1. Anatomy of the Muscular System

2. A Few Facts… There are more than 600 skeletal muscles in the body
They constitute 40-50% of our body weight
Along with the skeleton they determine the form and contours of our body

3. Skeletal Muscle Structure

4. Connective Tissue Components
Muscles cells (fibers) are covered by a delicate connective tissue membrane called the endomysium.
Groups of skeletal muscle fibers are called fascicles, and bound together by a tougher connective tissue envelope called the perimysium.
The muscle as a whole is covered by a course sheath called the epimysium.

5. Skeletal Muscle Structure

6. Aponeurosis – broad, flat sheet of connective tissue
Tendon – bands or cords of fibrous connective tissue that attach a muscle to a bone or other structure
Aponeurosis – broad, flat sheet of connective tissue
Fascia – surrounds the muscle organ and outside the epimysium
Superficial
Deep

8. Size, Shape, and Fiber Arrangement
Skeletal muscles are organs
Vary widely in size and shape
Muscle fiber arrangement differs
Parallel to the long axis of the muscle
Converge to a narrow attachment
Oblique and pennate (like a feather pen)
Bipennate (double-feathered)
Curved -- sphincter

9. Fiber Arrangement
Parallel
Convergent
Pennate
Bipennate
Sphincter

10. Attachment of Skeletal Muscle
Most muscles span at least one joint and attach to both articulating bones
Origin – attachment of a muscle to the bone, which does not move when contraction occurs
Insertion – attachment of a muscle to the bone that it moves when conctraction occurs

11. Muscle Attachment

12. Muscle Actions
Most muscles act in groups and not alone—some contract while others relax
Agonist (prime mover) – used to describe a muscle or group of muscles that directly performs a specific movement. Example: biceps brachii is the prime mover in the flexion of the forearm.
Antagonists – muscles that, when contracting, directly oppose prime movers – they relax while the prime mover is contracting

13. Synergists – muscles that contract at the same time as the prime mover
Fixator muscles – generally function as joint stabilizers
Most muscles function not only as prime movers but also as antagonists, synergists, and fixators. A prime mover in a particular movement , such as flexion, may be an antagonist during extension

15. Lever Systems
A lever is any rigid bar free to turn about a fixed point called its fulcrum.
Bones serve as levers and joints serve as fulcrums

16. First Class Lever

17. Second Class Lever

18. Third Class Lever

19. How Muscles are Named Most are Latin in origin (some Greek)
Location (gluteus = buttock)
Function (adductor)
Shape (deltoid = triangular)

20. Muscle Naming Continued…
Direction of fibers (rectus = straight)
Number of heads of divisions (biceps = two points of origin)
Points of attachment (sternocleidomastoid = origin on the sternum and clavicle and inserts on the mastoid process)
Size of muscle (maximus = largest)