Chapter 6: The Muscular System PDF

 Chapter 6 The Muscular System Lecture Presentation by Patty Bostwick-Taylor Florence-Darlington Technical College...

 Chapter 6 The Muscular System Lecture Presentation by Patty Bostwick-Taylor Florence-Darlington Technical College © 2018 Pearson Education, Inc. The Muscular System Muscles are responsible for all types of body movement Three basic muscle types are found in the body 1. Skeletal muscle 2. Cardiac muscle 3. Smooth muscle © 2018 Pearson Education, Inc. Muscle Types Skeletal and smooth muscle cells are elongated (muscle cell = muscle fiber) Contraction and shortening of muscles are due to the movement of microfilaments All muscles share some terminology Prefixes myo- and mys- refer to “muscle” Prefix sarco- refers to “flesh” © 2018 Pearson Education, Inc. Table 6.1 Comparison of Skeletal, Cardiac, and Smooth Muscles © 2018 Pearson Education, Inc. Table 6.1 Comparison of Skeletal, Cardiac, and Smooth Muscles (1 of 2) © 2018 Pearson Education, Inc. Table 6.1 Comparison of Skeletal, Cardiac, and Smooth Muscles (2 of 2) © 2018 Pearson Education, Inc. Muscle Types Skeletal muscle Most skeletal muscle fibers are attached by tendons to bones Skeletal muscle cells are large, cigar-shaped, and multinucleate Also known as striated muscle because of its obvious stripes Also known as voluntary muscle because it is the only muscle tissue subject to conscious control © 2018 Pearson Education, Inc. Muscle Types Skeletal muscle cells are surrounded and bundled by connective tissue Endomysium—encloses a single muscle fiber Perimysium—wraps around a fascicle (bundle) of muscle fibers Epimysium—covers the entire skeletal muscle Fascia—on the outside of the epimysium © 2018 Pearson Education, Inc.  Muscle Figure 6.1 Blood Connective vessel tissue wrappings of fiber (cell) skeletal muscle. Perimysium Epimysium (wraps entire muscle) Fascicle (wrapped by perimysium) Endomysium (between fibers) Tendon Bone © 2018 Pearson Education, Inc. Muscle Types The epimysium of skeletal muscle blends into a connective tissue attachment Tendons—cordlike structures Mostly collagen fibers Often cross a joint because of their toughness and small size Aponeuroses—sheetlike structures Attach muscles indirectly to bones, cartilages, or connective tissue coverings © 2018 Pearson Education, Inc. Muscle Types Smooth muscle No striations Involuntary—no conscious control Found mainly in the walls of hollow visceral organs (such as stomach, urinary bladder, respiratory passages) Spindle-shaped fibers that are uninucleate Contractions are slow and sustained © 2018 Pearson Education, Inc.  Circular layer Figure 6.2a Arrangement of smooth and of smooth muscle (longitudinal view of cells) cardiac muscle cells. Mucosa Longitudinal layer Submucosa of smooth muscle (cross-sectional view of cells) (a) © 2018 Pearson Education, Inc. Muscle Types Cardiac muscle Striations Involuntary Found only in the walls of the heart Uninucleate Branching cells joined by gap junctions called intercalated discs Contracts at a steady rate set by pacemaker © 2018 Pearson Education, Inc. Figure 6.2b Arrangement of smooth and cardiac muscle cells. Cardiac muscle bundles (b) © 2018 Pearson Education, Inc. Muscle Functions Whereas all muscle types produce movement, skeletal muscle has three other important roles: Maintain posture and body position Stabilize joints Generate heat © 2018 Pearson Education, Inc. Microscopic Anatomy of Skeletal Muscle Sarcolemma—specialized plasma membrane Myofibrils—long organelles inside muscle cell Light (I) bands and dark (A) bands give the muscle its striated (banded) appearance © 2018 Pearson Education, Inc. Figure 6.3a Anatomy of a skeletal muscle fiber (cell). Sarcolemma Myofibril Dark Light Nucleus (A) band (I) band (a) Segment of a muscle fiber (cell) © 2018 Pearson Education, Inc. Microscopic Anatomy of Skeletal Muscle Banding pattern of myofibrils I band = light band Contains only thin filaments Z disc is a midline interruption A band = dark band Contains the entire length of the thick filaments H zone is a lighter central area M line is in center of H zone © 2018 Pearson Education, Inc. Figure 6.3b Anatomy of a skeletal muscle fiber (cell). Z disc H zone Z disc Thin (actin) myofilament Thick (myosin) myofilament (b) Myofibril or fibril I band A band I band M line (complex organelle composed of bundles of myofilaments) © 2018 Pearson Education, Inc. Microscopic Anatomy of Skeletal Muscle Sarcomere—contractile unit of a muscle fiber Structural and functional unit of skeletal muscle Organization of the sarcomere Myofilaments