Power Point Lecture Slides Prepared by Patty BostwickTaylor

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.

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.

© 2012 Pearson Education, Inc. Table 6. 1

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 © 2012 Pearson Education, Inc.

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

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.

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.

Muscle fiber (cell) Blood vessel Perimysium Epimysium (wraps entire muscle) Fascicle (wrapped by perimysium)

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.

Skeletal Muscle Attachments • Sites of muscle attachment • Bones • Cartilages • Connective

Smooth Muscle Characteristics • Lacks striations • Spindle-shaped cells • Single nucleus • Involuntary—no

Mucosa Submucosa (a) © 2012 Pearson Education, Inc. Circular layer of smooth muscle (longitudinal

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.

Cardiac muscle bundles (b) © 2012 Pearson Education, Inc. Figure 6. 2 b

Skeletal Muscle Functions • Produce movement • Maintain posture • Stabilize joints • Generate

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.

Sarcolemma Myofibril Light Dark (A) band (I) band Nucleus (a) Segment of a muscle

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.

Z disc H zone Z disc Thin (actin) filament Thick (myosin) filament (b) Myofibril or fibril (complex organelle composed of bundles of myofilaments) © 2012 Pearson Education, Inc. I band A band I band M line Figure 6. 3 b

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.

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.

Sarcomere Thin (actin) filament Z disc M line Z disc Thick (myosin) filament (c)

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.

Thick filament Bare zone Thin filament (d) Myofilament structure (within one sarcomere) © 2012

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.

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.

Axon terminals at neuromuscular junctions Spinal cord Motor unit 1 unit 2 Nerve Motor

Axon terminals at neuromuscular junctions Muscle fibers Branching axon to motor unit (b) ©

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

© 2012 Pearson Education, Inc. Figure 6. 5

The Nerve Stimulus and Action Potential • Synaptic cleft • Gap between nerve and muscle • Nerve and muscle do not make contact • Area between nerve and muscle is filled with interstitial fluid • Action potential reaches the axon terminal of the motor neuron • Calcium channels open and calcium ions enter the axon terminal © 2012 Pearson Education, Inc.

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.

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.

Synaptic vesicle containing ACh 1 Action potential reaches axon terminal of motor neuron. Axon terminal of motor neuron Mitochondrion Ca 2+ Synaptic cleft Ca 2+ ACh receptor © 2012 Pearson Education, Inc. Sarcolemma Fusing synaptic vesicle Sarcoplasm of muscle fiber Folds of sarcolemma Figure 6. 5, step 1

Synaptic vesicle containing ACh 1 Action potential reaches axon terminal of motor neuron. Axon terminal of motor neuron Mitochondrion 2 Calcium (Ca 2+) channels open and Ca 2+ enters the axon terminal. Ca 2+ Synaptic cleft Ca 2+ ACh receptor © 2012 Pearson Education, Inc. Sarcolemma Fusing synaptic vesicle Sarcoplasm of muscle fiber Folds of sarcolemma Figure 6. 5, step 2

Synaptic vesicle containing ACh 1 Action potential reaches axon terminal of motor neuron. Axon terminal of motor neuron Mitochondrion 2 Calcium (Ca 2+) channels open and Ca 2+ enters the axon terminal. 3 Ca 2+ entry causes some synaptic vesicles to release their contents (acetylcholine, a neurotransmitter) by exocytosis. © 2012 Pearson Education, Inc. Ca 2+ Synaptic cleft Ca 2+ ACh receptor Sarcolemma Fusing synaptic vesicle Sarcoplasm of muscle fiber Folds of sarcolemma Figure 6. 5, step 3

Synaptic vesicle containing ACh 1 Action potential reaches axon terminal of motor neuron. Axon terminal of motor neuron Mitochondrion 2 Calcium (Ca 2+) channels open and Ca 2+ enters the axon terminal. 3 Ca 2+ entry causes some synaptic vesicles to release their contents (acetylcholine, a neurotransmitter) by exocytosis. Ca 2+ Synaptic cleft Ca 2+ ACh receptor Sarcolemma Fusing synaptic vesicle Sarcoplasm of muscle fiber Folds of sarcolemma 4 Acetylcholine diffuses across the synaptic cleft and binds to receptors in the sarcolemma. © 2012 Pearson Education, Inc. Figure 6. 5, step 4

