chapter 6: the muscular system
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Chapter 6: The Muscular System. Anatomy & Physiology. Five Golden Rules of Skeletal Muscle Activity. Muscles and Body Movements. Movement can occur because muscles attach to our bones Muscles are attached to at least two points known as: Origin Attachment to a moveable bone Insertion - PowerPoint PPT PresentationTRANSCRIPT
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Anatomy & Physiology
Chapter 6: The Muscular System
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Five Golden Rules of Skeletal Muscle Activity
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Movement can occur because muscles attach to our bones
Muscles are attached to at least two points known as:Origin
Attachment to a moveable boneInsertion
Attachment to an immovable bone
Muscles and Body Movements
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TYPES OF BODY MOVEMENTSFlexion
Decreases the angle of the joint
Brings two bones closer together
Typical of hinge joints like knee and elbow
ExtensionOpposite of flexionIncreases angle
between two bones
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TYPES OF BODY MOVEMENTSRotation
Movement of a bone around its longitudinal axis
Common in ball-and-socket joints
Example is when you move atlas around the dens of axis (shake your head “no”)
Internal Rotation: Moving towards the midline around an axis of rotation
External Rotation: Moving away from the midline around an axis of rotation
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TYPES OF BODY MOVEMENTSAbduction
Movement of a limb AWAY from the midline
AdductionOpposite of
abductionMovement of a limb
TOWARD the midline
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CircumductionCombination of flexion, extension, abduction,
and adductionCommon in ball-and-socket jointsMoving in a “circular” motion
TYPES OF BODY MOVEMENTS
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These movements are only specific to the ankle:Dorsiflexion
Lifting the foot so that the superior surface approaches the shin
Plantar flexionDepressing the foot (pointing the toes)Moving foot downward as if you’re pushing on a gas pedal.
InversionTurn sole of foot medially/inwards/towards body
EversionTurn sole of foot laterally/outwards/away from body
Special Movements
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Special MovementsThese movements
are specific to the elbow joint
SupinationForearm rotates
laterally so palm faces anteriorly
PronationForearm rotates
medially so palm faces posteriorly
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Special MovementsThis movement is
specific to the phalanges
OppositionMove thumb to
touch the tips of other fingers on the same hand
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Prime mover—muscle with the major responsibility for a certain movement i.e. biceps brachii is mainly responsible for flexion of the
elbow jointAntagonist—muscle that opposes or reverses a prime
mover i.e. triceps does the opposite of flexion and helps extend
the elbow jointSynergist—muscle that aids a prime mover in a
movement and helps prevent rotation i.e. biceps brachii also does shoulder flexion and receives
help from the anterior deltoidFixator—stabilizes the origin of a prime mover
Terms of Muscle Descriptors
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NAMING OF SKELETAL MUSCLESBy direction of muscle
fibersExample: Rectus (straight)
By relative size of the muscleExample: Maximus
(largest)By location of the muscle
Example: Temporalis (temporal bone)
By number of originsExample: Triceps (three
heads)
By location of the muscle’s origin and insertionExample: Sterno (on
the sternum)By shape of the muscle
Example: Deltoid (triangular)
By action of the muscleExample: Flexor and extensor (flexes or extends a bone)
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ARRANGEMENT OF FIBERS
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Facial muscles Frontalis—raises eyebrows Orbicularis oculi—closes eyes, squints, blinks, winks Orbicularis oris—closes mouth and protrudes the lips Buccinator—flattens the cheek, chews Zygomaticus—raises corners of the mouth
Chewing muscles Masseter—closes the jaw and elevates mandible Temporalis—synergist of the masseter, closes jaw
Neck muscles Platysma—pulls the corners of the mouth inferiorly Sternocleidomastoid—flexes the neck, rotates the head
Head and Neck Muscles
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Anterior musclesPectoralis major—adducts and flexes the
humerusIntercostal muscles
External intercostals—raise rib cage during inhalation
Internal intercostals—depress the rib cage to move air out of the lungs when you exhale forcibly
Muscles of Trunk, Shoulder, Arm
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Anterior Muscles of Trunk, Shoulder, Arm
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Muscles of TrunkMuscles of the abdominal
girdleRectus abdominis—flexes
vertebral column and compresses abdominal contents (defecation, childbirth, forced breathing)
External and internal obliques—flex vertebral column; rotate trunk and bend it laterally
Transversus abdominis—flexes trunk diagonally
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Muscles of the Shoulder and ArmPosterior muscles
Trapezius—elevates, depresses, adducts, and stabilizes the scapula
Latissimus dorsi—extends and adducts the humerus
Erector spinae—back extension
Quadratus lumborum—flexes the spine laterally (side-to side)
Deltoid—arm abduction
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Biceps brachii: flexes shoulder and elbow jointBrachialis: flexes the elbow joint
Think “reverse curls”
Brachioradialis: helps with elbow flexion in conjunction with radial deviation
Triceps brachii—elbow extension (antagonist to biceps brachii)
Muscles of the Upper Limb
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Muscles of the Lower LimbGluteus maximus—hip
extensionGluteus medius—hip
abduction, steadies pelvis when walking
Iliopsoas—hip flexion & knee extension, keeps the upper body from falling backward when standing erect
Adductor muscles—adduct the thighs
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Muscles of the Lower LimbMuscles causing
movement at the knee and hip jointHamstring group—
hip extension and knee flexionBiceps femorisSemimembranosusSemitendinosus
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Muscles of the Lower LimbMuscles causing
movement at the knee jointSartorius—flexes the
hip and externally rotates
Quadriceps group—extends the kneeRectus femorisVastus muscles (three)
Vastus medialisVastus lateralisVastus intermedius
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Muscles of the Lower LimbMuscles causing movement at
ankle and foot Tibialis anterior—dorsiflexion
and foot inversion Extensor digitorum longus—
toe extension and dorsiflexion of the foot
Soleus—plantar flexion Fibularis muscles are
commonly known as Peroneals Peroneus brevis Peroneus longus Peroneus tertius
*Perform eversion of the foot/ankle
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Anterior Muscles
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Posterior Muscles