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The Muscular System By: Christopher Lee Publications Edited By: D. McNeese II. Students understand structures and functions of body systems. (2.2.1) >Identify and describe how body systems work together. Study Sheet A Name:______________________________ The Muscular System-Introduction Muscles are responsible for all of the movements of the body. Without muscles a person cannot move, speak, or breathe. Each muscle is made up of long slender cells called fibers. Muscles produce their movement by the shortening of these fibers. Skeletal muscles are under voluntary control, whereas muscles of the heart and other internal organs function automatically. Either type of muscle must receive a nerve impulse before it will contract. Skeletal muscle fibers are attached to strong connective cords called tendons. The tendons are attached to bones. The two places where a muscle is attached to the bone are called the origin and insertion. The origin is located on the bone that remains relative to the insertion. The origin is located on the bone that remains relatively stationary and the insertion is located on the bone that moves when the muscle contracts. As a muscle contracts, the insertion moves toward the origin. Skeletal muscles can pull, but they cannot push. Therefore, muscles must work in pairs. Thus, for each muscle there is another that opposes it. For example, the biceps muscle bends the elbow while the triceps muscle straightens the elbow. When one muscle contracts, the opposing muscle relaxes. Most of the time both opposing muscles are partially contracted. This is called muscle tone. Tone makes it possible for a muscle to react more quickly when needed. Skeletal muscles are named according to location and function. There are at least nine different groups of muscles based on function. Examples are rotators, which pivot a bone upon its axis; flexors, which bend or decrease the angle of a joint; extensors, which straighten or increase the angle; adductors, which move one part toward another or toward a midline; and their opposing muscles, the abductors. Questions 1. Muscle cells are called muscle________________. 2. Skeletal Muscles are attached to bones by__________________________. 3. The _________________ moves toward the origin. 4. Skeletal muscles cannot ____________, the can only ________________. 5. A skeletal muscle that bends a joint is a called a _________________ muscle. Activity Glue activity sheets 1 and 2 together to make your display sheet for the front view of the muscular system. Then, glue activity sheets 3 and 4 together to make your display sheet for the back view of the muscular system. Study Sheet B Name:______________________________ The Muscular System-Three Kinds of Muscle The three kinds of muscle tissue are: skeletal, heart, and smooth. Under voluntary control, skeletal muscles produce movement by pulling on bones. The muscles of the face, for example, do not necessarily move bones; they pull on bones. Skeletal muscles also give form to the body. Viewed under a microscope, they appear striped and for that reason are sometimes called striped or striated muscles. Skeletal muscle fibers are about the same diameter as human hair and are longer than either heart muscle or smooth muscle. The fibers are united into compact bundles and covered with a transparent membrane. The fibers are connected to the bones by tendons. Skeletal muscles are capable of strong contractions for a short time. If it were not for the contractions of over 400 skeletal muscles, movement, and even talking and breathing, would be impossible. Heart muscle, also called cardiac muscle, makes up the wall of the heart. Thus, the heart is actually a hollow muscle. Operating like a pump, the heart contracts automatically (involuntarily) over 100,000 times a day. With each contraction blood is forced out of the heart and into the arteries of the body. The muscle fibers forming the heart are smaller than those of skeletal muscles and the ends of the fibers are fused together. This gives the heart great strength. Cardiac muscle, like skeletal muscle is striated. Smooth, or non-striated muscle is found in the walls of blood vessels, most internal organs, and the eyes. The contractions are slow but capable of being sustained for long periods of time. The muscle fibers are small and pointed. Each fiber has a nucleus and there are no stripes, hence the name smooth. Two of the functions of smooth muscle include the movement of food through the digestive system and the opening and closing of the pupil of the eye in response to light conditions. Smooth muscle operates involuntarily. Questions 1. ________________ muscle is voluntarily controlled. 2. _________________ muscle is found in the walls of blood vessels. 3. Heart muscle is sometimes called _____________ muscle. 