being evaluated. After instructing them to "resist the force," apply resistance slowly and steadily. It is important to always compare with the unaffected side (the opposite healthy side).
Caution:
In SATA (Select All That Apply) questions, you may be asked to choose all descriptors related to "normal muscle strength." You should look for a sentence that includes all three elements: "full range of motion," "against gravity," and "against resistance." Also, if a situation is given where "resistance testing cannot be fully performed due to pain," the muscle strength grade should not be recorded as "5/5," but rather documented as "unable to assess accurately due to pain."
Manual Muscle Testing — Manual muscle testing. A standardized method where the examiner applies resistance to a specific muscle or muscle group while the patient moves, grading muscle strength on a scale from 0 to 5.
Range of Motion — Range of motion. The angle or distance a joint can move normally. It is divided into active range of motion (Active ROM, the patient moves on their own) and passive range of motion (Passive ROM, the examiner moves it).
Gravity — Gravity (in muscle strength assessment). It is the natural resistance that serves as a key criterion when grading muscle strength. Grade 3 is considered the minimum normal muscle strength that can move against gravity.
Resistance — Resistance (in muscle strength testing). External pressure applied by the examiner in the opposite direction to the patient's movement. It is an essential element for determining normal muscle strength (Grade 5).
Muscle Strength Grading Scale (0-5) — Muscle strength grading scale. It is classified as 0 (no contraction), 1 (flicker only), 2 (full ROM with gravity eliminated), 3 (full ROM against gravity), 4 (full ROM against gravity + against weak resistance), 5 (full ROM against gravity + against normal/strong resistance).