Question 1

Tizanidine (Zanaflex)may help reduce spasticity in some patients by ______ receptors in the spinal cord.&#10;A)stimulating alpha-1&#10;B)inhibiting alpha-1&#10;C)stimulating alpha-2&#10;D)inhibiting alpha-2&#10;E)stimulating GABA

Accepted Answer

Tizanidine (Zanaflex) reduces spasticity by stimulating alpha-2 receptors in the spinal cord. This leads to a decrease in the amount of neurotransmitters (such as norepinephrine) released from nerve endings, which in turn reduces muscle tone and spasticity.

Question 2

Diazepam (Valium)appears to work as a muscle relaxant by increasing the inhibitory effect of ____ on alpha motor neuron activity in the spinal cord.&#10;A)norepinephrine&#10;B)epinephrine&#10;C)acetylcholine&#10;D)5-hydroxytryptamine (serotonin)&#10;E)gamma aminobutyric acid (GABA)

Accepted Answer

Diazepam (Valium) works primarily by enhancing the effect of gamma aminobutyric acid (GABA), an inhibitory neurotransmitter in the central nervous system. By increasing the effect of GABA, Diazepam reduces the excitability of alpha motor neurons in the spinal cord, leading to muscle relaxation.

Question 3

Intrathecal administration of baclofen typically refers to drug delivery into:&#10;A)the epidural space.&#10;B)the subarachnoid space.&#10;C)a sympathetic chain ganglion.&#10;D)the third ventricle of the brain.&#10;E)the gray matter of the spinal cord.

Accepted Answer

Intrathecal administration of baclofen means delivering the drug into the space around the spinal cord, called the subarachnoid space. This allows the drug to directly target the spinal cord and is used in the management of spasticity associated with conditions like multiple sclerosis, cerebral palsy, and spinal cord injuries. The other choices, such as the epidural space, sympathetic chain ganglion, or third ventricle of the brain, are not typically targeted with intrathecal delivery of baclofen.

Question 4

Muscle relaxant effects of botulinum toxin appear to diminish or wear off after several months because:&#10;A)the immune system destroys the toxin.&#10;B)the muscle hypertrophies and generates more muscle fibers.&#10;C)a new presynaptic terminal &#34;sprouts&#34; from the axon that was originally affected by the toxin.&#10;D)the liver metabolizes the toxin.&#10;E)the toxin is excreted intact in the urine.

Accepted Answer

The muscle relaxant effects of botulinum toxin diminish or wear off after several months because a new presynaptic terminal "sprouts" from the axon that was originally affected by the toxin. This process is called collateral sprouting and it allows the affected muscle to regain some of its function. The immune system does not destroy the toxin, the muscle does not hypertrophy and generate more muscle fibers, the liver does not metabolize the toxin, and the toxin is not excreted intact in the urine.

Question 5

The drug that inhibits spasticity by selectively inhibiting calcium release from skeletal muscle sarcoplasmic reticulum is:&#10;A)diazepam (Valium).&#10;B)baclofen (Lioresal).&#10;C)dantrolene sodium (Dantrium).&#10;D)tizanidine (Zanaflex).&#10;E)botulinum toxin (Botox).

Accepted Answer

Dantrolene sodium selectively inhibits calcium release from the sarcoplasmic reticulum in skeletal muscle, which reduces spasticity. Diazepam and tizanidine work by enhancing the inhibitory effects of GABA in the CNS, while baclofen acts as an agonist at GABA-B receptors. Botulinum toxin inhibits the release of acetylcholine at the neuromuscular junction.

Question 6

Muscle relaxants that supposedly inhibit polysynaptic reflexes in the spinal cord (polysynaptic inhibitors)may actually work by producing:&#10;A)decreased acetylcholine release at the neuromuscular junction.&#10;B)decreased calcium release from the sarcoplasmic reticulum.&#10;C)generalized sedation in the central nervous system.&#10;D)inhibition of myosin ATPase activity.&#10;E)increased vasodilation of skeletal muscle vasculature.

Accepted Answer

Polysynaptic inhibitors are believed to work by causing generalized sedation in the central nervous system, which reduces muscle spasm and pain perception rather than directly affecting neuromuscular transmission or muscle contraction mechanisms.

Question 7

The muscle relaxant that directly inhibits acetylcholine release from presynaptic terminals at the skeletal neuromuscular junction is:&#10;A)baclofen (Lioresal).&#10;B)botulinum toxin (Botox).&#10;C)dantrolene sodium (Dantrium).&#10;D)tizanidine (Zanaflex).&#10;E)none of the above

Accepted Answer

Botulinum toxin (Botox) is a muscle relaxant that directly inhibits acetylcholine release from presynaptic terminals at the skeletal neuromuscular junction. It is commonly used for cosmetic purposes and to treat muscle spasms and dystonia. Baclofen, dantrolene sodium, and tizanidine work through different mechanisms and do not directly inhibit acetylcholine release.

Question 8

Botulinum toxin is used to treat spasticity by injecting this drug:&#10;A)intravenously.&#10;B)intrathecally.&#10;C)subcutaneously.&#10;D)directly into the spastic muscle.&#10;E)none of the above;botulinum toxin is not used to treat spasticity.

Accepted Answer

Botulinum toxin is injected directly into the spastic muscle to reduce muscle stiffness and improve mobility. This treatment is typically used for conditions such as cerebral palsy, multiple sclerosis, and traumatic brain injury.

Question 9

Long-term use of diazepam (Valium)as a muscle relaxant is often limited due to problems with:&#10;A)sedation.&#10;B)tolerance.&#10;C)physical dependence.&#10;D)all of the above&#10;E)none of the above

Accepted Answer

Long-term use of diazepam as a muscle relaxant is often limited due to sedative effects that can impair daily functioning. Tolerance can develop, leading to the need for higher doses to achieve the same effect. Patients may also develop physical dependence, which can lead to withdrawal symptoms if the medication is stopped abruptly. Therefore, all of the above options limit the long-term use of diazepam as a muscle relaxant.

Deck 13: Skeletal Muscle Relaxants