Muscular System
2012-2013
Vocab development
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Calat- something inserted
Erg- work
Fasc- bundle
-gram- something written
Hyper- over, more
inter;- between
Iso-equal
Laten- hidden
Myo- muscle
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Reticul- a net
Sarco- flesh
Syn- together
Tetan- stiff
-tonic- stretched
-troph- well fed
Voluntar- of one’s free
will
Introduction
• Muscles are organs made of cells that use
chemical energy stored in nutrients to exert a
force on the structures they are attached to.
• Muscle actions provide:
– Muscle tone
– Propel body fluids and food
– Generate the heartbeat
– Distribute heat
Introduction
• 3 types of muscle
– Skeletal
– Smooth
– Cardiac
Structure of Skeletal Muscle
• Composed mostly of skeletal muscle tissue,
nervous tissue, blood, and other connective
tissues
• Layers of connective tissue enclose and
separate all parts of a skeletal muscle allowing
the parts to move somewhat independently.
Skeletal Muscle: Connective Tissue
Coverings
• Fascia
– Separates a muscle from its adjacent muscles;
covers the whole muscle
• Tendon
– Connect a muscle to a bone
• Aponeuroses
– connects muscle to bone and other muscles
Skeletal Muscle: Connective Tissue
Coverings
• Epimysium
– Closely surrounds a skeletal muscle
• Perimysium
– Extends inward from epimysium & separates the
muscle tissue into small sections called fascicles
• Endomysium
– Each muscle fiber within a fascicle is covered by
this
Skeletal Muscle Fibers
• Each muscle fiber forms from many
undifferentiated cells that fuse together
• Each muscle fiber is multinucleate
• Shaped like a long, thin cylinder with rounded
ends
• Sarcolemma- just beneath the muscle cell
membrane
• Sarcoplasm- cytoplasm of the fiber
Skeletal Muscle Fibers
• Myofibrils
– Bundles of threadlike structures found within muscle
fibers
– Fundamental in the muscle contraction mechanism
– Consist of 2 types of proteins
• Myosin- thick filaments
• Actin- thin filaments
– Alternating of the myosin & actin causes the striations
found in skeletal muscle
• Sarcomeres- repeating patterns of striations along each
muscle fiber
Skeletal Muscle Fibers
Skeletal Muscle Fibers
Skeletal Muscle Fibers
• Sarcoplasmic reticulum
– Within the sarcoplasm of a muscle fiber
– Network of channels that surrounds each
myofibril
Skeletal Muscle Contraction
• Complex interaction of cellular and chemical
pieces
• The result is movement within the myofibrils
where the filaments of actin and myosin slide
past each other causing the sarcomere to
shorten
Skeletal Muscle Contraction
• Energy Sources
– ATP
• Muscle fiber only has enough ATP to contract briefly so
it must be able to regenerate ATP
– Creatine Phosphate
• Initial source of energy to regenerate ATP
• Much more abundant in muscle fibers than ATP, but it
cannot supply energy directly to the cell
– Cellular Respiration
Skeletal Muscle Contraction
• 10 steps to muscle contraction
1. An action potential is conducted down a motor
neuron axon
2. The motor neuron terminal releases the
neurotransmitter acetylcholine (ACh)
3. ACh binds to ACh receptors on the muscle fiber
4. The sarcolemma is stimulated, an action potential
is generated, and the impulse is conducted over
the surface of the muscle fiber and deep into the
fiber through the transverse tubules.
Skeletal Muscle Contraction
5. The impulse reaches the sarcoplasmic reticulum, and
calcium channels open.
6. Calcium ions diffuse from the sarcoplasmic reticulum
into the sarcoplasm and bind to tropin molecules.
7. Tropomyosin molecules move and expose specific
sites on actin.
8. Actin and myosin link, forming cross-bridges.
9. Thin (actin) filaments are pulled toward the center of
the sarcomere by myosin cross-bridges increasing the
overlap of the thin and thick filaments.
