Chapter 6 The Muscle Anatomy. The Muscular System Functions Movement Maintain posture Stabilize...
-
Upload
violet-merritt -
Category
Documents
-
view
224 -
download
0
description
Transcript of Chapter 6 The Muscle Anatomy. The Muscular System Functions Movement Maintain posture Stabilize...
Chapter 6 The Muscle Anatomy
The Muscular SystemThe Muscular System
Functions Movement Maintain posture Stabilize joints Generate heat
Three basic muscle types Skeletal muscle* Cardiac muscle Smooth muscle
Muscles and Body MovementsMuscles 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
an immoveable bone Insertion – attachment
to a movable bone
Types of MusclesTypes 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
HamstringQuadsCalf & Glutes
Flexion Extension Rotation Abduction Adduction Circumduction
Ordinary Body Movements - Skeletal
Special Movements - SkeletalSpecial Movements - Skeletal
Dorsifelxion Plantar flexion Inversion Eversion Supination Pronation Opposition
Naming of Skeletal MusclesNaming of Skeletal Muscles
1. Direction. Ex: rectus (straight)
2. Size. Ex: maximus (largest)
3. Location. Ex: many named for bones (temporalis)
4. Number of origins. Ex: triceps (three heads)
5. Origin & insertion. Ex: sterno (on the sternum)
6. Shape. Ex: deltoid (triangular)
7. Action. Ex: flexor & extensor (flexes or extends bone)
Characteristics of MusclesCharacteristics of Muscles
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 Most attached to bones by
tendons Multinucleate Striated – visible banding Voluntary – conscious
control Cells surrounded &
bundled by connective tissue
Connective Tissue WrappingsConnective Tissue Wrappings
Endomysium – around single muscle fiber
Perimysium – around a fascicle (bundle) of fibers
Epimysium – covers the entire skeletal muscle
Fascia – on the outside of the epimysium
Skeletal Muscle AttachmentsSkeletal Muscle Attachments 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
No striations Spindle-shaped
cells Single nucleus Involuntary – no
conscious control Found mainly in
the walls of hollow organs
Cardiac Muscle CharacteristicsCardiac Muscle Characteristics
Has striations Single nucleus Joined to another
muscle cell at an intercalated disc
Involuntary Found only in the
heart
Microscopic Anatomy of Skeletal MuscleMicroscopic Anatomy of Skeletal Muscle
Nuclei are just beneath the sarcolemma
Sarcolemma – specialized plasma membrane
Sarcoplasmic reticulum – specialized smooth endoplasmic reticulum
Microscopic Anatomy of Skeletal MuscleMicroscopic Anatomy of Skeletal Muscle
Myofibrils - Bundles of myofilaments
- aligned to give distrinct bands I band = light band A band = dark band
Sarcomere - Contractile unit of a muscle fiber
Organization of the Sarcomere Thick filaments = myosin filaments
- protein myosin- ATPase enzymes
Thin filaments = actin filaments- protein actin
Microscopic AnatomyMicroscopic Anatomy Myosin filaments have heads (extensions or
cross bridges) Myosin and actin overlap somewhat At rest, there is a bare zone that lacks actin
filaments Sarcoplasmic
reticulum (SR) – for storage of calcium
Properties of Skeletal MuscleProperties of Skeletal Muscle 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
Skeletal muscles must be stimulated by a nerve to contract
Motor unit- One neuron- Muscle cells
stimulated by that neuron
Nerve Stimulus to MusclesNerve Stimulus to Muscles Neuromuscular junctions – association
site of nerve and muscle