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Questions and Answers
What is an upper motor neuron lesion?
A lesion of the neural pathway above the anterior horn of the spinal cord or motor nuclei of the cranial nerves.
Which conditions can lead to upper motor neuron lesions?
Which of the following is NOT a characteristic of upper motor neuron lesions?
What is clonus?
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UMN lesions result in ______ muscle tone.
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Which of the following describes the muscle tone in LMN lesions?
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Upper motor neuron lesions typically show muscle wasting.
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What physiological changes occur with weakness caused by lack of muscle activity?
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Study Notes
Objectives of the Lecture
- Define motor neuron and differentiate between upper motor neuron (UMN) and lower motor neuron (LMN).
- Review the anatomy related to UMN and LMN.
- Identify key features and conditions related to UMN and LMN dysfunction.
- Classify conditions associated with UMN and LMN lesions.
Nervous System Overview
- Central Nervous System (CNS) consists of the brain and spinal cord.
- Peripheral Nervous System (PNS) includes nerve roots and peripheral nerves.
- Autonomic Nervous System (ANS) regulates internal organ functions via sympathetic and parasympathetic pathways.
Upper Motor Neuron Lesions
- Defined as lesions above the anterior horn of the spinal cord or cranial nerve motor nuclei.
- Locations for UMN lesions can include the cortex, internal capsule, brain stem, or spinal cord.
- Common causes of UMN lesions: stroke, head injury, brain tumor, spinal cord injury, and multiple sclerosis.
Lower Motor Neuron Lesions
- Occur in the spinal cord, nerve plexus, and peripheral nerves.
- Conditions associated with LMN lesions: Guillain-Barré Syndrome, motor neuron disease, plexus injuries (e.g., Erb's palsy), and peripheral nerve injuries (e.g., crutch palsy).
Key Differences Between UMN and LMN Lesions
- Weakness: Both types present with weakness, but UMN typically exhibits more graded weakness (paresis) while LMN may lead to complete loss of muscle activity (plegia).
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Muscle Tone:
- UMN lesions cause increased muscle tone (hypertonia), leading to spasticity.
- LMN lesions result in decreased tone (hypotonia), often described as "floppy."
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Muscle Wasting:
- UMN lesions show no wasting initially; atrophy may occur over time due to disuse.
- LMN lesions result in muscle wasting due to denervation.
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Fasciculations:
- Absent in UMN lesions.
- Present in LMN lesions, resulting in involuntary muscle twitches.
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Reflexes:
- UMN lesions cause hyperreflexia (exaggerated reflexes).
- LMN lesions show hyporeflexia (diminished reflexes).
Physiological Changes from Muscle Inactivity
- Altered cross bridge connections due to lack of movement.
- Connective tissue undergoes water loss and collagen deposition.
- Fatty tissue proliferates within joint spaces, contributing to cartilage atrophy.
- Ligament insertion sites weaken, leading to osteoporosis in affected areas.
Spasticity
- Described as a motor disorder characterized by an increase in muscle tone that is dependent on the speed of movement.
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Description
This quiz covers the fundamentals of upper motor neuron lesions as presented in Lecture 2.2 of BPT 223, focusing on definitions, anatomy, and key features. It aims to enhance understanding of UMN conditions relevant to physiotherapy and neurology. Engage with the material to solidify your knowledge.
