Essentials of Human Anatomy & Physiology Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slides 6.1 – 6.17 Seventh Edition Elaine.

Essentials of Human Anatomy & Physiology

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Slides 6.1 – 6.17

Seventh EditionElaine N. Marieb

Chapter 6The Muscular System

Lecture Slides in PowerPoint by Jerry L. Cook

The Muscular SystemThe Muscular System

Slide 6.1Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Muscles are responsible for all types of body movement

Three basic muscle types are found in the body

Skeletal muscle

Cardiac muscle

Smooth muscle

Characteristics of MusclesCharacteristics of Muscles

Slide 6.2Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Muscle cells are elongated (muscle cell = muscle fiber)

Contraction of muscles is due to the movement of microfilaments

All muscles share some terminology

Prefix myo refers to muscle

Prefix mys refers to muscle

Prefix sarco refers to flesh

Skeletal Muscle CharacteristicsSkeletal Muscle Characteristics

Slide 6.3Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Most are attached by tendons to bones

Cells are multinucleate

Striated – have visible banding

Voluntary – subject to conscious control

Cells are surrounded and bundled by connective tissue

Connective Tissue Wrappings ofConnective Tissue Wrappings ofSkeletal MuscleSkeletal Muscle

Slide 6.4aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Endomysium – around single muscle fiber

Perimysium – around a fascicle (bundle) of fibers Figure 6.1

Connective Tissue Wrappings ofConnective Tissue Wrappings ofSkeletal MuscleSkeletal Muscle

Slide 6.4bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Epimysium – covers the entire skeletal muscle

Fascia – on the outside of the epimysium

Figure 6.1

Skeletal Muscle AttachmentsSkeletal Muscle Attachments

Slide 6.5Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Epimysium blends into a connective tissue attachment Tendon – cord-like structure

Aponeuroses – sheet-like structure

Sites of muscle attachment Bones

Cartilages

Connective tissue coverings

Smooth Muscle CharacteristicsSmooth Muscle Characteristics

Slide 6.6Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Has no striations

Spindle-shaped cells

Single nucleus

Involuntary – no conscious control

Found mainly in the walls of hollow organs

Figure 6.2a

Cardiac Muscle CharacteristicsCardiac Muscle Characteristics

Slide 6.7Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Has striations

Usually has a single nucleus

Joined to another muscle cell at an intercalated disc

Involuntary

Found only in the heart Figure 6.2b

Function of MusclesFunction of Muscles

Slide 6.8Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Produce movement

Maintain posture

Stabilize joints

Generate heat

Microscopic Anatomy of SkeletalMicroscopic Anatomy of SkeletalMuscleMuscle

Slide 6.9aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Cells are multinucleate

Nuclei are just beneath the sarcolemma

Figure 6.3a

Microscopic Anatomy of SkeletalMicroscopic Anatomy of SkeletalMuscleMuscle

Slide 6.9bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Sarcolemma – specialized plasma membrane

Sarcoplasmic reticulum – specialized smooth endoplasmic reticulum

Figure 6.3a

Microscopic Anatomy of Skeletal Microscopic Anatomy of Skeletal MuscleMuscle

Slide 6.10aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Myofibril

Bundles of myofilaments

Myofibrils are aligned to give distrinct bands

I band = light band

A band = dark band

Figure 6.3b

Microscopic Anatomy of Skeletal Microscopic Anatomy of Skeletal MuscleMuscle

Slide 6.10bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Sarcomere Contractile unit of a muscle fiber

Figure 6.3b

Microscopic Anatomy of Skeletal Microscopic Anatomy of Skeletal MuscleMuscle

Slide 6.11aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Organization of the sarcomere Thick filaments = myosin filaments

Composed of the protein myosin

Has ATPase enzymes

Figure 6.3c

Microscopic Anatomy of Skeletal Microscopic Anatomy of Skeletal MuscleMuscle

Slide 6.11bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Organization of the sarcomere Thin filaments = actin filaments

Composed of the protein actin

Figure 6.3c

Microscopic Anatomy of Skeletal Microscopic Anatomy of Skeletal MuscleMuscle

Slide 6.12aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Myosin filaments have heads (extensions, or cross bridges)

