Hi,
I need help writing a timed assignment; the topic of the assignment is on human physiology, once I begin the assignment the built-in timer will countdown
1-hour. Consequently, I'll send you (expert) the screenshots of the questions, and you would respond to me with the solutions or answers soon after,and that’s before the 1-hour time; there are around 50 multiple-choice questions. We can agree on the day and time as to when to start the assignment and what you charge for it. Thus, can you able to assist me with this assignment?
Relevant chapters, from which the assignments are extracted, would be attached herewith as “Unit 3” file.
Thanks, look forward to working with you.
Daniel
HUMAN ANATOMY & PHYSIOLOGY Copyright W iley, 2020 330 CHAPTER 11 Almost all of the 700 individual muscles that make up the muscular system, such as the biceps brachii muscle, include both skeletal muscle tissue and connective tissue. The function of most muscles is to produce movements of body parts. A few muscles function mainly to stabilize bones so that other skeletal muscles can execute a movement more eff ectively. This chapter presents many of the major skeletal muscles in the body, most of which are found on both the right and left sides. We will identify the attachment sites and innervation (the nerve or nerves that stimulate contraction) of each muscle described. Developing a working knowledge of these key aspects of skeletal muscle anatomy will enable you to understand how normal movements occur. This knowledge is especially crucial for professionals, such as those in the allied health and physical rehabilitation fields, who work with patients whose normal patterns of movement and physical mobility have been disrupted by physical trauma, surgery, or muscular paralysis. Q Did you ever wonder how carpal tunnel syndrome occurs? The Muscular System The Muscular System and Homeostasis The muscular system and muscular tissue of your body contribute to homeostasis by stabilizing body position, producing movements, regulating organ volume, moving substances within the body, and producing heat. c11TheMuscularSystem.indd Page 330 03/10/16 9:14 AM f-389 /208/WB01989/9781119287759/ch11/text_s 312 Copyright W iley, 2020 11.1 How Skeletal Muscles Produce Movements 331 11.1 How Skeletal Muscles Produce Movements OBJECTIVES • Describe the relationship between bones and skeletal muscles in producing body movements. • Define lever and fulcrum, and compare the three types of levers based on location of the fulcrum, eff ort, and load. • Identify the types of fascicle arrangements in a skeletal muscle, and relate the arrangements to strength of contraction and range of motion. • Explain how the prime mover, antagonist, synergist, and fixator in a muscle group work together to produce movement. Muscle Attachment Sites: Origin and Insertion Together, the voluntarily controlled muscles of your body compose the muscular system. Those skeletal muscles that produce move- ments do so by exerting force on tendons, which in turn pull on bones or other structures (such as skin). Most muscles cross at least one joint and are usually attached to articulating bones that form the joint (Figure 11.1a). When a skeletal muscle contracts, it moves one of the articulating bones. The two articulating bones usually do not move equally in response to contraction. One bone remains stationary or near its original position, either because other muscles stabilize that bone by contracting and pulling it in the opposite direction or because its structure makes it less movable. Ordinarily, the attachment of a mus- cle’s tendon to the stationary bone is called the origin (OR-i-jin); the attachment of the muscle’s other tendon to the movable bone is called the insertion (in-SER-shun). A good analogy is a spring on a door. In this example, the part of the spring attached to the frame is the origin; the part attached to the door represents the insertion. A useful rule of thumb is that the origin is usually proximal and the insertion distal; the insertion is usually pulled toward the origin. The fleshy portion of the muscle between the tendons is called the belly (body), the coiled middle portion of the spring in our example. The actions of a muscle are the main movements that occur when the muscle contracts. In our spring example, this would be the closing of the door. Certain muscles are also capable of reverse muscle action (RMA). This means that during specific movements of