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Muscular SystemMuscular System
Essential QuestionEssential Question
• How does the muscular system support human life?
• How does the muscular system support human life?
Muscular SystemMuscular System
• Muscles are responsible for all types of body movement.
• There are more than 600 individual muscles.
• Together muscles are about 40 % of our weight.
• Muscles are responsible for all types of body movement.
• There are more than 600 individual muscles.
• Together muscles are about 40 % of our weight.
Muscular SystemMuscular System
•Three types of muscle–Skeletal–Smooth–Cardiac
•Three types of muscle–Skeletal–Smooth–Cardiac
Skeletal MusclesSkeletal Muscles
• Generally attached to bone by tendon• Voluntary Muscle ~ controlled by
choice• Produce movement• Maintain body posture• Stabilize joints• Produce heat ~ thus help to maintain
body temperature
• Generally attached to bone by tendon• Voluntary Muscle ~ controlled by
choice• Produce movement• Maintain body posture• Stabilize joints• Produce heat ~ thus help to maintain
body temperature
Skeletal MusclesSkeletal Muscles• Cell structure:
– Long– Shaped like cylinders or tubes– Composed of proteins arranged to make the
muscle appear striped or striated.
• Contraction ~ tightening of muscles to induce movement
• Contraction can be slow or fast with no rhythm
• Cell structure:– Long– Shaped like cylinders or tubes– Composed of proteins arranged to make the
muscle appear striped or striated.
• Contraction ~ tightening of muscles to induce movement
• Contraction can be slow or fast with no rhythm
Smooth MuscleSmooth Muscle• Found mainly in the walls of the viscera
~ hollow organs• Often called visceral muscle• Functions automatically ~ involuntary
muscle• Governs movement of respiration,
urination and digestion • Nonstriated ~ does not appear striped
• Found mainly in the walls of the viscera ~ hollow organs
• Often called visceral muscle• Functions automatically ~ involuntary
muscle• Governs movement of respiration,
urination and digestion • Nonstriated ~ does not appear striped
Smooth MuscleSmooth Muscle• Smooth muscle contraction slower
and more rhythmic than skeletal muscle
• Smooth muscle more stretchy than skeletal muscle– Allows for uterus, bladder and
stomach to expand• Smooth muscle has a better
capacity for regeneration than does skeletal muscle.
• Smooth muscle contraction slower and more rhythmic than skeletal muscle
• Smooth muscle more stretchy than skeletal muscle– Allows for uterus, bladder and
stomach to expand• Smooth muscle has a better
capacity for regeneration than does skeletal muscle.
Cardiac MuscleCardiac Muscle• Found only in the heart• Cell structure
– Cells are long branching and fit together tightly at junctions.
– Classified as striated.
• Found only in the heart• Cell structure
– Cells are long branching and fit together tightly at junctions.
– Classified as striated.
Cardiac MuscleCardiac Muscle• Involuntary contractions• Contracts to pump blood
throughout the body.• Contractions are slow• Have no capacity for regeneration
• Involuntary contractions• Contracts to pump blood
throughout the body.• Contractions are slow• Have no capacity for regeneration
How muscles contractHow muscles contract• Muscles can only pull, not push!• To pull, muscles contract.• When muscles contract they
shorten.• Muscles shorten because the
muscles fibers slide past each other.– The sliding is like a trombone
• Muscles can only pull, not push!• To pull, muscles contract.• When muscles contract they
shorten.• Muscles shorten because the
muscles fibers slide past each other.– The sliding is like a trombone
HandoutHandout
• How a Muscle Works• How a Muscle Works
Muscle Contraction
Muscle TermsMuscle Terms• Origin and Insertion ~ refer to
the sites of muscle attachment• When muscles contract across a
joint, one bone remains relatively stationary or immovable.
• The ORIGIN attaches to the stationary bone
• The INSERTION attaches to the more moveable bone.
• Origin and Insertion ~ refer to the sites of muscle attachment
• When muscles contract across a joint, one bone remains relatively stationary or immovable.
• The ORIGIN attaches to the stationary bone
• The INSERTION attaches to the more moveable bone.
