The Muscular System Objectives :

1. The Muscular System Objectives: Describe the three types of muscle tissue and their function and location. Explain the function, location, origin, and insertion of the major skeletal muscles. Evaluate the role of vitamins and other nutrients in muscle contraction and strength Compare and contrast tendons and ligaments. List examples of flexor and extensor pairs of muscles. Vocabulary: Smooth or involuntary muscle, skeletal, striated or voluntary muscle, cardiac muscle, flexors, extensors, actin, myosin, myo, striations, sprain, tendon, rigor mortis, myoglobin, origin, insertion, proximal, distal, abductors, adductors, Muscular Dystrophy, hamstrings, Achilles tendon

2. There are three types of muscle tissue: • Smooth muscle - this is often also referred to as involuntary muscle because we have no conscious control over it. It consists of filaments that are NOT aligned with each other, but generally form “sheets” of cells. It lines the blood vessels and the gastrointestinal tract and controls the iris of the eye. • Skeletal Muscle - this is also called striated or voluntary muscle. The filaments are aligned and sometimes look like they form bands, or striations. These muscles are used to control our skeleton. For example, flexors bend our skeleton at the joints and extensors straighten it. Flexors and extensors are paired together. We can easily consciously control these muscles. 3) Cardiac muscle - this is the heart muscle. The fibers of cardiac muscle branch and interconnect. It is primarily the work of the proteins actin and myosin that allow muscles to contract. However, other proteins, such as dystrophin, are also necessary. If missing, muscles gradually weaken with age and death follows. This is what happens in the inherited disease, Muscular Dystrophy.

3. In order for muscles to contract, they require ATP. Therefore all of the vitamins and other nutrients we said were important for glycolysis, the Kreb’s cycle (a.k.a.the citric acid cycle), and the electron transport chain are important for muscle strength and contraction. These included vitamin C, tyrosine, and numerous B vitamins because of their role in making Coenzyme Q-10 (which is especially important for the heart of patient’s suffering from congestive heart failure). And, riboflavin (part of FADH), niacin (part of NADH, etc.), and pantethine (part of Coenzyme A) - to name a few. Muscles also need lots of calcium and magnesium for contraction strength and muscle relaxation. Of course, in order to maintain high levels of ATP for the muscles, our bodies need plenty of oxygen or else we will be forced from aerobic respiration into lactic acid fermentation. This provides little energy so the muscles become fatigued and begin aching as lactic acid builds up in the muscle tissue.

4. Bundles of skeletal muscle fibers are made of small fibers called myofibrils (“myo“ means muscle). These contain the proteins actin and myosin. These lie parallel to each other and are arranged in repeating bundles called sarcomeres which are bound on each end by “Z lines”. This arrangement is what creates the banding pattern, or striations, that give us the name “striated muscle” for skeletal muscles. In order for a muscle to contract (shorten), the myosin and actin protein fibers must slide past each other, overlapping. In order to maintain this position, calcium and ATP must be available. In order to release the contraction, magnesium must be available and calcium must exit the area. Magnesium is a natural muscle relaxant. In rigor mortis, a corpse becomes stiff because ATP is no longer being made to move calcium out of the actin/myosin bridge. The contraction of skeletal muscle usually produces movement of the bones because the muscles are attached to the bones by tendons. Like ligaments, which connect bones to other bones at joints, tendons are connective tissue. Both ligaments and tendons can be overstretched or torn causing movement problems. For tendons, this is usually called a “sprain.”

5. Many advertisements have been made claiming to improve athletic performance through creatine phosphate supplements. This substance can donate a phosphate to ADP to regenerate ATP. Normally, the muscle will rely on stored glycogen within the muscle to help form ATP. Remember, oxygen is needed to make ATP in sufficient amounts. Providing the oxygen is a substance called myoglobin. Myoglobin is a protein similar to the hemoglobin protein in blood. Myoglobin carries oxygen to the muscles that get heavy use. Myoglobin has a reddish color. It gives muscles their reddish color. The more heavily the muscle is used, the redder it is. In birds that fly a lot, like wild geese and ducks, the breasts are “dark” meat but on home raised birds, like chickens, that walk rather than fly, the breast is “white” meat. The muscles that are “red” from heavy use are generally “slow twitch” fibers that fatigue slowly due to the rich oxygen supply from myoglobin. Fast- twitch fibers don’t have a good oxygen supply so they are good only for quick, short periods of contraction.

6. Every skeletal muscle inserts into bone via a tendon at 2 places. These are the origin (the end of the muscle attached to the bone that remains stationary during contraction) which is usually the proximal end (closer to the main body) and the insertion (the end of the muscle that attaches to the bone that moves during contraction), which is usually more distal (further from the main body). How much strength is applied, for example, when lifting a feather versus lifting a 100 pound weight, is determined by the number of muscle fibers innervated (activated). Many muscles come in opposing pairs. Abductors are muscles that move the arms and legs away from the body and out to the sides. Adductors are muscles that pull the arms and legs back in toward the body. (Think of “jumping jacks”.) Flexors bend one bone up closer to another while extensors return them to an un-bent angle.