produce banding (striped) pattern Thick filaments = myosin filaments Thin filaments = actin filaments © 2018 Pearson Education, Inc. Microscopic Anatomy of Skeletal Muscle Thick filaments = myosin filaments Composed of the protein myosin Contain ATPase enzymes to split ATP to release energy for muscle contractions Possess projections known as myosin heads Myosin heads are known as cross bridges when they link thick and thin filaments during contraction © 2018 Pearson Education, Inc. Microscopic Anatomy of Skeletal Muscle Thin filaments = actin filaments Composed of the contractile protein actin Actin is anchored to the Z disc At rest, within the A band there is a zone that lacks actin filaments called the H zone During contraction, H zones disappear as actin and myosin filaments overlap © 2018 Pearson Education, Inc. Figure 6.3c Anatomy of a skeletal muscle fiber (cell). Sarcomere M line Z disc Z disc Thin (actin) myofilament Thick (myosin) myofilament (c) Sarcomere (segment of a myofibril) © 2018 Pearson Education, Inc. Microscopic Anatomy of Skeletal Muscle Sarcoplasmic reticulum (SR) Specialized smooth endoplasmic reticulum Surrounds the myofibril Stores and releases calcium © 2018 Pearson Education, Inc. Stimulation and Contraction of Single Skeletal Muscle Cells Special functional properties of skeletal muscles Irritability (also called responsiveness)—ability to receive and respond to a stimulus Contractility—ability to forcibly shorten when an adequate stimulus is received Extensibility—ability of muscle cells to be stretched Elasticity—ability to recoil and resume resting length after stretching © 2018 Pearson Education, Inc. The Nerve Stimulus and Action Potential Skeletal muscles must be stimulated by a motor neuron (nerve cell) to contract Motor unit—one motor neuron and all the skeletal muscle cells stimulated by that neuron © 2018 Pearson Education, Inc.  Axon terminals at neuromuscular junctions Figure 6.4a Motor units. Spinal cord Motor Motor unit 1 unit 2 Nerve Axon of Motor motor neuron neuron cell bodies Muscle Muscle fibers (a) © 2018 Pearson Education, Inc.  Axon terminals at Muscle neuromuscular junctions fibers Figure 6.4b Motor units. Branching axon to motor unit (b) © 2018 Pearson Education, Inc. The Nerve Stimulus and Action Potential Neuromuscular junction Association site of axon terminal of the motor neuron and sarcolemma of a muscle Neurotransmitter Chemical released by nerve upon arrival of nerve impulse in the axon terminal Acetylcholine (ACh) is the neurotransmitter that stimulates skeletal muscle © 2018 Pearson Education, Inc. The Nerve Stimulus and Action Potential Synaptic cleft Gap between nerve and muscle filled with interstitial fluid Although very close, the nerve and muscle do not make contact © 2018 Pearson Education, Inc. The Nerve Stimulus and Action Potential When a nerve impulse reaches the axon terminal of the motor neuron, Step 1: Calcium channels open, and calcium ions enter the axon terminal Step 2: Calcium ion entry causes some synaptic vesicles to release acetylcholine (ACh) Step 3: ACh diffuses across the synaptic cleft and attaches to receptors on the sarcolemma of the muscle cell © 2018 Pearson Education, Inc. The Nerve Stimulus and Action Potential Step 4: If enough ACh is released, the sarcolemma becomes temporarily more permeable to sodium ions (Na+) Potassium ions (K+) diffuse out of the cell More sodium ions enter than potassium ions leave Establishes an imbalance in which interior has more positive ions (depolarization), thereby opening more Na+ channels © 2018 Pearson Education, Inc. The Nerve Stimulus and Action Potential Step 5: Depolarization opens more sodium channels that allow sodium ions to enter the cell An action potential is created Once begun, the action potential is unstoppable Conducts the electrical impulse from one end of the cell to the other Step 6: Acetylcholinesterase (AChE) breaks down acetylcholine into acetic acid and choline AChE ends muscle contraction A single nerve impulse produces only one contraction © 2018 Pearson Education, Inc. The Nerve Stimulus and Action Potential Cell returns to its resting state when: 1. Potassium ions (K+) diffuse out of the cell 2. Sodium-potassium pump moves sodium and potassium ions back to their original positions © 2018 Pearson Education, Inc.  