Muscle Insertions, Origins, And Actions

Front 1

Deltoid

Back 1

Location: Shoulder
Origin: clavicle, the acromion and spine of scapula
Insertion: Deltoid tuberosity of the humerus
Action: Flex and medially rotate, abduction, extend and laterally rotate
Notes: Is assisted by the supraspinatus

Front 2

Pectoralis Major

Back 2

Location: Chest
Origin: Medial clavicle, sternum, costal cartilage of upper ribs
Insertion: Lateral portion of the intertubecular groove of the humerus
Action: Flexes, adducts, and rotates arm medially at shoulder joint

Front 3

Biceps brachii

Back 3

Location: Anterior portion of humerus
Origin: Long head supraglenoid tubercle of scapula, short head coracoid process of scapula
Insertion: Radial tuberosity of radius and bicipital aponeurosis
Action: flexes the elbow joint, powerful supinator of forearm at the elbow joint; flexes arm

Front 4

Coracobrachialis

Back 4

Location: Axillary region
Origin: coracoid process of scapula
Insertion: middle medial shaft of humerus
Action: Adducts and flexes arm

Front 5

Teres Major

Back 5

Location: Just superior and deep to latissimus dorsi
Origin: Lateral border and inferior angle of the scapula
Insertion: Lesser tubercle of humerus
Action: Extends and adducts arm at shoulder joint, drawing it down and back while rotating it medially

Front 6

Latissimus dorsi

Back 6

Location: on back and sides
Origin: spinous processes of lower thoracic vertebrae, lower ribs, iliac crest, thoracolumbar fascia
Insertion: Intertubercular groove of the humerus
Action: Extends and adducts arm at shoulder joint (bring to center), draws humerus down and back while rotating it medially (swimming)

Front 7

Supraspinatus

Back 7

Location: supraspinous fossa of scapula
Origin: supraspinous fossa of scapula
Insertion: greater tubercle of the humerus
Action: Abducts and laterally rotates shoulder joint
Notes: supraspinatus initiates abduction of the arm, then the deltoid muscle completes the action (throwing the ball)

Front 8

Infraspinatus

Back 8

Location: infraspinous fossa of scapula
Origin: infraspinous fossa of scapula
Insertion: greater tubercle of the humerus
Action: Adducts and laterally rotates shoulder joint

Front 9

Teres Minor

Back 9

Location: just superior to teres major and inferior to infraspinatus muscle
Origin: Lateral (axillary region) border of the scapula
Insertion: greater tubercle of the humerus
Action: adducts and laterally rotates shoulder joint
Notes: fixes the head of the humerus in the glenoid fossa during abduction and flexion of the arm

Front 10

Triceps brachii

Back 10

Location: Posterior portion of humerus
Origin: 1) long head: infraglenoid tubercule of scapula 2) Lateral head: above radial groove of humerus 3) Medial head: below the radial groove of the humerus
Insertion: Olecranon of ulna
Action: extends elbow at joint - antagonistic to biceps brachii (long head of triceps also extends and adducts arm)

Front 11

Serratus Anterior

Back 11

Location: Sides of body under axillary region
Origin: Upper ribs (lateral surface 1-8)
Insertion: Medial border of scapula (on the deep side of scapula)
Action: Pulls scapula forward (protracts) and down (depresses); superiorly rotates scapula

Front 12

Pectoralis Minor

Back 12

Location: Deep to the pectoralis major
Origin: Sternal end of upper ribs (3, 4, 5)
Insertion: Coracoid process of scapula
Action: pulls scapula forward (protracts) and down (depresses)
Notes: superior

Front 13

Trapezius

Back 13

Location: The visible neck and medial shoulder muscle
Origin: Ligamentum nuchae, spinous processes of C7 - T12 and occipital bone, superior nuchal line
Insertion: Clavicle, spine of scapula, acromion of scapula
Action: elevates and adducts scapula, draws head back

Front 14

Rhomboideus Major

Back 14

Location: Top and middle portion of back (deep to trapezius)
Origin: Spines of several thoracic vertebrae (T2-T5)
Insertion: Medial border of scapula
Action: Elevates and adducts scapula, inferiorly rotate the scapula
Notes: inferior

Front 15

Rhomboideus Minor

Back 15

Location: Just superior to rhomboideus major (deep to trapezius)
Origin: Spinous process C7-T1 vertebrae
Insertion: Medial border of scapula
Action: Elevates and adducts scapula, inferiorly rotate the scapula, lateral rotation
Notes: superior

Front 16

Psoas Major

Back 16

Location: Passes deep to the inguinal ligament from the lower spine
Origin: Transverse processes and bodies of lower vertebrae
Insertion: Lesser trochanter of femur with iliacus
Action: Flexes the thigh

