Human Muscles/ Origin/insertion/action/function

Front 1

occipitalis

Back 1

origin: occipital bone, mastoid process temporal bone
insertion: galea aponeurotica
action: pulls scalp backward
function: raises eyebrows, wrinkles skin of forehead horizontally

Front 2

frontalis

Back 2

origin: galea aponeurotica
insertion: fascia and skin above eyes and nose
action: pulls skull forwards
function: raises eyebrows, wrinkles skin of forehead horizontally

Front 3

orbicularis oculi

Back 3

origin: frontal bone, medial wall of orbit (on maxilla)
insertion: circular path around orbit returning to origin
action: closes eyelids, dilate lacrimal sac and brings lacrimal glands onto surface of eyes
function: keeps eyes healthy and moisturised and passes and drains tears

Front 4

orbicularis oris

Back 4

origin: muscle fibres surrounding the mouth, skin and muscle fascia of lips
insertion: skin and fascia at corner of mouth
action: closes lips, compresses lips against teeth, protrudes and shapes lips during
speech
function: facial expression involving the lips

Front 5

massetter

Back 5

origin: zygomatic arch
insertion: lateral surface of lower mandible
action: closes jaw, clenches teeth, assists side to side movement of mandible
function: chewing food

Front 6

temporalis

Back 6

origin: temporal fossa
insertion: coronoid process and ramus of mandible
action: clenches teeth, closes jaw, assists in side movement of mandible,
function: chewing food

Front 7

scalenes

Back 7

actually three muscles anterior, medius, posterior
origin: transverse processes of cervical vertebrae
insertion: first and second rib
action: neck flexion laterally and rotation, also raise first rib during strong inhalation
function: primarily muscles of inspiration

Front 8

sterno-cleido-mastoid

Back 8

origin: anterior surface of upper sternum, medial third of clavicle
insertion:mastoid process of temporal bone
action: flexes neck (both sides contract) draws head forward, raises sternum and ribs during deep inhalation, tilts the heard sideways (one side contracts) , rotates it to opposite side
function: turning head to look over shoulder, raising head from pillow

Front 9

platysma

Back 9

origin: subcutaneus fascia of upper quarter of chest
insertion: subcutaneus fascia of chin and jaw
action: pulls lower lip from corner of mouth downward and laterally
function: gives expression of being startled r sudden fright

Front 10

erector spinae (sacrospinalis)

Back 10

actually three sets of muscles:
illiocostalis, longissimus, spinalis

origin: slips of muscle arising from the sacrum, iliac crest, spinous and transverse processes of vertebrae, ribs
insertion: ribs, transverse and spinous processes of vertebrae, occipital bone
action: extend and laterally flexes vertebral column, maintain curvature of spine in erect and sitting position
function: keeps back straight, maintains posture

Front 11

external intercostals

Back 11

origin: lower border of a rib
insertion: upper border of a rib below
action: muscles contract to stabilise ribcage, draws ribs superiorly during inhalation
function: assists inhalation

Front 12

internal intercostals

Back 12

origin: upper border of a rib
insertion: lower border of rib above
action: draws ribs inferiorly, stabilising the ribcage
function: assists exhalation

Front 13

diaphragm

Back 13

origin: lower tip of sternum , lower six ribs and their costal cartilages, upper two or three lumbar vertebrae
insertion: all fibres converge and attach onto a central tendon, this muscle inserts upon itself
action: forms floor of thoracic cavity,draws central tendon downwards during inhalation, increasing volume of thoracic cavity
function: produces 60% of breathing capacity

Front 14

external obliques

Back 14

origin: lower eight ribs
insertion: anterior half of iliac crest and into abdominal aponeurosis
action: compresses abdomen
function: flexes and twist trunk

Front 15

internal obliques

Back 15

origin: iliac crest, lateral two thirds of inguinal ligament, fascia in lower back
insertion: bottom three or four ribs, linea alba via aponeurosis
action: compresses abdomen
function: flexes and twists trunk

Front 16

transversus abdominis

Back 16

origin: anterior two thirds of iliac crest, lateral third of inguinal ligament, costal cartilages of lower six ribs, lower back fascia
insertion: linea alba via abdominal aponeurosis
action: compresses abdomen, helping to support the viscera against the pull of gravity
function: important during forced expiration, sneezing, coughing,helps maintain good posture

Front 17

rectus abdominis

Back 17

origin: pubic crest and sympysis
insertion: base of sternum, fifth, sixth, seventh costal cartilages
action: flexes lumbar spine, depresses ribcage, stabilises pelvis during walking
function: getting up out of low chairs

Front 18

quadratus lumborum

Back 18

origin: iliac crest, iliolumbar ligament
insertion: twelfth rib, transverse processes of upper four lumbar vertebrae (L1-L4)
action: laterally flexes vertebral column, helps extend lumbar part of vertebral column,
function: lateral stability, aids in expiration

Front 19

ilio psoas

Back 19

actually iliacus and psoas major
origin: psoas major; anterior surfaces and lower borders of transverse processes L1 - L5/ iliacus; iliac fossa and crest
insertion: lesser trochanter of femur
action: main flexor of hip joint, flexes and laterally rotates thigh, flexes the trunk acting from its insertion
function: like in going up a step

Front 20

trapezius

Back 20

origin: base of skull, occipital bone, spinous processes of seventh cervical (C7) and all thoracic vertebrae (T1-T12)
insertion: lateral third of clavicle, acromion process, spine of scapula
action: retraction, superior rotation , elevation and depression of scapula
function: extends head

Front 21

levator scapulae

Back 21

origin: transverse processes of first three or four cervical vertebrae (C1-C4)
insertion: upper medial border of scapula
action: elevates the scapula,
function: helps retract scapula, bends neck laterally

Front 22

serratus anterior

Back 22

origin: outer surfaces and superior border of upper eight or nine ribs, fascia covering their intercostal spaces
insertion: anterior surface of medial border of scapula and inferior angle of scapula
action: protracts scapula( pulls it forward on the ribs closely into the chest wall)
function: rotates scapula for abduction and flexion of arm

Front 23

pectoralis minor

Back 23

origin: