Lesson 7.2 Major Muscles

Frontalis

Origin: epicranial aponeurosis

Insertion: skin of eyebrows and root of nose

Action: raise eyebrows and wrinkle forehead horizontally

Occipitalis:

origin: temporal and occipital bones

insertion: epicranial aponeurosis

action: pull scalp posteriorly and anchor aponeurosis

Temporalis

origin: temporal fossa

insertion: coronoid process of mandible

action: close jaw and hold it steady at rest

Orbicularis Oculi:

origin: frontal and maxillary bones

insertion: tissue of the eyelid

action: help close your eyes, and blinking

Orbicularis Oris:

origin: maxilla and mandible

insertion: skin at mouth angles

action: close lips, purse lips, kissing, whistling

Masseter:

origin: zygomatic bone

insertion: angle and ramus of mandible

action: prime mover of jaw closure

Buccinator:

origin: maxilla and mandible

insertion: orbicularis oris

action: compress cheeks, sucking, and whistling

Sternocleidomastoid:

-origin: manubrium

-insertion: temporal bone

action: flexes and laterally rotates head

Platsyma:

origin: chest wall/soft tissues

insertion: mandible

action: flexes neck, opens jaw

Internal Intercoastals:

origin: superior border of rib below it

insertion: inferior border of rib above it

-action: to draw ribs together and depress rib cage to force air expiration

External Intercoastals:

origin: inferior border of rib above it

insertion: superior border or rib below it

action: pull ribs towards each other to elevate rib cage and to aid in air inspiration

Diaphragm:

origin: internal inferior surface of rib cage

insertion: central tendon of the diaphragm

action: prime mover of inspiration, flatten upon contraction

External Oblique:

origin: outer surface of lower 8 ribs

insertion: linea alba, pubic crest, iliac crest

action: rotate trunk and flex it laterally

Internal Oblique:

origin: lumbar fascia, and iliac crest

insertion: linea alba, last 3 ribs, costal margins

action: rotate trunk and flex it laterally

Rectus Abdominis:

origin: pubic crest and symphysis

insertion: xiphoid process and costal cartilage

action: flex and rotate lumbar region

Transverse abdominis:

origin: inguinal ligament, cartilage of last 6 ribs

insertion: linea alba, pubic crest

action: compress adominal contents

Pectoralis Major:

origin: sternal end of clavicle, sternum, cartilage of ribs 1-6

insertion: humerus

action: adduct and medially rotate arm

Pectoralis Minor:

origin: anterior rib surface

insertion: coracoid process of scapula

action: draw scapula forward and downward

Serratus Anterior:

origin: ribs 1-8

insertion: anterior surface of vertebral border of scapula

action: rotate scapula laterally and upward, raises shoulders, abduction of arm

Trapezius

origin: occipital bone, spinous process of thoracic vertebrae

insertion: acromion, spine of scapula, and clavicle

action: elevate, retract, and rotate scapula as in shoulder shrugging

Deltoid:

origin: clavicle and scapula

I: humerus

action: abduct and rotate arm

Latissimus Dorsi:

origin: spines of thoracic vertebrae, iliac crest, scapula

insertion: humerus

action: prime mover of arm extension, arm adduction, medial rotation of arm at shoulder

Levator Scapulae:

origin: transverse process of C1-C4

Insertion: medial border of scapula

Action: elevates and adducts scapula

Rhomboids Major and Minor:

Origin: spinous process of C7, T1-T5

Insertion: medial border of scapula

action: stabilize scapula

Supraspinatus

origin: supraspinous fossa of scapula

insertion: lesser tubercle of the humerus

action: chief medial rotator of arm

Infraspinatous:

origin: infraspinous fossa of scapula

insertion: greater tubercle of humerus

action: rotate the arm laterally

Teres Major:

origin: posterior surface of the scapula

insertion: crest of the lesser tubercle of the humerus, and latissismus dorsi

action: extend, rotate medially, and adduct arm

Teres Minor:

