Muscle Actions

Front 1

Elevates the eyebrows, wrinkles the skin of the forehead.

Back 1

Frontalis

Front 2

Closes the eyelids (as in blinking or winking).

Back 2

Orbicularis Oculi

Front 3

Elevates the angle of the mouth upward and lateral (as when smiling).

Back 3

Zygomaticus Major

Front 4

Closes lips (as in kissing or making the "O" sound).

Back 4

Orbicularis Oris

Front 5

Draws cheeks in against the teeth (as when sucking through a straw, blowing, or whistling).

Back 5

Buccinator

Front 6

Depresses the angle of the mouth (as when frowning) and depresses the mandible.

Back 6

Platysma

Front 7

Elevates and retracts (moves backwards) the mandible (as when chewing food).

Back 7

Temporalis

Front 8

Elevates the mandible (as when chewing food).

Back 8

Masseter

Front 9

Together they flex the cervical spine (tips head forward); if only one contracts it laterally rotates the neck and head to the opposite side.

Back 9

Sternocleidomastoid

Front 10

Flexes the lumbar spine (as when doing a sit-up) and compresses the abdomen for defecation, urination, and childbirth.

Back 10

Rectus Abdominus

Front 11

Compresses the abdomen and flexes the lumbar spine.

Back 11

Internal AND External Abdominal Oblique

Front 12

Compresses the abdomen, but does not flex the lumbar spine.

Back 12

Transverse Abdominis

Front 13

Extends the spine, holding the body in an upright posture.

Back 13

Erector Spinae

Front 14

Forms the floor of the thoracic cavity. Causes inspiration during contraction and expiration during relaxation.

Back 14

Diaphragm

Front 15

Elevates the ribs, expanding the rib cage during inspiration.

Back 15

External Intercostals

Front 16

Depresses the ribs, compressing the rib cage during forced expiration.

Back 16

Internal Intercostals

Front 17

Closes the opening of the anus.

Back 17

External Anal Sphincter

Front 18

A group of muscles that support the pelvic floor.

Back 18

Levator Ani

Front 19

Abducts the scapula, rotates it downward, and pulls it against the ribs. Can also assist with forced breathing by elevating the ribs.

Back 19

Pectoralis Minor

Front 20

Abducts the scapula and rotates it upwards (as when lifting the arms).

Back 20

Serratus Anterior

Front 21

Adducts the scapula and rotates it upwards (as when lifting the arms).

Back 21

Trapezius

Front 22

Adducts, elevates, and rotates the scapula downwards.

Back 22

Rhomboideus Major

Front 23

Adducts, flexes, and medially rotates the humerus at the shoulder.

Back 23

Pectoralis Major

Front 24

Adducts, extends, and medially rotates the humerus at the shoulder.

Back 24

Latissimus Dorsi

Front 25

Abducts, flexes, extends and rotates the humerus at the shoulder.

Back 25

Deltoid

Front 26

Assists the deltoid in abducting the humerus at the shoulder.

Back 26

Supraspinatus

Front 27

Laterally rotates the humerus at the shoulder.

Back 27

Infraspinatus

Front 28

Laterally rotates and extends the humerus at the shoulder.

Back 28

Teres Minor

Front 29

Medially rotates the arm at the shoulder.

Back 29

Subscapularis

Front 30

Flexes the forearm at the elbow and the humerus at the shoulder.

Back 30

Biceps Brachii

Front 31

Extends the forearm at the elbow and extends the humerus at the shoulder.

Back 31

Triceps Brachii

Front 32

Flexes and laterally rotates the femur at the hip, as well as flexes the trunk at the hip as when sitting up from a supine position.

Back 32

Iliopsoas

Front 33

Extends and laterally rotates the femur at the hip.

Back 33

Gluteus Maximus

Front 34

Abducts and medially rotates the femur at the hip.

Back 34

Gluteus Medius

Front 35

Plantar flexes and everts the foot at the ankle.

Back 35

Fibularis Longus

Front 36

Adducts and flexes the femur at the hip.

Back 36

Adductor Muscles (Adductor Brevis, Longus, and Magnus)

Front 37

Abducts and flexes the femur at the hip.

Back 37

Tensor Fasciae Latae

Front 38

Flexes the femur at the hip, flexes and laterally rotates the leg at the knee (allows the legs to be crossed).

Back 38

Sartorius

Front 39

Extends the leg at the knee. Acting alone it also flexes the femur at the hip.

Back 39

Rectus Femoris

Front 40

Extends the leg at the knee.

Back 40

Quadriceps Femoris (Rectus Femoris, Vastus, Lateralis, Vastus Medialis, Vastus Intermedius)

Front 41

Flexes the leg at the knee and extends the femur at the hip.

Back 41

Hamstrings (Biceps Femoris, Semitendinosus, Semimembranosus)

Front 42

Plantar flexes the foot at the ankle and flexes the leg at the knee.

Back 42

Gastrocnemius

Front 43

Dorsiflexes and inverts the foot at the ankle.

Back 43

Tibialis Anterior

Front 44

Abducts and medially rotates the femur at the hip.

Back 44

Gluteus Minimus