Front 17

Iliacus

Back 17

Location: passes deep to the inguinal ligament fromt he lower spine
Origin: Iliac fossa
Insertion: Lesser trochanter of femur with psoas major
Action: Flexes the thigh

Front 18

Tensor fasciae latae

Back 18

Location: lateral surface of hip
Origin: Iliac crest and lateral surface of anterior superior iliac spine
Insertion: Iliotibial (I.T.) tract
Action: abducts thigh at the hip joint
Notes: tensor fascia latae redirects the rotational forces of the gluteus maximus

Front 19

Sartorius

Back 19

Location: obliquely crosses the anterior aspect of the thigh; longest muscle in the body
Origin: anterior superior iliac spine
Insertion: Medial side of tibial tuberosity
Action: Flexes thigh and rotates thigh laterall; flexes leg at knee joint and rotates crural (leg) region medially (hacky sack motion)
Notes: sartorius means "tailor"; its actions put the lower linb in the traditional corss-legged seated position of a tailor

Front 20

Rectus Femoris

Back 20

Location: Superficial (middle) anterior thigh
Origin: anterior inferior iliac spine
Insertion: quadriceps tendon to patella and then patellar ligament to tibial tuberosity
Action: Causes leg flexion of the leg at the acetabulofemoral joint, extends leg at knee joint

Front 21

Gracilis

Back 21

Location: Medial surface of thigh
Origin: Inferior edge of ramus of pubis, near symphysis pubis
Insertion: Proximal medial surface of tibia
Action: Adducts thigh at hip joint, flexes leg at knee joint

Front 22

Gluteus maximus

Back 22

Location: Buttock (good for intramuscular injections
Origin: Iliac crest, sacrum, coccyx
Insertion: Linea aspera of the femur and iliotibial tract of fascia lata
action: extends thigh, also laterall rotates thigh (important for bipedal standing and walking/running)

Front 23

Biceps femoris

Back 23

Location: posterior lateral surface of thigh
Origin: Long head: ischial tuberosity; Short head: Linea aspera
Insertion: Long head: head of fibiula; Short head: lateral condyle of tibia
Action: extends thigh and flexes knee joint. Also, biceps femoris laterally rotates thigh

Front 24

Semimembranosus

Back 24

Location: Deep and medial to semitendinosus
Origin: Ischial tuberosity
Insertion: Posterior surface of medial condyle of tibia
Action: Extends thigh and flexes knee joint, laterally rotates thigh

Front 25

Semitendinosus

Back 25

Location: posterior medial surface of thigh
Origin: ischial tuberosity
Insertion: Proximal medial surface of tibia
Action: extends thigh and flexes knee joint, laterally rotates thigh

Front 26

Vastus Lateralis

Back 26

Location: anterolateral surface of thigh
Origin: greater trochanter and linea aspera of femur
Insertion: quadriceps tendon to patella and then patellar ligament to tibial tuberosity
Action: extends leg at knee joint

Front 27

Vastus Medialis

Back 27

Location: anteriomedial surface of thigh
Origin: Linea aspera and intertrochanteric line of femur
Insertion: quadriceps tendon to patella and then patellar ligament to tibial tuberosity

Front 28

Vastus Intermedius

Back 28

Location: Deep to the rectus femoris
Origin: anterior and lateral surfaces of femur
Insertion: quadriceps tendon to patella and then patellar ligament to tibial tuberosity
Action: extends leg at knee joint

Front 29

Gastrocnemius

Back 29

Location: the calf muscle
Origin: Superior posterior lateral and medial condyles of femur (2 heads)
Insertion: calcaneus via the calcaneal tendon (achilles tendon)
Action: plantar flexes foot at ankle and flexes knee joint

Front 30

Tibialis anterior

Back 30

Location: Anterior lateral portion of tibia
Origin: Lateral condyle and proximal shaft of tibia
Insertion: 1st metatarsal and 1st cuneiform (tarsal) bone
Action: Dorsiflexes and inverts foot at ankle
Notes: antagonist (dorsiflexion/plantar flexion) and a synergist (inversion) of the tibialis posterior m.

