The Muscular System. PowerPoint Lecture Slides C H A P T E R 6. Prepared by Patty Bostwick-Taylor, Florence-Darlington Technical College

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1 PowerPoint Lecture Slides Prepared by Patty Bostwick-Taylor, Florence-Darlington Technical College C H A P T E R 6 The Muscular System 2012 Pearson Education, Inc.

2 The Muscular System Muscles are responsible for all types of body movement Three basic muscle types are found in the body Skeletal muscle Cardiac muscle Smooth muscle 2012 Pearson Education, Inc.

3 Characteristics of Muscles Skeletal and smooth muscle cells are elongated (muscle cell = muscle fiber) Contraction and shortening of muscles is due to the movement of microfilaments All muscles share some terminology Prefixes myo and mys refer to muscle Prefix sarco refers to flesh 2012 Pearson Education, Inc.

4 2012 Pearson Education, Inc. Table 6.1

5 Comparison of Skeletal, Cardiac, and Smooth Muscles Characteristic Skeletal Cardiac Smooth Body location Attached to bone or skin (for some facial muscles) Walls of the heart Mostly in walls of visceral organs (other than the heart) Cell shape and appearance Single, very long, cylindrical, multinucleate cells with very obvious striations Branching chains of cells, uninucleate, striations, intercalated discs Single, fusiform, uninucleate, no striations Connective tissue components Endomysium, perimysium, and epimysium Endomysium Endomysium 2012 Pearson Education, Inc.

6 Comparison of Skeletal, Cardiac, and Smooth Muscles Characteristic Skeletal Cardiac Smooth Regulation of contraction Voluntary Involuntary Involuntary Speed of contraction Slow to fast Slow Very slow Rhythmic contractions No Yes Yes, in some 2012 Pearson Education, Inc.

7 Skeletal Muscle Characteristics Most are attached by tendons to bones Cells are multinucleate Striated have visible banding Voluntary subject to conscious control 2012 Pearson Education, Inc.

8 Connective Tissue Wrappings of 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 2012 Pearson Education, Inc.

9 Blood vessel Muscle fiber (cell) Perimysium Epimysium (wraps entire muscle) Fascicle (wrapped by perimysium) Tendon Endomysium (between fibers) Bone 2012 Pearson Education, Inc. Figure 6.1

10 Skeletal Muscle Attachments Epimysium blends into a connective tissue attachment Tendons cord-like structures Mostly collagen fibers Often cross a joint due to toughness and small size Aponeuroses sheet-like structures Attach muscles indirectly to bones, cartilages, or connective tissue coverings 2012 Pearson Education, Inc.

11 Skeletal Muscle Attachments Sites of muscle attachment Bones Cartilages Connective tissue coverings 2012 Pearson Education, Inc.

12 Smooth Muscle Characteristics Lacks striations Spindle-shaped cells Single nucleus Involuntary no conscious control Found mainly in the walls of hollow organs 2012 Pearson Education, Inc.

13 Mucosa Circular layer of smooth muscle (longitudinal view of cells) Submucosa (a) Longitudinal layer of smooth muscle (cross-sectional view of cells) 2012 Pearson Education, Inc. Figure 6.2a

14 Cardiac Muscle Characteristics Striations Usually has a single nucleus Branching cells Joined to another muscle cell at an intercalated disc Involuntary Found only in the walls of the heart 2012 Pearson Education, Inc.

15 Cardiac muscle bundles (b) 2012 Pearson Education, Inc. Figure 6.2b

16 Skeletal Muscle Functions Produce movement Maintain posture Stabilize joints Generate heat 2012 Pearson Education, Inc.

17 Microscopic Anatomy of Skeletal Muscle Sarcolemma specialized plasma membrane Myofibrils long organelles inside muscle cell Sarcoplasmic reticulum specialized smooth endoplasmic reticulum 2012 Pearson Education, Inc.

18 Sarcolemma Myofibril Dark (A) band Light (I) band Nucleus (a) Segment of a muscle fiber (cell) 2012 Pearson Education, Inc. Figure 6.3a

19 Microscopic Anatomy of Skeletal Muscle Myofibrils are aligned to give distinct bands I band = light band Contains only thin filaments A band = dark band Contains the entire length of the thick filaments 2012 Pearson Education, Inc.

