MMT Trunk Assessment 3 — Questions and Answers
Question 1: When palpating the rectus abdominis during MMT, where is the optimal location to assess muscle contraction?
- Lateral to the umbilicus
- Between the xiphoid process and pubic symphysis along the midline (Correct answer)
- Over the iliac crest
- At the inguinal ligament
Correct answer: Between the xiphoid process and pubic symphysis along the midline
The rectus abdominis runs vertically between the xiphoid process and pubic symphysis and is best palpated along this midline path.
Question 2: Which trunk MMT grade requires the patient to maintain a position against maximum resistance for the full test duration?
- Grade 3
- Grade 4
- Grade 5 (Correct answer)
- Grade 3+
Correct answer: Grade 5
Grade 5 indicates normal strength, meaning the muscle holds against maximum resistance without yielding.
Question 3: During prone trunk extension testing, the therapist notices asymmetric paraspinal muscle bulk. What should be the next clinical step?
- Proceed with bilateral resistance testing simultaneously
- Test each side independently and document any asymmetry (Correct answer)
- Reassign a single bilateral grade based on the stronger side
- Terminate testing due to safety concerns
Correct answer: Test each side independently and document any asymmetry
Asymmetry warrants independent bilateral testing and documentation to accurately capture unilateral deficits.
Question 4: The quadratus lumborum contributes to which trunk movement assessed in MMT?
- Trunk flexion
- Trunk extension
- Trunk lateral flexion (Correct answer)
- Trunk rotation
Correct answer: Trunk lateral flexion
The quadratus lumborum laterally flexes the trunk and is a key stabilizer assessed during trunk lateral flexion MMT.
Question 5: A patient scores Grade 4 on trunk flexion but Grade 2 on trunk extension. This pattern most commonly suggests:
- Malingering
- Upper motor neuron lesion affecting extensors preferentially
- Anterior cord syndrome or abdominal muscle hypertrophy with weak back extensors (Correct answer)
- Normal aging variation
Correct answer: Anterior cord syndrome or abdominal muscle hypertrophy with weak back extensors
Disproportionately weak trunk extensors relative to flexors can indicate anterior cord syndrome or selective extensor weakness from disuse or pathology.
Question 6: In the Kendall MMT system, what position is used to test the lower rectus abdominis with an emphasis on pelvic tilt?
- Supine, patient posteriorly tilts pelvis lifting legs to 90° (Correct answer)
- Sitting, patient leans backward 45°
- Standing, patient flexes trunk forward
- Prone, patient lifts pelvis off table
Correct answer: Supine, patient posteriorly tilts pelvis lifting legs to 90°
The lower abdominals are emphasized when the patient posteriorly tilts the pelvis and lifts the legs in supine, stressing the lower portion of the rectus abdominis.
Question 7: Which nerve root level primarily innervates the erector spinae muscles throughout the thoracolumbar region?
- C5–C6
- T1–T4
- Posterior primary rami of spinal nerves throughout their levels (Correct answer)
- L4–S1 only
Correct answer: Posterior primary rami of spinal nerves throughout their levels
The erector spinae are innervated segmentally by the posterior primary rami (dorsal rami) of the corresponding spinal nerve levels.
MMT Trunk Assessment 3
When palpating the rectus abdominis during MMT, where is the optimal location to assess muscle contraction?