Myosin and actin overlap somewhat

Figure 6.3d

Microscopic Anatomy of Skeletal Microscopic Anatomy of Skeletal MuscleMuscle

Slide 6.12bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

At rest, there is a bare zone that lacks actin filaments

Sarcoplasmic reticulum (SR) – for storage of calcium

Figure 6.3d

Properties of Skeletal Muscle Properties of Skeletal Muscle ActivityActivity

Slide 6.13Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Irritability – ability to receive and respond to a stimulus

Contractility – ability to shorten when an adequate stimulus is received

Nerve Stimulus to MusclesNerve Stimulus to Muscles

Slide 6.14Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Skeletal muscles must be stimulated by a nerve to contract

Motor unit One neuron

Muscle cells stimulated by that neuron Figure 6.4a

Nerve Stimulus to MusclesNerve Stimulus to Muscles

Slide 6.15aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Neuromuscular junctions – association site of nerve and muscle

Figure 6.5b

Nerve Stimulus to MusclesNerve Stimulus to Muscles

Slide 6.15bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Synaptic cleft – gap between nerve and muscle Nerve and

muscle do not make contact

Area between nerve and muscle is filled with interstitial fluid Figure 6.5b

Transmission of Nerve Impulse to Transmission of Nerve Impulse to MuscleMuscle

Slide 6.16aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Neurotransmitter – chemical released by nerve upon arrival of nerve impulse

The neurotransmitter for skeletal muscle is acetylcholine

Neurotransmitter attaches to receptors on the sarcolemma

Sarcolemma becomes permeable to sodium (Na+)

Transmission of Nerve Impulse to Transmission of Nerve Impulse to MuscleMuscle

Slide 6.16bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Sodium rushing into the cell generates an action potential

Once started, muscle contraction cannot be stopped

The Sliding Filament Theory of The Sliding Filament Theory of Muscle ContractionMuscle Contraction

Slide 6.17aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Activation by nerve causes myosin heads (crossbridges) to attach to binding sites on the thin filament

Myosin heads then bind to the next site of the thin filament

Figure 6.7

The Sliding Filament Theory of The Sliding Filament Theory of Muscle ContractionMuscle Contraction

Slide 6.17bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

This continued action causes a sliding of the myosin along the actin

The result is that the muscle is shortened (contracted)

Figure 6.7

Types of Ordinary Body MovementsTypes of Ordinary Body Movements

Slide 6.32Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Flexion

Extension

Rotation

Abduction

Circumduction

Body MovementsBody Movements

Slide 6.33Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 6.13

Special MovementsSpecial Movements

Slide 6.34Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Dorsifelxion

Plantar flexion

Inversion

Eversion

Supination

Pronation

Opposition

Types of MusclesTypes of Muscles

Slide 6.35Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

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

Naming of Skeletal MusclesNaming of Skeletal Muscles

Slide 6.36aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Direction of muscle fibers

Example: rectus (straight)

Relative size of the muscle

Example: maximus (largest)

Naming of Skeletal MusclesNaming of Skeletal Muscles

Slide 6.36bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Location of the muscle

Example: many muscles are named for bones (e.g., temporalis)

Number of origins

Example: triceps (three heads)

Naming of Skeletal MusclesNaming of Skeletal Muscles

Slide 6.37Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Location of the muscles origin and insertion

Example: sterno (on the sternum)

Shape of the muscle

Example: deltoid (triangular)

Action of the muscle

Example: flexor and extensor (flexes or extends a bone)

Head and Neck MusclesHead and Neck Muscles

Slide 6.38Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 6.14

Trunk MusclesTrunk Muscles

Slide 6.39Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 6.15

Deep Trunk and Arm MusclesDeep Trunk and Arm Muscles

Slide 6.40Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 6.16

Muscles of the Pelvis, Hip, and ThighMuscles of the Pelvis, Hip, and Thigh

Slide 6.41Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 6.18c

Muscles of the Lower LegMuscles of the Lower Leg

Slide 6.42Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 6.19

Superficial Muscles: AnteriorSuperficial Muscles: Anterior

Slide 6.43Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 6.20

Superficial Muscles: PosteriorSuperficial Muscles: Posterior

Slide 6.44Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 6.21