Spring 2016 Fullerton College Anatomy 250 (Muscles)

Lateral rectus
Lateral rectus
ORIGIN: annulus of Zinn at the orbital apex

INSERTION: 7 mm temporal to the limbus

ACTION: abduction of the eyeball

ANTAGONIST: medial rectus

Medial rectus
Medial rectus
ORIGIN: annulus of Zinn at the orbital apex

INSERTION: 5.5 mm medial to the limbus

ACTION: adduction of the eyeball

ANTAGONIST: lateral rectus

Superior rectus
Superior rectus
ORIGIN: annulus of Zinn at the orbital apex

INSERTION: 7.5 mm superior to the limbus

ACTION: elevation and abduction of the eyeball

ANTAGONIST: inferior rectus

Inferior rectus
Inferior rectus
ORIGIN: annulus of Zinn at the orbital apex

INSERTION: 6.5 mm inferior to the limbus

ACTION: depression and adduction of the eyeball

ANTAGONIST: superior rectus

***Thyroid cartilage
***Thyroid cartilage
ORIGIN/INSERTION: larynx
ACTION: protects vocal cords
Epicranius (occipitofrontalis)
Epicranius (occipitofrontalis)
ORIGIN: Galea aponeurotica (frontal belly); Occipital an temporal bones (occipital belly)

INSERTION: Skin of eyebrows and root of nose (frontal belly); Galea aponeurotica (occipital belly)

ACTION: with aponeurosis fixed, raises the eybrows (as in surprise); wrinkles forehead skin horizontally; fixes aponeurosis and pulls scalp posteriorly

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Occipital frontalis
Occipital frontalis
ORIGIN: Two occipital bellies and two frontal bellies.

INSERTION: Galea aponeurosis

ACTION: Raises eyebrows, wrinkles forehead

Orbicularis oculi
Orbicularis oculi
ORIGIN: frontal and maxillary bones and ligaments around orbit

INSERTION: tissue of eyelid

ACTION: closes eye; various parts can be activated individually; produces blinking, squinting, and draws eyebrows inferiorly

ANTAGONIST: Levator palpebrae superioris muscle

Zygomaticus
Zygomaticus
ORIGIN: zygomatic bone

INSERTION: skina nd muscle at corner of mouth

ACTION: raises lateral corners of mouth upward (smiling muscle)

ANTAGONIST: orbicularis oris

Orbicularis oris
Orbicularis oris
ORIGIN: arises indirectly from maxilla and mandible; fibers blended with fibers of other facial muscles associated with the lips

INSERTION: encircles mouth; inserts into muscle and skin at angles of the mouth

ACTION: closes lips; purses and protrudes lips; kissing and whistling muscles

Platysma
Platysma
ORIGIN: fascia of chest (over pectoral muscles and deltoid)

INSERTION: lower margin of mandible and skin and muscle at corner of the mouth

ACTION: tenses skin of neck (e.g. during shaving); helps depress mandible; pulls lower lip back and down, i.e. produces downward sag of mouth

ANTAGONIST: Masseter, Temporalis

Buccinator
Buccinator
ORIGIN: molar region of maxilla and mandible

INSERTION: orbicular oris

ACTION: compresses cheek (as in whistling and sucking); draws corner of mouth laterally; holds food between teeth during chewing well developed in nursing infants

Masseter
Masseter
ORIGIN: ‎zygomatic arch‎ and ‎zygomatic bone

INSERTION: angle and ramus of mandible

ACTION: Prime mover of jaw closure; elevates mandible

Temporalis
Temporalis
ORIGIN: Temporal fossa

INSERTION: Coronoid process of mandible via a tendon that passes deep to zygomatic arch

ACTION: CLoses jaw; elevates and retracts mandible; maintains position of the mandible at rest; deep anterior part may help protract mandible

