Which is a large, fan-shaped muscle that forms the chest and enables several arm movements?

Pectoral Muscles.

Explanation: Pectoral Muscles can be defined as the fan shaped muscles that connects the front of the human chest with the bones of the shoulder and upper arm.

Mainly the Pectoralis major can be defined as the fan shaped muscle,which is responsible for the bulk that is found in the chest muscle. It lies just below the breast and helps in the flex and extent. It also helps in the rotation of the upper arm.

answer:

convection currents in the magma drive plate tectonics. heat generated from the radioactive decay of elements deep in the interior of the earth creates magma (molten rock) in the aesthenosphere. the aesthenosphere (70 ~ 250 km) is part of the mantle, the middle sphere of the earth that extends to 2900 km.