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. © 2012 Pearson Education, Inc. Na+ K+ Ion channel in sarcolemma opens; ions pass. Figure 6. 5, step 5

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+ © 2012 Pearson Education, Inc. Figure 6. 5, step 6

Neuromuscular junction Nerve fiber Small twig Match flame 1 Flame ignites the twig. (a) © 2012 Pearson Education, Inc. Striations Muscle cell or fiber 1 Na+ diffuses into the cell. 2 Action potential spreads rapidly along the sarcolemma. 2 Flame spreads rapidly along the twig. (b) Figure 6. 6 a-b

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.

Actin Myosin Z H Z I A I (a) Z I © 2012 Pearson

Protein complex (a) Myosin myofilament © 2012 Pearson Education, Inc. 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). Actin myofilament Figure 6. 8 a

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. (b) © 2012 Pearson Education, Inc. Figure 6. 8 b

PLAY © 2012 Pearson Education, Inc. A&P Flix™: The Cross Bridge Cycle Figure 6.

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.

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.

Types of Graded Responses • Twitch • Single, brief contraction • Not a normal

© 2012 Pearson Education, Inc. Figure 6. 9 a

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.

© 2012 Pearson Education, Inc. Figure 6. 9 b

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.

© 2012 Pearson Education, Inc. Figure 6. 9 c

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.

© 2012 Pearson Education, Inc. Figure 6. 9 d

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.

Energy for Muscle Contraction • Initially, 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.

Energy for Muscle Contraction • Direct phosphorylation of ADP by creatine phosphate (CP) • Muscle cells store CP • 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 © 2012 Pearson Education, Inc.

© 2012 Pearson Education, Inc. Figure 6. 10 a

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.

© 2012 Pearson Education, Inc. Figure 6. 10 c

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.

© 2012 Pearson Education, Inc. Figure 6. 10 b

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.

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.

Muscle Tone • Some fibers are contracted even in a relaxed muscle • Different

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.

© 2012 Pearson Education, Inc. Figure 6. 11 a-b

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. © 2012 Pearson Education, Inc.

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.

Muscle contracting Origin Brachialis Tendon Insertion © 2012 Pearson Education, Inc. Figure 6. 12

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.

© 2012 Pearson Education, Inc. Figure 6. 13 a

© 2012 Pearson Education, Inc. Figure 6. 13 b

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.

© 2012 Pearson Education, Inc. Figure 6. 13 c

Types of Body Movements • Abduction • Movement of a limb away from the

© 2012 Pearson Education, Inc. Figure 6. 13 d

Types of Body Movements • Circumduction • Combination of flexion, extension, abduction, and adduction

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.

© 2012 Pearson Education, Inc. Figure 6. 13 e

Special Movements • Inversion • Turn sole of foot medially • Eversion • Turn

© 2012 Pearson Education, Inc. Figure 6. 13 f

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.

© 2012 Pearson Education, Inc. Figure 6. 13 g

Special Movements • Opposition • Move thumb to touch the tips of other fingers

© 2012 Pearson Education, Inc. Figure 6. 13 h

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.

(a) A muscle that crosses on the anterior side of a joint produces flexion*

(b) A muscle that crosses on the posterior side of a joint produces extension*

(c) A muscle that crosses on the lateral side of a joint produces abduction

(d) A muscle that crosses on the medial side of a joint produces adduction

Naming Skeletal Muscles • By direction of muscle fibers • Example: Rectus (straight) •

Naming Skeletal Muscles • By location of the muscle • Example: Temporalis (temporal bone)

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.

Orbicularis oris Deltoid Pectoralis major (d) Circular (a) Convergent (e) Multipennate Biceps brachii (d) (a) Rectus femoris (e) (b) Fusiform (c) (f) Bipennate Sartorius (f) Extensor digitorum longus (g) © 2012 Pearson Education, Inc. (c) Parallel (g) Unipennate Figure 6. 15

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.