10. The muscle fiber contracts.
Skeletal Muscle Relaxation
• 1. Acetylcholinesterase decomposes acetylcholine, and
the muscle fiber membrane is no longer stimulated.
• 2. Calcium ions are actively transported into the
sarcoplasmic reticulum.
• 3. ATP breaks linkages between actin and myosin
filaments without breakdown of ATP itself
• 4. Breakdown of ATP “cocks” the myosin heads.
• 5. Troponin and tropomyosin molecules inhibit the
interaction between myosin and actin filaments.
• 6. Muscle fiber remains relaxed until it is stimulated
again.
Muscle Fatigue
• Caused by
– Decreased blood flow
– Ion imbalances due to repeated stimulation
– Psychological loss of desire to continue
– Lactic acid accumulation
– Oxygen debt
• Lactic acid accumulation
– Accumulates in the muscles when ATP production
goes from aerobic to anaerobic
Muscular Responses
• Threshold Stimulus
– A muscle fiber remains unresponsive until a
certain strength of stimulation is reached, once
this is reached an action potential is generated
and the process of muscle contraction begins
Muscular Responses
• Recording a Muscle Contraction
Muscular Responses
• Summation
–
Muscular Responses
• Types of Contractions
– Isotonic Contractions (equal force –change in
length)—allow you to move things
• Concentric-muscle contracts with greater force than
resistance and shortens
• Eccentric- muscle contracts with less force than
resistance and lengthens
– Isometric Contractions – (equal length- change in
force) – allow you to sit and hold your posture
Muscular Responses
• Fast & Slow Twitch Muscle Fibers
– 3 types
• Slow twitch fibers (red fibers)
– Produce ATP from oxygen making them more resistant to fatigue
– These fibers can contract for long periods of time without fatigue
• Fast twitch fibers (white fibers)
– Produce ATP primarily through glycolysis
– Can contract rapidly but also fatigue rapidly as lactic acid
accumulates in them
• Intermediate Fibers (white fibers)
– Can contract rapidly and also have a larger respiratory capacity so
they don’t fatigue like fast-twitch fibers
Smooth Muscles
• Smooth muscles lack striations
• Cells have only one nucleus
• 2 major types of smooth muscles
– Multiunit
– Visceral
Smooth Muscles
• Multiunit Smooth Muscle
– Muscle fibers function as separate units
– Found in the irises of the eyes & walls of large
blood vessels
– Contract after stimulation by neurons or certain
hormones
Smooth Muscles
• Visceral Smooth Muscle
– Fibers respond as a single unit
– Found in the walls of hollow organs (intestines,
stomach, bladder, uterus)
– Two features- conduction of impulses and rythmicity
produce peristalsis
• Peristalsis- wavelike motion of contraction
– Peristalsis is what help your body move food from
organ in the digestive system to the next
– Vascular smooth muscle
• Found in the walls of small blood vessels where it helps
control blood pressure and blood flow
Cardiac Muscle
• Found only in the heart
• Composed of striated cells joined end to end
• Opposite ends of cardiac cells are connected
by intercalated discs
– Help join cells, transmit the force of contraction, &
diffuse ions from cell to cell
Skeletal Muscle Actions
• Skeletal action depends on
– Type of joint it is associated with
– The way the muscle is attached on either side of
the joint
Skeletal Muscle Actions
• Body Movement
– When a body part moves bones and muscles
interact as a lever
– 3 types of levers
• 1st class- resistance-fulcrum, force (seesaw; when the
arm straightens at the elbow)
• 2nd class- fulcrum- resistance- force (wheelbarrow;
when you chew something up)
• 3rd class- resistance-force-fulcrum (tweezers- when the
arm bends at the elbow)
Skeletal Muscle Actions
• Origin and Insertion
– Origin- less moveable end of the muscle
– Insertion- more moveable end of the muscle
– When a muscle contracts
• Insertion is pulled toward its origin
• Head of the muscle is the part closest to its origin
Skeletal Muscle Action
Skeletal Muscle Actions
• Interaction of Skeletal Muscles
– Agonist- muscle that causes an action
– Synergists- muscles that work together
