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A&P I chapter 11
Question | Answer | |
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Muscle shape: convergent | Convergent muscles: Fascicles radiate out from a small to a wider point of attachment. Like blades of a fan. EX: pectoralis major. | |
Muscle shape: pennate (uni-, bi-, and multipennate) | Pennate muscles: “Feather-like” in appearance 3 types: 1. Unipennate muscles: Fascicles anchor to only one side of the connective tissue shaft. EX: soleus. | 2.Bipennate muscles: Type of double-feathered attachment of fascicles. EX: rectus femoris in thigh. 3. Multipennate muscles: Numerous interconnecting quill-like fascicles converge on common point of attachment. EX: deltoid |
Muscle shape: fusiform | Fusiform muscles. Fascicles close to parallel in “belly” of muscle but converge to tendon at one or both ends. EX: brachioradialis | |
Muscle shape: spiral | Spiral Muscles. Fibers twist between their points of attachment. EX: latissimus dorsi. | |
Muscle shape: circular | Circular Muscles. “Sphincters”. Often circle body tubes or openings. EX: orbicularis oris around the mouth | |
define lever | Lever. Any rigid bar free to turn about in a fixed point (fulcrum. Bones | |
know the parts of a lever | Composed of 4 parts. 1.Rigid rod or bar: Bone. 2.Fixed pivot or fulcrum (F): Around which the rod moves. Joint. 3.Load (L): Resistance that is moved. 4.Force or pull (P):Which produces movement. Muscle contraction | |
know and describe the different classes of levers | 1. First-Class Levers: Fulcrum lies between the pull and the load as in a set of scales or a seesaw. EX: head tilted forward or backward on atlas. | 2. Second-Class Levers: Load lies between fulcrum and point where pull is exerted like a wheelbarrow. EX: raising body on toes. Point of contact between toes and ground |
define origin and insertion | 1. Origin: Point of attachment that does not move. More stationary of the 2 bones. 2. Insertion: Point of attachment that moves. Moves toward the origin bone when muscle shortens. | |
know and describe different muscle actions: prime mover (agonist) | Prime mover or agonist. Muscle or group of muscles that directly performs a specific movement. The movement of this muscle is described as the “action” or “function” of that muscle. | |
Muscle actions: synergists | Synergists. Muscles that contract at the same time as the prime mover. Facilitate or complement prime mover actions. Produces a more effective movement. | |
Muscle actions: fixator | Fixator: Joint stabilizers. Maintain posture or balance during contraction of prime movers acting on joints in arms and legs. Muscle movements are complex. Most muscles function as most of these at one point or another | |
know and describe the divisions of the muscular system | 1. Axial muscles: Position head and spinal column. Move rib cage. 60% of skeletal muscles. 2. Appendicular muscles: Support pectoral and pelvic girdles. Support limbs. 40% of skeletal muscles. | |
define mastication | chewing | |
define linea alba | Fuse in the midline to form tough band called linea alba (white line). Extends from xiphoid process to the pubis | |
know the difference between extrinsic and intrinsic muscles in terms of the hands and feet | 1.Extrinsic: From the outside. Refers to muscles originating outside part of the skeleton moved. | Muscles in forearm that pull on their insertions in wrist, hand, and fingers to move them. 2.Intrinsic: From within. Refers to muscles that are actually within the part moved. Muscles that begin and end at different points within the hand; produce fine fi |
define posture | Posture: Maintaining optimal body position. “Good posture” means: Body alignment that favor function. Requires least muscle work to maintain. Places least strain on muscles, ligaments, and bones. Keeping body’s center of gravity over its base | |
define tonicity in regards to muscles | Property of muscles that allow them to have this function. Means tension. Continuous, low level of sustained contraction maintained by all skeletal muscles. | Tonicity is absent during sleep. Muscle pull can’t counteract the pull of gravity. This is why we can’t sleep standing up. know effects of poor posture |
know and describe different muscle shapes: parallel | Parallel muscles: Long strap-like muscles with parallel fascicles. Vary in length. EX: sartorius of leg. EX: rectis abdominis . fascicles are “interrupted” by transverse intersections. |