4. ________________ muscles produce movement by pulling on bones. Activity 1. Color the muscles on your display sheets (shaded areas only) red. (these are the ones you already glued on). 2. Locate diagrams 1, 2, and 3 on your display sheets. Color the muscle red and the nuclei black. Study Sheet C Name:______________________________ The Muscular System-Front View A-F A: Facial Muscles: The principal muscles of the head are those concerned with facial expression and chewing. The facial muscles include nearly circular ones around the eyes which are used for squinting and circular ones around the lips which are used for whistling. B: Masseter Muscles: There are several muscles used in chewing. All are attached to the mandible or lower jaw. Two of the largest of these are the masseters. They are located near the angle of the jaw. C: Sternomastoids: These prominent muscles extend along the front and side of the neck. They draw the head towards the shoulder and rotate the chin upwards. If they become injured, they often produce a condition we call stiff neck. D: Pectoralis Major Muscles: These fan shaped muscles are found on either side of the sternum. Their action is to flex the arms across the chest, bringing the arms and shoulders forward and rotating the arms towards the middle of the body. These muscles are used by shot putters and swimmers on the downward stroke. E: Biceps: These large muscles form the front of the upper arms. These are the muscles generally used when a person wants to show how strong he or she is. The action is to flex the elbow and at the same time impart a slight rotary motion to the forearm. This rotary makes it possible for a person to use a screwdriver. They are opposed by the triceps muscle which is located on the back of the upper arms. F: Forearm Flexors: These muscles produce many movements of the wrist. Also located in the forearm are muscles of the fingers and thumbs. The long tendons of these muscles can be seen extending over the wrist when the fingers are moved. Questions 1. The masseters are attached to the lower jaw or ________________. 2. The _________________ muscle flexes the elbow. 3. An injured ______________________ muscle often causes a stiff neck. 4. The ___________________ muscles are on either side of the sternum. 5. _________________ muscles are used when a person grins. Activity 1. Locate the muscles lettered A-F on activity sheet 5. Color these muscles, using a different color for each muscle. Do not color over the identifying letters. 2. On your front view display sheet, color the box beside the description of each muscle the same color as the muscle. 3. Cut out each muscle A-F and attach it with glue to your front view display sheet. Study Sheet D Name:______________________________ The Muscular System-Front View G-L G: Abdominus Rectus: This muscle runs from the pelvic area to the ribs. This muscle helps a person have a flat stomach by compressing the internal organs. It also flexes the trunk and can be used to bend the trunk from side to side. It is also of importance in expelling fecal matter from the rectum and urine from the urinary bladder. H: Vastus Lateralis Muscles: These are one of the two prominent muscles of the thighs. They pass along the side of the thigh between the patella and the hip bone. These powerful extensors of the legs allow a person to swing his or her legs back and forth. These muscles are also used when kicking a football. I: Rectus Femoris Muscles: This muscle is one of a group of four muscles often referred to as the quadriceps group. This muscle is located on the front of the thigh with its origin on the hip and its insertion of the tibia or shinbone. Its action is to flex the thigh or extend the leg. J: Adductors: These muscles are found on the inside of the thighs and are used to press the thighs together. These muscles are used extensively when riding a horse. K: Sartorius Muscles: These are long narrow muscles that run from the spine downward across the entire thigh until they end at the upper end of the shinbone or tibias. They are used when a person sits down. L: Anterior Tibialis Muscles: These lower leg muscles oppose the action of the calf muscles or gastrocnemius muscles. They are located just outside the shinbones or tibias. Their origin is on the shinbones and they insert on the anklebones. When the anterior tibialis contracts, the foot is drawn upwards. Questions 1. The ________________ muscles are used when a person sits down. 2. The _____________ ______________ help to keep a flat stomach. 3. The rectus femoris belongs to the ______________ muscle group. 4. The _________________ muscles can keep you from falling off a horse. 5. The ________________ _________________ has its origin on the shinbone and its insertion on the ankle bone. Activity 1. Locate the muscles lettered G-L on activity sheet 5. Color these muscles, using a different color for each muscle. Do not color over the identifying letters. 