Slide 1 Figure 6.5 Events at the neuromuscular Myelinated axon Nerve of motor neuron impulse Axon terminal of Nucleus neuromuscular junction junction. Sarcolemma of the muscle fiber Synaptic vesicle containing ACh 1 Nerve impulse reaches axon terminal of motor neuron. Axon terminal of motor neuron Mitochondrion 2 Calcium (Ca2+) channels Ca2+ Ca2+ open, and Ca2+ enters the Synaptic axon terminal. cleft Sarcolemma Fusing synaptic vesicle Sarcoplasm 3 Ca2+ entry causes some ACh of muscle fiber synaptic vesicles to release their Folds of contents (the neurotransmitter ACh receptor sarcolemma acetylcholine) by exocytosis. 4 Acetylcholine diffuses across the synaptic cleft and binds to receptors in the sarcolemma. Ion channel in 5 ACh binds and opens channels Na+ K+ sarcolemma opens; that allow simultaneous passage ions pass. of Na+ into the muscle fiber and K+ out of the muscle fiber. More Na+ ions enter than K+ ions leave, producing a local change in the electrical conditions of the membrane (depolarization). This eventually leads to an action potential. ACh Degraded ACh Ion channel closes; Na+ ions cannot pass. 6 The enzyme acetylcholinesterase breaks down ACh in the synaptic cleft, ending the process. Acetylcholinesterase K+  Slide 2 Figure 6.5 Events at the neuromuscular Nerve Myelinated axon of motor neuron junction. impulse Nucleus Axon terminal of neuromuscular junction Sarcolemma of the muscle fiber Synaptic vesicle containing ACh 1 Nerve impulse reaches axon terminal of motor neuron. Axon terminal of motor neuron Mitochondrion Ca2+ Ca2+ Synaptic cleft Sarcolemma Fusing synaptic vesicle Sarcoplasm ACh of muscle fiber ACh Folds of receptor sarcolemma  Slide 3 Figure 6.5 Events at the neuromuscular junction. Synaptic vesicle containing ACh 1 Nerve impulse reaches axon terminal of motor neuron. Axon terminal of motor neuron Mitochondrion 2 Calcium (Ca2+) channels Ca2+ Ca2+ open, and Ca2+ enters the Synaptic axon terminal. cleft Sarcolemma Fusing synaptic vesicle Sarcoplasm ACh of muscle fiber ACh Folds of receptor sarcolemma  Slide 4 Figure 6.5 Events at the neuromuscular junction. Synaptic vesicle containing ACh 1 Nerve impulse reaches axon terminal of motor neuron. Axon terminal of motor neuron Mitochondrion 2 Calcium (Ca2+) channels Ca2+ Ca2+ open, and Ca2+ enters the Synaptic axon terminal. cleft Sarcolemma Fusing synaptic vesicle Sarcoplasm 3 Ca2+ entry causes some ACh of muscle fiber synaptic vesicles to release their Folds of contents (the neurotransmitter ACh receptor sarcolemma acetylcholine) by exocytosis.  Slide 5 Figure 6.5 Events at the neuromuscular junction. Synaptic vesicle containing ACh 1 Nerve impulse reaches axon terminal of motor neuron. Axon terminal of motor neuron Mitochondrion 2 Calcium (Ca2+) channels Ca2+ Ca2+ open, and Ca2+ enters the Synaptic axon terminal. cleft Sarcolemma Fusing synaptic vesicle Sarcoplasm 3 Ca2+ entry causes some ACh of muscle fiber synaptic vesicles to release their Folds of contents (the neurotransmitter ACh receptor sarcolemma acetylcholine) by exocytosis. 4 Acetylcholine diffuses across the synaptic cleft and binds to receptors in the sarcolemma.  Slide 6 Figure 6.5 Events at the neuromuscular junction. Ion channel in 5 ACh binds and opens channels Na+ K+ sarcolemma opens; that allow simultaneous passage ions pass. of Na+ into the muscle fiber and K+ out of the muscle fiber. More Na+ ions enter than K+ ions leave, producing a local change in the electrical conditions of the membrane (depolarization). This eventually leads to an action potential.  Slide 7 Figure 6.5 Events at the neuromuscular junction. ACh Degraded ACh Ion channel closes; Na+ ions cannot pass. 6 The enzyme acetylcholinesterase breaks down ACh in the synaptic cleft, ending the process. Acetylcholinesterase K+  Slide 8 Figure 6.5 Events at the neuromuscular Myelinated axon Nerve of motor neuron impulse Axon terminal of Nucleus neuromuscular junction junction. Sarcolemma of the muscle fiber Synaptic vesicle containing ACh 1 Nerve impulse reaches axon terminal of motor neuron. Axon terminal of motor neuron Mitochondrion 2 Calcium (Ca2+) channels Ca2+ Ca2+ open, and Ca2+ enters the Synaptic axon terminal. cleft Sarcolemma Fusing synaptic vesicle Sarcoplasm 3 Ca2+ entry causes some ACh of muscle fiber synaptic vesicles to release their Folds of contents (the neurotransmitter ACh receptor sarcolemma acetylcholine) by exocytosis. 