Muscles of the Body Chapter 11 ehow.com

Objectives Know the five main shapes of muscle Understand how muscles fit into functional groups and what those functional groups are Know how muscles are named

Muscle Shapes Determined by the orientation of the fascicles Five main shapes – Fusiform – Parallel – Triangular convergent – Pennate Unipennate Bipennate Multipennate – Circular classes.midlandstech.com

Functional Groups of Muscles Action – the effect produced by a muscle – To move or not to move Four categories (based on action) – Prime mover (agonist) Produces most of the force during a joint action – Synergist Aids the prime mover by having similar effect on joint or stabilizing and focusing action of prime mover – Antagonist Opposes the prime mover – Fixator Muscle that prevents a bone from moving

Naming Muscles Named according to various descriptive criteria – Location of muscle – indicate the bone or body region muscle associated with Temporalis, intercostals – Shape of the muscle Trapezius, deltoid

Naming Muscles – Relative size of muscle Maximus, minimus, longus (long), brevis (short) – Direction of muscle fibers Named in relation to a line running the length of the body Rectus, transverse, oblique – Number of origins (heads) Bi, tri, and quad

Naming Muscles – Location of attachments – named according to their points of origin and insertion Sternocleidomastoid Origin is always first – Action – named according to the effect of the muscle Flexor, extensor, adductor