20 Z disc H zone Z disc Thin (actin) filament Thick (myosin) filament (b) Myofibril or fibril (complex organelle composed of bundles of myofilaments) I band A band I band M line 2012 Pearson Education, Inc. Figure 6.3b

21 Microscopic Anatomy of Skeletal Muscle Sarcomere contractile unit of a muscle fiber Organization of the sarcomere Myofilaments Thick filaments = myosin filaments Thin filaments = actin filaments 2012 Pearson Education, Inc.

22 Microscopic Anatomy of Skeletal Muscle Thick filaments = myosin filaments Composed of the protein myosin Has ATPase enzymes Myosin filaments have heads (extensions, or cross bridges) Myosin and actin overlap somewhat Thin filaments = actin filaments Composed of the protein actin Anchored to the Z disc 2012 Pearson Education, Inc.

23 Sarcomere Thin (actin) filament Z disc M line Z disc Thick (myosin) filament (c) Sarcomere (segment of a myofibril) 2012 Pearson Education, Inc. Figure 6.3c

24 Microscopic Anatomy of Skeletal Muscle At rest, within the A band there is a zone that lacks actin filaments Called either the H zone or bare zone Sarcoplasmic reticulum (SR) Stores and releases calcium Surrounds the myofibril 2012 Pearson Education, Inc.

25 Thick filament Bare zone Thin filament (d) Myofilament structure (within one sarcomere) 2012 Pearson Education, Inc. Figure 6.3d

26 2012 Pearson Education, Inc.

27 Stimulation and Contraction of Single Skeletal Muscle Cells Excitability (also called responsiveness or irritability) ability to receive and respond to a stimulus Contractility ability to 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 2012 Pearson Education, Inc.

28 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 2012 Pearson Education, Inc.

29 Spinal cord Axon terminals at neuromuscular junctions Motor unit 1 Motor unit 2 Nerve Motor neuron cell bodies Axon of motor neuron Muscle Muscle fibers (a) 2012 Pearson Education, Inc. Figure 6.4a

30 Axon terminals at neuromuscular junctions Muscle fibers Branching axon to motor unit 2012 Pearson Education, Inc. Figure 6.4b (b)

31 The Nerve Stimulus and Action Potential Neuromuscular junction Association site of axon terminal of the motor neuron and muscle PLAY A&P Flix : Events at the Neuromuscular Junction 2012 Pearson Education, Inc.

32 2012 Pearson Education, Inc. Figure 6.5

33 The Nerve Stimulus and Action Potential Synaptic cleft Gap between nerve and muscle Nerve and muscle do not make contact Action potential (nerve impulse) reaches the axon terminal of the motor neuron Calcium channels open and calcium ions enter the axon terminal 2012 Pearson Education, Inc.

34 Transmission of Nerve Impulse to Muscle Calcium ion entry causes some synaptic vesicles to release their contents (acetylcholine, a neurotransmitter) by exocytosis Neurotransmitter chemical released by nerve upon arrival of nerve impulse in the axon terminal The neurotransmitter for skeletal muscle is acetylcholine (ACh) 2012 Pearson Education, Inc.

35 Transmission of Nerve Impulse to Muscle Acetylcholine attaches to receptors on the sarcolemma of the muscle cell In response to the binding of ACh to a receptor, the sarcolemma becomes permeable to sodium (Na + ) Sodium rushes into the cell generating an action potential and potassium leaves the cell Once started, muscle contraction cannot be stopped 2012 Pearson Education, Inc.

36 1 Action potential reaches axon terminal of motor neuron. Synaptic vesicle containing ACh Axon terminal of motor neuron Mitochondrion Ca 2+ Ca 2+ Synaptic cleft Sarcolemma ACh receptor ACh Fusing synaptic vesicle Sarcoplasm of muscle fiber Folds of sarcolemma 2012 Pearson Education, Inc. Figure 6.5, step 1

37 1 Action potential reaches axon terminal of motor neuron. Synaptic vesicle containing ACh Axon terminal of motor neuron Mitochondrion 2 Calcium (Ca 2+ ) channels open and Ca 2+ enters the axon terminal. Ca 2+ Ca 2+ Synaptic cleft Sarcolemma ACh receptor ACh Fusing synaptic vesicle Sarcoplasm of muscle fiber Folds of sarcolemma 2012 Pearson Education, Inc. Figure 6.5, step 2

