Ch 6 The Muscular System Notes - Weebly
Name Block DateCh 6 The Muscular System NotesLisa PeckMuscular System: consists of skeletal muscles and their connective tissue attachmentsorgan- skeletal muscleconsists of hundreds of muscle fibers (cells) bound tog. by connective tissuecell- muscle fibers- elongated cellslargest (compared to smooth muscle)primary function is contraction: ability to shorten dep. on myofilamentsmuscle prefixes“myo” - muscle“mys” - muscle“sarco” - flesh3 Muscle Types (p 178-181)1. Skeletal Muscle- skeletal, striated, & voluntaryreferred to as the human body’s “muscular system”location: attach to bones or indirectly to other connective tissues or cartilageattach via tendons or aponeurosesexception: some facial muscles attach to soft tissues (oth. muscles or skin)function: create movement of bones or facial skin via contractionscontraction 1. regulation: voluntarysubject to conscious control via nervous systemonly muscle type that is voluntary2. speed: rapidly w/ great forcetire easilymust rest after activity3. no rhythmic contractionsmorphology: single cellelongated cylindrical shapemyofiber (cell):sarcolemma- muscle cell membranemyofibrils- contractile organelles found in cytoplasm of muscle cellslong tube-likehave light and dark bands along lengthmany aligned perfectly w/ in sarcolemmagiving a striated appearance to cellmultinucleated- nuclei and cytoplasm pushed to edge of sarcolemma bynumerous myofibrilssarcoplasmic reticulum- ER of cellstores calcium (for contraction)striated- banded appearance due to alignment of bands on myofibrilsmyofibril bands created by arrangement of myofilaments within myofibrilmyofilaments- filaments composing the myofibrilstwo types: actin & myosin
Skeletal Muscle2connective tissue coverings of skeletal muscleendomysium- thin connective tissue covering muscle cell (fiber)perimysium- coarser fibrous membrane covering bundles of muscle fiberscreating a fascicle- bundle of muscle fibers bound tog. by connective tissueepimysium- tough fibrous connective tissue surrounding many fasciclescreating a skeletal muscleouter covering of entire skeletal muscleblend into strong, cordlike tendons or into sheetlike aponeurosistendon- cord of dense fibrous tissue attaching a muscle to a boneaponeuroses- fibrous or membranous sheet connecting a muscle & the part it movesfascia- layers of fibrous tissue covering and separating musclestendon f’ns: 1. provide durability & conserve space2. tough collagenic fibers, can cross rough bony projections (would tear muscle)3. have small size, therefore more tendons than fleshy muscles can passover a joint
3 types of muscle cells:SkeletalCardiacSmooth Muscle- visceral, nonstriated, & involuntarylocation: walls of hollow visceral organsstomach, urinary bladder, respiratory passagesfunction: create movement of substances through a tract or pathwaycontraction 1. regulation: involuntarycontrol via nervous systemendocrine system (hormones)chemicalsmechanical stretching2. speed: very slow & sustaineddoes not tire easily3. rhythmic contractions in somemorphology: single cellfusiform shape (spindle shaped)nonstriateduninucleatedarranged in sheets or layers1. runs circularly2. runs longitudinally-layers alternatively contract & relax-changing shape & size of organ-moving substances through tractSmooth3
Cardiac Muscle- cardiac, striated, & involuntary4location: walls of the heartfunction: force movement of blood through heart chambers to arteriescontraction 1. regulation: involuntarycontrol via heart “pacemaker” (for rhythmic contraction)nervous system (for increased # of contractions for short period)endocrine system (hormones)2. speed: slowdoes not tire easily3. rhythmic contractionsmorphology: branching chains of cellsstriateduninucleatedfibers cushioned with soft connective tissuefibers arranged in spiral or figure 8 shaped bundlesenables heart activity to be closely coordinatedbranching cells joined by intercalated discsMuscle Functions (pp 181-182)1. producing movement- result of contractionskeletal muscles: enable quick response to changes in environmentenable expression of emotions (facial & neck muscles)smooth muscles: force substances to move thru visceral tractscardiac muscles: circulate blood & maintain blood pressure2. maintaining posture- via skeletal musclesovercoming gravity effects while sitting or standing3. stabilizing joints- pull of skeletal muscles on bonestendons important in reinforcing & stabilizing joints too4. generating heat- by-product of muscle activity75% of ATP energy creates heat (only 25% used to contract muscle)
