1. Chapter 6 The Muscle Anatomy

2. The Muscular System Functions Three basic muscle types Movement
Maintain posture
Stabilize joints
Generate heat
Three basic muscle types
Skeletal muscle*
Cardiac muscle
Smooth muscle

3. 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 an immoveable bone
Insertion – attachment to a movable bone

4. 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
Hamstring
Quads
Calf & Glutes

5. Ordinary Body Movements - Skeletal
Flexion
Extension
Rotation
Abduction
Adduction
Circumduction

6. Special Movements - Skeletal
Dorsifelxion
Plantar flexion
Inversion
Eversion
Supination
Pronation
Opposition

7. Naming 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)

8. Characteristics 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

9. Skeletal Muscle Characteristics
Most attached to bones by tendons
Multinucleate
Striated – visible banding
Voluntary – conscious control
Cells surrounded & bundled by connective tissue

10. Connective 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

11. Skeletal 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

12. Smooth Muscle Characteristics
No striations
Spindle-shaped cells
Single nucleus
Involuntary – no conscious control
Found mainly in the walls of hollow organs

13. Cardiac Muscle Characteristics
Has striations
Single nucleus
Joined to another muscle cell at an intercalated disc
Involuntary
Found only in the heart

14. Microscopic Anatomy of Skeletal Muscle
Sarcolemma – specialized plasma membrane
Sarcoplasmic reticulum – specialized smooth endoplasmic reticulum
Nuclei are just beneath the sarcolemma

15. Microscopic 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

16. Organization of the Sarcomere
Thick filaments = myosin filaments
protein myosin
ATPase enzymes
Thin filaments = actin filaments
- protein actin

17. Microscopic 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

18. Properties of Skeletal Muscle
Irritability – ability to receive and respond to a stimulus
Contractility – ability to shorten when an adequate stimulus is received

19. Nerve Stimulus to Muscles
Skeletal muscles must be stimulated by a nerve to contract
Motor unit
- One neuron
- Muscle cells stimulated by that neuron

20. Nerve Stimulus to Muscles
Neuromuscular junctions – association site of nerve and muscle