A motor unit is made up of a motor neuron and the skeletal muscle fibers innervated by that motor neuron's axonal terminals.roups of motor units often work together to coordinate the contractions of a single muscle; all of the motor units within a muscle are considered a motor pool. All muscle fibers in a motor unit are of the same fiber type.
SURFACE STRUCTURE. Basaltic lava flows erupt primarily from shield volcanoes, fissure systems, scoria cones, and spatter cones. These fluid lava flows can be subdivided into two end-member structural types, based primarily on the nature of lava flow surfaces: 1  Pahoehoe Lava -- Surfaces are smooth, billowy, or ropy.
Shield volcanoes have very fluid lava composed almost entirely of basalt. The lava which arrives at the surface is hot and little changed since the time it was generated. Shield volcanoes are the largest volcanoes on Earth.The basaltic lava can pile up producing huge shields with gentle slopes and convex outlines.hield volcanoes have very fluid lava composed almost entirely of basalt. The lava which arrives at the surface is hot and little changed since the time it was generated. Shield volcanoes are the largest volcanoes on Earth.