Muscular System

How Muscles Move-  Muscle knows no direction, it just shortens.  So when a muscle contracts one end of the joint moves toward the other.

Muscle System Video on muscle contraction  Watch and listen, it is complicated, but I want you to see it and we will discuss.

Muscle System Insertion-the more movable end of the bone, usually more distal. Origin-attached to the stable bone, the more proximal end of the bone.

Exceptions to the Rule Latissimus Dorsi-pg 137 Proximal (origin) attachment pulls toward the distal (insertion) attachment, instead of the more common distal attachment pulling toward the proximal. Reversal of muscle function.

Muscle System So the insertion moves towards the origin. Movable end of the bone moves towards the more stable end of the bone. Origin Insertion

Muscle System Naming Muscles-use these to find it  Location  Shape  Action  Number of heads or divisions  Attachments  Direction  size

Muscle System Tibialis Anterior Extensor carpi ulnaris Serratus anterior Triceps Brachii Sternocleidomastoid Go find a muscle and tell me about it. Not one of mine. It needs to have 2 qualities from the last list.

Muscle System Muscle fibers run  Parallel fibers are longer and have more range of motion potential.  Oblique fibers are shorter but broad, so have a greater strength potential for short range.

Muscle System

Parallel Muscles Strap muscles-long and thin, fibers run the full length of muscle. Sternocleidomastoid Fusiform muscle-shaped like a spindle, wide in middle tapers at ends, biceps. Rhomboidal muscle- broad and flat all through attachments, gluteus maximus Triangular- flat and fan shaped, pec major.

Muscle System Pectoralis Major Glute Max Biceps What is each of these??

Muscle System Oblique muscle-  Unipennate-like one side of a feather, semimembranosus  Bipennate- like a common feather, bicep femoris muscle  Mulipennate- tendons with oblique fibers in between. Deltoid and subscapularis

Muscle System

What are these??

Characteristics of muscle Reverse contractability-  When the proximal end moves toward the distal end it is a reversal of muscle action.  Examples???? Look at the bicep. Rectus femoris doing a leg raise vs a sit up.

Characteristics of a Muscle Stretch a muscle, and it will lengthen (extensibility). Remove the stretch, it will return to normal resting position (elasticity). Stimulate a muscle, and it will respond (irritability) by shortening (contractility). Remove the stimulus and it will return to its normal resting position (elasticity).

Muscle System Tension is the force built up in a muscle.  Stretching a muscle builds up passive tension  Active tension is when the muscle is contracted.  Combine active and passive tension, and you get total tension.  Think of kicking a soccer ball, hyperextend, then contract quads, think of the power you have generated.

Muscle System The length tension relationship is the optimal contraction of a muscle when it is strongest. A two joint muscle has an advantage over a one joint muscle. Why? Read together

Muscle System Active Insufficiency- muscle cannot shorten or contract through full ROM. The muscle will lose tension. Passive Insufficiency- muscle cannot lengthen or stretch through full ROM. These are only in two joint muscles like the hamstring and quadriceps.

Stretching An agonist usually becomes actively insufficient (cannot contract more) before the antagonist becomes passively insufficient (cannot be stretched anymore). In other words if you contract your hamstring actively, you can push it further with a stretch.

Stretching To stretch a one joint muscle you must relax the two joint muscles involved. The soleus is a one joint muscle the gastrocnemius is two. You must flex the knee to stretch the soleus and dorsiflex the ankle.

Tendon action of a muscle (Tenodesis) Using passive insufficiency to create tenodesis is helpful in quadriplegics. Lets try it, read page 41 together.

Types of Muscle Contraction Isometric Contraction-same length  Muscle contracts producing for but does not lengthen.

Types of Muscle Contraction Isotonic Contraction-same tone  Muscles contracts and the length of the muscle changes. Concentric- shorten, attachments move together. accelerated act Eccentric- lengthen, attachments separate decelerated act Examples

Types of Muscle Contraction Isokinetic Contraction-  Resistance to the part varies, but speed stay the same. In isotonic the resistance remains constant but speed varies.  Think about a biceps curl, when is it hard when is it easy. Does resistance stay the same?  Safer way, you can stop at anytime.

Roles of Muscles Muscles assume different roles during joint motion.  Agonist/prime mover- causes the motion  Assisting mover- depends of angle, size leverage. Some muscles are only assisters  Antagonist- opposite motion of the agonist.

Roles of Mucles Stabilizer is a a group that supports and allows the agonist to work more efficiently.

Roles of Muscles Neutralizer-Contracts to prevent the unwanted motion. For example the biceps muscle flexes the elbow and supinate the forearm. If we want just flexion the pronator teres will act to prevent supination.

Kinetic Chain Engineering definition- Kinetic Chain consists of a series of rigid links connected in such a way as to allow motion. Human Body Kinetic chain can be closed or open chain movement that allows motion.

Kinetic Chain Closed Chain requires that the distal segment is fixed to something, the floor, wall, a bar. Open Chain is when the distal segment is free to move and proximal segment is stationary.

Lab time