Microscopic Anatomy of Skeletal Muscle (pp 182-184)5
Microscopic Anatomy of Skeletal Muscle (pp 182-184)6Muscle Fiber (cell) --- bundles of Myofibrils --- bundles of Myofilaments (actin & myosin)Sarcolemma- muscle cell membraneencloses many myofibrils, many nuclei, sarcoplasmic reticulum, mitochondria etc.Myofibrils- contractile organelles found in cytoplasm of muscle cellslong tube-likehave light and dark bands along length-striations created by perfectly aligned myofibrils w/ in sarcolemmaconsists of chains of sarcomeres- tiny contractile units consisting of actin & myosinbanding pattern: light & dark bands created by the arrangement of myofilaments (thick- myosin &thin- actin) in sarcomeresLight (I) Bands- contain - only actin filaments (thin filament)-parts of two adjacent sarcomeresZ disk - a darker area in middle of I band (a midline interruption)- connection of actin filaments (thin filaments)Dark (A) Bands- consists of actin & myosin filamentsmyosin filaments extend the entire length of A bandhas a lighter central area, H zone (bcs no actin filaments located here)H zone has a central line called M lineM line- protein rods connecting myosin filamentsMyofilaments- protein strands2 types: myosin filament- thick protein filamentmiddle is smoothends contain numerous myosin headsactin filament- thin protein filamentanchored to the Z disc in I Banddon’t overlap ends of myosin fibersdon’t extend into middle of A band (H zone)Cross Bridges formed when the myosin heads link to the actin filaments (at myosin binding sites)Sarcoplasmic Reticulum (SR)- smooth endoplasmic reticulum that surrounds every myofibrilf’n: stores calcium needed for contraction (filament sliding)
Skeletal Muscle Activity (pp 184-192)7irritability- the ability to receive and respond to a stimuluscontractility- the ability to shorten (forcibly) when an adequate stimulus is receivedStimulation and contraction of Single Skeletal Muscle Cells (pp184-187)one motor neuron (nerve cell) may stimulate a few muscle cells or hundreds of muscle cells1. Nerve stimulus & the action potentialmotor unit- a motor neuron and all the muscle cells it stimulatesaxon- long threadlike extension of the neuronaxon terminal- end of neuron that branches into numerous endsform neuromuscular junction with muscle cellneuromuscular junction- junction @ motor neuron’s axonal ending & sarcolemma of muscle cellsynaptic cleft- gap b/ w axon terminal of motor neuron and muscle cell sarcolemmafilled w/ interstitial fluidneurotransmitter- chemical subst. released by neuron when nerve impulse reaches axonal endsacetylcholine in skeletal muscle1. Acetylcholine is released into the neuromuscular junction by axonal terminal2. Acetylcholine diffuses across the neuromuscular junction & binds to receptors on the sarcolemma3. Depolarization occurs, and the action potential is generated (see next page)4. Action potential, carried deep into cell, causes sarcoplasmic reticulum to release calcium ions5. Calcium ion concentration @ myofilaments increases; myofilaments slide past one another,and muscle cell shortens6. As calcium is actively reabsorbed into the sarcoplasmic reticulum, its concentration at themyofilaments decreases7. The muscle cell relaxes and lengthens
Stimulation & contraction of Single Skeletal Muscle Cells2. Mechanism of muscle contraction: the sliding filament theory8Depolarization of Muscle Cellnerve stimulus------ changes in sarcolemma permeability---- enables change in concentrations ofsodium & potassium ions---- wh/ generates an electrical current- action potential---- wh/travels over entire surface of sarcolemma---- action potential carried deep into cell---- causessarcoplasmic reticulum to release calcium ions---- calcium ions enable myosin heads to form crossbridges with actin filaments---- initiating filament slidingwhen action potential ends---- calcium ions are immediately reabsorbed into sarcoplasmicreticulum---- muscle cell relaxes back to its original lengthAction Potential Generation:Resting: greater conc. of sodium ions outsidegreater conc. of potassium ions insideinside is more negative than outsideStimulus: sarcolemma permeability changesDepolarization: sodium diffuses into cell changing polarity of membrane (outside more negative)inside more positively charged than outside---- creates electrical currentRepolarization: potassium diffuses out of cell to restore the electrical conditions of membraneSodium-Potassium pump- uses ATP to restore resting state conc. of sodium & potassium ions--pumps excess sodium ions out of cell--brings potassium ions back into cell
