LT5.2 Muscle Anatomy (Micro & Macro)

Muscular System

1. Unit 5 The Muscular System DeFord Standard LT5.2 Muscle Anatomy

2. Muscular System Tissue Types Muscles are responsible for all types of body movement There are t hree basic muscle tissue types found in the body Cardiac Muscle Smooth Muscle Skeletal (or Striated) Muscle

3. Cardiac Muscle Tissue The characteristics of cardiac muscle include: Makes up myocardium of heart Tissue is unconsciously ( involuntarily ) controlled Microscopically appears striated Cells are short , branching and have a single nucleus Cells connect to each other at intercalated discs

4. Smooth Muscle Tissue The characteristics of smooth muscle include: Found in the lining of internal organs (GI tract, uterus, blood vessels, eyes, etc.) It controls the involuntary constriction of these regions (e.g., peristalsis, vasoconstriction, pupil dilation) Cells (fibers) are non-striated , have a short spindle-shape and each fiber contains a single nucleus Tissue is extremely extensible, while still retaining ability to contract

5. Skeletal Muscle Tissue The characteristics of skeletal muscle include: Associated with and attached to the skeleton Responsible for moving parts of the body, such as the limbs, trunk, and face Under our conscious ( voluntary ) control Cells (fibers) are long and cylindrical Cells (fibers) run in parallel tracts and are multinucleated and heavily striated

6. Comparison of Muscle Tissue Types Characteristic Skeletal Cardiac Smooth Body L ocation a ttached to bone (by tendons) or skin (for some facial muscles) w alls of the heart m ostly in walls of visceral organs (other than the heart) Cell S hape and A ppearance s ingle, very long, cylindrical, multinucleate cells with very obvious striations b ranching chains of cells, uninucleate, striations, intercalated discs s ingle, fusiform, uninucleate, no striations Connective T issue C omponents e ndomysium, perimysium, and epimysium e ndomysium e ndomysium

7. Connective Tissue Components Skeletal Cardiac Smooth

8. Comparison of Muscle Tissue Types Characteristic Skeletal Cardiac Smooth Regulation of C ontraction v oluntary i nvoluntary i nvoluntary Speed of C ontraction s low to f ast s low v ery slow Rhythmic C ontractions n o y es y es, in some

9. Skeletal Muscle Structure Although muscle fiber makes up most of the muscle tissue, a large amount of connective tissue, blood vessels, and nerves are also present. Connective tissue covers and supports each muscle fiber and reinforces the muscle as a whole. The health of muscle depends on a sufficient nerve and blood supply. Each skeletal muscle has a nerve ending that controls its activity. Active muscles use a lot of energy and require a continuous supply of oxygen and nutrients, which are supplied by arteries. Muscles produce large amounts of metabolic waste that must be removed by veins.

10. Gross Anatomy of Skeletal Muscles Cells are surrounded and bundled by connective tissue! Connective Tissue Organization: Endomysium – encloses a single muscle fiber Perimysium – wraps around a fascicle (bundle) of muscle fibers Epimysium – covers the entire skeletal muscle Fascia – outer layer of the epimysium

11. Blood V essel Perimysium (surrounds fascicle) Epimysium (wraps around entire muscle , surrounded by fascia ) Muscle F iber (cell) Fascicle ( bundle of muscle fibers, surrounded by perimysium ) Endomysium ( encloses each muscle fiber) Tendon Bone

12. Arrangement of Fascicles The fascicles of muscles can be arranged in a variety of ways – the most common are: Parallel – fascicles are parallel to the long axis of the muscle. Some of these are also classified as fusiform muscles. Pennate – the fascicles are short and attach to a central tendon. Can be unipennate, bipennate or multipennate. Convergent – the muscle has a broad origin but the fascicles converge to one tendon. Circular – muscle has the fascicles arranged in concentric circles.

13. Skeletal Muscle Attachments Skeletal muscles attach to bones, cartilage, and connective tissue coverings. Epimysium blends into a connective tissue attachment Tendons – cord-like structures Mostly collagen fibers Often cross a joint due to toughness and small size Aponeuroses – sheet-like structures Attach muscles indirectly to bones, cartilages, or connective tissue coverings

14. Microanatomy of Skeletal Muscles Sarcolemma – specialized cell membrane Sarcoplasm – muscle cell cytoplasm Sarcoplasmic Reticulum – specialized smooth endoplasmic reticulum used to store and maintain calcium ion levels surrounds the myofibril

15. Microanatomy of Skeletal Muscles T Tubules – tubules running through the muscle fibers through which calcium ions flow Sarcomeres – repeating contractile unit of the myofibril Myofibril – long contraction organelle aligned to give distinct bands I band = l i ght band that contains only thin filaments called actin . A band = d a rk band that contains thick filaments called myosin . Z-lines at each end provide anchors for thin filaments