Summary 11.1 Interactions of Skeletal Muscles, Their Fascicle Arrangement, and Their Lever Systems - Anatomy and Physiology 2e | OpenStax openstax.org
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This text explains how skeletal muscles connect to bones through tendons, how their origin and insertion points determine their mobility, how agonist and antagonist muscles have opposing actions, how muscles are organized into fascicles, and how the skeleton acts as a lever for muscles to provide effort through contraction.
Slides
Slide Presentation (10 slides)
Key Points
- Skeletal muscles work in pairs and are attached to bones via tendons.
- The moveable end of the muscle is called the insertion, while the end attached to a fixed bone is called the origin.
- The principal muscle involved in an action is called the agonist or prime mover, while the muscle with the opposite action is called the antagonist.
- Muscles can be organized into fascicles, which are bundled groups of muscle fibers.
- Fascicles can be arranged in different patterns, including parallel, circular, convergent, and pennate.
- The skeleton acts as a lever, with bones as stiff levers and the articular endings of the bones acting as fulcrums.
- The load being lifted or any resistance to movement is the load, while the effort comes from contracting skeletal muscle.
Summaries
38 word summary
Skeletal muscles connect to bones through tendons. Origin and insertion points distinguish movable and fixed ends. Agonist and antagonist muscles have opposing actions. Muscles are organized into fascicles. Skeleton acts as a lever. Muscles provide effort through contraction.
60 word summary
Skeletal muscles connect to bones through tendons. The insertion is the movable end, while the origin is attached to a fixed bone. The agonist is the main muscle involved in an action, while the antagonist has the opposite action. Muscles can be organized into fascicles with different arrangements. The skeleton acts as a lever and muscles provide effort through contraction.
121 word summary
Skeletal muscles are paired and connected to bones by tendons. The insertion is the movable end of the muscle, while the origin is attached to a fixed bone. The agonist or prime mover is the main muscle involved in an action, while the antagonist has the opposite action. Agonist muscles create movement, while antagonist muscles maintain body position and control rapid movement. Some muscles, like facial muscles and those in the tongue and sphincters, do not move the skeleton. Muscles are organized into fascicles, which can have different arrangements such as parallel, circular, convergent, and pennate. The skeleton and muscles work together to move the body, with the skeleton acting as a lever and the muscles providing the effort through contraction.
286 word summary
Skeletal muscles work in pairs and are attached to bones via tendons. The moveable end of the muscle is called the insertion, while the end attached to a fixed bone is called the origin. The principal muscle involved in an action is called the agonist or prime mover, while the muscle with the opposite action is called the antagonist. Agonist muscles contract to produce movement, while antagonist muscles maintain body or limb position and control rapid movement. There are also muscles that do not pull against the skeleton for movement, such as facial muscles and muscles in the tongue and urinary and anal sphincters.
Muscles are organized into fascicles, which are bundled groups of muscle fibers. Fascicles can be arranged in different patterns, including parallel, circular, convergent, and pennate. Parallel muscles have fascicles that run in the same direction as the long axis of the muscle and are the most common type of muscle organization. Circular muscles, also known as sphincters, have concentrically arranged bundles of muscle fibers that can open or close an opening. Convergent muscles have a widespread expansion that converges on a common attachment point. Pennate muscles have fascicles that blend into a tendon running through the central region of the muscle. Unipennate muscles have fascicles on one side of the tendon, bipennate muscles have fascicles on both sides of the tendon, and multipennate muscles have fascicles that wrap around the tendon.
The skeleton and muscles work together to move the body. The skeleton acts as a lever, with bones as stiff levers and the articular endings of the bones acting as fulcrums. The load being lifted or any resistance to movement is the load, while the effort comes from contracting skeletal muscle.