– Prime mover- muscle that does most of the work
during an action
– Antagonists- muscle that opposes action
Major Skeletal Muscles
• Muscles of Facial Expression
– Innervated by the facial nerve (CN VII)
– Lack of symmetry in facial expression may indicate
nerve damage
Muscles of Facial Expression
• Orbicularis oculi
– orbicular= circular
– Oculi= eye
– Origin: orbital rim,
frontal & maxillary bones
– Insertion: lateral region
of eye, some encircle the
eye
– Action: closing the eyelid
– Expression: form’s crows
feet
Muscles of Facial Expression
• Corrugator
– Origin: frontal bone
– Insertion: eyebrow
– Action: draws eyebrow
medially & inferiorly
– Expression: frowning &
suffering
Muscles of Facial Expression
• Procerus
– Origin: fascia covering
the lower nasal bone &
upper lateral nasal
cartilage
– Insertion: skin between
and above the eyebrows
– Action: causes
transverse wrinkles over
the bridge of the nose
– Expression: squinting
Muscles of Facial Expression
• Nasalis
– Circles the opening of
the nostrils
– Has 2 parts:
• Dilator naris
• Compressor naris
– Action: dilates &
compresses nostrils
• Wiggles your nostrils
Muscles of Facial Expression
• Epicranius
– Origin: occipital bone
– Insertion: skin around
the eye & orbicularis
oculi
– Action: elevates
eyebrows, moves scalp
forward & backward
– Expression: surprise
Muscles of Facial Expression
• Orbicularis Oris
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Oribicular= circle
oris = mouth
Origin: encircles mouth
Insertion: angle of mouth
Action: encloses &
protrudes up; helps keep
food on occlusal surfaces
during chewing
– Expression: closing or
pursing lips
Muscles of Facial Expression
• Quadratus Labii
Superioris
– 4 muscles of the upper
lip
• Levator labii superioris
alaeque nasi
• Levator labii superioris
• Zygomaticus minor
• Zygomaticus major
– Allow you to frown and
smile
Muscles of Facial Expression
• Quadratus Labii
Superioris cont…
– Levator labii superioris
alaeque nasi
• Origin: maxilla
• Insertion: nose
• Action: dilates nostrils &
raises upper lip
Muscles of Facial Expression
• Quadratus Labii
Superioris
– Levator labii superioris
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Origin: maxilla
Insertion: upper lip
Action: raises upper lip
Expression: scorn
Muscles of Facial Expresssion
• Quadratus Labii
Superioris Cont…
– Zygomaticus minor
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Origin: zygomatic bone
Insertion: upper lip
Action: raises upper lip
Expression: scorn
– Zygomaticus major
• Origin: zygomatic bone
• Insertion: angle of mouth
• Action: elevates the corner
of the mouth
• Expression: smiling
Muscles of Facial Expression
• Levator Anguli Oris
– Origin: canine fossa (on
the maxilla)
– Insertion: orbicularis oris
– Action: elevates the
angle of the mouth
– Expression: smiling
(laughing)
Muscles of Facial Expression
• Smiling
– Produced by the
contraction of 2 facial
muscles:
• Zygomaticus major
• Oribicularis oculi
Muscles of Facial Expression
• Risorius
– Origin: fasica superficial
to masseter muscle
– Insertion: angle of the
mouth
– Action: pulls angle of the
mouth laterally
– Expression: smiling
widely; grinning
Muscles of Facial Expression
• Depressor labii inferioris
– Origin: mandible
– Insertion: lower lip
– Action: depresses the
angle of the mouth
– Expression: sadness;
grief
Muscles of Facial Expression
• Depressor Anguli Oris
– A.K.A triagularis
– Origin: mandible
– Insertion: angle of the
mouth
– Action: depresses angle
of the mouth
– Expression: frowning
Muscles of Facial Expression
• Mentalis
– Origin: mandible near
the incisive fossa
– Insertion: skin of the
chin
– Action: pulls skin of chin
upward; protrudes lower
lip; raise lower lip
– Expression: doubt;
disdain
Muscles of Facial Expression
• Buccinator
– 2 origins:
• Pterygomandibular raphe
• Alveolar process of the
mandible & maxilla
– Insertion: orbicularis oris
– Action: draws the corners
of the lips laterally,
compresses cheek, helps
keep food on occlusal
surface during chewing
– Plays and important role in
chewing
– Makes up the musculature