ANTAGONIST: Platysma muscle

Hyoglossus
Hyoglossus
ORIGIN: Hyoid

INSERTION: side of tongue

ACTION: depresses and retracts the tongue

Styloglossus
Styloglossus
ORIGIN: ‎styloid process of temporal bone

INSERTION: ‎lateral inferior aspect of tongue

ACTION: retracts and elevates tongue

Digastric
Digastric
ORIGIN:lower margin of mandible (anterior belly) and mastoid process of the temporal bone (posterior belly)

INSERTION: by a connective tissue loop to hyoid bone

ACTION: open mouth and depress mandible; acting in concert, the digastric muscles elevate hyoid bone and steady it during swallowing and speech

Stylohyoid
Stylohyoid
ORIGIN: styloid process of temporal bone

INSERTION: hyoid bone

ACTION: Elevate and retract hyoid, thereby elongating floor of mouth during swallowing

Sternohyoid
Sternohyoid
ORIGIN: ‎manubrium and medial end of clavicle

ORIGIN: lower margin of hyoid bone

ACTION: depresses larynx and hyoid bone if mandible is fixed

Thyrohyoid
Thyrohyoid
ORIGIN: thyroid cartilage

INSERTION: Hyoid bone

ACTION: depresses hyoid bone or elevates larynx if hyoid is fixed

Sternocleidomastoid
Sternocleidomastoid
ORIGIN: Manubrium of sternum and medial portion of clavicle

INSERTION: mastoid process of temporal bone and superior nuchal line of occipital bone

ACTION: flexes and laterally rotates the head; simultaneous contraction of both muscles causes neck flexion, generally against resistance as when one raises head when lying on back; acting alone, each muscle rotates head toward shoulder on opposite side and tilts or laterally flexes head on its own side

Splenius
Splenius
ORIGIN: ligamentum nuchae spinous process of vertebra C7-T6

INSERTION: Mastoid process of temporal bone and occipital bone (capitis); transverse processes of C2-C4 vertebrae (cervicis)

ACTION: Extend the head; when splenius muscles on one side are activated, head is rotted and bent laterally towards the same side

Semispinalis
Semispinalis
ORIGIN: Transverse processes of C7-T12

INSERTION: occipital bone (capitis) and spinous processes of cervical (cervicis) and thoracic vertebrae T1 to T4 (thoracis)

ACTION: extends vertebral column and head and rotates them to opposite sides; acts synergisically with sternocleidomastoid muscle of opposite side

External intercostals
External intercostals
ORIGIN: inferior border of rib above

INSERTION: superior border of rib below

ACTION:with first ribs fixed by scalene muscles, the external intercostals pull ribs toward one another to elevate rib cage; aid in inspiration; synergists of diaphragm

ANTAGONIST: intercostales interni muscles

Internal intercostals
Internal intercostals
ORIGIN: superior border of rib below

INSERTION: inferior border of rib above

ACTION: with 12th ribs fixed by quadratus lumborum, muscles of posterior abdominal wall, and oblique muscles of the abdominal wall, the internal intercostals draw ribs together and depress rib cage; aid in forced expiration; antagonistic to external intercostals

ANTAGONIST: External intercostal muscles

Diaphragm
Diaphragm
ORIGIN: inferior internal surface of rib cage and sternum, costal cartilages of last six ribs, and lumbar vertebrae

INSERTION: Central tendon

ACTION: prime mover of inspiration; flattens on contraction, increasing vertical dimensions of thorax; when strongly contracted, dramatically increases intrabdominal pressure

ANTAGONIST: internal intercostals

Transversus abdominis
Transversus abdominis
ORIGIN: inguinal ligament, lumbar fascia, cartilages of last 6 ribs; iliac crest

INSERTION: linea alba, pubic crest

ACTION: compresses abdominal contents

Rectus abdominis
Rectus abdominis
ORIGIN: Pubic crest and symphysis

INSERTION: xiphoid process and costal cartilages of ribs 5-7

ACTION: flex and rotate lumbar region of vertebral column; fix and depress ribs, stabilize pelvis during walking, increases intra-abdominal pressure; used in sit-ups/curls

