Anatomy and Cell Biology 3319 Lecture Notes - Lecture 7: Orbicularis Oris Muscle, Orbicularis Oculi Muscle, Rectus Femoris Muscle
15 Dec 2017
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Introduction to the muscular system: muscles of the head - facial expression, mastication and tongue. Skeletal muscles consist of fascicles (bundles of fibers: different arrangement in different muscles. Fascicles arranged in concentric rings form a circular pattern: these muscles surround external body openings, which they close by contracting, general name is sphincter, e. g. the orbicularis oris muscle around the mouth, orbicularis oculi around the eyes. Arrangement of fascicles influences: amount of movement produced when a muscle shortens (range of motion, amount of force the muscle produces (power) The more nearly parallel the fibers are to the muscle"s long axis, the more the muscle can shorten, resulting in a larger distance of movement: these muscles are usually not powerful. Muscle power depends more on the total number of fibers it contains: bipennate and multipennate muscles contain the most fibers, they shorten very little but tend to be powerful.