4 Acetylcholine diffuses across the synaptic cleft and binds to receptors in the sarcolemma. Ion channel in 5 ACh binds and opens channels Na+ K+ sarcolemma opens; that allow simultaneous passage ions pass. of Na+ into the muscle fiber and K+ out of the muscle fiber. More Na+ ions enter than K+ ions leave, producing a local change in the electrical conditions of the membrane (depolarization). This eventually leads to an action potential. ACh Degraded ACh Ion channel closes; Na+ ions cannot pass. 6 The enzyme acetylcholinesterase breaks down ACh in the synaptic cleft, ending the process. Acetylcholinesterase K+ Figure 6.6 Comparing Small twig the action potential to a flame consuming a dry twig. Match flame 1 Flame ignites 2 Flame spreads the twig. rapidly along the twig. (a) Neuromuscular junction Muscle fiber Nerve (cell) Striations fiber 1 Na+ diffuses into the cell. 2 Action potential spreads rapidly along the sarcolemma. (b) © 2018 Pearson Education, Inc. A&P Flix™: Events at the Neuromuscular Junction © 2018 Pearson Education, Inc. Mechanism of Muscle Contraction: The Sliding Filament Theory What causes filaments to slide? Calcium ions (Ca2+) bind regulatory proteins on thin filaments and expose myosin-binding sites, allowing the myosin heads on the thick filaments to attach Each cross bridge pivots, causing the thin filaments to slide toward the center of the sarcomere Contraction occurs, and the cell shortens During a contraction, a cross bridge attaches and detaches several times ATP provides the energy for the sliding process, which continues as long as calcium ions are present © 2018 Pearson Education, Inc.  Myosin Actin Figure 6.7 Diagrammatic views of a sarcomere. Z H Z I A I (a) Relaxed sarcomere Z Z I A I (b) Fully contracted sarcomere © 2018 Pearson Education, Inc. Figure 6.8a Schematic representation of contraction mechanism: the sliding filament theory. Regulatory proteins In a relaxed muscle fiber, the regulatory proteins forming part of the actin myofilaments prevent myosin binding (see a). When an action potential (AP) sweeps along its sarcolemma and a muscle fiber is excited, calcium ions (Ca2+) are released from intracellular storage areas (the sacs of the sarcoplasmic reticulum). Myosin myofilament Actin myofilament (a) © 2018 Pearson Education, Inc. Figure 6.8b Schematic representation of contraction mechanism: the sliding filament theory. Myosin-binding site The flood of calcium acts as the final trigger for Ca2+ contraction, because as calcium binds to the regulatory proteins on the actin filaments, the proteins undergo a change in both their shape and their position on the thin filaments. This action exposes myosin-binding sites on the actin, to which the myosin heads can attach (see b), and the myosin heads immediately begin seeking out binding sites. Upper part of thick filament only (b) © 2018 Pearson Education, Inc. Figure 6.8c Schematic representation of contraction mechanism: the sliding filament theory. The free myosin heads are “cocked,” much like an oar ready to be pulled on for rowing. Myosin attachment to actin causes the myosin heads to snap (pivot) toward the center of the sarcomere in a rowing motion. When this happens, the thin filaments are (c) slightly pulled toward the center of the sarcomere (see c). ATP provides the energy needed to release and recock each myosin head so that it is ready to attach to a binding site farther along the thin filament. © 2018 Pearson Education, Inc. A&P Flix™: The Cross Bridge Cycle © 2018 Pearson Education, Inc. Contraction of a Skeletal Muscle as a Whole Graded responses Muscle fiber contraction is “all-or-none,” meaning it will contract to its fullest when stimulated adequately Within a whole skeletal muscle, not all fibers may be stimulated during the same interval Different combinations of muscle fiber contractions may give differing responses Graded responses—different degrees of skeletal muscle shortening © 2018 Pearson Education, Inc. Contraction of a Skeletal Muscle as a Whole Graded responses can be produced in two ways By changing the frequency of muscle stimulation By changing the number of muscle cells being stimulated at one time © 2018 Pearson Education, Inc. Contraction of a Skeletal Muscle as a Whole Muscle response to increasingly rapid stimulation Muscle twitch Single, brief, jerky contraction Not a normal muscle function © 2018 Pearson Education, Inc. Figure 6.9a A whole muscle’s response to different stimulation rates. Tension (g) (Stimuli) (a) Twitch © 2018 Pearson Education, Inc. Contraction of a Skeletal Muscle as a Whole Muscle response to increasingly rapid stimulation (continued) In most types of muscle activity, nerve impulses are delivered at a rapid rate As a result, contractions are “summed” (added) together, and one contraction is immediately followed by another © 2018 Pearson Education, Inc. Figure 6.9b A whole muscle’s response to different stimulation rates. Tension (g) (Stimuli) (b) Summing of contractions © 2018 Pearson Education, Inc. Contraction of a Skeletal Muscle as a Whole