Muscle Cell Contraction Mechanism: Sliding Filament Theory9B. Contraction of a skeletal muscle as a whole (pp 187-192)graded responsesmuscle response to increasing rapid stimulationmuscle twitchescomplete tetanus- fused continuous contraction that shows no evidence of relaxationincomplete tetanus- unfusedstrong contraction: many motor units are stimulated at a rapid rateweak but smooth muscle contraction: fewer motor units are stimulated at a rapid rateproviding energy for muscle contraction1. direct phosphorylation of ADP by creatine phosphate(found in muscle cells lasts 20sec.)2. aerobic respiration (makes more ATP but is slower than anaerobic respiration & needs O2)3. anaerobic glycolysis & lactic acid formation (makes 5% as much ATP but is faster)
Contraction of a skeletal muscle as a whole (pp 187-192)muscle fatigue and oxygen debt10fatigue- when a muscle is being stimulated but is not able to contractdue to oxygen debt from prolonged muscle activityoxygen debt: .anaerobic respiration--- build up of lactic acid (muscle pain & poor contractions)recovery from oxygen debt: breath rapidly and deeplytypes of muscle contractionsisotonic- “same tone”myofilaments slide past each othermuscle contracts and shortensisometric- “same length”myofilaments trying to slide past each other but can not slide past each othertension in the muscle keeps increasing“contraction without muscle shortening”eg: pushing on a wall or immovable objectmuscle tone-state of continuous partial contractionseven when muscle is relaxed.some of its fibers are contractingresult of different motor units along muscle are stimulated in a systematic waykeeps muscle firm, healthy, and ready for usecannot be consciously controlledLoss of muscle tone: if motor neuron is damaged (no more stimulation of muscle)muscle becomes 1. paralyzed2. flaccid- soft and flabby3. atrophied- wastes awayeffect of exercise on musclesincreases muscle size, strength, and enduranceaerobic exercise- (endurance)results in 1. stronger, more flexible muscles (does not increase size)2. muscles with greater resistance to fatiguebcs- increased blood supply to muscle (more oxygen)muscle cells form more mitochondria (site of respiration) & store more O2other benefits: 1. improves overall body metabolism2. improves digestion & elimination3. enhances neuromuscular coordination4. strengthens skeleton5. increase heart size.increase blood volume pumpedfat cleared from blood vessel walls6. lungs become more efficientresistant exercise- (isometric) muscles working against an immovable object (or nearly so)key: forcing muscles to contract with as much force as possibleincrease in muscle size.bcs enlargement of muscle cells.bcs increase # of filaments
Muscle Movements, Types, and Names (pp 192-200)11over 600 muscles in bodya muscle can only pulltendons attach muscle to bone & make them work like leversthe joint acts as the fulcrum & muscles provide the force to move the leverFive Golden Rules of Muscle Activity1. cross at least one joint- with a few exceptions2. bulk of muscle lies proximal to joint crossed3. at least two attachmentsorigin- attachment of a muscle that remains relatively fixed during muscular contractioninsertion- the movable attachment of a muscleas muscle contracts: the insertion area is pulled towards the origin4. can only pull- never push5. insertion moves toward origin during contractionInteractions of Skeletal Muscles in the body(p 196)most muscles act in pairs (together or against each other)prime mover- (agonist) muscle whose contractions are primarily responsible for a particularmovementantagonists-muscles that act in opposition to an agonist or prime movernever completely relaxed, its function is to provide