ANTAGONIST: Erector spinae

Pectoralis minor
Pectoralis minor
ORIGIN: anterior surfaces of ribs 3-5 (or 2-4)

INSERTION: caracoid process pf scapula

ACTION: with ribs fixed, draws scapula forward and downward; with scapula fixed, draws rib cage superiorly

Serratus anterior
Serratus anterior
ORIGIN: by a series of muscle slips from ribs 1-8 (or 9)

INSERTION: entire anterior surface of vertebral border of scapula

ACTION: rotates scapula so that its inferior angle moves laterally and upward; prime move to protract and hold scapula against chest wall; raises point of shoulder; important role in abduction and raising of arm and in horizontal arm movements (pushing, punching); called “boxer’s muscle”

ANTAGONIST: Rhomboid major, Rhomboid minor, Trapezius

Trapezius
Trapezius
ORIGIN: ocipital bone, ligamentum nuchae, and spine of C7 and all thoracic vertebrae

INSERTION: a continuous insertion along acromion and spine of scapula and lateral third of clavicle

ACTION: stabilizes, raises, retracts, and rotates scapula; middles fivers retract (adduct) scapula; superior fibers elevate scapula (as in shrugging shoulders) or can help extend head when scapula is fixed; inferior fibers depress scapula (and shoulder)

ANTAGONIST: serratus anterior muscle, Latissimus dorsi

Pectoralis major
Pectoralis major
ORIGIN: sternal end of clavicle, sternum, cartilage of ribs 1-6 (or 7) , and aponeurosis of external oblique muscle

INSERTION: fibers converge to insert by a short tendon into greater tubercle of humerus

ACTION: prime mover of arm flexion; rotates arm medially; adducts arm against resistance; with scapula (and arm) fixed, pulls rib cage upward, and thus can help in climbing, throwing, pushing, and in forced inspiration

Deltoid
Deltoid
ORIGIN: embraces insertion of the trapezius; lateral third of clavicle; acromion and spine of scapula

INSERTION: deltoid tuberosity of humerus

ACTION: prime mover of arm abduction when all its fibers ontract simoutaneously; antagonist of pectoralis major and latissimus dorsi, which adducts the arm; if only anterior fibers are active, can act powerfully in flexion and medial rotation of humerus, and is therefor synergist of pectoralis major; if only posterior fibers are active, causes extension and lateral rotation of arm; active during rhythmic arm swinging movements during walking

ANTAGONIST: Latissimus dorsi

Latissimus dorsi
Latissimus dorsi
ORIGIN: indirect attachment via thoracolumnar fascia into spines of lower six thoracic vertebrae, lumbar vertebrae, lower 3 or 4 ribs, and iliac crest

INSERTION: spirals aroudn teres major to insert in floor of intertubercular sulcus of humerus

ACTION: prime mover of arm extension; adduction and medial rotation at shoulder; it plays an important role in bringing the arm down in a power stroke as in striking a blow, hammering, and swimming; with arms reaching overhead, it pulls the rest of the body upward and forward

ANTAGONIST: Deltoid

Subscapularis
Subscapularis
ORIGIN: subscapular fossa of scapula

INSERTION: Lesser tubercle of humerus

ACTION: chief medial rotator of humerus; assisted by pectoralis major; helps to hold head of humerus in glenoid cavity, thereby stabilizing shoulder joints

Supraspinatus
Supraspinatus
ORIGIN: supraspinous fossa of scapula

INSERTION: superior part of greater tubercle of humerus

ACTION: initiates abduction; stabilizes shoulder joint; helps to prevent downward dislocation of humerus, as when carrying a heavy suitcase

Infraspinatus
Infraspinatus
ORIGIN: infraspinous fossa of the scapula

INSERTION: greater tubercle of humerus posterior to insertion of supraspinatus

ACTION: rotates humerus lateay; helps to hold head of humerus in glenoid cavity, stabilizing the shoulder joint