the body the actions are reversed; therefore, the positions of the origin and inser- tion of a specific muscle are switched. Muscles that move a body part oft en do not cover the moving part. Figure 11.1b shows that although one of the functions of the biceps brachii muscle is to move the forearm, the belly of the muscle lies over the humerus, not over the forearm. You will also see that Shoulder joint Scapula Origins from scapula and humerus Belly of triceps brachii muscle Tendon Insertion on ulna Elbow joint Ulna (a) Origin and insertion of a skeletal muscle Origins from scapula Belly of biceps brachii muscle Humerus Tendon Insertion on radius Radius Tendons FIGURE 11.1 Relationship of skeletal muscles to bones. Muscles are attached to bones by tendons at their origins and insertions. Skeletal muscles produce movements by pulling on bones. Bones serve as levers, and joints act as fulcrums for the levers. Here the lever–fulcrum principle is illustrated by the movement of the forearm. Note where the load (resistance) and effort are applied in (b). In the limbs, the origin of a muscle is usually proximal and the insertion is usually distal. Q Where is the belly of the muscle that extends the forearm located? Fulcrum (F) = elbow joint (b) Movement of the forearm lifting a weight Load (L) = weight of object plus forearm Biceps brachii muscle Effort (E) = contraction of biceps brachii L F L E Effort Fulcrum Load= = = Key: F c11TheMuscularSystem.indd Page 331 03/10/16 9:14 AM f-389 /208/WB01989/9781119287759/ch11/text_s 313 johnup Underline johnup Underline johnup Underline johnup Underline johnup Underline johnup Underline johnup Highlight johnup Highlight johnup Highlight johnup Highlight johnup Highlight johnup Highlight Copyright W iley, 2020 332 CHAPTER 11 The Muscular System muscles that cross two joints, such as the rectus femoris and sartorius of the thigh, have more complex actions than muscles that cross only one joint. Lever Systems and Leverage In producing movement, bones act as levers, and joints function as the fulcrums of these levers. A lever is a rigid structure that can move around a fixed point called a fulcrum, symbolized by F . A lever is acted on at two diff erent points by two diff erent forces: the eff ort (E), which causes movement, and the load L or resistance, which opposes movement. The eff ort is the force exerted by muscular con- traction; the load is typically the weight of the body part that is moved or some resistance that the moving body part is trying to overcome (such as the weight of a book you might be picking up). Motion occurs when the eff ort applied to the bone at the insertion exceeds the load. Consider the biceps brachii flexing the forearm at the elbow as an object is lift ed (Figure 11.1b). When the forearm is raised, the elbow is the fulcrum. The weight of the forearm plus the weight of the object in the hand is the load. The force of contraction of the biceps brachii pulling the forearm up is the eff ort. The relative distance between the fulcrum and load and the point at which the eff ort is applied determine whether a given lever oper- ates at a mechanical advantage or a mechanical disadvantage. For example, if the load is closer to the fulcrum and the eff ort farther from the fulcrum, then only a relatively small eff ort is required to move a large load over a small distance. This is called a mechanical advan- tage. If, instead, the load is farther from the fulcrum and the eff ort is applied closer to the fulcrum, then a relatively large eff ort is required to move a small load (but at greater speed). This is called a mechani- cal disadvantage. Compare chewing something hard (the load) with your front teeth to chewing it with the teeth in the back of your mouth. It is much easier to crush the hard food item with the back teeth be- cause they are closer to the fulcrum (the jaw or temporomandibular joint) than are the front teeth. Here is one more example you can try. Straighten out a paper clip. Now get a pair of scissors and try to cut the paper clip with the tip of the scissors (mechanical disadvantage) versus near the pivot point of the scissors (mechanical advantage). Levers are categorized into three types according to the positions of the fulcrum, the eff ort, and the load: 1. The fulcrum is between the eff ort and the load in first-class levers (Figure 11.2a). (Think EFL.) Scissors and seesaws are examples of first-class levers. A first-class lever can produce either