control and damping ofmovement by maintaining tone against the agonist/ prime moverwhen movement reverses: the names switchexample: flexing elbow: biceps brachii is the prime mover (agonist)triceps brachii is the antagonistextending elbow: triceps brachii is the prime moverbiceps brachii is the antagonistssynergists- muscles cooperating w/ other muscle (s) to 1. produce a desired movement2. reduce undesired movementsynergists have the same functionthis movement can be different from that performed when the muscles work independentlyexample: the sternocleidomastoid muscles each rotate the head ina differentdirection, but as synergists they flex the neck (working together)*help stabilize joints to make a more precise movement possibleexample: synergists stabilize the wrist as clench fingers so only the fingers movenot the wrist
Interactions of Skeletal Muscles in the body (p 196)fixators- muscles acting to immobilize a joint or a bonefixes the origin of a muscle so that muscle action can be exerted at the insertionexample: fixators act as postural muscles to keep the spine erect & the leg andvertebral column extended when standingrhomboids & levator scapulae keep the scapula from moving duringactions such as lifting w/ the armsTypes of Body Movements (pp192-196)1. flexion- movement in the anterior-posterior plane (sagittal plane)decreases the angle or distance between two bones or parts of bodybrings 2 bones closer togethertypical in hinge & ball-and-socket jointseg: bending knee, elbow, or forward at the hipbringing head toward the chest (flexing the intervertebral jts of neck)2. extension- movement in the anterior- posterior plane (sagittal plane)increases the angle or distance between two bones or parts of bodyreverses movement of flexioneg. straightening the knee or elbowhyperextension- increasing angle beyond 180 continuation of mvmt past the anatomical positioncan cause injuryeg: tip head or torso posteriorly pointing chin to ceiling3. rotation- turning the body or a limb around the longitudinal axiscommon in ball-and-socket jointseg. rotating the arm to screw in a light bulbrotating the atlas around the dens of axis (shaking head “no”)4. abduction- movement away from the center of body; midlinefanning movement of the fingers or toes (when they are spread apart)movement of the appendicular skeleton5. adduction- movement toward the midline of the bodyopposite of abductionmovement of the appendicular skeleton12
Types of Body Movements (pp13192-196)6. circumduction- a special type of angular motioncombination of flexion, extension, abduction, and adductiontypical of ball-and-socket joint (shoulder)proximal end of limb is stationary and its distal end moves in a circlelimb as a whole outlines a cone7. dorsiflexion and plantar flexion- movements of the footdorsiflexion- movement of ankle while elevating the solesuperior surface moves towards shin (tibia)“digging in heels”(corresponds to extension of the hand at the wrist)plantar flexion- extending the ankle and elevating the heeldepressing the foot, pointing the toes“standing on tip toes”(corresponds to flexion of the hand at the wrist)8. inversion and eversion- movements of the footinversion- turn sole mediallyeversion- turn sole laterally9. supination and pronation- movements of the radius and ulnasupination- forearm rotates laterally .palm faces anteriorly(radius uncrossed)pronation- forearm rotates medially .palm faces posteriorly (radius crossed)rotation of the distal end of the radius across theanterior surface of the ulna10. opposition- movement of the thumb at saddle joint b/w metacarpal 1 & carpalsthumb touching the tips of the other fingers of same handenables thumb to grasp and hold an object11. elevation and depression- occurs when structure moves in a superior or inferior directionmandible is depressed when mouth is openedmandible is elevated when mouth is closedraising or lowering scapula (“shrugging shoulders”)12. protraction and retractionprotraction- moving part of body anteriorly in the horizontal planeeg: jutting face or jaw forward “hunching shoulders”retraction- moving part of body posteriorly in horizontal planeeg: moving jaw towards spine “squaring shoulders”
