Transcript Muscles of the Body

Chapter 11
Muscles of the
Body
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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
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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