Triceps brachii
Triceps brachii
ORIGIN: Long head: infraglenoid tubercle of scapula
Lateral head: posterior shaft of humerus
Medial head: posterior humeral shaft distal to radial groove

INSERTION: by common tendon into olecranon process of ulna

ACTION: Epowerful forearm extensor (prime mover, particularly medial head); antagonist of forearm flexors; long and lateral heads mainly active in extension against resistance; long head tendon may help stabilize shoulder joint and assist in arm adduction

ANTAGONIST: Biceps brachii muscle

Biceps brachii
Biceps brachii
ORIGIN: Short head: coracoid process
Long head: supraglenoid tubercle and lip of glenoid cavity; tendon of long head runs within cpsule and descends into tubercular sulcus of humerus

INSERTION: by common tendon into radial tuberosity

ACTION: Flexes elbow joint and supinates forearm; these actions usually occur at same time (e.g. when you open a bottle of wine it turns the corkscrew and pulls the cork); weak flexor of arm at shoulder

ANTAGONIST: Triceps brachii muscle

Brachialis
Brachialis
ORIGIN: front of distal humerus; embraces insertion of deltoid muscle

INSERTION: coronoid process of ulna and capsule of elbow joint

ACTION: a major forearm flexor (lifts ulna as biceps lift the radius)

Flexor carpi radialis
Flexor carpi radialis
ORIGIN: medial epicondyle of humerus

INSERTION: base of second and third metacarpals; insertion tendon easily seen and provides guide to position of radial artery (used for pulse taking) at wrist

ACTION: powerful flexor of wrist

ANTAGONIST: Extensor carpi radialis brevis muscle and extensor carpi radialis longus muscle

Flexor carpi ulnaris
Flexor carpi ulnaris
ORIGIN: medial epicondyle of humerus; olecranon process and posterior surface of ulna

INSERTION: pisiform and hamate bones and base of fifth metacarpal

ACTION: Powerful flexor of writ; also adducts hand in concert with extensor carpi ulnaris (posterior muscle); stabilizes extension

Flexor digitorum superficialis
Flexor digitorum superficialis
ORIGIN: medial epicondyle of the humerus, coronoid process of ulna; shaft of radius

INSERTION: by four tendons into middle phalanges of fingers 2-5

ACTION: flexes wrist and middle phalanges of fingers 2-4; the important finger flexor when speed and flexion against resistance are required

ANTAGONIST: Extensor digitorum muscle

Flexor pollicis longus
Flexor pollicis longus
ORIGIN: anterior surface of radius and interosseous membrane

INSERTION: distal phalanx of thumb

ACTION: flexes distal phalanx of thumb

ANTAGONIST: Extensor pollicis longus muscle, Extensor pollicis brevis muscle

Extensor carpi radialis longus
Extensor carpi radialis longus
ORIGIN: lateral supracondylar ridge of humerus

INSERTION: base of metacarpal

ACTION: extends wrist in conjunction with the extensor carpi ulnaris and abducts wrist in conjunction with the flexor carpi radialis

ANTAGONIST: Flexor carpi ulnaris muscle

Extensor digitorum
Extensor digitorum
ORIGIN: lateral epicondyle of humerus

INSERTION: by four tendons into extensor expansions and distal phalanges of fingers 2-5

ACTION: prime mover of finger extension; extends wrist; can abduct (flare) fingers

ANTAGONIST: Flexor digitorum superficialis muscle, Flexor digitorum profundus muscle

Extensor carpi ulnaris
Extensor carpi ulnaris
ORIGIN: lateral epicondyle of humerus and posterior border of ulna

INSERTION: base of 5th metacarpal

ACTION: extends wrist in conjunction with the extensor carpi radialis and adducts writ in conjunction with flexor carpi ulnaris

ANTAGONIST: Flexor carpi radialis

Extensor pollicis brevis and longus
Extensor pollicis brevis and longus
ORIGIN: dorsal shaft of radius and ulna; interosseous membrane