Naming Skeletal Muscles (pp 196 and 198)14names describe a feature of muscle, often several criteria are combined into one namedirection relative to body axis of muscle fibersanterior- frontposterior- backlateralis- lateralmedialis/medius- medialcircularis- circularinferioris- inferiorsuperiorus- superiorprofundus- deepsuperficialis- superficialoblique- at an angleexternus- superficialinternus- deep, internaltransverse- acrossintrinsic- insideextrinsic- outsiderectus- straight, parallellocation of the muscleabdominus- abdomenanconeus- elbowbrachialis- brachiumcapitis- headcarpi- wristcervicis- necknasalis- nosecoccgeus- coccyxcostalis- ribscutaneous- skinfemoris- femurgenio- chinglosso/ glossal- tonguehallucis- great toeilio- iliuminguinal- groinlumborum- lumbar regiontibialis- tibiaoculo- eyeoris- mouthpalpebrae- eyelidpollicis- thumbpsoas- loinradialis- radiusscapularis- scapulatemporalis- templescleido/ clavius- clavicleulnaris- ulnauro- urinarythoracis- thoracic regionpopliteur- behind the kneenumber of originsbiceps- two headstriceps- three headsquadriceps- four headsbody location of the muscle’s origin and insertionbrachii- armgluteus- buttocksinfra- belowlateralis- lateralpectoralis- chestsub- underneathsupra- above
Naming Musclesaction of the muscle15abduction- moves away from the midlineadduction- moves closer to the midlinedepressorextension- increases the angle of a jointflexion- decreases the angle of a jointlevatatorpronation- turns the palm of the hand downrotation- moves bone around its longitudinal axissupination- turns the palm of the hand uptensordorsiflexion- elevates the footplantar flexion- lowers the foot, pointing the toesmasseter- chewingshape, size, & color of the musclealba- whitebrevis- shortdeltoid- trianglegracillis- slenderlata- widelatissimus- widestlongus- longmagnus- largermajor- largermaximus- largestminimus- smallestminor- smallerorbicularis- circlepectinate- comblikepiriformis- pear-shapedplatys- flatpyramidal- pyramidrhomboideus- rhomboidserratus- serratedsplenius- bandageteres- long & roundtrapezius- trapezoidvastus- huge or greatArrangement of Fascicles ( pp 199-200)a fascicle is a bundle of muscle fibers enclosed by perimysiumfascicle arrangement varies.creating muscles w/ different structures and functional propertiescircular- fascicles arranged in concentric ringssurrounds external body openings .closed by contracting circular muscles“sphincters”convergent- fascicles converge toward a single insertion tendonmuscles appears triangular or fan-shapedparallel-fascicles run parallel to the long axis of the musclesstrap-like appearancefusiform- modified parallel arrangementspindle-shaped muscles w/ expanded midsectionpennate- feather pattern; fascicles are short & attached obliquely (on a slant) to a central tendonunipennate- fascicles insert into only ones side of the tendonbipennate- fascicles insert into opposite sides of the tendonmultipennate- fascicles insert into many different sides of the tendon
Relationship of fascicle arrangement to muscle structure16
Gross Anatomy of Skeletal Muscles (pp 200-208; Fig. 6.21-6.22; Tables 6.3-6.4)Head and Neck Muscles (pp 200-201)17Facial MusclesFrontalis- covers the frontal boneorigin- cranial aponeurosisinsertion- skin of eyebrowsaction- raises eyebrowswrinkles forehead; forms the horizontal frown crease on the foreheadOrbicularis Oculi- fibers run in circles around eyesorigin- frontal bone & maxilla inserts to medial side of orbit (tissue around eye)action- closes eye; squinting, blinking, & winking the eyesOrbicularis Oris- circular muscles of lipsorigin- maxilla & mandibleinsertion- skin & muscle around lipsaction- closes, compresses & protrudes lips “kissing muscle”Buccinator- flattens the cheekorigin- maxillary & mandibleinsertion- orbicularis orisaction- flattens & sucks in the cheek “whistling & sucking”holds the food between the teeth during chewingZygomaticus- “smiling” muscleorigin- zygomatic boneinsertion- skin & muscles at corner of mouthaction- raises the corners of the mouth upward