a mechanical advantage or a mechanical disadvantage depending on whether the eff ort or the load is closer to the fulcrum. (Think of an adult and a child on a seesaw.) As we have seen in the preceding examples, if the eff ort (child) is farther from the fulcrum than the load (adult), a heavy load can be moved, but not very far or fast. If the eff ort is closer to the fulcrum than the load, only a lighter load can be moved, but it moves far and fast. There are few first-class levers in the body. One example is the lever formed by the head resting on the vertebral column (Figure 11.2a). When the head is raised, the contraction of the posterior neck muscles provides the eff ort (E), the joint between the atlas and the occipital bone (atlanto- occipital Clinical Connection Intramuscular Injections An intramuscular (IM) injection penetrates the skin and subcutaneous layer to enter the muscle itself. Intramuscular injections are preferred when prompt absorption is desired, when larger doses than can be given subcutaneously are indicated, or when the drug is too irritating to give subcutaneously. The common sites for intramuscular injections include the gluteus medius muscle of the buttock (see Figure 11.3b), lateral side of the thigh in the midportion of the vastus lateralis muscle (see Figure 11.3a), and the deltoid muscle of the shoulder (see Figure 11.3b). Mus- cles in these areas, especially the gluteal muscles in the buttock, are fairly thick, and absorption is promoted by their extensive blood supply. To avoid injury, intramuscular injections are given deep within the muscle, away from major nerves and blood vessels. Intramuscular injections have a faster speed of delivery than oral medications but are slower than intra- venous infusions. joint) forms the fulcrum F , and the weight of the anterior portion of the skull is the load L . 2. The load is between the fulcrum and the eff ort in second-class levers (Figure 11.2b). (Think ELF.) Second-class levers operate like a wheelbarrow. They always produce a mechanical advantage be- cause the load is always closer to the fulcrum than the eff ort. This arrangement sacrifices speed and range of motion for force; this type of lever produces the most force. This class of lever is uncom- mon in the human body. An example is standing up on your toes. The fulcrum F is the ball of the foot. The load L is the weight of the body. The eff ort (E) is the contraction of the muscles of the calf, which raise the heel off the ground. 3. The eff ort is between the fulcrum and the load in third-class levers (Figure 11.2c). (Think FEL.) These levers operate like a pair of for- ceps and are the most common levers in the body. Third-class levers always produce a mechanical disadvantage because the eff ort is always closer to the fulcrum than the load. In the body, this arrange- ment favors speed and range of motion over force. The elbow joint, the biceps brachii muscle, and the bones of the arm and forearm are one example of a third-class lever (Figure 11.2c). As we have seen, in flexing the forearm at the elbow, the elbow joint is the fulcrum F , the contraction of the biceps brachii muscle provides the eff ort (E) and the weight of the hand and forearm is the load L . Eff ects of Fascicle Arrangement Recall from Chapter 10 that the skeletal muscle fibers (cells) within a muscle are arranged in bundles known as fascicles (FAS-i-kuls). Within a fascicle, all muscle fibers are parallel to one another. The fas- cicles, however, may form one of five patterns with respect to the ten- dons: parallel, fusiform (spindle-shaped, narrow toward the ends and wide in the middle), circular, triangular, or pennate (shaped like a feather) (Table 11.1). Fascicular arrangement aff ects a muscle’s power and range of motion. As a muscle fiber contracts, it shortens to about 70% of its c11TheMuscularSystem.indd Page 332 03/10/16 9:14 AM f-389 /208/WB01989/9781119287759/ch11/text_s 314 johnup Cross-Out johnup Underline johnup Underline johnup Underline johnup Underline johnup Underline johnup Underline johnup Underline johnup Underline johnup Underline johnup Underline johnup Underline johnup Highlight johnup Highlight johnup Highlight johnup Highlight johnup Highlight johnup Highlight johnup Highlight johnup Highlight johnup Highlight johnup Highlight johnup Underline johnup Underline johnup Underline johnup Highlight johnup Highlight Copyright W iley, 2020 11.1 How Skeletal Muscles Produce Movements 333 so