Power Point Lecture Slides prepared by Meg Flemming

Chapter 7 Learning Outcomes • 7 -1 • Specify the functions of skeletal muscle tissue. • 7 -2 • Describe the organization of muscle at the tissue level. • 7 -3 • Identify the structural components of a sarcomere. • 7 -4 • Explain the key steps involved in the contraction of a skeletal muscle fiber beginning at the neuromuscular junction. • 7 -5 • Compare the different types of muscle contractions. © 2013 Pearson Education, Inc.

Chapter 7 Learning Outcomes • 7 -6 • Describe the mechanisms by which muscles obtain the energy to power contractions. • 7 -7 • Relate the types of muscle fibers to muscle performance, and distinguish between aerobic and anaerobic endurance. • 7 -8 • Contrast the structures and functions of skeletal, cardiac, and smooth muscle tissues. • 7 -9 • Explain how the name of a muscle can help identify its location, appearance, or function. © 2013 Pearson Education, Inc.

Chapter 7 Learning Outcomes • 7 -10 • Identify the main axial muscles of the body together with their origins, insertions, and actions. • 7 -11 • Identify the main appendicular muscles of the body together with their origins, insertions, and actions. • 7 -12 • Describe the effects of aging on muscle tissue. • 7 -13 • Discuss the functional relationships between the muscular system and other organ systems. © 2013 Pearson Education, Inc.

Five Skeletal Muscle Functions (7 -1) 1. Produce movement of the skeleton • By pulling on tendons that then move bones 2. Maintain posture and body position 3. Support soft tissues • With the muscles of the abdominal wall and the pelvic floor 4. Guard entrances and exits • In the form of sphincters 5. Maintain body temperature • When contraction occurs, energy is used and converted to heat © 2013 Pearson Education, Inc.

Checkpoint (7 -1) 1. Identify the five primary functions of skeletal muscle. © 2013

Organization of Skeletal Muscle Tissue (7 -2) • Skeletal muscles • Are organs that contain: • Connective tissue • Blood vessels • Nerves • Skeletal muscle tissue • Single skeletal muscle cells • Also called skeletal muscle fibers © 2013 Pearson Education, Inc.

Three Layers of Connective Tissue (7 -2) 1. Epimysium • Covers the entire muscle 2. Perimysium • Divides the muscle into bundles called fascicles • Blood vessels and nerves are contained in the perimysium 3. Endomysium • Covers each muscle fiber and ties fibers together • Contains capillaries and nerve tissue © 2013 Pearson Education, Inc.

Tendons (7 -2) • Where the ends of all three layers of connective tissue come together • And attach the muscle to a bone • Aponeurosis • A broad sheet of collagen fibers that connects muscles to each other • Similar to tendons, but do not connect to a bone © 2013 Pearson Education, Inc.

Blood Vessels and Nerves (7 -2) • Extensive network of blood vessels in skeletal muscle • Provides high amounts of nutrients and oxygen • To skeletal muscles which have high metabolic needs © 2013 Pearson Education, Inc.

Control of Skeletal Muscle (7 -2) • Mostly under voluntary control • Must be stimulated by the central nervous system • Axons • Push through the epimysium • Branch through the perimysium • And enter the endomysium • To control individual muscle fibers © 2013 Pearson Education, Inc.

Figure 7 -1 The Organization of Skeletal Muscles. Skeletal Muscle (organ) Epimysium Perimysium Endomysium Nerve Muscle Blood fascicle fibers vessels Muscle Fascicle (bundle of fibers) Perimysium Epimysium Blood vessels and nerves Muscle fiber Endomysium Tendon Endomysium Muscle Fiber (cell) Capillary Myofibril Endomysium Sarcoplasm Perimysium Mitochondrion Stem cell Sarcolemma Nucleus Axon of neuron © 2013 Pearson Education, Inc.

Checkpoint (7 -2) 2. Describe the connective tissue layers associated with a skeletal muscle. 3. How would severing the tendon attached to a muscle affect the muscle's ability to move a body part? © 2013 Pearson Education, Inc.

Features of Skeletal Muscle Fibers (7 -3) • Are specifically organized to produce contraction and have specific names for general cell structures • Can be very long and are multinucleated • Composed of highly organized structures, giving them a striped or striated appearance © 2013 Pearson Education, Inc.

The Sarcolemma and Transverse Tubules (7 -3) • The sarcolemma • Specific name of muscle fiber plasma membrane • Has openings across the surface that lead into a network of transverse tubules, or T tubules • T tubules allow for electrical stimuli to reach deep into each fiber • The sarcoplasm • Specific name for muscle fiber cytoplasm © 2013 Pearson Education, Inc.

Myofibrils in Muscle Fiber (7 -3) • Hundreds to thousands in each fiber • Are encircled by T tubules and are as long as the entire muscle fiber • Are bundles of thick and thin myofilaments • Actin molecules are found in thin filaments • Myosin molecules are found in thick filaments • Are the contractile proteins that shorten and are responsible for contraction © 2013 Pearson Education, Inc.

The Sarcoplasmic Reticulum (7 -3) • Or SR • Specialized smooth endoplasmic reticulum • Expanded end that is next to the T tubule is the terminal cisternae • Contain high concentrations of calcium ions • Triad • A combination of two terminal cisternae and one T tubule © 2013 Pearson Education, Inc.

Sarcomeres (7 -3) • Smallest functional unit of skeletal muscle fiber • Formed by repeating myofilament arrangements • Each myofibril has about 10, 000 sarcomeres • Thick and thin filament arrangements are what produce the striated appearance of the fiber • Overlapping filaments define lines and bands © 2013 Pearson Education, Inc.