of the cheek
Muscles of Facial Expresion
• Laughter
– Muscle that form the core
of the laughter of
exhilartion:
• Zygomatic major
• Oribicularis oculi
– Muscles used to enhance
laughter:
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Levator labii superioris
Risorius
Mentalis
Depressor anguli oris
Orbicularis oris
Muscles of Facial Expression
• Auriculares
– 3 small muscles around
the auricle of the ear
– Not well developed in
man
– Allow you to wiggle your
ears
Muscles of Facial Expression
• Platysma
– Broad, thin, superficial
muscle
– Origin: fascia below clavicle
– Insertion: lower border of
mandible from canine to
second molar
– Action: depresses angle of
the mouth, wrinkles the
skin of the neck & upper
chest
– Expression: dejection,
horror, grimacing
Muscles of Mastication
• 4 pairs of muscles attached to the mandible
– 3 pairs close the lower jaw
– 1 pair lowers the jaw & allows side to side
movement
Muscles of Mastication
• Masseter
– Origin: zygomatic arch
– Insertion: lateral surface
of the mandible
– Action: elevates the
mandible
Muscles of Mastication
• Temporalis
– Origin: temporal fossa
– Insertion: coronoid fossa
of the mandible
– Action: elevates the
mandible; retraction
Muscles of Mastication
• Lateral Pterygoid
– Origin: sphenoid bone
– Insertion: mandibular
condyle
– Action: depresses &
protracts mandible
Muscles of Mastication
• Medial Pterygoid
– Origin: sphenoid,
palatine, & maxilla
– Insertion: medial surface
of the mandible
– Action: elevates
mandible; moves it from
side to side
Muscles That Move the Head and
Vertebral Column
• Sternocleidomastoid
– Origin:sternum & collar
bone
– Insertion: temporal bone
– Action: pulls head to one
side, flexes neck or
elevates the sternum
Muscles That Move the Head &
Vertebral Column
• Splenis Capitis
– Origin: spinous process
of lower cervical &
upper thoracic vertebrae
– Insertion: occipital bone
– Action: rotates head,
bends head to one side,
or extends neck
Muscles That Move the Head &
Vertebral Column
• Semispinalis capitis
– Origin: processes of
lower cervical & upper
thoracic vertebrae
– Insertion: occipital bone
– Action: elevates head &
rotates the head
Muscles that Move the Head &
Vertebral Column
• Quadratus lumborum
– Origin: iliac crest
– Insertion: upper lumbar
vertebrae & twelfth rib
– Action: aids in breathing,
extends lumbar region of
vertebral column
Muscles That Move the Head &
Vertebral Column
• Erector Spinae
– Origin & Insertion at
many locations on the
axial skeleton
– Action: extend & rotate
the head & maintain the
erect position of the
vertebral column
Muscles That Move the Pectoral Girdle
• Work closely with the muscles that move the
arm
• Connect the scapula to near by bones & help
move the scapula up, down, forward, &
backward
Muscles That Move the Pectoral Girdle
• Trapezius
– Origin: occipital bone &
spines of the cervical &
thoracic vertebrae
– Insertion: clavicle, spine,
& acromion process of
scapula
– Action: rotates scapula;
shrugs shoulders
Muscles That Move the Pectoral Girdle
• Rhomboid Major
– Origin: spines of upper
thoracic vertebrae
– Insertion: medial border
of the scapula
– Action: retracts,
elevates, & rotates the
scapula
Muscles That Move the Pectoral Girdle
• Rhomboid Minor
– Origin: spines of the
lower cervical vertebrae
– Insertion: medial border
of the scapula
– Action: retracts &
elevates the scapula
Muscles That Move the Pectoral Girdle
• Levator Scapulae
– Origin: transverse
process of the cervical
vertebrae
– Insertion: medial margin
of the scapula
– Action: elevates scapula
Muscles That Move the Pectoral Girdle
• Serratus Anterior
– Origin: outer surfaces of
upper ribs
– Insertion: ventral surface
of scapula
– Action: pulls scapula
anteriorly & downward
Muscles That Move the Pectoral Girdle
• Pectoralis Minor
– Origin: sternal ends of
upper ribs
– Insertion: coracoid
process of scapula
– Action: pulls scapula
forward and downward
to raise ribs
Muscles That Move the Forearm
• Most forearm muscle movements are
produced by muscles that connect the radius
or ulna to the humerus or pectoral girdle.