7. Major Skeletal Muscles Although there are many, many muscles of the face and skull, the sternocleidomastoids are probably one of the most important. Many of the others are involved in facial expressions or chewing. The sternocleidomastoids have their origins at the temporal and occipitalbones and their insertions at the sternum and clavicle. They help us flex the neck (flexor) forward, rotate the head/neck, and tilt the head left or right.

8. The trapezius muscles’ origins are at the occipitalbone and the cervical and thoracicvertebrae and their insertions are at the clavicle and scapula. These help lift the shoulders (shrugging) and are needed to assist in lifting the arms above shoulder height and in rotating the arm. (The rotator cuffs {scapula and humerus attachments} and levator scapulae also help.) The deltoids cover the shoulder. They raise your arms to the front, side, and rear, but only to shoulder height. The deltoids are abductors because they take the arm “away” from the body) Their origin is at the clavicle and sternum and their insertions are in the humerus bones. Deltoid Trapezius

9. The pectoralis major muscles originate at the sternum, the clavicle, and the anterior medial side of the last few ribs. They insert under the humerus. If the arm is already raised, the pectoralis major contracts to lower it. The pectoralis major also pulls the shoulder forward and, along with the pectoralis minor (which is underneath the major), it can lift the rib cage to expand the chest cavity for inhalation. The intercostal muscles are located between the ribs and help raise and lower the rib cage for breathing purposes.

10. The obliques and rectus abdominis muscles control abdominal contractions, bending and twisting the torso. Pectoralis major Intercostals External obliques Rectus abdominis

11. The latissimus dorsi runs from the sacrum and thoracic (near the last 3 or 4 ribs) and lumbar vertebrae to the humerus. This contracts to bring the arm down (adducter) and also to rotate it. This muscle is used for chopping, paddling, climbing, etc.

12. The biceps brachii (flexor) have their origin in the scapula and their insertion in the radius. It flexes (bends) the forearm toward the upper arm and can turn the arm outward. The biceps femoris (aka the “hamstrings”) is located at the back of your upper leg. It is a flexor of the lower leg over the thigh and can rotate the thigh. Its origin is in the femur, its insertion is in the tibia. The triceps are located on the back of the upper arm. They originate in the scapula and upper humerus and insert in the ulna. They are extensors of the forearm.

13. The rectus femoris muscles are part of the quadriceps. The quadricepsfemoris are located on the front of the thigh. They act as an extensor of the lower leg but can flex the thigh toward the abdomen too. The gastrocnemius is the calf muscle of the lower legs. It originates at the femur and inserts in the calcaneous (heel) via its Achille’s tendon.

14. The gluteus maximus, medius, and minimus form most of our buttocks. They originate in the pelvis area and insert in the femur. They can work in rotating the thigh and in pulling the thigh backwards or supporting it upright when standing. Gluteal muscles and Hamstrings (back of thigh)

15. 1.Galea Aponeurotica 2. Epicranius 3. Orbicularis Oculi 4. Nasalis 5. Levator Labii Superioris 6. Zygomaticus major & minor 7. Orbicularis Oris 8. Risorius 9. Depressor Anguli Oris 10. Depressor Labii Inferioris 11. Mentalis 12. Omohyoid 13. Sternohyoid 14. Sternal Head of Sternocleidomastoid 15. Scalene 16. Trapezius 17. Deltoid 18. Pectoralis Major 19. Serratus Anterior 20. Rectus Abdominis 21. External Abdominal Oblique 22. Biceps Brachii 23. Brachialis 24. Pronator Teres 25. Brachioradialis 26. Flexor Carpi Radialis 27. Extensor Carpi Radialis 28. Tensor Fasciae Latae 29. Iliopsoas 30. Pectineus 31. Sartorius 32. Adductor Longus 33. Gracilis 34. Rectus Femoris 35. Vastus Intermedius 36. Vastus Lateralis 37. Vastus Medialis 38. Gastrocnemius 39. Peroneus Longus 40. Tibialis Anterior 41. Soleus 42. Peroneus Brevis 43. Extensor Digitorum Longus http://www.google.com/imgres?imgurl=http://www.sport-fitness-advisor.com/images/muscular_system_picture_front.jpg&imgrefurl=http://www.sport-fitness-advisor.com/muscular-system-picture.html&h=138&w=98&sz=53&tbnid=0w6CUrNWOVoJ:&tbnh=138&tbnw=98&prev=/images%3Fq%3Dmuscular%2Bsystem&sa=X&oi=image_result&resnum=1&ct=image&cd=1