Muscle TermsMuscle Terms• Hypertrophy ~ increase in size of a
muscle– Due to overuse– Purposely done by athletes
• Atrophy ~ decrease in size of a muscle– Wasting away– Lack of exercise : broken leg– Normal aging process
• Delayed with exercise
• Hypertrophy ~ increase in size of a muscle– Due to overuse– Purposely done by athletes
• Atrophy ~ decrease in size of a muscle– Wasting away– Lack of exercise : broken leg– Normal aging process
• Delayed with exercise
Muscle TermsMuscle Terms
• Contracture ~ an abnormal formation of fibrous tissue within the muscle.– Occurs when a muscle is immobilized
for a prolonged period of time.– “Freezes the muscle in a flexed
position and severely restricts joint mobility
• Contracture ~ an abnormal formation of fibrous tissue within the muscle.– Occurs when a muscle is immobilized
for a prolonged period of time.– “Freezes the muscle in a flexed
position and severely restricts joint mobility
Muscle TermsMuscle Terms• Most movement is performed by groups
of muscles working together; however, a single muscle is generally responsible for MOST of the movement.
• Prime mover ~ Chief muscle (responsible for movement)
• Snyergist ~ helper muscles• Antagonists ~ oppose the action of
another muscle• Muscle pairs
• Most movement is performed by groups of muscles working together; however, a single muscle is generally responsible for MOST of the movement.
• Prime mover ~ Chief muscle (responsible for movement)
• Snyergist ~ helper muscles• Antagonists ~ oppose the action of
another muscle• Muscle pairs
FlashcardsFlashcards• Smooth Muscle Prime mover• Cardiac Muscle Snyergist• Skeletal Muscle Antagonist• Hypertrophy• Atrophy• Contracture
• Smooth Muscle Prime mover• Cardiac Muscle Snyergist• Skeletal Muscle Antagonist• Hypertrophy• Atrophy• Contracture
Types of Muscle/Joint MovementTypes of Muscle/Joint Movement•Movements at freely
movable joints occur when the muscles that lie across the joints contract and exert pressure on the attached bone.
•Movements at freely movable joints occur when the muscles that lie across the joints contract and exert pressure on the attached bone.
Skeletal Muscle MovementSkeletal Muscle Movement
• Flexion ~ Bending of a joint that decreases the angle between the bones.– Bending of a leg at the knee
• Extension ~ Straightening of a joint so that the angle between the bones increases.– Straightening the leg at the knee
• Flexion ~ Bending of a joint that decreases the angle between the bones.– Bending of a leg at the knee
• Extension ~ Straightening of a joint so that the angle between the bones increases.– Straightening the leg at the knee
Skeletal Muscle MovementSkeletal Muscle Movement
• Plantar Flexion ~ Bending the foot down– Toe dancing
• Dorsiflexion ~ Bending to the foot up towards the leg
• Hyperextention ~ Overextending the joint beyond its normally straightened position.– Bending the wrist back
• Plantar Flexion ~ Bending the foot down– Toe dancing
• Dorsiflexion ~ Bending to the foot up towards the leg
• Hyperextention ~ Overextending the joint beyond its normally straightened position.– Bending the wrist back
Skeletal Muscle MovementSkeletal Muscle Movement
• Abduction ~ movement away from the midline of the body.– Move leg sideways
• Adduction ~ movement toward the midline of the body– Move leg toward your body
• Inversion ~ turning the sole of the foot inward so it faces the opposite foot.
• Abduction ~ movement away from the midline of the body.– Move leg sideways
• Adduction ~ movement toward the midline of the body– Move leg toward your body
• Inversion ~ turning the sole of the foot inward so it faces the opposite foot.
Skeletal Muscle MovementSkeletal Muscle Movement• Eversion ~ turning the sole of the foot
outward.• Supination ~ turning the hand so that
the palm faces upward• Pronation ~ turning the hand so that
the palm faces downward• Rotation ~ rotate or move around an
axis• Circumduction ~ combination of
movements performed by extremities in a circular motion.
• Eversion ~ turning the sole of the foot outward.
• Supination ~ turning the hand so that the palm faces upward
• Pronation ~ turning the hand so that the palm faces downward
• Rotation ~ rotate or move around an axis
• Circumduction ~ combination of movements performed by extremities in a circular motion.