Chewing MusclesBuccinator- holds food b/ w teeth during chewing .considered a “chewing” & facial muscleMasseter- prime mover of jaw closureorigin- zygomatic process of temporal bone & maxillainsertion- mandibleaction- closes jaw by elevating the mandible18temporalisTemporalis- fan shaped muscle covering temporal boneorigin- temporal lines of skullinsertion- coronoid process of mandibleaction- synergist to masseter in closing the jawmassetersternocleidomastoidNeck Muscles: move head& shoulder girdle,small and strap-likeplatysmatrapeziusPlatysma-single sheetlike muscle that covers ant. lat. neckorigin- cartilage of 2nd rib to acromion of scapulainsertion- mandible & skin of cheekaction- pull corners of mouth inferiorly (downward sag of mouth)tenses skin of neck & depresses mandibleSternocleidomastoid- paired muscles (one on each side of the neck)“prayer muscle”two headed (sternum & clavicle)origin- sternum & clavicleinsertion- mastoid process of temporal boneaction- prime mover of head flexion (when the 2 pairs contract together)single muscle contraction: head is rotated toward opposite sideTrapezius- most superficial posterior neck muscleorigin- occipital bone, spinous processes of cervical & throacic vertebrainsertion- acromion & spine of scapula and clavicleaction- depends on active region and state of other muscles*extends neck and headantagonist of sternocleidomastoids* may elevate, adduct, depress, or rotated scapula* elevate clavicle* hyperextend neck to “look at the sky”* elevate &/ or pull back shoulder “shrugging”
Anterior Trunk Muscles (pp 201-203)1. move the vertebral column (post. antigravity)192. move ribs, head, and arms (anterior thorax muscles)3. move vertebral column & form abdominal body wall musclePectoralis Major- anterior large fan-shaped muscle covering the upper chest, forms ant. axilla wallorigin- sternum, clavicle, 1-6 ribsinsertion- proximal end of humerus (greater tubercle)action- adducts, flexes & medial rotation of humerus at shoulder joint*prime mover for shoulder flexion and adductionIntercostal Muscles- deep muscles found between the ribsorigin- inferior border of rib & costal cartilageinsertion- superior border of rib & coastal cartilageaction- *external intercostals----elevates rib cage during inspiration*internal intercostals-----depress rib cage during expirationDiaphragm- “breathing muscle”origin- sternum (xiphoid process), last 6 costal cartilages, ant. surfaces of lumbar vert.insertion- central tendonaction- flattens to enlarge chest cavity for inhalationMuscles of the Abdominal Girdle- reinforce body trunk (protecting abdominal viscera)fibers of each muscle pair run in a different directionRectus Abdominis- paired strap-like muscles, most superficial abdominal muscleenclosed in aponeurosisname means “straight muscle of the abdomen”origin- pubis of coxal boneinsertion- sternum (xiphoid process) & 5th to 7th costal cartilageaction- flex vertebral columndepresses ribs for forced breathingcompress abdominal contents during defecation & childbirth
Muscles of the Abdominal Girdle(ant. trunk muscles)20great strength: layering & fibers running in diff. directionsreinforces body trunkRectus Abdominis- paired strap-like muscles, most superficial abdominal muscleenclosed in aponeurosis “straight muscle of the abdomen”action- flex vertebral columndepresses ribs for forced breathingcompress abdominal contents (defecation & childbirth)External Oblique- part of abdominal girdleforms the external lateral walls of the abdomenoblique.at a slantorigin- lower 8 ribsinsertion- iliac crest of coxal bone & linea albaaction- flex vertebral columnrotate vertebral column & trunk, bending it laterally toocompresses abdomenInternal Oblique- part of abdominal girdlepaired muscles deep to external obliquesfibers run at a right angle to external obliqueorigin- iliac crestinsertion- last 3 ribs, sternum (xiphoid), & linea albaaction- flex vertebral columnrotate vertebral column & trunk, bending it laterally toocompresses abdomenTransversus Abdominis- deepest muscle of abdomen wallfibers run horizontally across abdomenorigin- cartilage of lower ribs and iliac crestinsertion- linea alba, & pubisaction- compresses abdomen (contents)
