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Muscle relaxants
Learning objectives
Upon completion of this chapter, you should be able to:
1.
Describe a spinal reflex and discuss the pathophysiology of muscle spasm and muscle spasticity.
2.
Describe the therapeutic actions, indications, pharmacokinetics, contraindications, most common adverse
reactions and important drug–drug interactions associated with the centrally-acting and the direct-acting
skeletal muscle relaxants.
3.
Discuss the use of muscle relaxants across the lifespan.
4.
Compare and contrast the prototype drugs baclofen and dantrolene with other muscle relaxants in their
classes.
5.
Outline the care considerations, including important teaching points for people receiving muscle relaxants
as adjunct to anaesthesia.
Glossary of key terms
basal ganglia:
lower area of the brain, associated with coordination of unconscious muscle movements that involve movement and
position
cerebellum:
lower portion of the brain, associated with coordination of muscle movements, including voluntary motion, as well as
extrapyramidal control of unconscious muscle movements
extrapyramidal tract:
cells from the cortex and subcortical areas, including the basal ganglia and the cerebellum, which coordinate
unconsciously controlled muscle activity; allows the body to make automatic adjustments in posture or position and balance
hypertonia:
state of excessive muscle response and activity
interneuron:
neuron in the CNS that communicates with other neurons, not with muscles or glands
pyramidal tract:
fibres within the CNS that control precise, intentional movement
spasticity:
sustained muscle contractions
spindle gamma loop system:
simple reflex arcs that involve sensory receptors in the periphery that respond to stretch and spinal
motor nerves and cause muscle fibre contraction: responsible for maintaining muscle tone and keeping an upright position against
the pull of gravity
Test your current knowledge of muscle relaxants with a PrepU Practice Quiz!
CENTRALLY-ACTING SKELETAL
MUSCLE RELAXANTS
baclofen
diazepam
orphenadrine
DIRECT-ACTING SKELETAL
MUSCLE RELAXANTS
botulinum toxin type A
dantrolene
