Protraction - moves anteriorly Retraction - posterior motion Elevation - moves superiorly Depression - moves inferiorly Joint Movements
Rotation - twisting of a bone about its long axis Medial rotation - inward rotation Lateral rotation - outward rotation Pronation - radius rotates medially, crossing over ulna Supination - radius rotates laterally http:// Joint Movements
Special Foot Motions Dorsiflexion - moving foot dorsally Plantar Flexion - moving foot ventrally Inversion - sole of foot tilted medially Eversion - sole of foot tilted laterally Why is the top of the foot dorsal? Because our limbs start out like fish fins sticking out to side. As we develop, the legs rotate inward, moving dorsal anteriorly
Skeletal Muscle Organization Skeletal muscles are organized into 3 hierarchical levels: Muscle = organ composed of many fascicles Fascicles = a group of muscle fibers Muscle Fibers = muscle cells Each level is surrounded by a connective tissue capsule (epimysium, perimysium, etc.), all of which merge at end of muscle to form tendons that attach the muscle to bone.
Skeletal Muscle Contraction Muscles move bones by contracting and shortening, which pulls on the tendons, drawing ends of muscle (and attached bones) closer together.
What happens to muscle length in each of these cases? 1. Concentric Contraction : muscle tension > resistance 2. Eccentric Contraction : muscle tension < resistance 3. Isometric Contraction : muscle tension = resistance Types of Muscle Contractions Shortens Lengthens Stays same
Muscle Fiber Orientation Muscles come in different shapes based on the orientation of muscle fibers relative to each other: Parallel – muscle fibers parallel, in line with main axis of muscle Triangular – muscle fibers converge at an angle on tendon Pennate – muscle fibers attach to a central tendon at an angle Circular – muscle fibers encircle a tube or opening, and close that tube or opening. Also called sphincters Parallel Triangular Pennate Circular Which one is which below?
The power of parallel muscles is directly proportional to the number of muscle fibers, measured as the cross sectional area These are the most efficient muscles (produce the most force per unit of energy used during contraction) … why? Parallel Muscles Because all muscle fibers are directly in line with the direction of muscle movement, so all energy expended during contraction is used to move the muscle
Triangular & Pennate Muscles Triangular and pennate muscles are more powerful than parallel muscles because many more muscle fibers are packed into a similar sized muscle Power is slightly less than the total number of muscle fibers because these muscles are less efficient … why?
- Fall '16
- Vertebra, Pennate Muscles, Overview of Bones