INSERTION: base of proximal (brevis) and distal (longus) phalanx

ACTION: extends thumb

ANTAGONIST: Flexor pollicis longus muscle, Flexor pollicis brevis muscle

Iliacus
Iliacus
ORIGIN: iliac fossa, ala of sacrum

INSERTION: lesser trochanter of femur via iliopsoas

ACTION: iliopsoas is the prime mover in thigh flexion and in flexing trunk (as when bowling)

ANTAGONIST: Gluteus maximus

Psoas Major
Psoas Major
ORIGIN: anterior superior iliac spine

INSERTION: winds around medial aspect of knee an inserts into medial aspect of proximal tibia

ACTION: iliopsoas is the prime mover in thigh flexion and in flexing trunk (as when bowling); also causes lateral flexion of vertebral column; important postural muscle

ANTAGONIST: Gluteus maximus

Sartorius
Sartorius
ORIGIN: Anterior superior iliac spine

INSERTION: winds around medial aspect of knee and inserts into medial aspect of proximal tibia

ACTION: Flexes, abducts, and laterally rotates thigh; flexes knee (weak) as in a soccer kick; helps produce the cross legged position

Adductor longus
Adductor longus
ORIGIN: pubis near pubic symphysis

INSERTION: linea aspera

ACTION: adducts, flexes, and medially rotates thigh

Gracilis
Gracilis
ORIGIN: inferiro ramus and body of pubis and adjacent ischial ramus

INSERTION: medial surface of tibia just inferior to its medial condyle

ACTION: adducts thigh, flees and medially rotates leg, especially during walking

Rectus femoris
Rectus femoris
ORIGIN: anterior inferior iliac spine and superiors margin of acetabulum

INSERTION: patella and tibial tuberosity via patellar ligament

ACTION: Extends knee and flexes thigh at hip

ANTAGONIST: Hamstring

Vastus lateralis
Vastus lateralis
ORIGIN: Greater trochanter, Intertrochanteric line, Linea aspera

INSERTION: patella and tibial tuberosity via patellar ligament

ACTION: extends and stabilizes knee

ANTAGONIST: Hamstring

Vastus medialis
Vastus medialis
ORIGIN: linea aspera, medial supracondylar line, intertrochanteric line

INSERTION: patella and tibial tuberosity via patellar ligament

ACTION: Extends knee; inferior fibers stabilize patella

Vastus intermedius
Vastus intermedius
ORIGIN: anterior and lateral surfaces of proximal femur shaft

INSERTION: patella and tibial tuberosity via patellar ligament

ACTION: Extends knee

Tensor fasciae latae
Tensor fasciae latae
ORIGIN: anterior aspect of iliac crest and anterior superior iliac spine

INSERTION: iliotibial tract

ACTION: Steadies trunk on thigh by making iliotibial tract taut; flexes and abducts thigh; rotates thigh medially

Gluteus maximus
Gluteus maximus
ORIGIN: dorsal ilium, sacrum, and coccyx

INSERTION: gluteal tuberosity of femur; iliotibial tract

ACTION: major extensor of thigh; complex, powerful, and most effective when thigh is flexed and fore is necessary, as in rising from a forward flexed position and in thrusting the thigh posteriorly in climbing stairs and running, generally inactive during standing and walking; laterally rotates and abducts thigh

ANTAGONIST: Iliacus, psoas major and psoas minor

Gluteus medius
Gluteus medius
ORIGIN: between anterior and posterior gluteal lines on lateral surface of ilium

INSERTION: by short tendon into lateral aspect of greater trochanter of femur

ACTION: abduction of the hip; preventing adduction of the hip. Medial rotation of thigh.

