Anatomy and Chemistry Basics
The Muscular System
Skeletal muscles are often named after the following characteristics:
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Number of origins. Biceps, triceps, and quadriceps indicate two, three, and four origins, respectively.
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Location of origin or insertion. The sternocleidomastoid names the sternum (“sterno”) and clavicle (“cleido”) as its origins and the mastoid process of the temporal bone as its insertion.
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Location. In addition to its origin or insertion, a muscle name may indicate a nearby bone or body region. For example, the temporalis muscle covers the temporal bone.
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Shape. The deltoid (triangular), trapezius (trapezoid), serratus (sawtoothed) and rhomboideus major (rhomboid) muscles have names that describe their shapes.
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Direction of muscle fibers. The terms rectus (parallel), transverse (perpendicular), and oblique (at an angle) in muscle names refer to the direction of the muscle fibers with respect to the midline of the body.
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Size. Maximus (largest), minimus (smallest), longus (longest), and brevis (shortest) are common suffixes added to muscle names.
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Action. Terms such as flexor, extensor, abductor, and adductor are added as prefixes to muscle names to indicate the kind of movement generated by the muscle.
