NPTE-PT Neuromuscular and Nervous Systems 5 — Questions and Answers
Question 1: Which neurotransmitter is deficient in myasthenia gravis and what is the mechanism of dysfunction?
- Dopamine; presynaptic depletion
- Acetylcholine; autoimmune destruction of nicotinic receptors (Correct answer)
- GABA; loss of inhibitory interneurons
- Serotonin; reduced synaptic release
Correct answer: Acetylcholine; autoimmune destruction of nicotinic receptors
Myasthenia gravis is caused by autoimmune antibodies against nicotinic acetylcholine receptors at the neuromuscular junction, reducing functional receptor availability.
Question 2: A patient presents with a 'claw hand' deformity with hyperextension at the MCP joints and flexion at the IP joints of the ring and small fingers. Which nerve is injured?
- Median nerve
- Radial nerve
- Ulnar nerve (Correct answer)
- Anterior interosseous nerve
Correct answer: Ulnar nerve
Ulnar nerve injury causes claw hand of the ring and small fingers due to loss of intrinsic muscle function (lumbricals 3 and 4), resulting in unopposed extrinsic extensor and flexor forces.
Question 3: During the swing phase of gait, which muscle group is primarily responsible for foot clearance?
- Plantar flexors
- Ankle dorsiflexors (Correct answer)
- Knee flexors only
- Hip abductors
Correct answer: Ankle dorsiflexors
Ankle dorsiflexors (primarily tibialis anterior) lift the foot during swing phase to ensure clearance; weakness results in foot drop and compensatory circumduction or hip hiking.
Question 4: Which of the following is a characteristic feature of Guillain-Barré syndrome (GBS)?
- Ascending motor weakness with areflexia (Correct answer)
- Unilateral weakness with hyperreflexia
- Proximal muscle weakness only
- Sensory loss without motor involvement
Correct answer: Ascending motor weakness with areflexia
GBS is an acute demyelinating polyneuropathy characterized by ascending, typically symmetric motor weakness and areflexia, often following a respiratory or GI infection.
Question 5: A physical therapist is using PNF techniques with a patient post-stroke. Which PNF technique involves alternating isometric contractions of agonist and antagonist without joint movement?
- Repeated contractions
- Rhythmic stabilization (Correct answer)
- Slow reversal
- Contract-relax
Correct answer: Rhythmic stabilization
Rhythmic stabilization involves alternating isometric contractions of opposing muscle groups to improve stability, motor control, and cocontractions without movement.
Question 6: A patient with cerebellar ataxia demonstrates past-pointing on finger-nose testing. This error in overshooting a target is termed:
- Dysdiadochokinesia
- Dysmetria (Correct answer)
- Astereognosis
- Anosognosia
Correct answer: Dysmetria
Dysmetria is the inability to accurately judge distances and control movement termination, causing overshooting (hypermetria) or undershooting (hypometria) of a target.
Question 7: What is the primary purpose of constraint-induced movement therapy (CIMT) in stroke rehabilitation?
- Reduce spasticity through prolonged stretching
- Force use of the affected limb by restraining the unaffected limb (Correct answer)
- Improve gait through treadmill training
- Reduce learned non-use through bilateral arm training
Correct answer: Force use of the affected limb by restraining the unaffected limb
CIMT restrains the less-affected limb (usually with a mitt or sling) to force intensive use of the affected limb, overcoming learned non-use and promoting cortical reorganization.
NPTE-PT Neuromuscular and Nervous Systems 5
Which neurotransmitter is deficient in myasthenia gravis and what is the mechanism of dysfunction?