How Skeletal Muscles are NamedHow Skeletal Muscles are Named• Skeletal muscles are generally named
for one of the following characteristics.– Size– Shape– Direction of fibers– Location– Number of origins– Origin and insertion– Muscle action
• Skeletal muscles are generally named for one of the following characteristics.– Size– Shape– Direction of fibers– Location– Number of origins– Origin and insertion– Muscle action
SizeSize
• Vastus ~ huge• Maximus ~ large• Longus ~ long• Minimus ~ small• Brevis ~ short
• Vastus ~ huge• Maximus ~ large• Longus ~ long• Minimus ~ small• Brevis ~ short
ShapeShape
• Deltoid ~ triangular• Latissimus ~ wide• Trapezius ~ trapezoid• Rhomboideus ~ rhomboid• Teres ~ round
• Deltoid ~ triangular• Latissimus ~ wide• Trapezius ~ trapezoid• Rhomboideus ~ rhomboid• Teres ~ round
Directions of FibersDirections of Fibers
• Fibers are oriented or lined up, in several directions
• Rectus ~ straight• Oblique ~ diagonal• Transverse ~ across• Circularis ~ circular
• Fibers are oriented or lined up, in several directions
• Rectus ~ straight• Oblique ~ diagonal• Transverse ~ across• Circularis ~ circular
LocationLocation
• Pectoralis ~ chest• Gluteus ~ buttock• Branchii ~ arm• Supra ~ above• Infra ~ below• Sub ~ underneath• Lateralis ~ lateral
• Pectoralis ~ chest• Gluteus ~ buttock• Branchii ~ arm• Supra ~ above• Infra ~ below• Sub ~ underneath• Lateralis ~ lateral
Number of OriginsNumber of Origins
• Muscles can be named according to the number of sites to which it is anchored.– Biceps– Triceps– Quadriceps
• Muscles can be named according to the number of sites to which it is anchored.– Biceps– Triceps– Quadriceps
Origin and InsertionOrigin and Insertion
• Named for sites of attachment both at their origin and insertion– Sternocleidomatoid ~ origin on
the sternum and clavicle…..insertion on the mastoid process of the temporal bone
• Named for sites of attachment both at their origin and insertion– Sternocleidomatoid ~ origin on
the sternum and clavicle…..insertion on the mastoid process of the temporal bone
Muscle ActionMuscle Action
• How the muscle moves the body
• Abductor ~ moves the limb away from the midline
• Flexor ~ causes flexion• Levator ~ elevates
• How the muscle moves the body
• Abductor ~ moves the limb away from the midline
• Flexor ~ causes flexion• Levator ~ elevates
The Facial MusclesThe Facial Muscles
• Inserted directly into the soft tissue of the skin and other muscles of the face.
• Contraction pulls on the soft tissue–Responsible for our facial expressions
• Inserted directly into the soft tissue of the skin and other muscles of the face.
• Contraction pulls on the soft tissue–Responsible for our facial expressions
Facial MusclesFacial Muscles• Frontalis ~ covers the frontal bone
– Contraction raises the eyebrows and wrinkles the forehead
• Frontalis ~ covers the frontal bone– Contraction raises the eyebrows and
wrinkles the forehead
Facial MusclesFacial Muscles
• Orbicularis oculi ~ sphincter muscle that encircles the eyes.– Sphincter ~ a ring-shaped muscle
that controls the size of an opening– Contraction closes the eye, winking,
blinking
• Orbicularis oculi ~ sphincter muscle that encircles the eyes.– Sphincter ~ a ring-shaped muscle
that controls the size of an opening– Contraction closes the eye, winking,
blinking
Facial MusclesFacial Muscles• Orbicularis oris ~ sphincter
muscle that encircles the mouth.– Contraction assists in closing the
mouth, forming words and pursing the lips
– Sometimes called the kissing muscle
• Orbicularis oris ~ sphincter muscle that encircles the mouth.– Contraction assists in closing the
mouth, forming words and pursing the lips
– Sometimes called the kissing muscle
Facial MusclesFacial Muscles
• Buccinator ~ origin is the mandible and maxilla. Inserts on the orbicularis oris.– Used in sucking, whistling and playing
the trumpet
• Buccinator ~ origin is the mandible and maxilla. Inserts on the orbicularis oris.– Used in sucking, whistling and playing
the trumpet
Facial MusclesFacial Muscles
• Zygomaticus ~ extends from the corners of the mouth to the cheekbones– Smiling muscle
• Zygomaticus ~ extends from the corners of the mouth to the cheekbones– Smiling muscle
Facial MuscleFacial Muscle• Platysma ~ Originates in the
fascia of the shoulder and inserts on the mandible– Fascia ~ fibrous tissue enclosing a
muscle
• Responsible for pouting and opening your mouth wide.
