Naming MusclesNaming Muscles

Muscles causing Muscles causing movement…movement…

Skeletal Muscle – an organ made of Skeletal Muscle – an organ made of several different types of tissue several different types of tissue including muscle tissue, vascular including muscle tissue, vascular tissue and nervous tissuetissue and nervous tissue

Tendon – attaches the skeletal Tendon – attaches the skeletal muscle to bone and pulls on bone muscle to bone and pulls on bone when the muscle contractswhen the muscle contracts

JointsJoints

Skeletal muscles usually cross one or Skeletal muscles usually cross one or more joints. When a muscle more joints. When a muscle contracts it pulls one bone closer to contracts it pulls one bone closer to anotheranother One bone stays in place while the other One bone stays in place while the other

movesmoves

Parts of a skeletal muscleParts of a skeletal muscle

Origin – the attachment of a muscle Origin – the attachment of a muscle on a stationary boneon a stationary bone

Insertion – the attachment of a Insertion – the attachment of a muscle on the movable bonemuscle on the movable bone

Belly – the fleshy portion of muscle Belly – the fleshy portion of muscle between the origin and insertionbetween the origin and insertion

Group ActionsGroup Actions

Most movements occur because Most movements occur because groups of muscles work together, groups of muscles work together, generally grouped in opposing pairsgenerally grouped in opposing pairs Ex – abductors and adductorsEx – abductors and adductors Ex – extensors and flexorsEx – extensors and flexors

Agonist – muscle that produces the Agonist – muscle that produces the desired movementdesired movement

Antagonist – muscle that relaxes when the Antagonist – muscle that relaxes when the agonist contractsagonist contracts

Synergists – another skeletal muscle that Synergists – another skeletal muscle that moves in the same general direction as moves in the same general direction as the agonist increasing the forcethe agonist increasing the force

Fixators – stabilize the origin and hold Fixators – stabilize the origin and hold other joints still so the agonist can work other joints still so the agonist can work more efficientlymore efficiently

Principle Skeletal MusclesPrinciple Skeletal Muscles

With over 700 skeletal muscles in the With over 700 skeletal muscles in the body, it will be easier to first learn body, it will be easier to first learn the naming system and then learn the naming system and then learn specific muscles region by regionspecific muscles region by region

Naming Skeletal MusclesNaming Skeletal Muscles

Muscles are named according to the Muscles are named according to the direction the fibers run, the size of direction the fibers run, the size of the muscle, the shape of the muscle, the muscle, the shape of the muscle, the action the muscle produces, the the action the muscle produces, the number of origins the muscle has number of origins the muscle has and/or the location of the muscleand/or the location of the muscle

DirectionsDirections

The following terms refer to the The following terms refer to the direction the muscle fibers run in direction the muscle fibers run in relation to the midline.relation to the midline.

RectusRectus

Parallel to the midlineParallel to the midline

TransverseTransverse

Perpendicular to the midlinePerpendicular to the midline

ObliqueOblique

Diagonal to the midlineDiagonal to the midline

SizeSize

Relative to other muscles in that Relative to other muscles in that groupgroup

MaximusMaximus

LargestLargest

MinimusMinimus

SmallestSmallest

Longus or LongissimusLongus or Longissimus

LongestLongest

LatissimusLatissimus

WidestWidest

MagnusMagnus

LargeLarge

MajorMajor

LargerLarger

MinorMinor

smallersmaller

VastusVastus

greatgreat

ShapeShape

General shape of the muscleGeneral shape of the muscle

DeltoidDeltoid

TriangleTriangle

TrapeziusTrapezius

TrapezoidTrapezoid

SerratusSerratus

Saw-toothedSaw-toothed

RhomboidRhomboid

Diamond ShapedDiamond Shaped

OrbicularisOrbicularis

CircularCircular

PectinatePectinate

Comb-likeComb-like

PiriformisPiriformis

Pear shapedPear shaped

PlatysPlatys

FlatFlat

QuadratusQuadratus

squaresquare

GracilisGracilis

slenderslender

ActionAction

Based on the action the muscle Based on the action the muscle performsperforms

Flexor/ExtensorFlexor/Extensor

Flexor – decreases the angle between Flexor – decreases the angle between bonesbones

Extensor – increases the angle between Extensor – increases the angle between bonesbones

Abductor/AdductorAbductor/Adductor

Abductor – moves a bone away from Abductor – moves a bone away from the midlinethe midline

Adductor – moves a bone toward the Adductor – moves a bone toward the midlinemidline

Levator/DepressorLevator/Depressor

Levator – elevates body partLevator – elevates body part Depressor – lowers body partDepressor – lowers body part

Supinator/PronatorSupinator/Pronator Supinator – turns palms upSupinator – turns palms up Pronator – turns palms downPronator – turns palms down

SphincterSphincter

Decreases the size of an openingDecreases the size of an opening

TensorTensor

Makes a body part rigidMakes a body part rigid

Number of OriginsNumber of Origins

Biceps – 2 headsBiceps – 2 heads

Triceps – 3 headsTriceps – 3 heads

Quadriceps – 4 headsQuadriceps – 4 heads

LocationLocation Muscles named for the Muscles named for the

structures that they structures that they are by. Examples are by. Examples include the include the sternocleidomastoid sternocleidomastoid muscle (runs from the muscle (runs from the sternum across the sternum across the clavicle to the mastoid clavicle to the mastoid process) and the process) and the temporalis (near the temporalis (near the temporal bone)temporal bone)