Sarcomere Lines (7 -3) • Z lines • Thin filaments at both ends of the sarcomere • Another protein connects the Z lines to the thick filament to maintain alignment • M line • Made of connections between the thick filaments © 2013 Pearson Education, Inc.

Sarcomere Bands (7 -3) • A band • Contains the thick filaments • I

Figure 7 -2 The Organization of a Skeletal Muscle Fiber. Terminal Sarcoplasmic T tubules cisterna reticulum Triad Sarcolemma Mitochondria Thick filament Myofilaments Thin filament MYOFIBRIL The structure of a skeletal muscle fiber. SARCOMERE Z line Zone of overlap M line Myofibril H band I band Zone of overlap A band The organization of a sarcomere, part of a single myofibril. M line Z line A stretched out sarcomere. M line Z line and thin filaments Active site Myosin head Thick filaments Actin molecules Myosin tail ACTIN STRAND Tropomyosin Thin filament The structure of a thin filament. Troponin © 2013 Pearson Education, Inc. Hinge MYOSIN MOLECULE The structure of a thick filament.

Figure 7 -2 a The Organization of a Skeletal Muscle Fiber. Terminal Sarcoplasmic Triad Sarcolemma T tubules cisterna reticulum Mitochondria Thick filament Thin filament Myofilaments MYOFIBRIL The structure of a skeletal muscle fiber. © 2013 Pearson Education, Inc.

Figure 7 -2 b The Organization of a Skeletal Muscle Fiber. SARCOMERE Z line Zone of overlap M line Myofibril I band H band A band The organization of a sarcomere, part of a single myofibril. © 2013 Pearson Education, Inc. Zone of overlap

Figure 7 -2 c The Organization of a Skeletal Muscle Fiber. Z line M

Figure 7 -2 d The Organization of a Skeletal Muscle Fiber. Active site Actin

Figure 7 -2 e The Organization of a Skeletal Muscle Fiber. Myosin head Myosin

Thin and Thick Filaments (7 -3) • Actin • A thin twisted protein, with specific active sites for myosin to bind to • At rest, active sites are covered by strands of tropomyosin, held in position by troponin • Myosin • A thick filament with tail and globular head that attaches to actin active sites during contraction © 2013 Pearson Education, Inc.

Steps of Contraction (7 -3) 1. Calcium released from SR 2. Calcium binds to troponin 3. Change of troponin shape causes tropomyosin to move away from active sites 4. Myosin heads bind to active site, creating crossbridges, rotate and cause actin to slide over myosin © 2013 Pearson Education, Inc.

Sliding Filament Theory (7 -3) • Based on observed changes in sarcomere • I bands get smaller • Z lines move closer together • H bands decrease • A bands don't change, indicating that the thin filaments are sliding toward the center © 2013 Pearson Education, Inc.

Figure 7 -3 Changes in the Appearance of a Sarcomere during Contraction of a Skeletal Muscle Fiber. I band Z line A band H band Z line A relaxed sarcomere showing locations of the A band, Z lines, and I band. © 2013 Pearson Education, Inc. I band A band H band Z line During a contraction, the A band stays the same width, but the Z lines move closer together and the I band gets smaller.

Checkpoint (7 -3) 4. Describe the basic structure of a sarcomere. 5. Why do skeletal muscle fibers appear striated when viewed through a light microscope? 6. Where would you expect the greatest concentration of calcium ions to be in a resting skeletal muscle fiber? © 2013 Pearson Education, Inc.

The Neuromuscular Junction (7 -4) • Where a motor neuron communicates with a skeletal muscle fiber • Axon terminal of the neuron • An enlarged end that contains vesicles of the neurotransmitter • Acetylcholine (ACh) • The neurotransmitter that will cross the synaptic cleft © 2013 Pearson Education, Inc.

The Neuromuscular Junction (7 -4) • ACh binds to the receptor on the motor end plate • Cleft and the motor end plate contain acetylcholinesterase (ACh. E) • Which breaks down ACh • Neurons stimulate sarcolemma by generating an action potential • An electrical impulse © 2013 Pearson Education, Inc.

Figure 7 -4 Skeletal Muscle Innervation. The cytoplasm of the axon terminal contains vesicles filled with molecules of acetylcholine, or ACh. Acetylcholine is a neurotransmitter, a chemical released by a neuron to change the permeability or other properties of another cell’s plasma membrane. The synaptic cleft and the motor end plate contain molecules of the enzyme acetylcholinesterase (ACh. E), which breaks down ACh. Vesicles ACh Synaptic cleft Motor end plate © 2013 Pearson Education, Inc. ACh. E Slide 1

Figure 7 -4 Skeletal Muscle Innervation. Slide 2 The stimulus for ACh release is the arrival of an electrical impulse, or action potential, at the axon terminal. The action potential arrives at the NMJ after traveling along the length of the axon. Arriving action potential © 2013 Pearson Education, Inc.

Figure 7 -4 Skeletal Muscle Innervation. When the action potential reaches the neuron’s axon terminal, permeability changes in the membrane trigger the exocytosis of ACh into the synaptic cleft. Exocytosis occurs as vesicles fuse with the neuron’s plasma membrane. Motor end plate © 2013 Pearson Education, Inc. Slide 3

Figure 7 -4 Skeletal Muscle Innervation. Slide 4 ACh molecules diffuse across the synaptic cleft and bind to ACh receptors on the surface of the motor end plate. ACh binding alters the membrane’s permeability to sodium ions. Because the extracellular fluid contains a high concentration of sodium ions, and sodium ion concentration inside the cell is very low, sodium ions rush into the sarcoplasm. ACh receptor site © 2013 Pearson Education, Inc.