• Muscles that move the forearm are grouped
into three categories:
– Flexors– Extensors
– Rotators
Muscles That Move the Forearm
• Flexor:
– Biceps Brachii
• Origin: above the glenoid
cavity of the scapula
• Insertion: radius
• Action: flexes elbow &
rotates the hand laterally
(turning a doorknob or
screw driver)
Muscles That Move the Forearm
• Flexor
– Brachialis
• Origin: anterior shaft of
the humerus
• Insertion: coronoid
process of ulna
• Action: Flexes elbow
– Strongest flexor of the
elbow
Muscles That Move the Forearm
• Flexor:
– Brachioradialis
• Origin: distal lateral end
of humerus
• Insertion: lateral surface
of the radius above the
styloid process
• Action: flexes elbow
Muscles That Move the Forearm
• Extensor
– Triceps Brachii
• Origin: below glenoid
cavity & lateral & medial
surfaces of the humerus
• Insertion: olecranon
process of the ulna
• Action: extends elbow
• This is the only muscle on
the back of the arm.
Muscles That Move the Forearm
• Rotators:
– Supinator
• Origin: lateral epicondyle
of humerus & ulna
• Insertion: lateral surface
of radius
• Action: rotates forearm
laterally and supinates
the hand (palm facing
upward)
Muscles That Move the Forearm
• Rotators:
– Pronator teres
• Origin: medial epicondyle
of humerus and the ulna
• Insertion: lateral surface
of radius
• Action: rotates forearm
medially and pronates the
hand
Muscles That Move the Forearm
• Rotator:
– Pronator Quadratus
• Origin: anterior distal end
of ulna
• Insertion: anterior distal
end of radius
• Action: rotates forearm
medially and pronates
hand
Muscles That Move the Hand
• Movements of the hand include movements
of the wrist and fingers.
• 2 major groups of muscles
– Flexors- on anterior side of the forearm
– Extensors- on the posterior side of the forearm
Muscles That Move the Hand
• Flexors
– Flexor carpi radialis
• Origin: medial epicondyle
of the humerus
• Insertion: base of the 2nd
& 3rd metacarpals
• Action: flexes wrist &
abducts hand
Muscles That Move the Hand
• Flexor
– Flexor carpi ulnaris
• Origin: medial epicondyle
of the humerus
• Insertion: carpals &
metacarpals
• Action: flexes the wrist &
adducts the hand
Muscles that Move the Hand
• Flexors
– Palmaris longus
• Origin: medial epicondyle
of humerus
• Insertion: fascia of the
palm
• Action: flexes wrist; like
you are telling someone
to come here
Muscles That Move the Hand
• Flexors
– Flexor Digitorum
Profundus
• Origin: anterior surface of
the ulna
• Insertion: bases of distal
phalanges in fingers 2-5
• Action: flexes distal joints
of fingers
Muscles that Move the Hand
• Flexor
– Flexor digitorum
superficialis
• Origin: humerus
• Insertion: tendons of
fingers
• Action: flexes the fingers
and wrist
Muscles that Move the Hand
• Extensor
– Extensor Carpi Radialis
Longus
• Origin: distal end of the
humerus
• Insertion: base of 2nd
metacarpal
• Action: extends wrist and
abducts the hand
Muscles that Move the Hand
• Extensor
– Extensor carpi radialis
brevis
• Origin: lateral epicondyle
of the humerus
• Insertion: base of 2nd &
3rd metacarpals