• Platysma ~ Originates in the fascia of the shoulder and inserts on the mandible– Fascia ~ fibrous tissue enclosing a
muscle
• Responsible for pouting and opening your mouth wide.
Chewing MusclesChewing Muscles
• Muscles of mastication ~ chewing
• All are inserted on the mandible• Some are the strongest muscles of
the body
• Muscles of mastication ~ chewing
• All are inserted on the mandible• Some are the strongest muscles of
the body
Chewing MusclesChewing Muscles
• Masseter ~ origin on the temporal bone– Contraction closes the jaw
• Masseter ~ origin on the temporal bone– Contraction closes the jaw
Muscles of the NeckMuscles of the Neck• Sternocleidomastoid ~ extends
from sternum and clavicle to the mastoid process of the temporal bone– Contraction causes flexion of the
head•Praying muscle
• Sternocleidomastoid ~ extends from sternum and clavicle to the mastoid process of the temporal bone– Contraction causes flexion of the
head•Praying muscle
Muscles of the TrunkMuscles of the Trunk
• Involved in breathing• Form the abdominal wall• Move the vertebral column• Form the pelvic region
• Involved in breathing• Form the abdominal wall• Move the vertebral column• Form the pelvic region
Muscles for BreathingMuscles for Breathing• Intercostal Muscles ~ located
between the ribs– Origin and insertion on the ribs– Responsible for raising and lowering
the rib cage during breathing
• Intercostal Muscles ~ located between the ribs– Origin and insertion on the ribs– Responsible for raising and lowering
the rib cage during breathing
Muscles for BreathingMuscles for Breathing
• Diaphragm ~ dome-shaped muscle that separates the thoracic cavity from the abdominal cavity– Chief muscle of inhalation
• Diaphragm ~ dome-shaped muscle that separates the thoracic cavity from the abdominal cavity– Chief muscle of inhalation
Muscles of the Abdominal WallMuscles of the Abdominal Wall• Consists of 4 muscles• Muscles are layered at different depths
– Fibers of these muscles run in different directions
• Contain, support and protect abdominal organs
• Contraction causes flexion and rotation of vertebral column, urination, defecation, and childbirth.
• Consists of 4 muscles• Muscles are layered at different depths
– Fibers of these muscles run in different directions
• Contain, support and protect abdominal organs
• Contraction causes flexion and rotation of vertebral column, urination, defecation, and childbirth.
Abdominal MusclesAbdominal Muscles• Rectus abdominis ~ fibers run
up and down– Contraction flexes the vertebrae– Increases intra-abdominal
pressure
• Rectus abdominis ~ fibers run up and down– Contraction flexes the vertebrae– Increases intra-abdominal
pressure
Abdominal Wall MusclesAbdominal Wall Muscles• External oblique ~ lateral walls
of the abdomen– Fibers run obliquely (slanted)– Aids rectus abdominus (trunk
rotation/lateral flexion)
• External oblique ~ lateral walls of the abdomen– Fibers run obliquely (slanted)– Aids rectus abdominus (trunk
rotation/lateral flexion)
Abdominal Wall MusclesAbdominal Wall Muscles• Internal oblique ~ add strength
to the external oblique (crisscross with them)
• Internal oblique ~ add strength to the external oblique (crisscross with them)
Abdominal Wall MusclesAbdominal Wall Muscles• Transversus abdominis ~ fibers
run horizontally– Innermost layer of the abdominal
muscles– Responsible for compression
• Transversus abdominis ~ fibers run horizontally– Innermost layer of the abdominal
muscles– Responsible for compression
Muscles of the Vertebral ColumnMuscles of the Vertebral Column• Attach to the vertebrae• Move the vertebral column in
numerous directions• Numerous muscles….will not
discuss in detail.