Figure 7 -4 Skeletal Muscle Innervation. Slide 5 The sudden inrush of sodium ions results in the generation of an action potential in the sarcolemma. ACh. E quickly breaks down the ACh on the motor end plate and in the synaptic cleft, thus inactivating the ACh receptor sites. Action potential ACh. E © 2013 Pearson Education, Inc.

The Contraction Cycle (7 -4) • Involves the triads • Action potential travels over the sarcolemma, down into the T tubules • Causes release of calcium from the SR • Calcium binds to troponin and the contraction cycle starts © 2013 Pearson Education, Inc.

Figure 7 -5 The Contraction Cycle Slide 1 Contraction Cycle Begins Myosin head Troponin

Figure 7 -5 The Contraction Cycle Slide 2 Active-Site Exposure Sarcoplasm Active site ©

Figure 7 -5 The Contraction Cycle Slide 3 Cross-Bridge Formation © 2013 Pearson Education,

Figure 7 -5 The Contraction Cycle Slide 4 Myosin Head Pivoting © 2013 Pearson

Figure 7 -5 The Contraction Cycle Slide 5 Cross-Bridge Detachment © 2013 Pearson Education,

Figure 7 -5 The Contraction Cycle Slide 6 Myosin Reactivation © 2013 Pearson Education,

Table 7 -1 Steps Involved in Skeletal Muscle Contraction and Relaxation © 2013 Pearson

Checkpoint (7 -4) 7. Describe the neuromuscular junction. 8. How would a drug that blocks acetylcholine release affect muscle contraction? 9. What would you expect to happen to a resting skeletal muscle if the sarcolemma suddenly became very permeable to calcium ions? © 2013 Pearson Education, Inc.

Contraction Produces Tension (7 -5) • As sarcomeres contract, so does the entire muscle fiber • As fibers contract, tension is created by tendons pulling on bones • Movement will occur only if the tension is greater than the resistance • Compression is a force that pushes objects • Muscle cells create only tension, not compression © 2013 Pearson Education, Inc.

Contraction Produces Tension (7 -5) • Individual fibers • Are either contracted or relaxed • "On" or "off" • Tension is a product of the number of cross-bridges a fiber contains • Variation in tension can occur based on: • The amount of overlap of the myofilaments • The frequency of stimulation • The more frequent the stimulus, the more Ca 2+ builds up, resulting in greater contractions © 2013 Pearson Education, Inc.

Contraction Produces Tension (7 -5) • Whole skeletal muscle organ • Contracts with varying tensions based on: • Frequency of muscle fiber stimulation • Number of fibers activated © 2013 Pearson Education, Inc.

A Muscle Twitch (7 -5) • A single stimulus-contraction-relaxation cycle in a muscle fiber

Three Phases of a Muscle Twitch (7 -5) 1. Latent period • Starts at the point of stimulus and includes the action potential, release of Ca 2+, and the activation of troponin/tropomyosin 2. Contraction phase • Is the development of tension because of the cross-bridge cycle 3. Relaxation phase • Occurs when tension decreases due to the re-storage of Ca 2+ and covering of actin active sites © 2013 Pearson Education, Inc.

Figure 7 -6 The Twitch and Development of Tension Maximum tension development Stimulus Time (msec) 0 5 10 Resting Latent Contraction phase period phase © 2013 Pearson Education, Inc. 20 30 Relaxation phase 40

Summation and Tetanus (7 -5) • Summation • Occurs with repeated, frequent stimuli that trigger a response before full relaxation has occurred • Incomplete tetanus • Near peak tension with little relaxation • Complete tetanus • Stimuli are so frequent that relaxation does not occur PLAY ANIMATION Frog Wave Summation © 2013 Pearson Education, Inc.

Figure 7 -7 Effects of Repeated Stimulations. Maximum tension (in tetanus) Tension = Stimulus Time Summation of twitches occurs when successive stimuli arrive before the relaxation phase has been completed. © 2013 Pearson Education, Inc. Time Incomplete tetanus occurs if the stimulus frequency increases further. Tension production rises to a peak, and the periods of relaxation are very brief. Time Complete tetanus. During complete tetanus, the stimulus frequency is so high that the relaxation phase is eliminated; tension plateaus at maximal levels.

Varying Numbers of Fibers Activated (7 -5) • Allows for smooth contraction and a lot of control • Most motor neurons control a number of fibers through multiple, branching axon terminals © 2013 Pearson Education, Inc.

Motor Unit (7 -5) • A single motor neuron and all the muscle fibers it innervates • Motor units are dispersed throughout the muscle • Fine control movements • Use motor units with very few fibers per neuron • Gross movements • Motor units have a high fiber-to-neuron ratio © 2013 Pearson Education, Inc.

Recruitment (7 -5) • A mechanism for increasing tension to create more movement •

Figure 7 -8 Motor Units. Axons of motor neurons Motor nerve KEY Motor unit

Muscle Tone and Atrophy (7 -5) • Muscle tone • Some muscles at rest will still have a little tension • Primary function is stabilization of joints and posture • Atrophy • Occurs in a muscle that is not regularly stimulated • Muscle becomes small and weak • Can be observed after a cast comes off a fracture © 2013 Pearson Education, Inc.

Types of Contraction (7 -5) • Isotonic contraction • When the length of the muscle changes, but the tension remains the same until relaxation • For example, lifting a book • Isometric contraction • When the whole muscle length stays the same, the tension produced does not exceed the load • For example, pushing against a wall © 2013 Pearson Education, Inc.