Muscle response to increasingly rapid stimulation (continued) When stimulations become more frequent, muscle contractions get stronger and smoother The muscle now exhibits unfused (incomplete) tetanus © 2018 Pearson Education, Inc. Figure 6.9c A whole muscle’s response to different stimulation rates. Tension (g) (Stimuli) (c) Unfused (incomplete) tetanus © 2018 Pearson Education, Inc. Contraction of a Skeletal Muscle as a Whole Muscle response to increasingly rapid stimulation (continued) Fused (complete) tetanus is achieved when the muscle is stimulated so rapidly that no evidence of relaxation is seen Contractions are smooth and sustained © 2018 Pearson Education, Inc. Figure 6.9d A whole muscle’s response to different stimulation rates. Tension (g) (Stimuli) (d) Fused (complete) tetanus © 2018 Pearson Education, Inc. Contraction of a Skeletal Muscle as a Whole Muscle response to stronger stimuli Muscle force depends upon the number of fibers stimulated Contraction of more fibers results in greater muscle tension When all motor units are active and stimulated, the muscle contraction is as strong as it can get © 2018 Pearson Education, Inc. Providing Energy for Muscle Contraction ATP Only energy source that can be used to directly power muscle contraction Stored in muscle fibers in small amounts that are quickly used up After this initial time, other pathways must be utilized to produce ATP © 2018 Pearson Education, Inc. © 2018 Pearson Education, Inc. Providing Energy for Muscle Contraction Three pathways to regenerate ATP 1. Direct phosphorylation of ADP by creatine phosphate 2. Aerobic pathway 3. Anaerobic glycolysis and lactic acid formation © 2018 Pearson Education, Inc. Providing Energy for Muscle Contraction Direct phosphorylation of ADP by creatine phosphate (CP)—fastest Muscle cells store CP, a high-energy molecule After ATP is depleted, ADP remains CP transfers a phosphate group to ADP to regenerate ATP CP supplies are exhausted in less than 15 seconds 1 ATP is produced per CP molecule © 2018 Pearson Education, Inc.  (a) Direct phosphorylation Figure 6.10a Methods of regenerating ATP Coupled reaction of creatine phosphate (CP) and ADP during muscle activity. Energy source: CP P Creatine ADP Creatine ATP Oxygen use: None Products: 1 ATP per CP, creatine Duration of energy provision: 15 seconds © 2018 Pearson Education, Inc. Providing Energy for Muscle Contraction Aerobic respiration Supplies ATP at rest and during light/moderate exercise A series of metabolic pathways, called oxidative phosphorylation, use oxygen and occur in the mitochondria Glucose is broken down to carbon dioxide and water, releasing energy (about 32 ATP) This is a slower reaction that requires continuous delivery of oxygen and nutrients © 2018 Pearson Education, Inc.  (b) Aerobic pathway Figure 6.10b Methods of regenerating ATP Aerobic cellular respiration during muscle activity. Energy source: glucose; pyruvic acid; free fatty acids from adipose tissue; amino acids from protein catabolism Glucose (from glycogen breakdown or delivered from blood) Pyruvic acid Fatty acids O2 Aerobic respiration Amino in mitochondria acids 32 ATP CO2 H2O net gain per glucose Oxygen use: Required Products: 32 ATP per glucose, CO2, H2O Duration of energy provision: Hours © 2018 Pearson Education, Inc. Providing Energy for Muscle Contraction Anaerobic glycolysis and lactic acid formation Reaction that breaks down glucose without oxygen Glucose is broken down to pyruvic acid to produce about 2 ATP Pyruvic acid is converted to lactic acid, which causes muscle soreness This reaction is not as efficient, but it is fast Huge amounts of glucose are needed © 2018 Pearson Education, Inc.  (c) Anaerobic pathway Figure 6.10c Methods of regenerating ATP Glycolysis and lactic acid formation during muscle activity. Energy source: glucose Glucose (from glycogen breakdown or delivered from blood) Glycolysis in cytosol 2 ATP Pyruvic acid net gain Released Lactic acid to blood Oxygen use: None Products: 2 ATP per glucose, lactic acid Duration of energy provision: 40 seconds, or slightly more © 2018 Pearson Education, Inc. Muscle Fatigue and Oxygen Deficit If muscle activity is strenuous and prolonged, muscle fatigue occurs Suspected factors that contribute to muscle fatigue include: Ion imbalances (Ca2+, K+) Oxygen deficit and lactic acid accumulation Decrease in energy (ATP) supply After exercise, the oxygen deficit is repaid by rapid, deep breathing © 2018 Pearson Education, Inc. Types of Muscle Contractions Isotonic contractions Myofilaments are able to slide past each other during