ANTAGONIST: adductors

Bicep femoris
Bicep femoris
ORIGIN: ischial tuberosity (long head); linea aspera, lateral supracondylar line, and distal femur (short head)

INSERTION: common tendon passes downward and laterally (forming lateral border of popliteal fossa) to insert into head of fibula and lateral condyle of tibia

ACTION: extends thigh and flexes knee; laterally rotates leg, especially when knee is flexed

ANTAGONIST: Quadriceps muscle

Semitendinosus
Semitendinosus
ORIGIN: ischial tuberosity in common with long head of biceps femoris

INSERTION: medial aspect of upper tibial shaft

ACTION: Extends thigh and flexes knee; medially rotates leg

ANTAGONIST: Quadriceps muscle

Semimembranosus
Semimembranosus
ORIGIN: ischial tuberosity

INSERTION: Medial condyle of tibia; through oblique ligament to lateral condyle of femur

ACTION: Extends thigh and flexes knee; medially rotates leg

ANTAGONIST: Quadriceps muscle and Tensor fasciae latae

Tibialis anterior
Tibialis anterior
ORIGIN: lateral condyle and upper two thirds of tibial shaft; interosseous membrane

INSERTION: by tendon into inferior surface of medial cuneiform and first metatarsal bone

ACTION: prime mover of dorsiflexion; inverts foot; assists in supporting medial longitudinal arch of foot

ANTAGONIST: Fibularis longus, Gastrocnemius, Soleus, Plantaris, Tibialis posterior

Extensor digitorum longus
Extensor digitorum longus
ORIGIN: lateral condyle of tibia; proximal three-fourths of fibula; interosseous membrane

INSERTION: Middle and distal phalanges of toes 2-5 via extensor expansion

ACTION: Prime mover of tie extension (acts mainly at metatarsophalangeal joints); dorsiflexes foot

ANTAGONIST: Flexor digitorum longus, Flexor digitorum brevis

Extensor hallucis longus
Extensor hallucis longus
ORIGIN: anteromedial fibula shaft and interosseous membrane

INSERTION: tendon inserts on distal phalanx of great toe

ACTION: Extends great toe; dorsiflexes foot

ANTAGONIST: Flexor hallucis longus, Flexor hallucis brevis

Extensor (perenous) longus
Extensor (perenous) longus
ORIGIN: Head and upper portion of lateral side of fibula

INSERTION: by long tendon that curves under foot to first metatarsal and medial cuneiform

ACTION: plantarflexion, eversion, support arches

ANTAGONIST: Tibialis anterior muscle, T.A. does Inversion and Dorsiflexion

Gastrocnemius
Gastrocnemius
ORIGIN: by two heads from medial and lateral condyles of femur

INSERTION: posterior calcaneous via calcaneal tendon

ACTION: plantar flexes foot when when knee is extended; because it also crosses knee joint; it can flex knee when foot is dorsiflexed

ANTAGONIST: Tibialis anterior muscle

Soleus
Soleus
ORIGIN: extensive cone-shaped origin from superior tibia, fibula, and interosseous membrane

INSERTION: posterior calcaneous via calcaneal tendon

ACTION: plantar flexes foor; important locomotor and postural muscle during walking, running, and dancing

ANTAGONIST: tibialis anterior

Flexor digitorum longus
Flexor digitorum longus
ORIGIN: extensive origin on the posterior tibia

INSERTION: tendon runs behind medial malleolus and splits to insert into distal phalanges of toes 2-5

ACTION: Plantar flexes and inverts foot; flexes toes; helps foot “grip” ground

ANTAGONIST: Extensor digitorum longus, Extensor digitorum brevis

Flexor hallucis longus
Flexor hallucis longus
ORIGIN: middle part of shaft of fibulal interosseous membrane

INSERTION: tendon runs under foot to distal phalanx of great toe

ACTION: plantar flexes and inverts foot; flexes great to at all joints; “push off” muscle during walking

ANTAGONIST: Extensor hallucis longus muscle

Tibialis posterior
Tibialis posterior
ORIGIN: superior tibia nd fibula and interosseous membrane

INSERTION: tendon passes behind medial malleolus and under arch of footl inserts into several tarsals and metatarsals 2-4

ACTION: Prime mover of goot inversion; plantar flexes foot; stabilizes medial longitudinal arch of foot (as during ice skating)

ANTAGONIST: Fibularis brevis