Front 31

Soleus

Back 31

Location: Deep to gastrocnemius
Origin: head and proximal shaft of fibula, and medial border of tibia
Insertion: Calcaneus via the calcaneal tendon (achilles tendon)
Action: Plantar flexes foot at ankle

Front 32

External oblique

Back 32

Location: lateral and anterior superficial portions of abdominal cavity - forms inguinal ligament
Origin: external inferior border of lower ribs
Insertion: Linea alba by a broad aponeurosis and some to the iliac crest
Action: both contract they compress the abdomen and flex the vertebral column; when one contracts it causes lateral rotation

Front 33

Internal Oblique

Back 33

Location: immediately deep to the external oblique
Origin: iliac crest, lumbar fascia, and inguinal ligament
insertion: linea albe, lower ribs and costal cartilage (of ribs 8-10 (false)
Action: same as external obliques

Front 34

transverse abdominis

Back 34

location: immediately deep to the external oblique
origin: iliac crest, lumbar fascia, costal cartilage of lower ribs, inguinal ligament
insertion: xiphoid process, linea alba, and pubis
Action: compresses the abdomen
Notes: help with child delivery

Front 35

rectus abdominis

Back 35

location: anterior portion of abdomen, separated by linea alba
origin: symphysis pubis
insertion: xiphoid process, inferior surfaces of middle ribs
action: flexes the vertebral column and compress the abdominal
notes: important role in respiration

Front 36

masseter Muscle

Back 36

Location: Posterior to buccinator, superficial to temporalis, angle of mandible
Origin: zygomatic arch
insertion: lateral surface of ramus and angle of mandible and of coronoid process
action: elevates and protracts mandible
Notes: powerful chewing muscle

Front 37

temporalis

Back 37

location: temporal region of cranium
origin: superior and inferior portions of temporal bone
insertion: coronoid process of mandible
action: elevates and retracts mandible

Front 38

lateral pterygoid

Back 38

Location: internal to the mandible
Origin: pterygoid process of pshenoid bone
insertion: mandibular condyle
Action: elevate and protract mandible and moves it laterally (grinding)

Front 39

Medial pterygoid

Back 39

location: near TMJ, internal to the mandible
Origin: pterygoid process of sphenoid bone
insertion: medial surface of ramus of mandible
action: elevate and protract mandible and moves it laterally (grinding)

Front 40

diaphragm

Back 40

location: between thoracic and abdominal cavities
origin: xiphoid process, costal cartilage, lumbar vertebrae, inferior internal surface of lower ribs
insertion: central tendon
action: pulls central tendon inferiorly, increasing vertical dimension of thorax (thus drawing air into lungs)
notes: separates thoracic cavity from abdominal cavity

Front 41

linea alba

Back 41

median vertical tendinous line on the abdomen formed of fibers from the aponeuroses of the two rectus abdominis muscles and extending from the xiphoid process to the pubic symphysis

Front 42

linea semilunaris

Back 42

the curved line on the anterior abdominal wall that is parallel to the midline and halfway between it and the side of the body that marks the lateral border of the rectus abdominis muscles (also called semilunar line)

Front 43

Rectus sheath

Back 43

is formed from the aponeuroses of the external oblique, internal oblique, and transverses abdominis muscles. The left and right rectus sheaths are connected by a vertical firous strip termed the linea alba

Front 44

inguinal ligament

Back 44

spans the distance between the body of pubis and the anterior superior iliac spine

Front 45

Peroneus (fibularis) longus

Back 45

Location: superficial lateral, covers fibula
Origin: lateral condyle of tibia; head and body of fibula
Insertion: 1st metatarsal and 1st cuneiform (tarsal) bone
action: plantar flexes and everts foot at ankle

Front 46

Frontal belly of occipitofrontalis

Back 46

location: frontal bone
origin: frontal bone and skin of forehead
insertion: galea aponeurotica (aponeurosis - thin, flat tendon)
action: elevates the eyebrows, wrinkles skin of forehead

Front 47

Occipital belly of occipitofrontalis

Back 47

location: occipital bone
Origin: superior nuchal line
insertion: galea aponeurotica
action: retracts the scalp slightly

Front 48

orbicularis oris

Back 48

location: around the lips
origin: maxilla and mandible as well as fascia and fibers from other muscles
insertion: skin and lips surrounding mouth
action: closes lips, puckers up the lips (kissing)

Front 49

sternocleidomastoid

Back 49

lateral borders of the "suprasternal fossa: of the skin
origin: manubriuma nd sternal end of clavicles
insertion: mastoid processes of the temporal bones
action: both contracted, head is pulled forward and down (flexion); one contracts, head turns opposite direction of side contracted

Front 50

platysma

Back 50

location: anterior portion of the neck
origin: fascia of deltoid and pectoralis major plus acromion of scapula
insertion: skin of cheek and mandible
action: pulls lower lip inferiorly, tenses skin of neck

Front 51

Splenius capitus

Back 51

location: neck/shoulder junction
origin: ligamentum nuchae, ligament that runs length of cervical
insertion: occipital bone and mastoid process of temporal bone
action: both contract extends head/neck. unilateral contractions turn the head and neck to the same side

Front 52

semispinalis capitus

Back 52

location: neck/shoulder junction
origin: C7 and T6
insertion: between the superior and inferior nuchal lines of occipital bone
action: both contract extends head/neck. unilateral contractions turn the head an dneck to the same side