38 1 Action potential reaches axon terminal of motor neuron. Synaptic vesicle containing ACh Axon terminal of motor neuron Mitochondrion 2 Calcium (Ca 2+ ) channels open and Ca 2+ enters the axon terminal. Ca 2+ Ca 2+ Synaptic cleft Sarcolemma 3 Ca 2+ entry causes some synaptic vesicles to release their contents (acetylcholine, a neurotransmitter) by exocytosis. ACh receptor ACh Fusing synaptic vesicle Sarcoplasm of muscle fiber Folds of sarcolemma 2012 Pearson Education, Inc. Figure 6.5, step 3

39 1 Action potential reaches axon terminal of motor neuron. Synaptic vesicle containing ACh Axon terminal of motor neuron Mitochondrion 2 Calcium (Ca 2+ ) channels open and Ca 2+ enters the axon terminal. Ca 2+ Ca 2+ Synaptic cleft Sarcolemma 3 Ca 2+ entry causes some synaptic vesicles to release their contents (acetylcholine, a neurotransmitter) by exocytosis. ACh receptor ACh Fusing synaptic vesicle Sarcoplasm of muscle fiber Folds of sarcolemma 4 Acetylcholine diffuses across the synaptic cleft and binds to receptors in the sarcolemma Pearson Education, Inc. Figure 6.5, step 4

40 5 ACh binds and channels open that allow simultaneous passage of Na + into the muscle fiber and K + out of the muscle fiber. More Na + ions enter than K + ions leave and this produces a local change in the electrical conditions of the membrane (depolarization), which eventually leads to an action potential. Na + K + Ion channel in sarcolemma opens; ions pass Pearson Education, Inc. Figure 6.5, step 5

41 ACh Degraded ACh Na + Ion channel closed; ions cannot pass. 6 ACh effects are ended by its breakdown in the synaptic cleft by the enzyme acetylcholinesterase. Acetylcholinesterase K Pearson Education, Inc. Figure 6.5, step 6

42 Small twig Neuromuscular junction Nerve fiber Striations Muscle cell or fiber Match flame (a) 1 Flame ignites 2 Flame spreads the twig. rapidly along the twig. 1 Na + diffuses into the cell. 2 Action potential spreads rapidly along the sarcolemma. (b) 2012 Pearson Education, Inc. Figure 6.6a-b

43 The Sliding Filament Theory of Muscle Contraction Activation by nerve causes myosin heads (cross bridges) to attach to binding sites on the thin filament Myosin heads then bind to the next site of the thin filament and pull them toward the center of the sarcomere This continued action causes a sliding of the myosin along the actin The result is that the muscle is shortened (contracted) 2012 Pearson Education, Inc.

44 Myosin Actin Z I H A Z I (a) Z Z I A I (b) 2012 Pearson Education, Inc. Figure 6.7a b

45 Protein complex In a relaxed muscle cell, 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 cell is excited, calcium ions (Ca 2+ ) are released from intracellular storage areas (the sacs of the sarcoplasmic reticulum). (a) Myosin myofilament Actin myofilament 2012 Pearson Education, Inc. Figure 6.8a

46 (b) Myosin-binding site Ca 2+ Upper part of thick filament only The flood of calcium acts as the final trigger for 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 Pearson Education, Inc. Figure 6.8b

47 PLAY A&P Flix : The Cross Bridge Cycle 2012 Pearson Education, Inc. Figure 6.8c

48 Contraction of Skeletal Muscle Muscle fiber contraction is all or none Within a 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 2012 Pearson Education, Inc.

49 Contraction of Skeletal Muscle Graded responses can be produced by changing: The frequency of muscle stimulation The number of muscle cells being stimulated at one time 2012 Pearson Education, Inc.

50 Types of Graded Responses Twitch Single, brief contraction Not a normal muscle function 2012 Pearson Education, Inc.

51 2012 Pearson Education, Inc. Figure 6.9a

52 Types of Graded Responses Summing of contractions One contraction is immediately followed by another The muscle does not completely return to a resting state due to more frequent stimulations The effects are added 2012 Pearson Education, Inc.

