1. The Muscular System Chapter 10

2. Understanding Muscles Pull never push Attach to skeleton via tendons or muscles via aponeurosis Attachment points – Origin: end attaches to a stationary bone; doesn’t move – Insertion: end attaches to a moving bone; moves Contractions shorten muscles

3. Functional Groups Agonist (prime movers) – Prime responsibility for causing a movement Antagonist – Oppose/reverse movement – Regulate agonist by adding resistance Synergist – Assist prime mover – Add extra force or reduce undesirable movement Fixators – Immobilize bone or muscle origin Not mutually exclusive

4. Naming Muscles Location – Bone or region associated w/ – E.g. brachii and femoris Shape – E.g. deltoid and trapezius Size – E.g. maximus, minimus, longus Action – E.g. flexor, extensor, supinator Direction of fibers & fasicles – E.g. rectus, oblique, transversus Number of origins – E.g. biceps and triceps Location of attachment – Points of origin & insertion – E.g. sternocleidomastoid

5. Fasicle Arrangement Determines range of mov’t & power Types – Parallel (fusiform) Parallel to long axis – Pennate Short & attach obliquely to an insertion tendon Uni-, bi-, or multi – Convergent Broad origin converges to an insertion – Circular Concentric rings around external openings Contractions close

6. Lever Systems A lever (bones) moves on a fulcrum (joints) when effort (muscle contraction) moves a load (bone and everything else) Mechanical advantage (power lever) – Effort farther from load then fulcrum – Little effort needed – Force gained for speed and stability – E.g. car jack Mechanical disadvantage (speed lever) – Effort nearer load then fulcrum – Force lost for speed and range – E.g. shovel

7. First – Mechanical advantage or disadvantage Second – Uncommon in body – Always mechanical advantage Third – Most skeletal muscles – Always mechanical disadvantage Classes of Levers

8. Learning Muscles Need to know – Names of major muscles – Basic functions/actions of muscles Table 10.1 – Location Studying – Learn names Look for clues in names from existing knowledge Draw and or act out Identify on models or self