origin: lateral border of the dorsal scapular surface

insertion: greater tubercle of the humerus

action: rotate the arm laterally, rotator cuff muscle

Biceps Brachii:

origin: coracoid process, glenoid cavity

insertion: radial tuberosity

action: flex and supinate forearm

Triceps Brachii:

origin: tubercle of the scapula, humerus

insertion: olecranon of ulna

action: forearm extensor

Brachialis:

origin: distal humerus

insertion: coranoid process of the ulna

action: forearm flexor

Brachioradialis:

origin: distal humerus

insertion: radial styloid process

action: synergist forearm flexing

Flexor Carpi Radialis:

origin: medial epicondyle of humerus

insertion: base of metacarpals

action: powerful flexor and ABductor of hand

Flexor Carpi Ulnaris:

origin: medial epicondyle of humerus, olecranon of ulna

insertion: carpal and metacarpal bones

action: powerful flexor and ADDuctor of hand

Extensor digitorium:

origin: lateral epicondyle of humerus

insertion: phalanges

action: prime mover of finger extension

Psoas major:

origin: T12-L4 vertebrae

insertion: lesser trochanter of femur

action: flexion at hip joint, a major connector of upper and lower body

Iliacus:

origin: iliac fossa

insertion: lesser trochanter of femur

action: flexes and medially rotates the thigh

Sartorious:

origin: anterior superior iliac spine

Insertion: medial aspect of proximal tibia

action: flexes, abducts, and laterally rotates the thigh

Gluteus Maxmimus

origin: dorsal ilium and coccyx

insertion: gluteal tuberosity of femur

action: major extensor of thigh

Gluteus Medius:

Origin: lateral surface of ilium

Insertion: lateral aspect of greater trochanter of femur

Action: abducts and medially rotates the thigh

Gluteus minimus:

Origin: ilium

Insertion: greater trochanter of femur

Tensor Fascia latae

origin: iliac crest and spine

insertion: iliotibial tract

action: steadies leg when standing, abducts and rotates the thigh medially

Rectus femoris

origin: anterior inferior iliac spine and acetabulum

insertion: patella and tibial tuberosity

action: extends leg and flexes thigh at hip

Vastus Lateralis:

origin: greater trochanter and linea aspera

Insertion: patella and tibial tuberosity

action: extends and stabilizes leg

Vastus Medialis:

origin: linea aspera, others

insertion: patella and tibial tuberosity

action: extends leg

Vastus Intermedius:

Origin: femur shaft

Insertion: patella and tibial tuberosity

action: extends leg

Biceps Femoris:

Origin: ischial tuberosity

Insertion: fibula and tibia

action: extends thigh and flexes leg

Semitendinosus

origin: ischial tuberosity

insertion: tibial shaft

action: extends thigh and flexes leg

Semimembranousus:

Origin: ischial tuberosity

Insertion: femur and tibia

action: extends thigh and flexes leg

Adductor Longus:

origin: pubis near symphysis

insertion: linea aspera

action: adducts, flexes, and medially rotates thigh

Adductor Magnus:

origin: ischial and pubic rami

Insertion: linea aspera and femur

action: adducts and medially rotates and flexes thigh, extends thigh

Adductor brevis:

origin: pubic ramus

insertion: linea aspera

action: adducts, flexes, and medially rotates thigh

Pectineus:

origin: pubis

insertion: lesser trochanter of femur

action: adducts, flexes, and medially rotates thigh

Gracillis:

origin: inferior ramus and body of pubis

Insertion: medial surface of tibia

action: adducts thigh, flexes and medially rotates leg

Tibialis anterior:

O: lateral condyle and tibial shaft

I: medial cuneiform and first metatarsal

action: prime mover of dosrisflexion

Gastrocnemius:

O: medial and lateral condyles of femur

I: posterior calcaneus

action: plantar flexes foot

Soleus:

O: superior tibia, fibula, and interosseous membrane

I: calcaneus

action: plantar flexes foot

Fibularis Longus:

O: fibula

I: metatarsals

Action: plantar flexes foot; eversion and inversion of foot