Elongation of Muscle after Contraction (7 -5) • No active mechanism for returning a muscle to a pre-contracted, elongated state • Passively uses a combination of: • Gravity • Elastic forces • Opposing muscle movement © 2013 Pearson Education, Inc.

Checkpoint (7 -5) 10. What factors are responsible for the amount of tension a skeletal muscle develops? 11. A motor unit from a skeletal muscle contains 1500 muscle fibers. Would this muscle be involved in fine, delicate movements or in powerful, gross movements? Explain. 12. Can a skeletal muscle contract without shortening? Explain. © 2013 Pearson Education, Inc.

ATP and CP Reserves (7 -6) • At rest, muscle cells generate ATP, some of which will be held in reserve • Some is used to transfer high energy to creatine forming creatine phosphate (CP) © 2013 Pearson Education, Inc.

ATP and CP Reserves (7 -6) • During contraction each cross-bridge breaks down ATP into ADP and a phosphate group • CP is then used to recharge ATP • The enzyme creatine phosphokinase (CPK or CK) regulates this reaction • It lasts for about 15 seconds • ATP must then be generated in a different way © 2013 Pearson Education, Inc.

Aerobic Metabolism (7 -6) • Occurs in the mitochondria • Using ADP, oxygen, phosphate ions, and organic substrates from carbohydrates, lipids, or proteins • Substrates go through the citric acid cycle • A series of chemical reactions that result in energy to make ATP, water, and carbon dioxide • Oxygen supply decides ATP aerobic production © 2013 Pearson Education, Inc.

Glycolysis (7 -6) • Breaks glucose down to pyruvate in the cytoplasm of the cell • If pyruvate can go through the citric acid cycle with oxygen, it is very efficient • Forming about 34 ATP • With insufficient oxygen, pyruvate yields only 2 ATP • Pyruvate is converted to lactic acid • Potentially causing a p. H problem in cells © 2013 Pearson Education, Inc.

Figure 7 -9 Muscle Metabolism. Fatty acids G Blood vessels Glycogen Glucose Mitochondria Creatine Resting: Fatty acids are catabolized; the ATP produced is used to build energy reserves of ATP, CP, and glycogen. Fatty acids Glucose Glycogen 2 2 Pyruvate 34 34 To myofibrils to support muscle contraction Moderate activity: Glucose and fatty acids are catabolized; the ATP produced is used to power contraction. Lactate Glycogen Glucose 2 2 Pyruvate Creatine Lactate To myofibrils to support muscle contraction © 2013 Pearson Education, Inc. Peak activity: Most ATP is produced through glycolysis, with lactate and hydrogen ions as by-products. Mitochondrial activity (not shown) now provides only about one-third of the ATP consumed.

Figure 7 -9 a Muscle Metabolism. Fatty acids G Blood vessels Glucose Mitochondria Glycogen Creatine Resting: Fatty acids are catabolized; the ATP produced is used to build energy reserves of ATP, CP, and glycogen. © 2013 Pearson Education, Inc.

Figure 7 -9 b Muscle Metabolism. Fatty acids Glucose Glycogen 2 2 Pyruvate 34 34 To myofibrils to support muscle contraction Moderate activity: Glucose and fatty acids are catabolized; the ATP produced is used to power contraction. © 2013 Pearson Education, Inc.

Figure 7 -9 c Muscle Metabolism. Lactate Glucose Glycogen 2 2 Pyruvate Creatine Lactate To myofibrils to support muscle contraction Peak activity: Most ATP is produced through glycolysis, with lactate and hydrogen ions as by-products. Mitochondrial activity (not shown) now provides only about one-third of the ATP consumed. © 2013 Pearson Education, Inc.

Muscle Fatigue (7 -6) • Caused by depletion of energy reserves or a lowering of p. H • Muscle will no longer contract even if stimulated • Endurance athletes, using aerobic metabolism, can draw on stored glycogen and lipids • Sprinters, functioning anaerobically, deplete CP and ATP rapidly, and build up lactic acid PLAY ANIMATION Frog Fatigue © 2013 Pearson Education, Inc.

The Recovery Period (7 -6) • Requires "repaying" the oxygen debt by continuing to breathe faster • Even after the end of exercise, and recycling lactic acid • Heat production occurs during exercise • Raising the body temperature • Blood vessels in skin will dilate; sweat covers the skin and evaporates • Promoting heat loss © 2013 Pearson Education, Inc.

Checkpoint (7 -6) 13. How do muscle cells continuously synthesize ATP? 14. What is

Muscle Performance (7 -7) • Measured in force • The maximum amount of tension produced by a muscle or muscle group • Measured in endurance • The amount of time a particular activity can be performed • Two keys to performance 1. Types of fibers in muscle 2. Physical conditioning or training © 2013 Pearson Education, Inc.

Fast Fibers (7 -7) • The majority of muscle fibers in the body • Large in diameter • Large glycogen reserves • Few mitochondria • Rely on glycolysis • Are rapidly fatigued © 2013 Pearson Education, Inc.

Slow Fibers (7 -7) • About half the diameter of, and three times slower than, fast fibers • Are fatigue resistant because of three factors 1. Oxygen supply is greater due to more perfusion 2. Myoglobin stores oxygen in the fibers 3. Oxygen use is efficient due to large numbers of mitochondria © 2013 Pearson Education, Inc.

Percentages of Muscle Types Vary (7 -7) • Fast fibers appear pale and are called white muscles • Extensive vasculature and myoglobin in slow fibers cause them to appear reddish and are called red muscles • Human muscles are a mixture of fiber types and appear pink © 2013 Pearson Education, Inc.