contractions The muscle shortens, and movement occurs Example: bending the knee; lifting weights, smiling Isometric contractions Muscle filaments are trying to slide, but the muscle is pitted against an immovable object Tension increases, but muscles do not shorten Example: pushing your palms together in front of you © 2018 Pearson Education, Inc. Muscle Tone Muscle tone State of continuous partial contractions Result of different motor units being stimulated in a systematic way Muscle remains firm, healthy, and constantly ready for action © 2018 Pearson Education, Inc. Effect of Exercise on Muscles Exercise increases muscle size, strength, and endurance Aerobic (endurance) exercise (biking, jogging) results in stronger, more flexible muscles with greater resistance to fatigue Makes body metabolism more efficient Improves digestion, coordination Resistance (isometric) exercise (weight lifting) increases muscle size and strength Individual muscle fibers enlarge © 2018 Pearson Education, Inc. Figure 6.11 The effects of aerobic training versus strength training. (a) (b) © 2018 Pearson Education, Inc.  Chapter 6 The Muscular System Lecture Presentation by Patty Bostwick-Taylor Florence-Darlington Technical College © 2018 Pearson Education, Inc. Muscle Movements, Roles, and Names Follow the Five Golden Rules for understanding skeletal muscle activity (in Table 6.2, shown next) © 2018 Pearson Education, Inc. Table 6.2 The Five Golden Rules of Skeletal Muscle Activity © 2018 Pearson Education, Inc. Types of Body Movements Muscles are attached to no fewer than two points 1. Origin: attachment to an immovable or less movable bone 2. Insertion: attachment to a movable bone When the muscle contracts, the insertion moves toward the origin Body movement occurs when muscles contract across joints © 2018 Pearson Education, Inc. Figure 6.12 Muscle attachments (origin and insertion). Muscle contracting Origin Brachialis Tendon Insertion © 2018 Pearson Education, Inc. Types of Body Movements Flexion Decreases the angle of the joint Brings two bones closer together Typical of bending hinge joints (e.g., knee and elbow) or ball-and-socket joints (e.g., the hip) Extension Opposite of flexion Increases angle between two bones Typical of straightening the elbow or knee Extension beyond 180º is hyperextension © 2018 Pearson Education, Inc. Figure 6.13a Body movements. Flexion Hyperextension Extension Flexion Extension (a) Flexion, extension, and hyperextension of the shoulder and knee © 2018 Pearson Education, Inc. Figure 6.13b Body Hyperextension movements. Extension Flexion (b) Flexion, extension, and hyperextension © 2018 Pearson Education, Inc. Types of Body Movements Rotation Movement of a bone around its longitudinal axis Common in ball-and-socket joints Example: moving the atlas around the dens of axis (i.e., shaking your head “no”) © 2018 Pearson Education, Inc. Figure 6.13c Body movements. Rotation Lateral rotation Medial rotation (c) Rotation © 2018 Pearson Education, Inc. Types of Body Movements Abduction Movement of a limb away from the midline Adduction Opposite of abduction Movement of a limb toward the midline © 2018 Pearson Education, Inc. Figure 6.13d Body movements. Abduction Adduction Circumduction (d) Abduction, adduction, and circumduction © 2018 Pearson Education, Inc. Types of Body Movements Circumduction Combination of flexion, extension, abduction, and adduction Common in ball-and-socket joints Proximal end of bone is stationary, and distal end moves in a circle © 2018 Pearson Education, Inc. Figure 6.13d Body movements. Abduction Adduction Circumduction (d) Abduction, adduction, and circumduction © 2018 Pearson Education, Inc. Special Movements Dorsiflexion Lifting the foot so that the superior surface approaches the shin (toward the dorsum) Plantar flexion Pointing the toes away from the head © 2018 Pearson Education, Inc. Figure 6.13e Body movements. Dorsiflexion Plantar flexion (e) Dorsiflexion and plantar flexion © 2018 Pearson Education, Inc. Special Movements Inversion Turning sole of foot medially Eversion Turning sole of foot laterally © 2018 Pearson Education, Inc. Figure 6.13f Body movements. Inversion Eversion (f) Inversion and eversion © 2018 Pearson Education, Inc. Special Movements Supination Forearm rotates laterally so palm faces anteriorly Radius and ulna are parallel Pronation Forearm rotates medially so palm faces posteriorly Radius and ulna cross each other like an X © 2018 Pearson Education, Inc. Figure 6.13g Body movements. Pronation Supination (radius rotates (radius and ulna over ulna) are parallel) P P s (g) Supination (S) and pronation (P) © 2018 Pearson Education, Inc. Special Movements Opposition Moving the thumb to touch the tips of other fingers on the same hand © 2018 Pearson Education, Inc. Figure 6.13h Body movements. Opposition (h) Opposition © 2018 Pearson Education, Inc. Interactions of Skeletal Muscles in the Body Muscles can only pull as they contract—not push In general, groups of muscles that produce opposite actions lie on opposite sides of a joint © 2018 Pearson Education, Inc. Interactions of Skeletal Muscles in the Body Prime mover—muscle with the major responsibility for a certain movement Antagonist—muscle that opposes or reverses a prime mover Synergist—muscle that aids a prime mover in a movement or reduces undesirable movements Fixator—specialized synergists that hold a bone still or stabilize the origin of a prime mover © 2018 Pearson Education, Inc. Figure 6.14a Muscle action. (a) A muscle that crosses on the anterior side of a joint produces flexion* Example: Pectoralis major (anterior view) * These generalities do not apply to the knee and ankle because the lower limb is rotated during development. The muscles that cross these joints posteriorly produce flexion, and those that cross anteriorly produce extension. © 2018 Pearson Education, Inc. Figure 6.14b Muscle action. (b) A muscle that crosses on the posterior side of a joint produces extension* Example: Latissimus dorsi (posterior view) The latissimus dorsi is the antagonist of the pectoralis major. * These generalities do not apply to the knee and ankle because the lower limb is rotated during development. The muscles that cross these joints posteriorly produce flexion, and those that cross anteriorly produce extension. © 2018 Pearson Education, Inc. Figure 6.14c Muscle action. (c) A muscle that crosses on the lateral side of a joint produces abduction Example: Deltoid middle fibers (anterolateral view) © 2018 Pearson Education, Inc. Figure 6.14d Muscle action. (d) A muscle that crosses on the medial side of a joint produces adduction Example: Teres major (posterolateral view) The teres major is the antagonist of the deltoid. © 2018 Pearson Education, Inc. Naming Skeletal Muscles Muscles are named on the basis of several criteria By direction of muscle fibers Example: rectus (straight) By relative size of the muscle Example: maximus (largest) © 2018 Pearson Education, Inc. Naming Skeletal Muscles Muscles are named on the basis of several criteria (continued) By location of the muscle Example: temporalis (temporal bone) By number of origins Example: triceps (three heads) © 2018 Pearson Education, Inc. Naming Skeletal Muscles Muscles are named on the basis of several criteria (continued) By location of the muscle’s origin and insertion Example: sterno (on the sternum) By shape of the muscle Example: deltoid (triangular) By action of the muscle Example: flexor and extensor (flexes or extends a bone) © 2018 Pearson Education, Inc. Figure 6.15 Relationship of fascicle arrangement to muscle structure. (a) (b) (e) (c) (a) Circular (b) Convergent (e) Multipennate (orbicularis oris) (pectoralis major) (deltoid) (d) (f) (f) Bipennate (g) (rectus femoris) (c) Fusiform (d) Parallel (g) Unipennate (biceps brachii) (sartorius) (extensor digitorum longus) © 2018 Pearson Education, Inc. Table 6.3 Superficial Anterior Muscles of the Body (See Figure 6.22) (1 of 3) © 2018 Pearson Education, Inc. and neck. Cranial Frontalis aponeurosis Temporalis Orbicularis oculi Occipitalis Zygomaticus Buccinator Masseter Orbicularis oris Sternocleidomastoid Trapezius Platysma © 2018 Pearson Education, Inc. Table 6.3 Superficial Anterior Muscles of the Body (See Figure 6.22) (2 of 3) © 2018 Pearson Education, Inc.  Clavicle Figure 6.17a Muscles of the anterior trunk, shoulder, and arm. Deltoid Sternum Pectoralis major Biceps brachii Brachialis Brachio- radialis (a) © 2018 Pearson Education, Inc.  Pectoralis Figure 6.17b Muscles of the anterior trunk, major shoulder, and arm. Rectus abdominis Transversus abdominis Internal oblique External oblique Aponeurosis (b) © 2018 Pearson Education, Inc. Table 6.3 Superficial Anterior Muscles of the Body (See Figure 6.22) (3 of 3) © 2018 Pearson Education, Inc.  12th Figure 6.20c Pelvic, hip, and thigh muscles of 12th rib thoracic vertebra the right side of the body. Iliac crest Psoas major Iliopsoas Iliacus 5th lumbar vertebra Anterior superior iliac spine Sartorius Adductor group Quadriceps* Rectus femoris Vastus lateralis Vastus medialis Patella Patellar ligament (c) © 2018 Pearson Education, Inc. Figure 6.20d Pelvic, hip, and thigh muscles of the right side of the body. Inguinal ligament Adductor muscles Sartorius Vastus lateralis (d) © 2018 Pearson Education, Inc. Figure 6.21a Superficial muscles of the right leg. Fibularis longus Tibia Fibularis brevis Soleus Tibialis anterior Extensor digitorum longus Fibularis tertius (a) © 2018 Pearson Education, Inc. Table 6.4 Superficial Posterior Muscles of the Body (Some Forearm Muscles Also Shown) (See Figure 6.23) (1 of 3) © 2018 Pearson Education, Inc.  