53 2012 Pearson Education, Inc. Figure 6.9b

54 Types of Graded Responses Unfused (incomplete) tetanus Some relaxation occurs between contractions but nerve stimuli arrive at an even faster rate than during summing of contractions Unless the muscle contraction is smooth and sustained, it is said to be in unfused tetanus 2012 Pearson Education, Inc.

55 2012 Pearson Education, Inc. Figure 6.9c

56 Types of Graded Responses Fused (complete) tetanus No evidence of relaxation before the following contractions Frequency of stimulations does not allow for relaxation between contractions The result is a smooth and sustained muscle contraction 2012 Pearson Education, Inc.

57 2012 Pearson Education, Inc. Figure 6.9d

58 Muscle Response to Strong Stimuli Muscle force depends upon the number of fibers stimulated More fibers contracting results in greater muscle tension Muscles can continue to contract unless they run out of energy 2012 Pearson Education, Inc.

59 Energy for Muscle Contraction Muscles use stored ATP for energy ATP bonds are broken to release energy Only 4 6 seconds worth of ATP is stored by muscles After this initial time, other pathways must be utilized to produce ATP 2012 Pearson Education, Inc.

60 Energy for Muscle Contraction Direct phosphorylation of ADP by creatine phosphate (CP) Muscle cells store CP 2012 Pearson Education, Inc. CP is a high-energy molecule After ATP is depleted, ADP is left CP transfers a phosphate group to ADP, to regenerate ATP CP supplies are exhausted in less than 15 seconds About 1 ATP is created per CP molecule

61 2012 Pearson Education, Inc. Figure 6.10a

62 Energy for Muscle Contraction Aerobic respiration Glucose is broken down to carbon dioxide and water, releasing energy (about 32 ATP) A series of metabolic pathways occur in the mitochondria This is a slower reaction that requires continuous oxygen Carbon dioxide and water are produced 2012 Pearson Education, Inc.

63 2012 Pearson Education, Inc. Figure 6.10c

64 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 This reaction is not as efficient, but is fast Huge amounts of glucose are needed Lactic acid produces muscle fatigue 2012 Pearson Education, Inc.

65 2012 Pearson Education, Inc. Figure 6.10b

66 Muscle Fatigue and Oxygen Deficit When a muscle is fatigued, it is unable to contract even with a stimulus Common cause for muscle fatigue is oxygen debt Oxygen must be repaid to tissue to remove oxygen deficit Oxygen is required to get rid of accumulated lactic acid Increasing acidity (from lactic acid) and lack of ATP causes the muscle to contract less 2012 Pearson Education, Inc.

67 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; rotating the arm Isometric contractions Tension in the muscles increases The muscle is unable to shorten or produce movement Example: push against a wall with bent elbows 2012 Pearson Education, Inc.

68 Muscle Tone Some fibers are contracted even in a relaxed muscle Different fibers contract at different times to provide muscle tone and to be constantly ready 2012 Pearson Education, Inc.

69 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 2012 Pearson Education, Inc.

70 2012 Pearson Education, Inc. Figure 6.11a-b

71 Five Golden Rules of Skeletal Muscle Activity 1. With a few exceptions, all skeletal muscles cross at least one joint. 2. Typically, the bulk of a skeletal muscle lies proximal to the joint crossed. 3. All skeletal muscles have at least two attachments: the origin and the insertion. 4. Skeletal muscles can only pull; they never push. 5. During contraction, a skeletal muscle insertion moves toward the origin Pearson Education, Inc.

72 Muscles and Body Movements Movement is attained due to a muscle moving an attached bone Muscles are attached to at least two points Origin Attachment to a moveable bone Insertion Attachment to an immovable bone 2012 Pearson Education, Inc.

73 Muscle contracting Origin Brachialis Tendon Insertion 2012 Pearson Education, Inc. Figure 6.12

74 Types of Body Movements Flexion Decreases the angle of the joint Brings two bones closer together Typical of bending hinge joints like knee and elbow or ball-and-socket joints like the hip Extension Opposite of flexion Increases angle between two bones Typical of straightening the elbow or knee Extension beyond 180 is hypertension 2012 Pearson Education, Inc.

