A&P Chapter 12

You have a patient experiencing an essential tremor, which makes it hard for him to dress and feed himself. Imaging has detected a lesion in the basal nuclei. How would you best explain the function of these cerebral structures to him?

"This group of cells monitors all of our outgoing motor signals and makes sure there isn't any excessive activity. Your injury is preventing them from doing their job." One of the primary roles of the basal nuclei is to prevent or inhibit unwanted muscle contraction. This is why the symptoms of Parkinson's and Huntington's disease are of such.

Amyotrophic lateral sclerosis is a neurodegenerative disease in which motor neurons are progressively destroyed. Excess levels of the neurotransmitter glutamate have been implicated in this process. Which type of neuroglia would play a role in controlling glutamate levels in the chemical environment of neurons?

Astrocytes

Which statement is true of both poliomyelitis and amyotrophic lateral sclerosis (ALS)?

Both conditions are caused by destruction of the ventral horn neurons in the spinal cord. Destruction of neurons in the ventral motor horns of spinal cord gray matter results in the paralysis in both conditions.

What brain structure interacts with the thalamus in directing cortical activity, and like the cerebrum, may be affected by unresponsive wakefulness syndrome (UWS)?

Cerebellum

Your patient's CT scan demonstrates a cerebral vascular accident causing damage to the inferior and posterior portions of her left cerebral hemisphere. Your patient is right-handed. What deficits should you expect?

Difficulty with movement on the right side of her body and difficulty with speech. Broca's area, which controls the production of speech is found on the left frontal lobe in 90% of right-handed people. Her primary motor cortex for the right side of her body is in the posterior portion of her left cerebral hemisphere.

Besides being a relay station for all sensory input, what other key role does the thalamus play?

It helps mediate memory.

When eating or drinking something ice cold, what branch (division) of the trigeminal nerve serving the palate receives the initial cold stimulus?

Maxillary

A brain hemorrhage within the region of the right internal capsule results in paralysis of the left side of the body. Explain why the left side (rather than the right side) is affected.

Motor neurons undergo decussation (crossing over) in the medulla oblongata on their way to the periphery.

Peripheral neuropathy has a variety of causes. Worldwide, the most common cause is leprosy, also known as Hansen's disease. Would you expect peripheral neuropathy to cause damage to tracts or to nerves? Why?

Nerves are damaged in the periphery as a result of a bacterial infection.

Wrist drop results in an inability to extend the hand at the wrist. Which nerve would most likely be affected in this injury?

Radial Nerve

Damage to which of these brain regions would be the most life-threatening? Explain your answer.

The brain stem because it controls many of the body's functions that are essential for life.

Patients with unresponsive wakefulness syndrome (UWS) have lost awareness of self and their environment. In many cases, there is no damage to the cerebral cortex or the brain stem. If signal transmission to the cerebral cortex is affected, what part of the brain is most likely to have been damaged?

The thalamus is most likely the problem because this is the relay center for sensory information trying to reach the cerebrum.