Muscle Conditioning and Performance (7 -7) • Physical conditioning and training • Can increase power and endurance • Anaerobic endurance • Is increased by brief, intense workouts • Hypertrophy of muscles results • Aerobic endurance • Is increased by sustained, low levels of activity © 2013 Pearson Education, Inc.

Checkpoint (7 -7) 16. Why would a sprinter experience muscle fatigue before a marathon runner would? 17. Which activity would be more likely to create an oxygen debt in an individual who regularly exercises: swimming laps or lifting weights? 18. Which type of muscle fibers would you expect to predominate in the large leg muscles of someone who excels at endurance activities such as cycling or long-distance running? © 2013 Pearson Education, Inc.

Cardiac Muscle Tissue (7 -8) • Found only in heart • Cardiac muscle cells • Relatively small with usually one central nucleus • Striated and branched • Intercalated discs, which connect cells to other cells • Communicate through gap junctions, allowing all the fibers to work together © 2013 Pearson Education, Inc.

Cardiac Pacemaker Cells (7 -8) • Exhibit automaticity • Make up only 1 percent

Cardiac Contractile Cells (7 -8) • 99 percent of myocardium • Contract for longer period than skeletal muscle fibers • Unique sarcolemmas make tetanus impossible • Are permeable to calcium • Rely on aerobic metabolism © 2013 Pearson Education, Inc.

Smooth Muscle Tissue (7 -8) • Found in the walls of most organs, in the form of sheets, bundles, or sheaths • Lacks myofibrils, sarcomeres, or striations • Smooth muscle cells • Also smaller than skeletal fibers • Spindle-shaped and have a single nucleus © 2013 Pearson Education, Inc.

Smooth Muscle Tissue (7 -8) • Thick filaments are scattered throughout sarcoplasm • Thin filaments are anchored to the sarcolemma • Causing contraction to be like a twisting corkscrew • Cells are bound together • Resulting in forces being transmitted throughout the tissue © 2013 Pearson Education, Inc.

Smooth Muscle Tissue (7 -8) • Different from other muscle types • Calcium ions from the extracellular fluid are needed to trigger a contraction mechanism that is different from other muscle tissues • Function involuntarily • Can respond to hormones or pacesetter cells © 2013 Pearson Education, Inc.

Figure 7 -10 Cardiac and Smooth Muscle Tissues. Cardiac muscle cell Intercalated discs Cardiac muscle tissue LM x 575 A light micrograph of cardiac muscle tissue. T L Circular muscle layer Longitudinal muscle layer Smooth muscle tissue LM x 100 © 2013 Pearson Education, Inc. Many visceral organs contain several layers of smooth muscle tissue oriented in different directions. Here, a single sectional view shows smooth muscle cells in both longitudinal (L) and transverse (T) sections.

Table 7 -2 A Comparison of Skeletal, Cardiac, and Smooth Muscle Tissues © 2013

Checkpoint (7 -8) 19. How do intercalated discs enhance the functioning of cardiac muscle tissue? 20. Extracellular calcium ions are important for the contraction of what type(s) of muscle tissue? 21. Why can smooth muscle contract over a wider range of resting lengths than skeletal muscle? © 2013 Pearson Education, Inc.

Skeletal Muscle System Names (7 -9) • Based on: • Action • What they

Actions (7 -9) • Described as relative to the bone that is moved • Example, "flexion of the forearm" • Described as the joint that is involved • Example, "flexion at the elbow" © 2013 Pearson Education, Inc.

Primary Actions of Muscles (7 -9) • Prime mover, or agonist • The muscle that is chiefly responsible for producing a movement • Antagonist • A muscle that opposes another muscle • Synergist • A muscle that helps the prime mover • Example, flexion of the elbow • The biceps brachii is the prime mover, the triceps brachii is the antagonist, and the brachialis is the synergist © 2013 Pearson Education, Inc.

Table 7 -3 Muscle Terminology (1 of 2) © 2013 Pearson Education, Inc.

Table 7 -3 Muscle Terminology (2 of 2) © 2013 Pearson Education, Inc.

Muscle Terminology (7 -9) • Combining the various terms in Table 7 -3, anatomists name the muscles using: • Location, direction of fibers, number of origins, and/or function • Muscles are organized into two groups 1. Axial muscles (mostly stabilizers) 2. Appendicular muscles (stabilizers or movers of the limbs) © 2013 Pearson Education, Inc.

Figure 7 -11 a An Overview of the Major Skeletal Muscles. Frontalis Temporalis Trapezius Clavicle Deltoid Masseter Sternocleidomastoid Pectoralis major Sternum Latissimus dorsi Serratus anterior External oblique Rectus abdominis Extensor carpi radialis Brachioradialis Flexor carpi ulnaris Biceps brachii Triceps brachii Brachialis Pronator teres Palmaris longus Flexor carpi radialis Flexor digitorum Tensor fasciae latae Vastus lateralis Rectus femoris Patella Tibialis anterior Extensor digitorum © 2013 Pearson Education, Inc. Gluteus medius Iliopsoas Adductor longus Gracilis Sartorius Vastus medialis Fibularis Gastrocnemius Soleus Anterior view

Figure 7 -11 b An Overview of the Major Skeletal Muscles. Sternocleidomastoid Trapezius Deltoid Infraspinatus Teres minor Teres major Latissimus dorsi Brachioradialis Extensor carpi radialis Tensor fasciae latae Semitendinosus Biceps femoris Gastrocnemius Occipitalis Triceps brachii Rhomboid major Flexor carpi ulnaris External oblique Extensor digitorum Extensor carpi ulnaris Gluteus medius Gluteus maximus Adductor magnus Semimembranosus Gracilis Sartorius Soleus Calcaneal tendon © 2013 Pearson Education, Inc. Calcaneus Posterior view

Checkpoint (7 -9) 22. Identify the kinds of descriptive information used to name skeletal muscles. 23. Which muscle is the antagonist of the biceps brachii? 24. What does the name flexor carpi radialis longus tell you about this muscle? © 2013 Pearson Education, Inc.