75 2012 Pearson Education, Inc. Figure 6.13a

76 2012 Pearson Education, Inc. Figure 6.13b

77 Types of Body Movements Rotation Movement of a bone around its longitudinal axis Common in ball-and-socket joints Example is when you move atlas around the dens of axis (shake your head no ) 2012 Pearson Education, Inc.

78 2012 Pearson Education, Inc. Figure 6.13c

79 Types of Body Movements Abduction Movement of a limb away from the midline Adduction Opposite of abduction Movement of a limb toward the midline 2012 Pearson Education, Inc.

80 2012 Pearson Education, Inc. Figure 6.13d

81 Types of Body Movements Circumduction Combination of flexion, extension, abduction, and adduction Common in ball-and-socket joints 2012 Pearson Education, Inc.

82 2012 Pearson Education, Inc. Figure 6.13d

83 Special Movements Dorsiflexion Lifting the foot so that the superior surface approaches the shin (toward the dorsum) Plantar flexion Depressing the foot (pointing the toes) Planting the foot toward the sole 2012 Pearson Education, Inc.

84 2012 Pearson Education, Inc. Figure 6.13e

85 Special Movements Inversion Turn sole of foot medially Eversion Turn sole of foot laterally 2012 Pearson Education, Inc.

86 2012 Pearson Education, Inc. Figure 6.13f

87 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 2012 Pearson Education, Inc.

88 2012 Pearson Education, Inc. Figure 6.13g

89 Special Movements Opposition Move thumb to touch the tips of other fingers on the same hand 2012 Pearson Education, Inc.

90 2012 Pearson Education, Inc. Figure 6.13h

91 Types of Muscles 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 and helps prevent rotation Fixator stabilizes the origin of a prime mover 2012 Pearson Education, Inc.

92 (a) A muscle that crosses on the anterior side of a joint produces flexion* Example: Pectoralis major (anterior view) 2012 Pearson Education, Inc. Figure 6.14a

93 (b) A muscle that crosses on the posterior side of a joint produces extension* Example: Latissimus dorsi (posterior view) 2012 Pearson Education, Inc. Figure 6.14b

94 (c) A muscle that crosses on the lateral side of a joint produces abduction Example: Medial deltoid (anterolateral view) 2012 Pearson Education, Inc. Figure 6.14c

95 (d) A muscle that crosses on the medial side of a joint produces adduction Example: Teres major (posterolateral view) 2012 Pearson Education, Inc. Figure 6.14d

96 Naming Skeletal Muscles By direction of muscle fibers Example: Rectus (straight) By relative size of the muscle Example: Maximus (largest) 2012 Pearson Education, Inc.

97 Naming Skeletal Muscles By location of the muscle Example: Temporalis (temporal bone) By number of origins Example: Triceps (three heads) 2012 Pearson Education, Inc.

98 Naming Skeletal Muscles 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) 2012 Pearson Education, Inc.

99 Pectoralis major Orbicularis oris Deltoid (d) Circular (a) Convergent Biceps brachii (a) (d) (e) (b) (e) Multipennate Rectus femoris (b) Fusiform Sartorius (c) (f) Bipennate (f) Extensor digitorum longus (g) (c) Parallel (g) Unipennate 2012 Pearson Education, Inc. Figure 6.15

100 Head and Neck Muscles Facial muscles Frontalis raises eyebrows Orbicularis oculi closes eyes, squints, blinks, winks Orbicularis oris closes mouth and protrudes the lips Buccinator flattens the cheek, chews Zygomaticus raises corners of the mouth Chewing muscles Masseter closes the jaw and elevates mandible Temporalis synergist of the masseter, closes jaw 2012 Pearson Education, Inc.

101 Head and Neck Muscles Neck muscles Platysma pulls the corners of the mouth inferiorly Sternocleidomastoid flexes the neck, rotates the head 2012 Pearson Education, Inc.

102 Frontalis Cranial aponeurosis Temporalis Orbicularis oculi Occipitalis Zygomaticus Buccinator Orbicularis oris Masseter Sternocleidomastoid Platysma Trapezius 2012 Pearson Education, Inc. Figure 6.16

103 Muscles of Trunk, Shoulder, Arm Anterior muscles Pectoralis major adducts and flexes the humerus Intercostal muscles External intercostals raise rib cage during inhalation Internal intercostals depress the rib cage to move air out of the lungs when you exhale forcibly 2012 Pearson Education, Inc.