• Attach to the vertebrae• Move the vertebral column in
numerous directions• Numerous muscles….will not
discuss in detail.
Muscles of the Pelvic FloorMuscles of the Pelvic Floor• Assist in expelling contents from
the urinary bladder and rectum• Will not be discussed in detail
• Assist in expelling contents from the urinary bladder and rectum
• Will not be discussed in detail
Muscles of the ShoulderMuscles of the Shoulder
Trapezius ~ origin in bases of the occipital bone and inserts on the scapula and clavicle– Hyperextends head– Contraction allows for shrugging
and rotating movement
–Right and left trapezius form the shape of a trapezoid
Trapezius ~ origin in bases of the occipital bone and inserts on the scapula and clavicle– Hyperextends head– Contraction allows for shrugging
and rotating movement
–Right and left trapezius form the shape of a trapezoid
Muscles of the ShoulderMuscles of the Shoulder• Pectoralis Major ~ forms the
anterior chest wall– Connects the humerus with the
clavicle and sternum– Contraction moves the arm
across the chest•Adducts the arm
• Pectoralis Major ~ forms the anterior chest wall– Connects the humerus with the
clavicle and sternum– Contraction moves the arm
across the chest•Adducts the arm
Muscles of the ShoulderMuscles of the Shoulder• Deltoid ~ forms the rounded
portion of your shoulder (shoulder pad)– Contraction abducts the arm
• Deltoid ~ forms the rounded portion of your shoulder (shoulder pad)– Contraction abducts the arm
Muscles of the ShoulderMuscles of the Shoulder• Latissimus dorsi ~ Broad muscle
located in the middle and lower back region.
• Origin vertebrae, insertion humerus
• Adducts shoulders and extends arm back.
• “Swimmers muscle”
• Latissimus dorsi ~ Broad muscle located in the middle and lower back region.
• Origin vertebrae, insertion humerus
• Adducts shoulders and extends arm back.
• “Swimmers muscle”
Muscles that Move the ForearmMuscles that Move the Forearm• Most are located along the humerus• Triceps brachii ~ located on the
posterior surface of the humerus.– Prime mover of extension of the
forearm– Supports weight for push-ups– Boxer muscle ~ packs the greatest
punch
• Most are located along the humerus• Triceps brachii ~ located on the
posterior surface of the humerus.– Prime mover of extension of the
forearm– Supports weight for push-ups– Boxer muscle ~ packs the greatest
punch
Muscles that Move the ForearmMuscles that Move the Forearm• Biceps brachii ~ located along
the anterior surface of the humerus.
• Flexes the forearm• “Make a muscle”
• Biceps brachii ~ located along the anterior surface of the humerus.
• Flexes the forearm• “Make a muscle”
Muscles that Move the ForearmMuscles that Move the Forearm• Branchioradialis ~ synergist of
biceps branchii• Origin on humerus, Inserts on
radius• Flexes forearm at elbow
• Branchioradialis ~ synergist of biceps branchii
• Origin on humerus, Inserts on radius
• Flexes forearm at elbow
Muscles that Move the Wrist, Hand, and Fingers
Muscles that Move the Wrist, Hand, and Fingers• More than 20 muscles• Small which makes for delicate
movement• Generally located along the forearm• The tendons of these muscles pass
through the wrist into the hand and fingers.
• More than 20 muscles• Small which makes for delicate
movement• Generally located along the forearm• The tendons of these muscles pass
through the wrist into the hand and fingers.
Muscles that Move the Wrist, Hand, and Fingers
Muscles that Move the Wrist, Hand, and Fingers• Flexor digitorum ~ flexes fingers
– Anterior muscle
• Flexor digitorum ~ flexes fingers– Anterior muscle
Muscles that Move the Wrist, Hand, and Fingers
Muscles that Move the Wrist, Hand, and Fingers
• Extensor digitorum ~ extends fingers– Posterior muscle
• Extensor digitorum ~ extends fingers– Posterior muscle
Carpal Tunnel SyndromeCarpal Tunnel Syndrome
Muscles that Move the Thigh, Leg, and FootMuscles that Move the Thigh, Leg, and Foot• Some of the largest and strongest
muscles of the body• Move the lower extremities• Help maintain posture
• Some of the largest and strongest muscles of the body
• Move the lower extremities• Help maintain posture
Muscles that Move the Femur (thighbone)Muscles that Move the Femur (thighbone)• All attach to some part of the
pelvic girdle (coxal bones) and the femur.
