1. Essentials of Human Anatomy Muscular System

2. Introduction There are more than 600 skeletal muscles in the body
From 40% to 50% of body weight is skeletal muscle
Muscles, along with the skeleton, determine the form and contour of the body

3. Functions of skeletal Muscles
Body movements
Maintaining Posture
Stabilizing Joints
Body positions
Generating heat

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

5. Types Of Muscle

6. 4 Unique Characteristics of Muscle Tissue
Excitability is equated with responsiveness.
Contractility causes the fiber to shorten resulting in either a pull on bones or the movement of specific body parts.
Elasticity is the muscle’s ability to return to its original length when tension is released.
Extensibility is capability of extending in length in response to the contraction of opposing muscle fibers.

7. Structure of a Skeletal Muscle
Organ of the muscular system
- skeletal muscle tissue
- nervous tissue
- blood
- connective tissues
Fascia
Tendons
Aponeuroses

8. Skeletal Muscle Tissue
Skeletal muscles are organs
Vary in shape and size
A skeletal muscle is composed of cells
Each cell is as long as the muscle
Small muscle:
100 micrometers long; 10 micrometers in diameter
Large muscle:
35 centimeters long; 100 micrometers in diameter

9. Skeletal Muscle Structure
Connective tissue components
Endomysium
Delicate connective tissue membrane that covers specialized skeletal muscle fibers
Perimysium
Tough connective tissue binding together fascicles
Epimysium
Coarse sheath covering the muscle as a whole
These three fibrous components may become a tendon or an aponeurosis

10. Skeletal Muscle Anatomy

12. Muscle Fiber Structure
Multiple nuclei
Sarcolemma
T-tubules
Sarcoplasmic reticulum
Sarcoplasm
Mitochondria
Glycogen & ions
Myofibrils

13. Muscle Fiber Structure

14. Sliding Filament Mechanism

15. Neuromuscular Junction
Also known as myoneural junction
Site where an axon and muscle fiber meet
Motor neuron
Motor end plate
Synapse
Synaptic cleft
Synaptic vesicles
Neurotransmitters

16. Motor Unit single motor neuron
all muscle fibers controlled by motor neuron

17. Types of Contractions Eccentric – lengthening contraction
Concentric – shortening contraction
Eccentric – lengthening contraction
Isometric – muscle contracts but does not change length
Isotonic – muscle contracts and changes length

18. Muscle Atrophy Reduction in muscle size, tone, and power.
Due to reduced stimulation, it loses both mass and tone.
Muscle becomes flaccid, and its fibers decrease in size and become weaker.
Even a temporary reduction in muscle use can lead to muscular atrophy.

19. Muscle Hypertrophy An increase in muscle fiber size.
Muscle size may be improved by exercising.
Repetitive, exhaustive stimulation of muscle fibers results in more mitochondria, larger glycogen reserves, and an increased ability to produce ATP.
Ultimately, each muscle fiber develops more myofibrils, and each myofibril contains a larger number of myofilaments.

20. Posture
Maintaining the posture of the body is one of the major roles muscles play
“Good posture”—body alignment that most favors function and requires the least muscular work to maintain, keeping the body’s center of gravity over its base

21. Posture How posture is maintained
Muscles exert a continual pull on bones in the opposite direction from gravity
Structures and systems other than muscle and bones have a role in maintaining posture
Nervous system—responsible for determining muscle tone and also regulation and coordination of the amount of pull exerted by individual muscles
Respiratory, digestive, excretory, and endocrine systems all contribute to maintain posture

22. Axial Muscles
Have both their origins and insertions on parts of the axial skeleton.
Support and move the head and spinal column.
Function in nonverbal communication by affecting facial features.
Move the lower jaw during chewing.
Assist in food processing and swallowing.
Aid breathing.
Support and protect the abdominal and pelvic organs.
Are not responsible for stabilizing or moving the pectoral or pelvic girdles or their attached limbs.

23. Appendicular Muscles
Control the movements of the upper and lower limbs.
Stabilize and control the movements of the pectoral and pelvic girdles.
Organized into groups based on their location in the body or the part of the skeleton they move.
Work in groups that are either synergistic or antagonistic.

24. Appendicular Muscles Organized into specific groups.
muscles that move the pectoral girdle
muscles that move the glenohumeral joint/arm
arm and forearm muscles that move the elbow joint/forearm
forearm muscles that move the wrist joint, hand, and fingers
intrinsic muscles of the hand

25. Intramuscular Injections
The gluteus maximus is a large, thick muscle with coarse Fasciculi that can be easily separated without damage.
The great thickness of this muscle makes it ideal for intramuscular Injections.
To avoid injury to the underlying Sciatic nerve, the injection should be given well forward On the upper outer quadrant of the buttock.

27. THE END