Occipital bone Figure 6.18a Muscles of the posterior neck, Sternocleidomastoid Spine of scapula trunk, and arm. Trapezius Deltoid (cut) Deltoid Triceps brachii Latissimus dorsi Humerus Olecranon process of (a) ulna (deep to tendon) © 2018 Pearson Education, Inc. Figure 6.18b Muscles of the posterior neck, C trunk, and arm. T 1 7 Erector spinae Iliocostalis Longissimus Spinalis Quadratus lumborum (b) © 2018 Pearson Education, Inc. Figure 6.19 The fleshy deltoid muscle is a favored site for administering intramuscular injections. Deltoid muscle Humerus © 2018 Pearson Education, Inc. Muscles of Trunk, Shoulder, Arm © 2018 Pearson Education, Inc. A&P Flix™: Muscles that act on the shoulder joint and humerus: An overview. © 2018 Pearson Education, Inc. A&P Flix™: Muscles of the pectoral girdle. © 2018 Pearson Education, Inc. A&P Flix™: Muscles of the pectoral girdle. © 2018 Pearson Education, Inc. A&P Flix™: Muscles of the pectoral girdle. © 2018 Pearson Education, Inc. A&P Flix™: Muscles that cross the glenohumeral joint. © 2018 Pearson Education, Inc. A&P Flix™: Movement at the glenohumeral joint: An overview. © 2018 Pearson Education, Inc. Table 6.4 Superficial Posterior Muscles of the Body (Some Forearm Muscles Also Shown) (See Figure 6.23) (2 of 3) © 2018 Pearson Education, Inc.  Occipital bone Figure 6.18a Muscles of the posterior neck, Sternocleidomastoid Spine of scapula trunk, and arm. Trapezius Deltoid (cut) Deltoid Triceps brachii Latissimus dorsi Humerus Olecranon process of (a) ulna (deep to tendon) © 2018 Pearson Education, Inc. Table 6.4 Superficial Posterior Muscles of the Body (Some Forearm Muscles Also Shown) (See Figure 6.23) (3 of 3) © 2018 Pearson Education, Inc.  Posterior superior Figure 6.20 Pelvic, hip, and thigh muscles of iliac spine Iliac crest Gluteus medius the right side of the body. Gluteus maximus Safe area in gluteus medius Gluteus maximus Adductor magnus Sciatic nerve Iliotibial tract (b) Biceps femoris Semitendinosus Hamstring group Semimembranosus Gastrocnemius (a) © 2018 Pearson Education, Inc. Figure 6.21b Superficial muscles of the right leg. Gastrocnemius Soleus Calcaneal (Achilles) tendon Medial malleolus Lateral malleolus (b) © 2018 Pearson Education, Inc. muscles of the anterior surface Facial Frontalis of the body. Facial Temporalis Masseter Orbicularis oculi Zygomaticus Orbicularis oris Neck Shoulder Platysma Trapezius Sternocleidomastoid Thorax Deltoid Pectoralis minor Pectoralis major Arm Serratus anterior Triceps brachii Biceps brachii Intercostals Brachialis Abdomen Rectus abdominis Forearm External oblique Brachioradialis Internal oblique Flexor carpi radialis Transversus abdominis Pelvis/thigh Iliopsoas Thigh Sartorius Adductor muscles Thigh (Quadriceps) Rectus femoris Vastus lateralis Vastus medialis Vastus intermedius (not shown, deep to rectus femoris) Leg Fibularis longus Extensor digitorum longus Leg Gastrocnemius Tibialis anterior Soleus © 2018 Pearson Education, Inc. Figure 6.23 Major superficial muscles of the Neck Occipitalis Sternocleidomastoid Trapezius posterior surface of the body. Arm Shoulder/Back Deltoid Triceps brachii Brachialis Forearm Latissimus dorsi Brachioradialis Extensor carpi radialis longus Flexor carpi ulnaris Hip Extensor carpi ulnaris Gluteus medius Extensor digitorum Gluteus maximus Thigh Iliotibial tract Adductor muscle Hamstrings: Biceps femoris Semitendinosus Semimembranosus Leg Gastrocnemius Soleus Fibularis longus Calcaneal (Achilles) tendon © 2018 Pearson Education, Inc. Developmental Aspects of the Muscular System Increasing muscular control reflects the maturation of the nervous system Muscle control is achieved in a superior/inferior and proximal/distal direction © 2018 Pearson Education, Inc. Developmental Aspects of the Muscular System To remain healthy, muscles must be exercised regularly Without exercise, muscles atrophy With extremely vigorous exercise, muscles hypertrophy © 2018 Pearson Education, Inc. Developmental Aspects of the Muscular System As we age, muscle mass decreases, and muscles become more sinewy Exercise helps retain muscle mass and strength © 2018 Pearson Education, Inc.