• Action: extends wrist &
abducts hand
Muscles that Move the Hand
• Extensors
– Extensor carpi ulnaris
• Origin: lateral epicondyle
of humerus
• Insertion: base of the 5th
metacarpal
• Action: extends wrist &
adducts hand
Muscles that Move the Hand
• Extensor
– Extensor Digitorum
• Origin: lateral epicondyle
of the humerus
• Insertion: posterior
surface of phalanges in
fingers 2-5
• Action: extends fingers
Muscles that Move the Arm
• Flexors
– Coracobrachialis
• Origin: coracoid process
of the scapula
• Insertion: shaft of the
humerus
• Action: flexes & adducts
the arm
Muscles that Move the Arm
• Flexor
– Pectoralis major
• Origin: clavicle, sternum,
& costal cartilages of
upper ribs
• Insertion: humerus
• Action: flexes, adducts,
and rotates arm medially
Muscles that Move the Arm
• Extensor
– Teres Major
• Origin: lateral border of
scapula
• Insertion: humerus
• Action: extends, adducts,
and rotates the arm
medially
Muscles that Move the Arm
• Extensor
– Latissimus Dorsi
• Origin: spines of scral,
lumbar, & lower thoracic
vertebrae, iliac crest, &
lower ribs
• Insertion: humerus
• Action: extends, adducts,
and rotates the arm
medially, or pulls the
should downward & back
Muscles that Move the Arm
• Abductors
– Supraspinatus
• Origin: posterior surface
of scapula above spine
• Insertion: humerus
• Action: abducts the arm
Muscles that Move the Arm
• Abductors
– Deltoid
• Origin: acromion process,
spine of the scapula, &
clavicle
• Insertion: humerus
• Action: abducts, extends,
& flexes the arm
Muscles that Move the Arm
• Rotators
– Subscapularis
• Origin: Anterior surface of
scapula
• Insertion: humerus
• Action: rotates arm
medially
Muscles that Move the Arm
• Rotators
– Infraspinatus
• Origin: posterior surface
of scapula below spine
• Insertion: humerus
• Action: rotates arm
laterally
Muscles that Move the Arm
• Rotators
– Teres Minor
• Origin: lateral border of
scapula
• Insertion: humerus
• Action: rotates arm
laterally
Muscles of the Abdominal Wall
• Muscles of the abdominal wall connect the rib
cage & vertebral column to the pelvic girdle
• Linea alba- band of tough connective tissue that
extends from the xiphoid process of the sternum
to the pubic symphysis & provides attachment for
some of the abdominal muscles
• Contraction of these muscles helps move air out
of the lungs during forceful exhalation & other
everyday functions of the body
Muscles of the Abdominal Wall
• External oblique
– Origin- outer surfaces of
the lower ribs
– Insertion- Outer lip of
iliac crest & linea alba
– Action- Tenses
abdominal wall &
compresses abdominal
contents
Muscles of the Abdominal Wall
• Internal Oblique
– Origin- crest of ilium &
inguinal ligament
– Insertion- cartilages of
the lower ribs, linea
alba, & crest of the pubis
– Action- Tenses
abdominal wall &
compresses abdominal
contents
Muscles of the Abdominal Wall
• Transversus abdominis
– Origin- costal cartilages of
the lower ribs, processes of
the lumbar vertebrae, lip
of iliac crest, & inguinal
ligament
– Insertion- linea alba &
crest of pubis
– Action- tenses abdominal
