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.
Volcanic Landforms Types of Volcanoes Volcanoes are classified by the types of eruption they produce. Broadly speaking, eruptions can be either effusive or explosive. Effusive eruptions are sometimes called quiet eruptions (if eruptions can be quiet!).ffusive Eruptions Effusive eruptions are those that create vast lava flows of low viscosity, fluid lava. Magma associated with effusive-type eruptions is relatively low in silica and thus easily flows up the vent and spreads across the surface. Moving across the land, these lava flows can take on two different forms.