Ch. 13 The Peripheral Nervous System

Amerman3rd EditionHuman Anatomy & PhysiologyISBN: 9780138247201, 9780138247928, 9780138201814Not the one you use?Change textbook

Amerman 3rd Edition

Ch. 13 The Peripheral Nervous System

Problem L3.1

Chapter 13, Problem L3.1

Complaining of muscle weakness, Delia goes to the doctor. Devise a series of physical examination tests that would help to determine if her problem involves upper or lower motor neurons.

Verified step by step guidance

Begin by conducting a detailed patient history to gather information about the onset, duration, and progression of muscle weakness, as well as any associated symptoms such as spasticity, reflex changes, or sensory deficits. This will help narrow down the potential involvement of upper or lower motor neurons.

Perform a reflex test using a reflex hammer to assess deep tendon reflexes (e.g., patellar reflex). Hyperactive reflexes may indicate upper motor neuron involvement, while diminished or absent reflexes may suggest lower motor neuron involvement.

Evaluate muscle tone by passively moving the patient's limbs. Increased muscle tone (spasticity) is characteristic of upper motor neuron lesions, whereas decreased muscle tone (flaccidity) is indicative of lower motor neuron lesions.

Conduct a strength test by asking the patient to perform specific movements against resistance (e.g., flexion, extension, abduction). Weakness in specific muscle groups may help localize the lesion and differentiate between upper and lower motor neuron involvement.

Assess for fasciculations (involuntary muscle twitches) and muscle atrophy by visually inspecting the affected muscles. Fasciculations and atrophy are hallmark signs of lower motor neuron damage, whereas these signs are typically absent in upper motor neuron lesions.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Upper Motor Neurons (UMN)

Upper motor neurons originate in the brain and project down to the spinal cord, where they synapse with lower motor neurons. They are responsible for initiating and regulating voluntary movements. Damage to UMNs can lead to symptoms such as spasticity, hyperreflexia, and weakness, but typically without muscle atrophy.

Lower Motor Neurons (LMN)

Lower motor neurons are located in the spinal cord and directly innervate skeletal muscles. They are crucial for executing movement. Damage to LMNs results in flaccid paralysis, muscle atrophy, and diminished reflexes, as the connection between the nervous system and muscles is disrupted.

Neurological Examination Tests

Neurological examination tests are clinical assessments used to evaluate the integrity of the nervous system. Tests such as the Babinski reflex, muscle strength assessments, and deep tendon reflex evaluations can help differentiate between UMN and LMN lesions. These tests provide critical information about the location and nature of the neurological issue.

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The Testes

Related Practice

Textbook Question

Match each type of neuroglial cell with its correct function.

____ Schwann cells

____ Ependymal cells

____ Microglial cells

____ Oligodendrocytes

____ Satellite cells

____ Astrocytes

a. Phagocytic cells of the CNS

b. Surround the cell bodies of neurons in the PNS

c. Create the myelin sheath in the PNS

d. Anchor neurons and blood vessels, maintain extracellular environment around neurons, assist in repair of damaged brain tissue

e. Create the myelin sheath in the CNS

f. Ciliated cells in the CNS that produce and circulate the fluid around the brain and spinal cord

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Textbook Question

Ramin presents for evaluation after a severe shoulder injury during which his entire brachial plexus suffered damage. What effects would you expect Ramin to have from this injury?

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Textbook Question

Maria is a 3-year-old who has been diagnosed with CIPA, or congenital insensitivity to pain with anhidrosis. This disease results from a genetic mutation that causes essentially all general sensory neurons to not function properly. What types of sensations will Maria be unable to detect (be specific)? Predict what problems she might face from her condition.

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Textbook Question

Predict what might happen if nociceptors were rapidly adapting instead of slowly adapting receptors. Would this change be beneficial or potentially harmful?

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Textbook Question

Define each of the following terms in your own words, using 20 or fewer words.

a. Peripheral nerve

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Textbook Question

When Mr. Dinh goes to the emergency department with pain in the area along the midline of the diaphragm, he worries he is having a heart attack. Could the pain be related to his heart? Could it be related to any other organ(s)? Explain.

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