Head and Neck Muscles • Neck muscles • Platysma—pulls the corners of the mouth

Frontalis Cranial aponeurosis Temporalis Orbicularis oculi Occipitalis Zygomaticus Buccinator Orbicularis oris Masseter Sternocleidomastoid Trapezius Platysma © 2012 Pearson Education, Inc. Figure 6. 16

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.

Clavicle Deltoid Sternum Pectoralis major Biceps brachii Brachialis Brachioradialis (a) © 2012 Pearson Education,

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.

Pectoralis major Rectus abdominis Transversus abdominis Internal oblique External oblique Aponeurosis (b) © 2012

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.

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 A&P Flix™: Muscles that act on the shoulder joint and humerus: An overview. A&P Flix™: Muscles of the pectoral girdle. PLAY A&P Flix™: Muscles that cross the glenohumeral joint. PLAY A&P Flix™: Movement at the glenohumeral joint: An overview. PLAY © 2012 Pearson Education, Inc.

Occipital bone Sternocleidomastoid Trapezius Spine of scapula Deltoid (cut) Deltoid Triceps brachii Latissimus dorsi (a) © 2012 Pearson Education, Inc. Humerus Olecranon process of ulna (deep to tendon) Figure 6. 18 a

C 7 T 1 Erector spinae • Iliocostalis • Longissimus • Spinalis Quadratus Iumborum

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 A&P Flix™: The elbow joint and forearm: An overview. PLAY A&P Flix™: Muscles of the elbow joint. PLAY A&P Flix™: Movement at the elbow joint. © 2012 Pearson Education, Inc.

Occipital bone Sternocleidomastoid Trapezius Spine of scapula Deltoid (cut) Deltoid Triceps brachii Latissimus dorsi (a) © 2012 Pearson Education, Inc. Humerus Olecranon process of ulna (deep to tendon) Figure 6. 18 a

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 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). PLAY © 2012 Pearson Education, Inc.

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 A&P Flix™: Muscles that act on the hip joint and femur: An overview. A&P Flix™: Movement at the hip joint: An overview. © 2012 Pearson Education, Inc.

Gluteus medius Gluteus maximus Adductor magnus Iliotibial tract Biceps femoris Semitendinosus Hamstring group Semimembranosus

Posterior superior iliac spine IIiac crest Safe area in gluteus medius Gluteus maximus Sciatic

12 th thoracic vertebra 12 th rib lliopsoas Iliac crest Psoas major lliacus 5 th lumbar vertebra Anterior superior iliac spine Quadriceps Sartorius Adductor group Rectus femoris Vastus lateralis Vastus medialis Patellar ligament (c) © 2012 Pearson Education, Inc. Figure 6. 20 c

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.

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. © 2012 Pearson Education, Inc.

12 th thoracic vertebra 12 th rib lliopsoas Iliac crest Psoas major lliacus 5 th lumbar vertebra Anterior superior iliac spine Quadriceps Sartorius Adductor group Rectus femoris Vastus lateralis Vastus medialis Patellar ligament (c) © 2012 Pearson Education, Inc. Figure 6. 20 c

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

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 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. PLAY © 2012 Pearson Education, Inc.

Fibularis longus Fibularis brevis Tibialis anterior Extensor digitorum longus Tibia Soleus Fibularis tertius (a)

Gastrocnemius Soleus Calcaneal (Achilles) tendon Medial malleolus © 2012 Pearson Education, Inc. Lateral malleolus

Facial • Frontalis Facial • Temporalis • Masseter Shoulder • Trapezius • Deltoid Arm • Triceps brachii • Brachialis Forearm • Brachioradialis • Flexor carpi radialis • 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 • Sartorius • Adductor muscle Thigh (Quadriceps) • Rectus femoris • Vastus lateralis • Vastus medialis • Gracilis Leg • Fibularis longus • Extensor digitorum longus • Tibialis anterior Leg • Gastrocnemius • Soleus © 2012 Pearson Education, Inc. Figure 6. 22

Neck • Occipitalis • Sternocleidomastoid • Trapezius Arm • Triceps brachii • Brachialis Forearm • Brachioradialis • Extensor carpi radialis longus • Flexor 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