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muscles lecture
notes
| Question | Answer |
|---|---|
| Muscles | a bundle of red contractile fibers held together by a sheath of connective tissue - it is attached to bone by means of tendons or aponeuroses (fibrous sheets) which stem from the connective tissue sheaths. |
| A muscle unattached on both ends and stimulated | would move toward the middle. |
| Muscles are attached to bones and | cross at least one joint. |
| When a muscle contracts, | one end of the joint moves toward the other bone. |
| the more moveable bone referred to as the | the insertion,moves toward the more stable bone the origin. |
| Origins tend to be closer to the trunk and | insertions tend to be more toward the distal end |
| Reversal of muscle action happens when the origin moves | toward the insertion because more moveable end becomes less moveable |
| Muscle Names- Location ex.Tibialis anterior | located on anterior surface of the tibialis) |
| Muscle Names--Shape ex. Trapezius | trapezoid shape, serratus anterior - serrated or jagged shaped attachment anteriorly |
| Muscle Names--Action- extensor carpi ulnaris | action is to extend the wrist on the ulnar side. |
| Muscle Names--Number of heads or divisions- triceps brachii - | 3 headed muscle on the arm, biceps femoris - 2 headed muscle on the thigh. |
| Muscle Names--Attachments = origin/insertion- sternocleidomastoid muscle - | attaches on the sternum, clavicle and mastoid bones. |
| Muscle Names--Direction of fibers- names like external, internal oblique | describe the direction of fibers and location to one another. |
| Muscle Names --Size of muscle. | Pectoralis major and pectoralis minor. |
| Fiber arrangement: | Muscle fibers are arranged within the muscle in a direction that is either parallel or oblique to the long axis of the muscle. |
| Parallel muscle fibers | tend to be longer and have greater ROM potential |
| strap | long, thin with fibers running entire length of muscle. (Sartorius, rectus abdominis, sternocleidomastoid |
| Fusiform - | shape similar to a spindle (wide middle, tapered ends) where it attaches to tendons. Ex. Biceps, brachialis, brachioradialis. |
| Rhomboidal--4 sided | , usually flat with broad attachments at each end. Ie. Pronator quadratus, rhomboids, gluetus maximus. |
| Triangular - flat/fan shaped | with fibers radiating from a narrow attachment at one end to a broad attachment at the other. Ex. Pectoralis major. |
| Oblique muscle fibers | tend to be shorter, more numerous, have greater strength potential. They have a feather arrangement in which a muscle attaches at an oblique angle to its tendon. |
| Unipennate: | look like one side of a feather. Tibialis posterior muscle of the ankle, flexor pollicis longus muscle of the hand. |
| Bipennate - | looks like a common feather, both sides attached to central tendon. Ex. Rectus femoris , interosssi muscles |
| Multipennate - | have many tendons with oblique fibers in between. Ex. Deltoid and subscapularis. |
| Functional characteristics of muscle tissue: | Muscles have a normal resting length when it is unstimulated and no forces or stresses are on it. |
| Irritability | ability to respond to a stimulus. Nerve or electrical current. |
| Contractility - | ability to shorten or contract thus producing tension b/w ends. May result in muscle shortening, staying same or lengthening. |
| Extensibility - | ability of a muscle to stretch or lengthen. |
| Elasticity - | ability to recoil or return to normal resting length when force is removed. |
| Tension-- | force built-up w/in a muscle necessary for a muscle to contract or recoil. Stretching builds up tension and contracting releases it. |
| Tension--range | There is an optimal range where a muscle contracts effectively. |
| muscle stretching | A muscle can be shortened approx ½ of it normal resting length. Ie 6 to 3" |
| muscle stretched/shorting | It can be stretched twice as far as shortened twice as far a shortened ie. 9" |
| Excursion - | distance from maximum elongation to maximum shortening. As above example would be 6" . Ratio of most muscle is 2:1 |
| Excursion-rom | usually a muscle has enough excursion to allow joint to move through full ROM. Esp, with a muscle that only crosses 1 joint. It may not if crosses 2 or more joints. |
| strength-maintaining length | A muscle is strongest when slightly stretched prior to contraction. Ex. Golf swing, kick, tennis, baseball. Requiring a lot of force you wind-up therefore stretching muscle a little bit. |
| active insufficiency | when a muscle cannot shorten any farther. This occurs to the agonist (muscle contracting) |
| Passive insufficiency | when a muscle cannot be elongated any further without damage. Occurs to the antagonist. (Muscle relaxed on the opposite side of the joint) |
| Stretching: | generally agonist becomes actively insufficient before antagonist becomes passively insufficient. We purposely stretch muscles in therapy to either maintain or regain normal resting length. |
| Tenodesis - | tendon action on a muscle. Some degree of opening and closing hand can be accomplished using passive insufficiency. 2 or multi-joint muscles don’t have sufficient length to be stretched over all joints at once. |
| Isometric - | muscle contrasts producing force without changing length of muscle. Muscle contracts but no joint motion. Tightening biceps |
| Isotonic - | when muscle contracts, the muscle length changes and joint angle changes - |
| Concentric - joint movement, | muscle shortens and O & I move toward one another -ie. Again 5# weight. |
| Eccentric - joint motion | but muscle appears to lengthen that is the muscle attachments separate. |
| Agonist | -muscle or muscle group that causes the motion. Aka. P1rime mover |
| Assisting mover | - helps provide the motion but not as effective. |
| Antagonist - | muscle that performs opposite motion of the agonist. |
| Cocontraction- | when the agonist contracts at the same time as the antagonist. Usually the antagonist is relaxed |
| Stabilizer-muscle | muscle groups that supports or makes firm a part and allows the agonist to work more efficiently. Push ups. Elbow extensors are agonist, abs are stabilizers to keep trunk straight. |
| Synergist - | a muscle that works with another muscle to enhance a particular motion. |
| Angle of pull - most muscles have a diagonal line of pull | muscles know one direction of pull visualizing the muscle will assist in knowing their action. |
| Kinetic Chains - | exercises apply to open or closed kinetic chains |
| Kinetic Chains - Closed | Closed - requires the distal segment to be fixed (closed) and proximal segments to move. |
| Kinetic Chains -Open | Open - the distal segment free to move while proximal segment stays stationary |
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learntime101
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