1. Introduction: Structure and Function
Muscular System
Introduction:
Structure and Function

2. Muscle Functions Producing movement Maintaining posture
Muscle performs four important functions in the body:
Producing movement
Maintaining posture
Stabilizing joints
Generating heat
Heat is generated from the mass of muscle. = cubic body area. Loss of heat is based on surface area. Elephant : 28 beats/minute. Human: 70 beats/minute, hummingbird: >200beats/minute. - mass compared to surface area is small so it needs to beat a lot more to maintain body heat.
Shivering – body response to generate heat
Fever: below 93 heart stops, 108 proteins denature.

3. Producing Movement Movement results from skeletal muscle contraction
Skeletal muscle are responsible for all locomotion and manipulation
Allows you to interact or react with your external environment

4. Producing Movement - eye movement - facial expression (skeletal)
Skeletal Muscle controls (besides the obvious locomotion.)
- eye movement
- facial expression (skeletal)
- circulation (cardiac)
- moves gas, liquids, and solids through organs (smooth)

5. Maintaining Posture
Skeletal muscles are utilized constantly to maintain sitting, standing, and moving postures
Postural muscle develop to compensate for the never ending pull of gravity
Our developmental milestones as an infant are our initial victories over gravity
Curves of the spinal column are shaped by the interplay of skeletal muscle and gravity
Most voluntary – concious control. Posture-holding head up, nod off -?
In pairs because they can only contract
Huge blood supply – high energy demand. Bleed a lot when cut through. Easily torn. Strong in ability to lift but not really against tearing.

6. Stabilizing Joints
Skeletal muscle provide the dynamic stability of joints
Many joints are poorly reinforced by ligaments and connective tissue
Many joints have noncomplementary surface which do not contribute
to stability

7. Generating Heat Muscles generate heat as they contract
The heat generated is vitally important to maintain normal body temperature
Skeletal muscle generates most of the heat because it represents 40% of body mass
Excess heat must released to maintain body temperature
Heat is generated from the mass of muscle = cubic body area. Loss of heat is based on surface area.
Elephant: 28 beats/minute, human: 70 beats/minute, hummingbird: >200 beats/minute – mass compared to surface area is small so it needs to beat a lot more to maintain body heat.
Shivering: body response to generate heat.
Fever: below 93 heart stops, 108, proteins denature

8. Overview of Muscle Tissue
There are three types of muscle tissue
Skeletal muscle
Cardiac muscle
Smooth muscle

9. Overview of Muscle Tissue
These muscle tissues differ in the structure of their cells, their body location, their function, and the means by which they are activated to contract

10. Overview of Muscle Tissue
All skeletal and smooth muscle cells are elongated and are referred to as muscle fibers

11. Skeletal Muscle Tissue
Skeletal muscle tissue appears as distinct skeletal muscle that attach to the skeletal system
Skeletal muscle has obvious striations
It is a voluntary muscle under conscious control

12. Cardiac Muscle Tissue Cardiac muscle occur only in the heart
The muscle is striated but involuntary
Cardiac fibers are short, fat, branched and interconnected
Cardiac muscle cells are interlocked by intercalated discs and function as a single unit
Not branching.

13. Smooth Muscle Tissue
It is found in the walls of hollow organs such as the stomach, urinary bladder, and intestines (visceral organs)
It has no striations
It is not subject to voluntary control

15. Differences in Contractions
Skeletal muscle can contract rapidly but tire easily and must be rested
Skeletal muscle contractions vary in force depending on use
Cardiac muscle contracts at a steady rate but can accelerate to cope with demand
Smooth muscle contracts in steady, sustained contractions and continues on tirelessly

16. Skeletal Muscle

17. Anatomy of a Skeletal Muscle
Each skeletal muscle is a discrete organ with thousands of fibers
Muscle fibers predominate the tissue but it also contains, blood vessels, nerve fibers, and connective tissue

18. Connective Tissue of Muscle
Fascia: broad band of dense connective tissue that may occupy the space between skin and muscle or may surround muscle and other organs
2. Deep Fascia: associated with muscles. Surrounds muscle and serves to support and hold it together.
3. Epimysium  perimosium  endomysium (Superficial to deep) 
4. Tendon: thick band of connective tissue that attach muscle to bone.

19. Connective Tissue Wrappings
Each muscle fiber is wrapped by a fine sheath of connective tissue called endomysium
Several fibers are gathered side by side into bundles called fascicles
Each fascicle is bound by collagen fiber layer

20. Connective Tissue Wrappings
Fascicles are bound by a dense fibrous connective tissue layer called the epimysium
The epimysium surrounds the entire muscle
External to the epimysium is the deep fascia that binds muscles into functional groups

21. Connective Tissue Wrappings
All the connective tissue layers are connected to each other as well as to the tendons that join muscles to bone
When muscle fibers contract they pull these connective tissue sheaths which in turn transmit the force to the bone to be moved
Connective tissues supports each cell
EPImysium Perimysium endomysium superficial to deep

22. Naming Skeletal muscles
Location of the muscle
Shape of the muscle
Relative Size of the muscle
Direction/Orientation of the muscle fibers/cells
Number of Origins
Location of the Attachments
Action of the muscle

23. By location Epicranius (around cranium)
Tibialis anterior (front of tibia)

24. Shape Shape: deltoid (triangle) trapezius (trapezoid)
serratus (saw-toothed)
rhomboideus (rhomboid)
orbicularis and sphincters (circular) Rhomboideus major

25. Size maximus (largest) minimis (smallest) longus (longest)
brevis (short)
major (large)
minor (small)

26. Direction of fibers Rectus (straight)-parallel to long axis Transverse
Oblique

27. Number of origins
biceps (2) biceps brachii
triceps (3)
quadriceps (4)

28. For origin and insertion
Sternocleidomastoid originates from sternum and clavicle and inserts on mastoid process of temporal bone

29. For action
Flexor carpi radialis (extensor carpi radialis) –flexes wrist
Abductor pollicis brevis (adductor pollicis) –flexes thumb
Abductor magnus – abducts thigh
Extensor digitorum – extends fingers