Posterior MusclesTrapezius- most superficial muscles of posterior neck & upper trunkorigin- occipital bone, spinous processes of cervical & throacic vertebrainsertion- acromion & spine of scapula and clavicleaction- depends on active region and state of other muscles*extends neck and headantagonist of sternocleidomastoids* may elevate, adduct, depress, or rotated scapula* elevate clavicle* hyperextend neck to “look at the sky”* elevate &/ or pull back shoulder “shrugging”Latissimus Dorsi- large , flat muscle pair that covers the lower backorigin- last 6 thoracic vertebrae, all lumbar vertebrae, sacrum, iliac crestinsertion- proximal end of humerusaction- extends and adducts humerus “power stroke brings down arm”Erector Spinae- composite muscle group spans entire length of vertebral columnconsists of 3 deep muscle columns: longissimus, iliocostalis, & spinalisorigin- iliac crests, ribs 3-12, & vertebraeinsertion- ribs, thoracic and cervical vertebraeaction- extends back (powerful) prime mover of back extensionprovides resistance controlling bending over at the waist21
Posterior Muscles22Deltoid- fleshy, triangular-shaped muscles of shouldersgive rounded shape of shoulder.site of IM injectionsorigin- scapular spine & clavicleinsertion- proximal humerus (deltoid tuberosity)action- prime movers of arm abduction“abducts humerus”raise arm overheadantagonist of latissimus dorsiMuscles of the Upper Limb 3 groups:1. muscles of shoulder jt & humerus causing arm mvmtpectoralis majorlatissimus dorsideltoid2. muscles causing movement at elbow jtenclose humerus & insert onto forearm bonesbiceps brachiibrachialisbrachioradialistriceps brachii3. muscles of forearm causing hand mvmtinsert on hand bones causing their mvmtnumerous thin, spindle shaped musclesMuscles of Humerus acting on Forearmall anterior arm muscles cause elbow flexionElbow FlexorsBiceps Brachii- originates by 2 heads from shoulderorigin- scapula of shoulder girdleinsertion- proximal radiusaction-flexes elbow (forearm)supinates forearmBrachialis- lies deep to bicepsorigin- distal humerusinsertion- proximal ulnaaction- flexes elbowBrachioradialis-fairly weak muscle, mostly in forearmorigin- humerusinsertion- radius (distal forearm)action- flexes (elbow) forearm
Muscles of Humerus acting on ForearmElbow Extensor:Triceps Brachii- only muscle fleshing out posterior humerusthree heads arise from shoulder girdleextends forearmorigin- shoulder girdle (scapula) & proximal humerusinsertion- olecranon process of ulnaaction- extends elbow prime mover of elbow extensionantagonist of biceps brachiiMuscles of Forearm Causing Hand Movementinsert on hand bones causing their mvmtnumerous thin, spindle shaped musclesWrist Flexors:Flexor Carpi Radialisorigin- distal humerusinsertion- 2nd & 3rd metacarpalsaction- flexes wristadducts handFlexor Carpi Ulnarisorigin- distal humerus & post. ulnainsertion- carpals & 5th metacarpalaction- flexes wristadducts handWrist ExtensorsExtensor Carpi Radialisorigin- humerusinsertion- 2nd & 3rd metacarpalaction- extends wristabducts handExtensor Carpi Ulnarisorigin- humerus & ulnainsertion- 5th metacarpalaction- extends wristabducts hand23
Muscles of Forearm causing hand movementFlexor Digitorumorigin- humerus, ulaninsertion- middle phalanges of 2nd to 5th fingersaction- flexes wristflexes fingersExtensor Digitorumorigin- humerusinsertion- distal phalanges of 2nd to 5th fingersaction- extend wristextends fingers24
Muscles of the Lower Limb(pp 204-208)largest and strongest muscles of bodypelvic girdle made of strong bonesno need for muscular stabilization like pectoralcause movement of hip, knee, & footwalking and balancing bodyMuscles Causing Movement of Hip JointGluteus Maximus- superficial muscle of hipforms most of buttockIM injection siteorigin- sacrum and iliacinsertion- proximal femur (gluteal tuberosity)action- lateral rotation of femur at hip jt.powerful hip extensorclimbing stairs & jumpingincreases angle/ dist. b/ w femur & hipGluteus Medius- runs beneath gluteus maximussmaller hip muscleIM injection siteorigin- ilium (lateral surface)insertion- proximal femur(greater trochanter)action- abducts thigh (hip abductor)steadies pelvis during walkingIliopsoas- fused 2 muscles( iliacus & psoas major)deep in pelvisorigin- ilium & lumbar vertebrainsertion- femur (lesser trochanter)action- flexes hipflexes lumbar spineAdductor Group- muscles of medial thighorigin- pelvisinsertion- proximal femuractio
Ch 6 The Muscular System Notes Lisa Peck Muscular System: consists of skeletal muscles and their connective tissue attachments organ- skeletal muscle consists of hundreds of muscle fibers (cells) bound tog. by connective tissue cell- muscle fi
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