1. Muscular System X

2. The Muscular System Main function of a muscle:
Contraction (shortening)
Because muscles can contract:
The main functions of the muscular system are:
Movement
Maintains Posture
Stabilizes Joints
Generates Heat
Controls Openings (sphincters)
Expressions
Protection (reflexes)

3. Characteristics of Muscles
Skeletal and smooth muscle cells are elongated
***(a muscle cell is also referred to as a muscle fiber)
Some skeletal muscle cells can be up to a foot long in length
All muscles share some terminology
If you see myo- mys- or sarc- you think MUSCLE!
Prefixes myo and mys refer to “muscle”
Prefix sarco refers to “flesh”

4. Three basic muscle types are found in the body
Skeletal muscle
Cardiac muscle
Smooth muscle

5. Skeletal (Striated) Muscle
Under voluntary control.
Thin cells that extend the entire length of muscle; multinucleated.
Location: Attached to bones through entire body
Function: Body movement, heat production

6. Cardiac Muscle Striated; involuntary control
Single cells with intercalated disks – cell to cell attachment points for communication.
Location: Heart
Function: Blood movement via heart contraction

7. Smooth Muscle Unstriated, under involuntary control.
Cells are longer but tapered at the ends; single nucleated, nucleus located in the middle of cell
Location: Walls of organs, blood vessels, eyes, glands, and skin
Function: Move products internally

8. Comparison of Skeletal, Cardiac, and Smooth Muscles
Table 6.1 (1 of 2)

9. Comparison of Skeletal, Cardiac, and Smooth Muscles
Table 6.1 (2 of 2)

10. Terminology Review Endo- Inside, Within (endoskeleton)
Peri- Around, surround (perimeter)
Epi- On, over, above (epidermis)

11. Our Focus: SKELETAL MUSCLE (Striated)

12. Skeletal Muscle Characteristics
Attached to the skeleton
Attached by tendons to bones (or aponeuroses)
Cells are multinucleate (many nuclei)
Striated (have visible banding)
Strong force
Tire easily (muscle fatigue)
Voluntary—you control them (exception = reflexes)

13. Connective Tissue Wrappings of Skeletal Muscle
Cells are surrounded and bundled by connective tissue
Endomysium—encloses a single muscle fiber
Perimysium—wraps around a group of muscle fibers forming a fascicle (bundle of muscle fibers)
Epimysium—covers the entire skeletal muscle (many fascicles)

14. Connective Tissue Wrappings of Skeletal Muscle
Figure 6.1

15. Skeletal Muscle Attachments
Epimysium blends into a connective tissue attachment at the ends of muscles
2 Types
Aponeuroses—sheet-like structures of connective tissue (sometimes referred to as fascia)
Attach muscles to bones, cartilages, or connective tissue coverings

16. Skeletal Muscle Attachments
Tendons—cord-like structures
Mostly collagen fibers
Often cross a joint due to toughness and small size