Axial Muscles (7 -10) • Muscles of the head and neck • Muscles of

Muscles of the Head and Neck (7 -10) • Orbicularis oris • Constricts the mouth opening • Buccinator • Compresses check to blow forcefully • Masseter • Prime mover for chewing • Temporalis and pterygoid • Synergists for chewing • Digastric • Depresses the mandible • Sternocleidomastoid • Rotates head or flexes neck © 2013 Pearson Education, Inc.

Muscles of the Head and Neck (7 -10) • Epicranium, or scalp, contains a two-part muscle, the occipitofrontalis 1. Anterior frontalis 2. Posterior occipitalis • Connected by epicranial aponeurosis • Platysma • Covers ventral neck extending from the base of the neck to the mandible • Mylohyoid • Supports the tongue • Stylohyoid • Connects hyoid to styloid process © 2013 Pearson Education, Inc.

Figure 7 -12 Muscles of the Head and Neck. Epicranial aponeurosis (tendinous sheet) Frontalis Temporalis Orbicularis oculi Occipitalis Buccinator Masseter Sternocleidomastoid Zygomaticus Orbicularis oris Depressor anguli oris Frontalis Temporalis Orbicularis oculi Platysma Lateral view Zygomaticus Orbicularis oris Platysma Sternocleidomastoid Lateral pterygoid Medial pterygoid Mandible © 2013 Pearson Education, Inc. Epicranial aponeurosis (tendinous sheet) Lateral view, pterygoid muscles exposed Masseter Buccinator Depressor anguli oris Trapezius Platysma (cut and reflected) Anterior view

Figure 7 -13 Muscles of the Anterior Neck. Mandible Mylohyoid Stylohyoid Hyoid bone Digastric Sternocleidomastoid (cut) Cartilages of larynx Sternothyroid Sternohyoid Clavicle Cut heads of sternocleidomastoid © 2013 Pearson Education, Inc. Sternocleidomastoid Sternum

Table 7 -4 Muscles of the Head and Neck (1 of 2) © 2013

Table 7 -4 Muscles of the Head and Neck (2 of 2) © 2013

Muscles of the Spine (7 -10) • Splenius capitis and semispinalis capitis • Work together to either extend the head or tilt the head • Erector spinae • Are spinal extensors and include spinalis, longissimus, and iliocostalis • Quadratus lumborum • Flex the spinal column and depress the ribs © 2013 Pearson Education, Inc.

Figure 7 -14 Muscles of the Spine. Semispinalis capitis Splenius capitis Iliocostalis Erector Longissimus

Table 7 -5 Muscles of the Spine © 2013 Pearson Education, Inc.

Axial Muscles of the Trunk (7 -10) • External and internal intercostals • Elevate and depress ribs, respectively • Diaphragm • Muscle used for inhalation of breath • External and internal obliques, and the transversus abdominis • Compress abdomen, can flex spine • Rectus abdominis • Depresses ribs, flexes spine © 2013 Pearson Education, Inc.

Figure 7 -15 Oblique and Rectus Muscles and the Diaphragm. Rectus Xiphoid abdominis process External oblique Inferior vena cava External intercostal Internal intercostal T 10 Central tendon of diaphragm Esophagus Serratus anterior Diaphragm Aorta Spinal cord Erector spinae group Superior view at the level of the diaphragm Serratus anterior Internal intercostal External oblique (cut) External oblique Aponeurosis Internal oblique Linea alba (midline band of dense connective tissue) Linea alba External oblique Transversus abdominis Internal oblique L 3 Quadratus lumborum Rectus abdominis Anterior view © 2013 Pearson Education, Inc. Rectus abdominis Horizontal section view at the level of the umbilicus

Table 7 -6 Axial Muscles of the Trunk © 2013 Pearson Education, Inc.

Muscles of the Pelvic Floor (7 -10) • Form the perineum and support the organs of the pelvic cavity • Flex the coccyx • Control materials moving through the anus and urethra with sphincters © 2013 Pearson Education, Inc.

Figure 7 -16 Muscles of the Pelvic Floor. Deep Dissections Superficial Dissections Urethra External urethral sphincter Ischiocavernosus Bulbospongiosus Vagina Transverse perineus Central tendon of perineum Levator ani Anus External anal sphincter Gluteus maximus Female No differences between deep musculature in male and female Testis Urethra (connecting segment removed) Ischiocavernosus Bulbospongiosus Transverse perineus Anus External urethral sphincter Central tendon of perineum Levator ani Gluteus maximus External anal sphincter Male © 2013 Pearson Education, Inc.

Table 7 -7 Muscles of the Pelvic Floor © 2013 Pearson Education, Inc.

Checkpoint (7 -10) 25. If you were contracting and relaxing your masseter muscle, what would you probably be doing? 26. Which facial muscle would you expect to be well developed in a trumpet player? 27. Damage to the external intercostal muscles would interfere with what important process? 28. If someone were to hit you in your rectus abdominis, how would your body position change? © 2013 Pearson Education, Inc.

