Muscle as an organ

Muscle tissue vs. Muscle as an organOne of the 4 primary tissue typesHow many subtypes?Made up of 4 tissue types.> 700 skeletal musclesWord roots:sarco mys

Overview of Muscle TissueFunctions of muscle tissue Movement Maintenance of posture enables the body to remain sitting or standing Joint stabilization Heat generation muscle contractions produce heat Helps maintain normal body temperature

Types of Muscle TissueThree types Skeletal muscle tissue packaged into skeletal muscles, Cells are striated, voluntary Makes up 40% of body weight Cardiac muscle tissue occurs only in the walls of the heart, striated, involuntary Smooth muscle tissue occupies the walls of hollow organs. Visceral, no striations, involuntary

Similarities of Muscle TissueCells of skeletal and smooth muscles are known as fibers Muscle contraction depends on two types of myofilaments One type contains actin Another type contains myosin These two proteins generate contractile force Plasma membrane is called a sarcolemma Cytoplasm is called sarcoplasm

Basic Features of a Skeletal MuscleConnective tissue sheaths bind a skeletal muscle and its fibers together Epimysium (overcoat) dense regular connective tissue surrounding entire muscle Perimysium surrounds each fascicle (group of muscle fibers) Endomysium a fine sheath of connective tissue wrapping each muscle cell Connective tissue sheaths are continuous with tendons

Gross AnatomyEach skeletal muscle is wrapped by 3 concentric layers of connective tissue.

myofilaments

Epi-, Peri-, and Endomysium Are interwoven - Go over into tendon Distinguish between:TendonAponeurosisLigament

Basic Features of a Skeletal Muscle Muscle attachments Most skeletal muscles run from one bone to another One bone will move other bone remains fixed Origin immovable or less movable bone that muscle moves toward when a muscle contracts Insertion Movable bone when a muscle contracts, moves towards origin

Muscle TerminologyOrigin stationaryInsertionmovesPossible: multiple origins

Basic Features of a Skeletal Muscle Muscle attachments Muscles attach to origins and insertions by connective tissue Direct (fleshy) attachments connective tissue fibers are short, epimysium of muscle is fused to the periosteum of a bone of perichondrium of a cartilage Indirect attachments connective tissue forms a tendon or aponeurosis Bone markings present where tendons meet bones Tubercles, trochanters, and crests

Arrangement of FasciclesParallel/Fusiform-long axis of fascicles run parallel to long axis of the muscle Pennate fascicles short and attach obliquely Convergent has broad origin and fascicles converge toward a single tendon Circular-fascicles arranged in concentric rings

Parallel MusclesMajoritySpindle shaped with cord-like tendons

Convergent musclesBroad origin, pointed insertion

Pennate Muscles: UnipennateOne or more tendons run though muscle bodyFascicles in oblique angle to tendonCan generate more tension

Pennate Muscles: Bipennate & MultipennateExamples

Circular Muscles = SphinctersConcentric fibers adjust openingExamples: orbicularis occuli and oris

Types of Actionsflexion, extensionadduction, abductionelevation, depressionrotationpronation, supination

Grouping of Muscles according to Primary ActionAgonist = Prime MoverAntagonist (action opposes agonist)Synergists = Assistants of prime mover

Naming the Skeletal MusclesLocation most often with regard to bone Shape the deltoid is triangular Relative size - Maximus (largest), minimus (smallest), longus (long), and brevis (short), indicate size Direction of fascicles and muscle fibers -Name tells direction in which fibers run Example rectus (straight) abdominis and transversus or oblique abdominis Location of attachments name reveals point of origin and insertion. Origin always named first! Example brachioradialis,

Naming the Skeletal MusclesNumber of origins two, three, or four origins Indicated by the words biceps, triceps, and quadriceps Action the action is part of the muscles name Flexor, extensor, adductor, or abductor