Georgetown ISD



HAP Muscular System NotesMuscles have always been associated with movement. There are 3 kinds of muscles:Skeletal muscle—responsible for voluntary movement that helps us get through our environment safely and successfully.Cardiac muscle—responsible for pumping blood through tiny little tubes called vessels. This is an involuntary movement.Smooth muscle—responsible for emptying and filling blood vessels and all hollow organs, plus they control the movement of air through the bronchi tubes. This muscle movement is also involuntary.Skeletal Muscles—move us through the world.Muscle movement involves three systems that are intimately coordinated:Muscular systemNervous systemSkeletal systemRules Muscles “Live” By!!!!Rule #1: Muscles must have at least two attachments. In addition they must cross at least one articulation (joint). *exceptions are in the face and pelvic floorThe attachment that remains in its original position is called the origin.The attachment that pulls or moves is called the insertion.Rule #2: To produce movement, muscles always pull and get shorter.The distal attachment moves toward the proximal attachment.Rule #3: Muscle fibers always point to their attachments and show direction of pull.Diagram #1: muscleDiagram #1: Muscle3611245-635belly of muscleligament or tendon—dense regular connective tissue4000020000belly of muscleligament or tendon—dense regular connective tissueDiagram #2: fascicles3992629360243Epimysium/fasciaFascicle—its outer wrapping of CT is called the perimysiumEndomysium00Epimysium/fasciaFascicle—its outer wrapping of CT is called the perimysiumEndomysiumIdentification of muscle movement and attachmentWhen muscles move ventral to ventral it is a flexor.When muscles move dorsal to dorsal they are extensors.Review of Directional Terms as they relate to muscle movement:Ventral—lighter side—flexorsDorsal—darker side—extensorsAnterior—anatomical term for front of body when in anatomical position.Posterior—anatomical term for back of body when in anatomical position.Exceptions to the rules:Hip flexion—dorsal side of leg up to the ventral torsoHip extension—ventral side of leg up the to the dorsal side of the torsoDorsiflexion—the dorsal side of the foot up to the dorsal side of the lower legPlantar flexion—(pointed toe) plantar side of foot flexes to the ventral side of the lower legMuscles work in opposing pairs.If a muscle can flex (ventral location) a joint then there is an opposite muscle on the other side that extends the joint (dorsal location). If there is a muscle that rotates a joint one way, there has to be a muscle on the opposite side that will rotate the muscle back. (Example: supinator rotates the palm up and pronator rotates the palm down.)Primary Movers vs. AntagonistThe muscle that pulls is known as the primary mover (agonist).The opposing muscle has to relax which is opposite of pulling, so it is known as the antagonist.Striation Patterns and StrengthFan shaped muscles create a greater force of pull because the fibers apply all of their effort on one point of the tendon, thus generating more power from the muscle. With fan shaped muscles the large top of the fan is the origin, and the fibers combine their efforts on the narrow insertion. Fan shaped muscles attach to Flat parts of bone (fossas) and have Fleshy attachments.Bone Markings and Muscle AttachmentsMuscles that have long tendons (tendenous attachments) will attach to a “bump” or “bar” of bone. The names of these markings are condyles, epicondyles, tuberosities, and trochanters. A “bar” of bone that sticks out begs for a tendon to attach to its process.These “bumps” or “bars” of bone are formed by the genetic code during embryo growth, but they can be enhanced by the amount of stress placed on the bone by either weight or muscle pull.Tendons attach to these structures by growing into the bone with Sharpey’s fibers… much like how a tree grows roots into the ground. The stronger the muscle becomes from activity or carrying weight, the stronger the pull on the bone. This stimulates osteoblasts to deposit more bone around the attachments. This causes the bump or bar of bone to become bigger and stronger to keep up with the pull of the muscle.Fan shaped muscles lay over a flat surface of bone (fossa) and attach to the bone by growing shorter Sharpey’s fibers into the bone. This is much like how grass roots grow into the soil. Their roots are shorter than a tree, but cover a larger surface area. These attachments that do not have a long tendon are known as “fleshy” attachments. ................
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