A77-year-old retired school superintendent comes to your office, complaining of unsteady hands. he says that for the past six months, when his hands are resting in his lap they shake uncontrollably. he says when he holds them out in front of his body the shaking diminishes, and when he uses his hands the shaking is also better. he also complains of some difficulty getting up out of his chair and walking around. he denies any recent illnesses or injuries. his past medical history is significant for high blood pressure and coronary artery disease, requiring a stent in the past. he has been married for more than 50 years and has five children and 12 grandchildren. he denies any tobacco, alcohol, or drug use. his mother died of a stroke in her 70s and his father died of a heart attack in his 60s. he has a younger sister who has arthritis problems. his children are all essentially healthy. on examination you see a fine, pill-rolling tremor of his left hand. his right shows less movement. his cranial nerve examination is normal. he has some difficulty rising from his chair, his gait is slow, and it takes him time to turn around to walk back toward you. he has almost no “arm swing” with his gait. what type of tremor is he most likely to have?

The type of tremors identified in this case is early parkinson disease tremors.

Explanation:

To understand our answer we need to analyze it. First of all, let's see his activity and exhaust. He doesn't say he has been physically active by performing heavy physical effort activities. He also doesn't recall a single moment of stress or substance abuse, so there is a very minimal chance to diagnose anxiety. But he does give you some elements. He says he has motor difficulties, he also says that he has less power in his muscles, and even though his movement decreases while he uses his hands. He can't control it, there is still shake in them. And those last factors are the classic symptoms to identify Parkinson's disease in its earliest stage.

the earth’s crust is broken into separate pieces called tectonic plates (fig. 7.14). recall that the crust is the solid, rocky, outer shell of the planet. it is composed of two distinctly different types of material: the less-dense continental crust and the more-dense oceanic crust. both types of crust rest atop solid, upper mantle material. the upper mantle, in turn, floats on a denser layer of lower mantle that is much like thick molten tar.

each tectonic plate is free-floating and can move independently. earthquakes and volcanoes are the direct result of the movement of tectonic plates at fault lines. the term fault is used to describe the boundary between tectonic plates. most of the earthquakes and volcanoes around the pacific ocean basin—a pattern known as the “ring of fire”—are due to the movement of tectonic plates in this region. other observable results of short-term plate movement include the gradual widening of the great rift lakes in eastern africa and the rising of the himalayan mountain range. the motion of plates can be described in four general patterns:

collision: when two continental plates are shoved together

subduction: when one plate plunges beneath another (fig. 7.15)

spreading: when two plates are pushed apart (fig. 7.15)

transform faulting: when two plates slide past each other (fig. 7.15)