Lec 5 Kines Doha PDF

Muscles DR. DOHA AL-AFIFY Classification of Muscles Three types of Muscles: Cardiac muscle tissue , located in the heart. Smooth muscle tissue, located in the walls of visceral organs and blood vessels. Skeletal muscle tissue, located in skeletal muscles Skeletal muscle tissue makes up app...

Muscles DR. DOHA AL-AFIFY Classification of Muscles Three types of Muscles: Cardiac muscle tissue , located in the heart. Smooth muscle tissue, located in the walls of visceral organs and blood vessels. Skeletal muscle tissue, located in skeletal muscles Skeletal muscle tissue makes up approximately 40% to 45% of total body weight. CHARACTERISTICS OF SKELETAL MUSCLE Skeletal muscle tissue and cardiac muscle tissue are both striated in appearance under a microscope; smooth muscle tissue is not. Skeletal muscle is under voluntary control Smooth muscle and cardiac muscle tissues are not under voluntary control A skeletal muscle attaches onto two bones, thereby crossing the joint that is located between them. A typical skeletal muscle has two attachments, each onto a bone. However, some skeletal muscles have more than two bony attachments, and some skeletal muscles attach into soft tissue instead of bone. This contraction creates a pulling force on the bony attachments of the muscle.  Muscular Fascia The tissue that creates the structural organization of a muscle is the tough fibrous fascia connective tissue that is also known as muscular fascia or deep fascia. The major component of muscular fascia is collagen fibers. A small component of elastin fibers exists in muscular fascia. Although all muscular fascia is uniform in its composition, it is given different names depending on its location The fibrous fascia that surrounds each individual muscle fiber is called endomysium. The fibrous fascia that surrounds a group of muscle fibers, dividing the muscle into bundles known as fascicles, is called perimysium. The fibrous fascia that surrounds an entire muscle is called epimysium. (Mys, epi, peri, and endo are all Greek roots. Mys refers to muscle; epi means upon; peri means around; endo means within.) It is important to note that all three of these layers of fibrous fascia blend together and continue beyond the muscle to attach the muscle to a bone. The role of the fascial attachment is to transfer the force of the muscle contraction to the bone. Interior of muscle Fiber Properties of skeletal muscle Irritability : Is the ability of the muscle to respond to stimulus. Contractility: Is the capacity of the muscle to produce tension between it’s ends. Relaxation: Is the opposite of contraction and is the giving up of tension. Distensibility: Is the ability of the muscle to be stretched or lengthened up to a certain limit. The muscle suffers no harm so long as it is not stretched beyond its physiological limits. Elasticity: Is the ability of the muscle to recoil to its original length when an outside force is removed unless it has been overstretched. Skeletal Muscles Are the prime movers of the human body. They produce forces under the control of the nervous system. Man has 640 skeletal muscles of many shapes and sizes from the tiny stapedius muscle of the middle ear to the massive hip extensor, the gluteus maximus). Muscles are situated across joints and are attached at two or more points to bony levers. Each muscle is well adapted to provide an appropriate range, direction and force of contraction to meet the requirements. Function of the skeletal Muscles Producing movement Stabilizing joints. Give shape to body segments. Maintaining posture and position. Forming supportive walls. Classification of Muscles Shape and Fascicular Architecture Myoglobin contents level of Contractile and fiber type activity Muscular attachment Muscle orientation of line of the pull of muscle to the joint structure Number of joints traversed  Classification of Muscles: 1- According to shape and fascicular architecture: The muscles designed for strength are of pinnate type and the ones designed for speed have parallel fibers. 2) According to the myoglobin content Red: contain more red fibers and they are responsible for movement, which require slow action for a long time e.g antigravity muscles. White: contain more white fibers and they are responsible for movement, which require rapid action for a short time. 3) According to the level of contractile activity: a. Tonic muscles (stabilizers): it demonstrates continuous low level of contractile activity which is required to maintain a given posture. b. Phasic muscle (mobilizers): it demonstrates rapid (fast twitch) activity which is required when changing from one position to another. 3) According to the orientation of the line of pull to the joint structure: ( e.g. flexors, extensors, abductors and adductors)  The muscle located anterior to a joint may be extensor as in the case of the knee joint or may be flexor as in the case of the elbow joint.  The possible axes of motion are determined by the structure of the joint itself. 4) According to the number of joints over which the muscle crosses: One joint muscle ( e.g. vastus mediales). Two joint muscle( e.g. rectus femoris). Multi-joint muscle ( e.g. finger flexors).