Muscular System

1. Muscular System Introduction: Structure and Function

2. Muscle Functions • Muscle performs four important functions in the body: • Producing movement • Maintaining posture • Stabilizing joints • Generating heat

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

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

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

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

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 appears as distinct skeletal muscle that attach to the skeletal system • Skeletal muscle has obvious striations Skeletal Muscle Tissue • 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

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

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