104 Clavicle Deltoid Sternum Pectoralis major Biceps brachii Brachialis Brachioradialis (a) 2012 Pearson Education, Inc. Figure 6.17a

105 Muscles of Trunk, Shoulder, Arm Muscles of the abdominal girdle Rectus abdominis flexes vertebral column and compresses abdominal contents (defecation, childbirth, forced breathing) External oblique flex vertebral column; rotate trunk and bend it laterally Internal oblique flex vertebral column; rotate trunk and bend it laterally Transversus abdominis compresses abdominal contents 2012 Pearson Education, Inc.

106 Pectoralis major Rectus abdominis Transversus abdominis Internal oblique External oblique Aponeurosis (b) 2012 Pearson Education, Inc. Figure 6.17b

107 Muscles of Trunk, Shoulder, Arm Posterior muscles Trapezius elevates, depresses, adducts, and stabilizes the scapula Latissimus dorsi extends and adducts the humerus Erector spinae back extension Quadratus lumborum flexes the spine laterally Deltoid arm abduction 2012 Pearson Education, Inc.

108 Muscles of Trunk, Shoulder, Arm Muscles that arise from the shoulder girdle and cross the shoulder joint to insert into the humerus include: Pectoralis major Latissimus dorsi Deltoid PLAY PLAY A&P Flix : Muscles that act on the shoulder joint and humerus: An overview. A&P Flix : Muscles of the pectoral girdle. PLAY PLAY A&P Flix : Muscles that cross the glenohumeral joint. A&P Flix : Movement at the glenohumeral joint: An overview Pearson Education, Inc.

109 Occipital bone Sternocleidomastoid Trapezius Deltoid Spine of scapula Deltoid (cut) Triceps brachii Latissimus dorsi (a) Humerus Olecranon process of ulna (deep to tendon) 2012 Pearson Education, Inc. Figure 6.18a

110 C 7 T 1 Erector spinae Iliocostalis Longissimus Spinalis Quadratus Iumborum (b) 2012 Pearson Education, Inc. Figure 6.18b

111 Muscles of the Upper Limb Biceps brachii supinates forearm, flexes elbow Brachialis elbow flexion Brachioradialis weak muscle; elbow flexion Triceps brachii elbow extension (antagonist to biceps brachii) PLAY PLAY PLAY A&P Flix : The elbow joint and forearm: An overview. A&P Flix : Muscles of the elbow joint. A&P Flix : Movement at the elbow joint Pearson Education, Inc.

112 Clavicle Deltoid Sternum Pectoralis major Biceps brachii Brachialis Brachioradialis (a) 2012 Pearson Education, Inc. Figure 6.17a

113 Occipital bone Sternocleidomastoid Trapezius Deltoid Spine of scapula Deltoid (cut) Triceps brachii Latissimus dorsi (a) Humerus Olecranon process of ulna (deep to tendon) 2012 Pearson Education, Inc. Figure 6.18a

114 Muscles of the Upper Limb Muscles of the forearm, which insert on the hand bones and cause their movement include: Flexor carpi wrist flexion Flexor digitorum finger flexion Extensor carpi wrist extension Extensor digitorum finger extension PLAY PLAY A&P Flix : Muscles that act on the wrist and fingers: An overview. A&P Flix : Movements of the wrist and fingers (a). PLAY A&P Flix : Movements of the wrist and fingers (b) Pearson Education, Inc.

115 Muscles of the Lower Limb Muscles causing movement at the hip joint include: Gluteus maximus hip extension Gluteus medius hip abduction, steadies pelvis when walking Iliopsoas hip flexion, keeps the upper body from falling backward when standing erect Adductor muscles adduct the thighs PLAY PLAY A&P Flix : Muscles that act on the hip joint and femur: An overview. A&P Flix : Movement at the hip joint: An overview Pearson Education, Inc.