2. On your front view display sheet, color the box beside the description of each muscle the same color as the muscle. 3. Cut out each muscle G-L and attach it with glue to your front view display sheet. Study Sheet E Name:______________________________ The Muscular System- Back View 1-6 1: Trapezius Muscles: The trapezius muscles are large muscles which raise the shoulders. Their origin is on the neck vertebrae (cervical) and chest vertebrae (thoracic) vertebrae and the base of the skull (occipital bone). Their insertion is on the collar bone (clavicle) and shoulder blade (scapula). These muscles are used to shrug the shoulders. 2: Deltoid Muscles: The origin of the deltoid muscles is on the collar bone (clavicle) and the shoulder blade (scapula). The insertion is on the upper arm bone (humerus). They aid in flexing and extending the upper arm. The shape of these muscles is like an upside down triangle as the form the caps of the shoulders. 3: Triceps: These muscles extend the lower arm. Their origin is on the shoulder blade (scapula) and upper arm bone (humerus). Their insertion is on the ulna of the lower arm. These muscles oppose the biceps are and located on the back of the arm. They are sometimes called the boxer’s muscles as they straighten the elbow when a blow is delivered. 4: Forearm Extensors: This is a series of muscles that extend the hand. Their origins are on the lower arm. The insertions are on the metacarpals or bones of the hands. 5: Tendons of the Hand: These long tendons connect the many muscles of the forearm to the wrist and fingers and fingers permitting a wide range of movement. 6: Latissimus Dorsi Muscles: These muscles of the lower back originate on the lower half of the vertebral column and the hip and insert on the ribs. They are used to bring the arm down as in swimming. They are also used when a person does a pull up and to help keep good posture. Questions 1. The _____________ muscles raise the shoulders. 2. The shape of the _______________ is similar to an upside down triangle. 3. The ___________________ have their insertion on the ulna of the lower arm. 4. The __________________ of the hand give the hands their versatility. Activity 1. Locate the muscles numbered 1-6 on activity sheet 6. Color these muscles, using a different color for each muscle. Do not color over the identifying numbers. 2. On your back view display sheet, color the box beside the description of each muscle the same color as the muscle. 3. Cut out each muscle 1-6 and attach it with glue to your back view display sheet. Study Sheet F Name:______________________________ The Muscular System- Back View 7-12 7: External Oblique Muscles: The external obliques compress the abdomen helping to keep the stomach flat. The origin is on the hip and the insertion is on the ribs. 8: Gluteus Maximus Muscles: These large muscles are located at the top of the hips. Their action is to extend the thighs. Their origin is on the hips (pelvic bones). Their insertion is on the femurs (thigh bones). These muscles, often called the buttocks, are needed to stand upright, walk, or run. 9: Biceps Femoris Muscles: These are one of three muscles often referred to as the hamstrings. Their origin is on the hip and femur and their insertion is on the two lower leg bones (tibia and fibula). The action of these muscles is to flex the knees. They also extend and rotate the thighs. These muscles are often injured by sprinting without proper warm-up. 10: Gastrocnemius Muscles: These are the two large muscles which form each calf. The largest of these is the gastrocnemius muscle. Its origin is on the femur and it inserts on the heel bone. It points the toes and is used extensively by ballet dancers. 11: Achilles Tendons: These heavy tendons connect the calf muscles or gastrocnemius muscles to the heel bones. They are the largest tendons in the body. 12: Tendons of the foot: These tendons connect the muscles of the lower leg to the ankles and toes. They permit the wide range of motion associated with the human foot. Questions 1. The _______________ _______________ is often called the buttocks. 2. The ______________ ______________ is one of three muscles called the hamstrings. 3. The _________________ is commonly called the calf muscle. 4. The Achilles tendon connects the __________________ muscle to the heel bone. 5. The ___________________ of the foot connect muscles of the lower leg to the ankles and toes. Activity 1. Locate the muscles numbered 7-12 on activity sheet 6. Color these muscles, using a different color for each muscle. Do not color over the identifying numbers. 2. On your back view display sheet, color the box beside the description of each muscle the same color as the muscle. 3. Cut out each muscle 7-12 and attach it with glue to your back view display sheet. 4. Locate diagram 4 on your back view display sheet. Color the triceps red, the biceps brown, and the bones orange. Leave the tendons white.