Appendicular Muscles (7 -11) • Muscles that position the pectoral girdle • Muscles that move the arm, forearm, and wrist • Muscles that move the hand fingers • Muscles of the pelvic girdle • Muscles that move thigh and leg • Muscles that move the foot and toes © 2013 Pearson Education, Inc.

Muscles That Position Pectoral Girdle (7 -11) • Trapezius • Diamond-shaped muscle, has many actions depending on the region • Rhomboid • Adducts and rotates scapula laterally • Levator scapulae • Adducts and elevates scapula • Serratus anterior • Abducts and rotates scapula • Pectoralis minor and subclavius • Depress and abduct shoulder © 2013 Pearson Education, Inc.

Figure 7 -17 Muscles That Position the Pectoral Girdle. Superficial Dissection Deep Dissection Muscles That Position the Pectoral Girdle Trapezius Muscles That Position the Pectoral Girdle Levator scapulae Rhomboid muscles Scapula Serratus anterior Triceps brachii Posterior view Muscles That Position the Pectoral Girdle Trapezius Levator scapulae Subclavius Pectoralis minor Muscles That Position the Pectoral Girdle Pectoralis minor (cut) Serratus anterior Pectoralis major (cut and reflected) Internal intercostals Biceps brachii External intercostals Anterior view © 2013 Pearson Education, Inc. T 12 vertebra

Table 7 -8 Muscles That Position the Pectoral Girdle © 2013 Pearson Education, Inc.

Muscles That Move the Arm (7 -11) • Deltoid • Abducts arm, supraspinatus assists • Subscapularis, teres major, infraspinatus, and teres minor • Form the rotator cuff • Pectoralis major • Flexes the arm at the shoulder • Latissimus dorsi • Extends the arm at the shoulder PLAY A&P FLIX™ Rotator cuff muscles: An overview (a) PLAY A&P FLIX™ Rotator cuff muscles: An overview (b) © 2013 Pearson Education, Inc.

Figure 7 -18 Muscles That Move the Arm. Deep Dissection Superficial Dissection Sternum Clavicle Ribs (cut) Muscles That Move the Arm Deltoid Pectoralis major Muscles That Move the Arm Subscapularis Coracobrachialis Teres major Biceps brachii Vertebra T 12 Anterior view Deep Dissection Superficial Dissection Muscles That Move the Arm Supraspinatus Deltoid Latissimus dorsi Vertebra T 1 Muscles That Move the Arm Supraspinatus Infraspinatus Teres minor Teres major Triceps brachii Posterior view © 2013 Pearson Education, Inc.

Table 7 -9 Muscles That Move the Arm © 2013 Pearson Education, Inc.

Muscles That Move the Forearm and Wrist (7 -11) • Biceps brachii • Flexes the elbow and supinates forearm • Triceps brachii • Extends elbow • Brachialis and brachioradialis • Flex elbow • Flexor carpi ulnaris, flexor carpi radialis, and palmaris longus • Flex wrist • Extensor carpi radialis and extensor carpi ulnaris • Extend wrist • Pronators and supinators • Rotate radius © 2013 Pearson Education, Inc.

Muscles That Move the Hand (7 -11) • Extensor digitorum • Extends fingers • Flexor digitorum • Flexes fingers • Abductor pollicis • Abducts thumb • Extensor pollicis • Extends thumb PLAY A&P FLIX™ The elbow joint and forearm: An overview © 2013 Pearson Education, Inc.

Figure 7 -19 Muscles That Move the Forearm and Wrist. Humerus Coracobrachialis Triceps brachii Brachioradialis Extensor carpi radialis Brachialis Flexor carpi Extensor radialis carpi ulnaris Flexor Extensor digitorum superficialis Abductor pollicis Flexor Extensor retinaculum pollicis Extensor retinaculum Flexor carpi ulnaris Ulna Posterior view of right upper limb © 2013 Pearson Education, Inc. Pronator teres Brachioradialis Palmaris longus Flexor carpi ulnaris Pronator quadratus Anterior view of right upper limb Supinator Pronator teres Ulna Radius Anterior view of the muscles of pronation and supination when the limb is supinated

Table 7 -10 Muscles That Move the Forearm, Wrist, and Hand (1 of 2)

Table 7 -10 Muscles That Move the Forearm, Wrist, and Hand (2 of 2)

Checkpoint (7 -11) 29. Which muscle do you use to shrug your shoulders? 30. Sometimes baseball pitchers suffer rotator cuff injuries. Which muscles are involved in this type of injury? 31. Injury to the flexor carpi ulnaris would impair which two movements? © 2013 Pearson Education, Inc.

Muscles That Move the Thigh (7 -11) • Gluteal group • Includes gluteus maximus, the largest and most posterior; is a hip extensor • Adductors • Include the adductor magnus, adductor brevis, adductor longus, the pectineus, and the gracilis • Largest hip flexor is the iliopsoas • Made up of the psoas major and the iliacus PLAY A&P FLIX™ Anterior muscles that cross the hip joint © 2013 Pearson Education, Inc.

Figure 7 -20 Muscles That Move the Thigh. Iliac crest Gluteus medius (cut) Gluteus maximus (cut) Sacrum Gluteal region, posterior view Gluteal Group Gluteus medius Gluteus maximus Gluteus minimus Tensor fasciae latae Iliotibial tract Vastus lateralis Sartorius Rectus femoris Biceps femoris Semimembranosus Plantaris Head of fibula L 5 Patellar Lateral ligament view Iliopsoas Group Psoas major Iliacus Adductor Group Pectineus Adductor brevis Adductor longus Adductor magnus Gracilis Anterior view of the iliopsoas muscle and the adductor group © 2013 Pearson Education, Inc.

