1. The Muscular System

2. Functions of the Muscular System
Movement
-what examples can you think of?
Maintaining posture and body position
Stabilizing joints
Heat generation (generates 85% of the body’s heat…especially skeletal muscle)
How does this happen?

3. Structures of the Muscular System
Muscle fibers
Long, slender cells that make up the muscle
Each muscle consists of a group of fibers that are held together by a connective tissue and enclosed in a fibrous sheath
Fascia
Sheet of connective tissue that covers, supports, and separates muscles or groups of muscles
Flexible tissue but not elastic. Crush injuries can cause compartment syndrome

4. Structures of the Muscular System
Tendons
Narrow band of non-elastic, dense fibrous connective tissue that attaches a muscle to a bone
***do not confuse with a ligament! Ligaments connect bone to bone

5. Types of Muscle Tissue Smooth
Located in the walls of internal organs like the digestive tract and blood vessels, and ducts
Move and control the flow of fluids through these structures
Unstriated
Involuntary

6. Types of Muscle Tissue Skeletal
Attached to the bones of the skeleton and make movement possible
Voluntary
Striated (appear striped)

7. Types of Muscle Tissue Myocardial (Cardiac)
Form the muscular walls of the heart
Striated
Involuntary

8. How do Muscle Move? Muscle innervation
Muscles are supplied with motor nerves
Motor nerves enable the brain to stimulate a muscle to contract
When the stimulus stops, the muscle relaxes
If nerve impulse is interrupted due to injury or disease, paralysis occurs

9. Muscle Innervation

10. Antagonistic Muscle Pairs
Muscles are arranged into antagonistic pairs
When one muscle contracts, it’s antagonist relaxes
Example: Biceps and Triceps work as a pair to make arm movement possible
Contraction: The tightening of a muscle. As a muscle contracts, it shortens and thickens causing the belly of the muscle to enlarge
Relaxation: Occurs when a muscle returns to its original form. As the muscle relaxes, it elongates, thins and the belly is no longer enlarged

11. Contrasting Muscle Motion
Abduction: moves away from the midline
Adduction: moves toward the midline
Flexion: decreases an angle as in bending a joint
Extension: increases an angle, as in straightening a joint
Elevation: raises a body part. Ex. Smiling
Depression: lowers a body part. Ex. Frowning
Rotation: turns a bone on its own axis
Circumduction: the circular movement at the far end of a limb
Supination: turns the palm of the hand upward or forward
Pronation: turns the palm of the hand downward or backward
Dorsiflexion: bends the foot upward at the ankle
Plantar flexion: bends the foot downward at the ankle
Hyperextension: extreme overextension of a limb or body part beyond its normal limit

12. How Muscles are Named
Muscles can be named for their insertion and origin points
Origin: the less moveable attachment. The place where the muscle begins
Insertion: the more moveable attachment. This is the place where the muscle ends by attaching to a bone or tendon.
Example: the sternocleidomastoid (SCM) muscle is named for its two points of origin (sternum and clavicle) and the one point of insertion (mastoid process).

13. Example: the sternocleidomastoid (SCM) muscle is named for its two points of origin (sternum and clavicle) and the one point of insertion (mastoid process).

14. How Muscles are Named
Some muscles can be named for their location on the body or the organ they are near:
Example: pectoralis major
Pectoral means pertaining to the chest and the Pectoralis major is the large, fan shaped muscle of the chest.

15. How Muscles are Named Muscles may be named for their action
Flexor carpi muscles flex the wrist
Extensor carpi muscles extend the wrist
Muscle may be named for fiber direction
Oblique means slanted or at an angle
Rectus means in strait alignment
Transverse means in a crosswise fashion
Sphincter is a ring-like muscle that constricts the opening of a passageway.
Ex. Anal sphincter

16. How Muscles are Named
Some muscles are named for the number of divisions forming them.
Biceps brachii is formed from 2 divisions
Tricps brachii is formed from 3 divisions
Muscles may be named for their size or shape
Gluteus maximus is the larges of the gluteal muscles
The Deltoid muscle is shaped like an inverted triangle or the Greek letter Delta

17. How Muscles are Named Some muscles are just named for strange reasons…
Example: the hamstring group is the group of muscles located at the back of the upper leg and these are the muscles by which a butcher hangs a slaughtered pig!