Basics of polymyalgia rheumatica. Polymyalgia rheumatica (PMR) is a disorder that causes stiffness and aching that begins in the neck, shoulder and hip areas. It is not known whether it is a disease of the joints muscles or arteries.However it is thought that inflammation in these areas leads to pain and stiffness.Incidence.olymyalgia rheumatica (PMR) is a disorder that causes stiffness and aching that begins in the neck, shoulder and hip areas. It is not known whether it is a disease of the joints muscles or arteries. However it is thought that inflammation in these areas leads to pain and stiffness. Incidence.
There are two main types of volcanic eruptions: Explosive and Nonexplosive eruptions.he types of volcanic eruptions are magmatic, phreatomagmatic, and phreatic. For a description of each type and different styles of each, refer to the link below.
A volcanic eruption occurs when molten rock, ash and steam pour through a vent in the earth's crust. Volcanoes are described as active (in eruption), dormant (not erupting at the present time), or extinct (having ceased eruption; no longer active).Some volcanoes explode.Others are slow-flowing fountains of lava, which is hot fluid rock. The following are examples of famous volcanic eruptions.olcanoes are described as active (in eruption), dormant (not erupting at the present time), or extinct (having ceased eruption; no longer active). Some volcanoes explode. Others are slow-flowing fountains of lava, which is hot fluid rock.