Table 7 -11 Muscles That Move the Thigh (1 of 3) © 2013 Pearson

Table 7 -11 Muscles That Move the Thigh (2 of 3) © 2013 Pearson

Table 7 -11 Muscles That Move the Thigh (3 of 3) © 2013 Pearson

Muscles That Move the Leg (7 -11) • Knee flexors are the hamstrings • Biceps femoris, semimembranosus, semitendinosus, and the sartorius • Knee extensors are the quadriceps femoris • Which include the rectus femoris and the three vastus muscles • Popliteus muscle • Unlocks the knee joint © 2013 Pearson Education, Inc.

Figure 7 -21 Muscles That Move the Leg. Iliac crest Gluteus medius Tensor fasciae latae Gluteus maximus Iliacus Psoas major Iliopsoas Tensor fasciae latae Pectineus Adductor longus Gracilis Adductor magnus Sartorius Gracilis Iliotibial tract Flexors of the Knee Extensors of the Knee (Quadriceps muscles) Rectus femoris Biceps femoris Vastus lateralis Semitendinosus Vastus medialis Vastus intermedius (deep to above muscles) Semimembranosus Quadriceps tendon Sartorius Patella Popliteus Patellar ligament Hip and thigh, posterior view © 2013 Pearson Education, Inc. Quadriceps and thigh muscles, anterior view

Table 7 -12 Muscles That Move the Leg © 2013 Pearson Education, Inc.

Muscles That Move the Foot and Toes (7 -11) • The gastrocnemius of the calf is assisted by the underlying soleus • They share a common calcaneal tendon, and are both plantar flexors • Fibularis muscles • Produce eversion and plantar flexion • Tibialis • Cause inversion of the foot • Tibialis anterior is largest and produces dorsiflexion © 2013 Pearson Education, Inc.

Figure 7 -22 a Muscles That Move the Foot and Toes. Superficial Dissection Deep Dissection Ankle Extensors Plantaris Head of fibula Gastrocnemius Soleus Popliteus Ankle Extensors (Deep) Tibialis posterior Fibularis longus Fibularis brevis Digital Flexors Gastrocnemius (cut and removed) Flexor digitorum longus Flexor hallucis longus Calcaneal tendon Tendon of flexor hallucis longus Calcaneus Tendons of fibularis muscles Posterior views © 2013 Pearson Education, Inc. Tendon of flexor digitorum longus

Figure 7 -22 b Muscles That Move the Foot and Toes. Iliotibial tract Head of fibula Ankle Extensors Gastrocnemius Ankle Flexors Fibularis longus Tibialis anterior Soleus Fibularis brevis Digital Extensors Extensor digitorum longus Tendon of extensor hallucis longus Calcaneal tendon Retinacula Lateral view © 2013 Pearson Education, Inc.

Figure 7 -22 c Muscles That Move the Foot and Toes. Patella Medial surface of tibial shaft Patellar ligament Ankle Flexors Ankle Extensors Tibialis anterior Gastrocnemius Soleus Digital Extensors Tibialis posterior Tendon of extensor hallucis longus Calcaneal tendon Retinacula Tendon of tibialis anterior © 2013 Pearson Education, Inc. Medial view

Table 7 -13 Muscles That Move the Foot and Toes (1 of 2) ©

Table 7 -13 Muscles That Move the Foot and Toes (2 of 2) ©

Checkpoint (7 -11) 32. You often hear of athletes suffering a "pulled hamstring. " To what does this phrase refer? 33. How would you expect a torn calcaneal tendon to affect movement of the foot? © 2013 Pearson Education, Inc.

Four Effects of Aging on Skeletal Muscle (7 -12) 1. Muscle fibers become smaller in diameter 2. Muscles become less elastic and more fibrous 3. Tolerance for exercise decreases due to a decrease in thermoregulation 4. Ability to recover from injury is decreased © 2013 Pearson Education, Inc.

Checkpoint (7 -12) 34. Describe general age-related effects on skeletal muscle tissue. © 2013

Exercise Engages Multiple Systems (7 -13) • Cardiovascular system • Increases heart rate and speeds up delivery of oxygen • Respiratory system • Increases rate and depth of respiration • Integumentary system • Dilation of blood vessels and sweating combine to increase cooling • Nervous and endocrine systems • Control of heart rate, respiratory rate, and release of stored energy © 2013 Pearson Education, Inc.

Skeletal Removes excess body heat; synthesizes vitamin D 3 for calcium and phosphate absorption; protects underlying muscles Provides mineral reserve for maintaining normal calcium and phosphate levels in body fluids; supports skeletal muscles; provides sites of attachment Muscular System Body System Skeletal muscles pulling on skin of face produce facial expressions Provides movement and support; stresses exerted by tendons maintain bone mass; stabilizes bones and joints (Page 138) SYSTEM INTEGRATOR Muscular System Integumentary Body System Skeletal (Page 188) Figure 7 -23 © 2013 Pearson Education, Inc. Endocrine (Page 376) Reproductive (Page 671) Urinary (Page 637) Digestive (Page 572) Respiratory (Page 532) Lymphatic (Page 500) Cardiovascular (Page 467) The muscular system performs five primary functions for the human body. It produces skeletal movement, helps maintain posture and body position, supports soft tissues, guards entrances and exits to the body, and helps maintain body temperature. Nervous (Page 302) The MUSCULAR System

Checkpoint (7 -13) 35. What major function does the muscular system perform for the body as a whole? 36. Identify the physiological effects of exercise on the cardiovascular, respiratory, and integumentary systems, and indicate the relationship between these physiological effects and the nervous and endocrine systems. © 2013 Pearson Education, Inc.