• Contraction of these muscles moves the hip joint
• All attach to some part of the pelvic girdle (coxal bones) and the femur.
• Contraction of these muscles moves the hip joint
Gluteal MusclesGluteal Muscles• Located on the posterior surface• Gluteus maximus ~ forms the
area of the buttocks– Largest muscle of the body– Rotates the thigh laterally and
extends the thigh at the hip (walking, stair climbing)
• Located on the posterior surface• Gluteus maximus ~ forms the
area of the buttocks– Largest muscle of the body– Rotates the thigh laterally and
extends the thigh at the hip (walking, stair climbing)
Gluteal MusclesGluteal Muscles
• Gluteus medius ~ abduct and rotate the thigh medially at the hip
• Gluteus medius ~ abduct and rotate the thigh medially at the hip
Muscles that Move the LegMuscles that Move the Leg
• Located on the thigh• Extensor muscles lie along the
anterior and lateral surfaces.• Flexors lie along the posterior and
medial surfaces
• Located on the thigh• Extensor muscles lie along the
anterior and lateral surfaces.• Flexors lie along the posterior and
medial surfaces
Muscles that Move the LegMuscles that Move the Leg• Quadriceps Femoris ~ located on the
anterior thigh– Most powerful muscle in the body– Contain four different parts
• Vastus lateralis• Vastus intermedius• Vastus medialis• Rectus femoris
– All four parts cause extension of the leg at the knee
• Quadriceps Femoris ~ located on the anterior thigh– Most powerful muscle in the body– Contain four different parts
• Vastus lateralis• Vastus intermedius• Vastus medialis• Rectus femoris
– All four parts cause extension of the leg at the knee
Quadriceps FemorisQuadriceps Femoris
• Vastus lateralis • Vastus lateralis
Quadriceps FemorisQuadriceps Femoris
• Vastus intermedius ~ sits directly below the rectus femoris
• Vastus intermedius ~ sits directly below the rectus femoris
Quadriceps FemorisQuadriceps Femoris
• Vastus medialis• Vastus medialis
Muscles that Move the LegMuscles that Move the Leg• Sartorius ~ crosses over anterior
thigh– Allows you to sit in cross leg position– Laterally rotates thigh at hip
• Sartorius ~ crosses over anterior thigh– Allows you to sit in cross leg position– Laterally rotates thigh at hip
Muscles that Move the LegMuscles that Move the Leg• Hamstrings ~ located on the
posterior surface of the thigh– Contain three different parts
•Biceps femoris•Semimembranosus•semitendinosus
• Hamstrings ~ located on the posterior surface of the thigh– Contain three different parts
•Biceps femoris•Semimembranosus•semitendinosus
HamstringsHamstrings
– Flex the leg at the knee– Extend the thigh– Strong tendons of these muscles
can be felt behind the knee
– Flex the leg at the knee– Extend the thigh– Strong tendons of these muscles
can be felt behind the knee
HamstringsHamstrings
• Biceps femoris• Biceps femoris
HamstringsHamstrings
• Semimembranosus• Semimembranosus
HamstringsHamstrings
• Semitendinosus• Semitendinosus
Muscles that Move the FootMuscles that Move the Foot
• Located on the anterior, lateral, and posterior surfaces of the leg
• Tibialis anterior ~ located on anterior surface– Causes dorsiflexion and inversion of
the foot
• Located on the anterior, lateral, and posterior surfaces of the leg
• Tibialis anterior ~ located on anterior surface– Causes dorsiflexion and inversion of
the foot
Muscles that Move the FootMuscles that Move the Foot• Gastronemius ~ forms the calf of
the leg– Attach to the heel bone by the
Achilles tendon• Strongest tendon in the body
– Causes plantar flexion– Toe dancer muscle
• Gastronemius ~ forms the calf of the leg– Attach to the heel bone by the
Achilles tendon• Strongest tendon in the body
– Causes plantar flexion– Toe dancer muscle