wall & compresses
abdominal contents
Muscles of the Abdominal Wall
• Rectus Abdominis
– Origin- Crest of the pubis
& pubic symphysis
– Insertion- xiphoid
process of sternum &
costal cartilage
– Action- tenses the
abdominal wall &
compresses abdominal
contents & also flexes
the vertebral column
Muscles that Move the Thigh
• Muscles that move the thigh are attached to
the femur & to part of the pelvic girdle
– Important exceptions: sartorius & rectus femoris
• Muscles can be separated into 2 groups:
– Anterior- primarily flexes the thigh; advance the
lower limb when walking
– Posterior- primarily extends, abducts, or rotates
the thigh
Muscles that Move the Thigh: Anterior
Group
• Psoas major
– Origin: lumbar
intervertebral discs;
bodies and transverse
processes of lumbar
vertebrae
– Insertion: lesser
trochanter of the femur
– Action: flexes the thigh
Muscles that Move the Thigh: Anterior
Group
• Iliacus
– Origin: Illiac fossa of
ilium
– Insertion: lesser
trochanter of the femur
– Action: Flexes thigh
Muscles that Move the Thigh:
Posterior Group
• Gluteus maximus
– Origin: sacrum, coccyx,
& posterior surface of
the ilium
– Insertion: posterior
surface of the femur &
fascia of the thigh
– Action: extends hip;
helps straighten the
lower limb at the hip
when you walk, run, or
climb
Muscles that Move the Thigh:
Posterior Group
• Gluteus minimus
– Origin: lateral surface of
the ilium
– Insertion: greater
trochanter of the femur
– Action: abducts &
rotates the thigh
medially
Muscles that Move the Thigh:
Posterior Group
• Gluteus medius
– Origin: lateral surface of
the ilium
– Insertion: greater
trochanter of the femur
– Action: abducts &
rotates thigh medially
Muscles that Move the Thigh:
Posterior Group
• Piriformis
– Origin: anterior surface
of the sacrum
– Insertion: greater
trochanter of the femur
– Action: abducts &
rotates the thigh
medially ; stabilizes the
hip
Muscles that Move the Thigh:
Posterior Group
• Tensor fasciae latae
– Origin: anterior iliac
crest
– Insertion: greater
trochanter of the femur
– Action: abducts, flexes,
& rotates thigh medially
Muscles that Move the Thigh:
Adductors
• Pectineus
– Origin: spine of the pubis
– Insertion: femur distal to
lesser trochanter
– Action: Flexes & adducts
thigh
Muscles that Move the Thigh:
Adductors
• Adductor brevis
– Origin: pubic bone
– Insertion: posterior
surface of femur
– Action: adducts & flexes
thigh
Muscles that Move the Thigh:
Adductors
• Adductor longus
– Origin: pubic bone near
the pubic symphysis
– Insertion: posterior
surface of the femur
– Action: adducts & flexes
the thigh
Muscles that Move the Thigh:
Adductors
• Adductor magnus
– Origin: Ischial tuberosity
– Insertion: posterior
surface of the femur
– Action: adducts thigh,
posterior portion
extends & anterior
portion flexes thigh
Muscles that Move the Thigh:
Adductors
• Gracilis
– Origin: Lower edge of
pubic symphysis
– Insertion: medial surface
of the tibia
– Action: adducts thigh &
flexes knee
Muscles that Move the Leg
• Connect the tibia or fibula to the femur or
pelvic girdle.
