Transcript The Muscular System

Chapter 10
Understanding Muscles
 Pull never push
 Attach to skeleton via tendons or muscles via
aponeurosis
 Attachment points
 Origin: end attaches to a stationary bone; doesn’t move
 Insertion: end attaches to a moving bone; moves
 Contractions shorten muscles
Functional Groups
 Agonist (prime movers)
 Prime responsibility for causing a movement
 Antagonist
 Oppose/reverse movement
 Regulate agonist by adding resistance
 Synergist
 Assist prime mover
 Add extra force or reduce undesirable movement
 Fixators
 Immobilize bone or muscle origin
 Not mutually exclusive
Naming Muscles
 Location
 Bone or region associated w/
 Brachii and femoris
 Shape
 Deltoid and trapezius
 Size
 Maximus, minimus, longus
 Direction of fibers & fasicles
 Rectus, oblique, transversus
 Number of origins
 Biceps and triceps
 Location of attachment
 Points of origin &
insertion
 Sternocleidomastoid
 Action
 Flexor , extensor,
supinator
Fasicle Arrangement
 Determines range of mov’t &
power
 Types
 Parallel
 Parallel to long axis
 Pennate
 Short & attach obliquely to an
insertion tendon
 Uni-, bi-, or multi
 Convergent
 Broad origin converges to an
insertion
 Circular
 Concentric rings around external
openings
 Contractions close
Lever Systems
 A lever is a rigid bar moving on a fixed point (fulcrum)
when force is applied (effort) to move resistance (load)
 Bones = levers, joints = fulcrums, muscle contract = effort
at insertion, load = bone and everything else
 Mechanical advantage (power lever)
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Effort farther from load then fulcrum
Little effort needed
Force gained for speed and stability
E.g. car jack
 Mechanical disadvantage (speed lever)
 Effort nearer load then fulcrum
 Force lost for speed and range
 E.g. shovel
Classes of Levers
 First
 Second
 Uncommon in body
 Always advantage
 Third
 Most skeletal muscles
 Always disadvantage
Learning Muscles
 Need to know
 Names of major muscles
 Functions/actions of muscles

Table 10.1
 Location
 Studying
 Learn names
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Look for clues in names from existing knowledge
Draw and or act out
Identify on models or self
Muscles to Know
 Facial expression
 Frontalis
 Orbicularis oculi & oris
 Zygomaticus major
 Buccinator
 Platysma
 Extrinsic eye
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Superior, inferior, medial, lateral
rectus
Superior & inferior oblique
 Mastication
 Masseter
 Temporalis
 Pterygoid
 Moving head & deep to back
 Sternocleidomastoid
 Capitis group
 Erector spinae group
 Abdominal wall
 Rectus abdominis
 External & internal oblique
 Transverse abdominis
 Scapula
 Trapezius
 Serratus anterior
 Pectoralis minor
 Levator scapula
 Rhomboids major & minor
 Humerus
 Pectoralis major
 Latissimus dorsi
 Deltoid
 Supraspinatus
 Infraspinatus
 Subscapularis
 Teres major
 Forearm
 Brachialis
 Brachioradialis
 Biceps & triceps brachii
 Supinator
 Pronator teres
Muscles to Know (cont.)
 Wrist
 Flexor carpi radialis & ulnaris
 Extensor carpi radialis & ulnaris
 Fingers
 Flexor digitorum superficialis &
profundus
 Extensor digitorum
 Thumb
 Extensor pollicis longus & brevis
 Abductor pollicis longus & brevis
 Breathing
 Diphragm
 External & internal intercostals
 Pelvic floor
 Coccygeus group
 Levator ani
 External anal sphincter
 Femur at hip
 Illiacus & psoas major (Iliopsoas)
 Gluteus maximus, medius, &
minimus
 Adductor group
 Thigh
 Gracilis
 Sartorius
 Leg at knee
 Quadriceps femoris
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Rectus femoris
Vastus intermedius, lateralis, and
medialis
 Hamstrings
 Semitendinosus
 Semimembranosus
 Biceps femoris
Muscles to Know (cont.)
 Foot at ankle
 Gastrocnemius
 Soleus
 Tibialis anterior & posterior
 Fibularus group (peroneus muscles)
 Toes
 Flexor & extensor digitorum longus
 Flexor & extensor hallucis longus