Unformatted text preview: B. Skeletal Muscle Shapes Fasciculi may run parallel to long axis of muscle (great range of motion, little strength) or
insert diagonally into a tendon running the length of the muscle (small range of motion,
greater strength). 1. Unipennate - all fasciculi insert on one side of a tendon - semimembranosus 2. Bipennate - fasciculi insert on both sides of tendon - rectus femoris 3. Multipennate - convergence of several tendons - deltoid 4. Longitudinal (strap) - fasciculi run parallel to the long axis of the muscle - sartorius,
rectus abdominus 5. Radiate - ﬁbers fan out from a single attachment - pectoralis major C. Muscle Actions Most movements require the cooperative action of several muscles ﬁmctioning as a group. 1. Prime mover - a muscle Whose contraction is primarily responsible for a particular
Most movements are the result of the contraction of more than one muscle, and
frequently a single muscle contributes to the production of two or more movements. 2. Antagonist - muscles that oppose one another upon contraction - biceps and triceps.
Antagonists are located on opposite sides of a joint. 3. Fixators/stabilizers - muscles that immobilize a bone or joint near the origin of the prime mover so that the prime mover can act more efﬁciently. II. Structure of Skeletal Muscle A. Gross Anatomy Tendons are extensions of connective tissue membranes beyond the end of the muscle.
Origin - less movable end of a muscle, usually proximal.
Insertion - more movable end of a muscle, usually distal. Belly - Widest portion of a muscle, between its origin and insertion. ...
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- Spring '09