116 Gluteus medius Gluteus maximus Adductor magnus Iliotibial tract Biceps femoris Semitendinosus Semimembranosus Hamstring group Gastrocnemius (a) 2012 Pearson Education, Inc. Figure 6.20a

117 Posterior superior iliac spine IIiac crest Safe area in gluteus medius Gluteus maximus Sciatic nerve (b) 2012 Pearson Education, Inc. Figure 6.20b

118 12th rib 12th thoracic vertebra lliopsoas Iliac crest Psoas major lliacus Anterior superior iliac spine 5th lumbar vertebra Quadriceps Sartorius Rectus femoris Vastus lateralis Vastus medialis Adductor group Patella Patellar ligament (c) 2012 Pearson Education, Inc. Figure 6.20c

119 Muscles of the Lower Limb Muscles causing movement at the knee joint Hamstring group thigh extension and knee flexion Biceps femoris Semimembranosus Semitendinosus 2012 Pearson Education, Inc.

120 Gluteus medius Gluteus maximus Adductor magnus Iliotibial tract Biceps femoris Semitendinosus Semimembranosus Hamstring group Gastrocnemius (a) 2012 Pearson Education, Inc. Figure 6.20a

121 Muscles of the Lower Limb Muscles causing movement at the knee joint Sartorius flexes the thigh Quadriceps group extends the knee Rectus femoris Vastus muscles (three) PLAY A&P Flix : Muscles that cross the knee joint: An overview Pearson Education, Inc.

122 12th rib 12th thoracic vertebra lliopsoas Iliac crest Psoas major lliacus Anterior superior iliac spine 5th lumbar vertebra Quadriceps Sartorius Rectus femoris Vastus lateralis Vastus medialis Adductor group Patella Patellar ligament (c) 2012 Pearson Education, Inc. Figure 6.20c

123 Inguinal ligament Adductor muscles Sartorius Vastus lateralis (d) 2012 Pearson Education, Inc. Figure 6.20d

124 Muscles of the Lower Limb Muscles causing movement at ankle and foot Tibialis anterior dorsiflexion, foot inversion Extensor digitorum longus toe extension and dorsiflexion of the foot Fibularis muscles plantar flexion, foot eversion Soleus plantar flexion PLAY PLAY A&P Flix : Muscles that act on the ankle and foot: An overview. A&P Flix : Posterior muscles that act on the ankle and foot. PLAY A&P Flix : Movements of the ankle and foot Pearson Education, Inc.

125 Fibularis longus Fibularis brevis Tibialis anterior Extensor digitorum longus Tibia Soleus Fibularis tertius (a) 2012 Pearson Education, Inc. Figure 6.21a

126 Gastrocnemius Soleus Calcaneal (Achilles) tendon Medial malleolus Lateral malleolus (b) 2012 Pearson Education, Inc. Figure 6.21b

127 Shoulder Trapezius Deltoid Arm Triceps brachii Biceps brachii Brachialis Forearm Brachioradialis Flexor carpi radialis Facial Temporalis Masseter Facial Frontalis Orbicularis oculi Zygomaticus Orbicularis oris Neck Platysma Sternocleidomastoid Thorax Pectoralis minor Pectoralis major Serratus anterior Intercostals Abdomen Rectus abdominis External oblique Internal oblique Transversus abdominis Pelvis/thigh lliopsoas Thigh (Quadriceps) Rectus femoris Vastus lateralis Vastus medialis Thigh Sartorius Adductor muscle Gracilis Leg Fibularis longus Extensor digitorum longus Tibialis anterior Leg Gastrocnemius Soleus 2012 Pearson Education, Inc. Figure 6.22

128 Neck Occipitalis Sternocleidomastoid Trapezius Arm Triceps brachii Brachialis Forearm Brachioradialis Extensor carpi radialis longus Flexor carpi ulnaris Extensor carpi ulnaris Extensor digitorum Shoulder/Back Deltoid Latissimus dorsi Hip Gluteus medius Gluteus maximus lliotibial tract Thigh Adductor muscle Hamstrings: Biceps femoris Semitendinosus Semimembranosus Leg Gastrocnemius Soleus Fibularis longus Calcaneal (Achilles) tendon 2012 Pearson Education, Inc. Figure 6.23

129 Deltoid muscle Humerus 2012 Pearson Education, Inc. Figure 6.19

130 Posterior superior iliac spine IIiac crest Safe area in gluteus medius Gluteus maximus Sciatic nerve (b) 2012 Pearson Education, Inc. Figure 6.20b

131 Inguinal ligament Adductor muscles Sartorius Vastus lateralis (d) 2012 Pearson Education, Inc. Figure 6.20d