• Two major groups:
– Flexors
– Extensors
Muscles that Move the Leg
• Hamstring Group
– Biceps femoris
• Origin: ischial tuberosity
& linea aspera
• Insertion: head of fibula &
lateral condyle of tibia
• Action: flexes knee,
rotates leg laterally &
extends thigh
Muscles that Move the Leg
• Hamstring Group
– Semitendinosus
• Origin: ischial tuberosity
• Insertion: medial surface
of the tibia
• Action: flexes knee,
rotates leg medially &
extends thigh
Muscles that Move the Leg
• Hamstring Group
– Semimembranosus
• Origin: ischial tuberosity
• Insertion: medial condyle
of tibia
• Action: Flexes the knee,
rotates the leg medially &
extends the thigh
Muscles that Move the Leg
• Sartorius
– Origin: anterior superior
iliac spine
– Insertion: medial surface
of tibia
– Action: flexes knee &
hip, abducts & rotates
thigh laterally
Muscles that Move the Leg
• Quadriceps Group
– Rectus Femoris
• Origin: spine of the illium
& margin of the
acetabulum
• Insertion: patella by
tendon, which continues
as the patellar ligament to
the tibia
• Action: extends knee,
flexes thigh
Muscles that Move the Leg
• Quadriceps Group
– Vastus Lateralis
• Origin: greater trochanter
& posterior surface of the
femur
• Insertion: patella by
tendon, which continues
as patellar ligament to the
tibia
• Action: extends knee
Muscles that Move the Leg
• Quadriceps Group
– Vastus medialis
• Origin: medial surface of
the femur
• Insertion: patella by
tendon, which continues
as patellar ligament to the
tibia
• Action: extends knee
Muscles that Move the Leg
• Quadriceps Group
– Vastus intermedius
• Origin: anterior & lateral
surfaces of femur
• Insertion: patella by
tendon, which continues
as patellar ligament to the
tibia
• Action: extends knee
Muscles that Move the Foot
• Movements of the foot include movements of
the ankle & toes
• Attach to the femur, tibia, & fibula to bones of
the foot
• Move the foot upward (dorsiflexion) or
downward (plantar flexion) and turn the foot so
the plantar surface faces medially (inversion) or
laterally (eversion)
• 4 types: dorsal flexors, plantar flexors, invertor,
evertor
Muscles that Move the Foot
• Dorsal Flexor
– Tibialis Anterior
• Origin: lateral condyle &
lateral surface of the tibia
• Insertion: tarsal bone &
first metatarsal
• Action: dorsiflexion &
inversion of foot
Muscles that Move the Foot
• Dorsal Flexor
– Fibularis Tertius
• Origin: anterior surface of
the tibia
• Insertion: dorsal surface
of the 5th metatarsal
• Action: dorsiflexion &
eversion of the foot
Muscles that Move the Foot
• Dorsal Flexor
– Extensor Digitorum
Longus
• Origin: lateral condyle of
tibia & anterior surface of
the fibula
• Insertion: dorsal surfaces
of 2nd & 3rd phalanges of
the 4 lateral toes
• Action: dorsiflexion &
eversion of the foot,
extends toes
Muscles that Move the Foot
• Dorsal Flexor
– Extensor Hallucis Longus
• Origin: anterior surface of
the fibula
• Insertion: distal phalanx
of the big toe
• Action: extends big toe,
dorsiflexion & inversion of
foot
Muscle that Move the Foot
• Plantar Flexor
– Gastrocnemius
• Origin: lateral & medial
condyles of femur
• Insertion: posterior
surface of calcaneus
• Action: plantar flexion of
foot, flexes knee
Muscles that Move the Foot
• Plantar Flexor
– Soleus
• Origin: head & shaft of
fibula & posterior surface
of the tibia
• Insertion: posterior
surface of the calcaneus
• Action: plantar flexion of
the foot
Muscles that Move the Foot
• Plantar Flexion
– Plantaris
• Origin: femur
• Insertion: calcaneus
• Action: plantar flexion of
foot, flexes knee
Muscles that Move the Foot
• Plantar Flexor
– Flexor Digitorum Longus
• Origin: posterior surface
of the tibia
• Insertion: distal phalanges
of four lateral toes
• Action: plantar flexion &
inversion of foot, flexes
four lateral toes
Muscles that Move the Foot
• Invertor
– Tibialis Posterior
• Origin: lateral condyle &
posterior surface of tibia
& posterior surface of
fibula
• Insertion: tarsal &
metatarsal bones
• Action: plantar flexion &
inversion of foot
Muscles that Move the Foot
• Evertor
– Fibularis Longus
• Origin: lateral condyle of
tibia & head & shaft of
the fibula
• Insertion: Tarsal &
metatarsal bones
• Action: plantar flexion &
eversion of foot, supports
arch