50 Muscle Atlas (Origin, Insertion, Action)

Question 1

Orbicularis Oris

Answer 1

Origin: muscle fibers surrounding opening of mouth
Insertion: skin at corner of mouth
Action: close lips, compress lips against teeth, protrude lips, shape lips during speech

Question 2

Orbicularis Oculi

Answer 2

Origin: medial orbital wall
Insertion: circular path around orbit
Action: close eyes

Question 3

Masseter

Answer 3

i) origin: maxilla and zygomatic arch
ii) insertion: angle and ramus of mandible
iii) action: elevates mandible as in closing mouth, assists in side-to-side movement of mandible, and protracts (protrudes) mandible

Question 4

Temporalis

Answer 4

i) origin: parietal bone
ii) insertion: coronoid process and ramus of mandible
iii) action: elevates and retracts mandible and assists in side-to-side movement of mandible

Question 5

Sternocleidomastoid

Answer 5

i) origin: sternum and clavicle
ii) insertion: mastoid process of temporal bone
iii) action: contraction of both muscles flexes the cervical part of the vertebral column and draws the head forward; contraction of one muscle rotates face toward side opposite of the contracting muscle

Question 6

Rectus Abdominus

Answer 6

i) origin: pubic crest and pubic symphysis
ii) insertion: cartilage of fifth to seventh ribs and xiphoid process
iii) action: flexes vertebral column and compresses abdomen to aid in defecation, urination, forced expiration, and childbirth

Question 7

Obliquus Externus Abdominis (External Oblique)

Answer 7

i) origin: inferior eight ribs
ii) insertion: iliac crest and linea alba
iii) action: contraction of both compresses abdomen and flexes vertebral column; contraction of one side alone bends vertebral column laterally; rotates vertebral column

Question 8

internal oblique

Answer 8

i) origin: iliac crest, inguinal ligament, and thoracolumbar fascia
ii) insertion: cartilage of ribs 7-10 and linea alba
iii) action: compresses abdomen

Question 9

transverse abdominis

Answer 9

i) origin: iliac crest, inguinal ligament, lumbar fascia, and cartilages of ribs 5-10
ii) insertion: xiphoid process, linea alba, and pubis
iii) action: compresses abdomen

Question 10

diaphragm

Answer 10

i) origin: xiphoid process of sternum, costal cartilages and adjacent portions of ribs 7-12, lumbar vertebrae and their intervertebral discs
ii) insertion: central tendon
iii) action: contraction [inspiration] elevates ribs and increases anteroposterior and lateral dimension of thoracic cavity (relaxation [expiration] does the opposite)

Question 11

trapezius

Answer 11

i) origin: occipital bone, ligamentum nuchae, and spines of seventh cervical and all thoracic vertebrae
ii) insertion: clavicle and acromion and spine of scapula
iii) action: elevates clavicle, adducts scapula, rotates scapula superiorly, elevates or depresses scapula, and extends head

Question 12

serratus anterior

Answer 12

i) origin: ribs 1-8 or 1-9
ii) insertion: vertebral border and inferior angle of scapula
iii) action: abducts scapula and rotates it upwards

Question 13

pectoralis major

Answer 13

i) origin: clavicle, sternum, and cartilages of second to sixth ribs
ii) insertion: greater tubercle and intertubercular sulcus of humerus
iii) action: flexes, adducts, and rotates arm medially

Question 14

Subscapularis

Answer 14

i) origin: subscapular fossa of scapula
ii) insertion: lesser tubercle of humerus
iii) action: medially rotates arm at shoulder joint

Question 15

Teres Major

Answer 15

i) origin: inferior angle of scapula
ii) insertion: lesser tubercle of humerus
iii) action: extends arm at shoulder joint, and assists in adduction and medial rotation of arm at shoulder joint

Question 16

Teres Minor

Answer 16

i) origin: inferior lateral border of scapula
ii) insertion: greater tubercle of humerus
iii) action: laterally rotates and extends arm at shoulder joint

Question 17

Deltoid

Answer 17

i) origin: acromial extremity of clavicle and acromion and spine of scapula
ii) insertion: deltoid tuberosity of humerus
iii) action: abducts, flexes, extends, and may alternately medially or laterally rotate arm

Question 18

Infraspinatus

Answer 18

Origin: infraspinous fossa of scapula
Insertion: greater tubercle of humerus (posterior)
Actions: extends arm; adducts and laterally rotates humerus

Question 19

Latissimus dorsi

Answer 19

i) origin: spines of inferior six thoracic vertebrae, lumbar vertebrae, crest of sacrum and ilium, inferior four ribs
ii) insertion: intertubercular sulcus of humerus (to anteromedial to humerus)
iii) action: extends, adducts, and rotates arm medially; draws arm inferiorly and posteriorly

Question 20

Biceps brachii

Answer 20

Flexor
Origins: 2 - long head from tubercle superior to glenoid cavity
short head from coracoid process of scapula
Insertion: radial tuberosity
Action: flexes and supinates forearm; flexes arm

Question 21

Brachioradialis

Answer 21

FLEXOR

i) origin: lateral border of distal end of humerus
ii) insertion: superior to styloid process of radius
iii) action: flexes forearm

Question 22

Brachialis

Answer 22

FLEXOR
Origin: distal, anterior surface of humerus
Insertion: ulnar tuberosity and coronoid process of ulna
Action: flexes forearm

Question 23

Triceps brachii

Answer 23

EXTENSOR

i) origins: 3
a) long head from a projection inferior to glenoid cavity of scapula
b) lateral head from lateral and posterior surface of humerus superior to radial groove
c) medial head from entire posterior surface of humerus inferior to a groove for the radial nerve
ii) insertion: olecranon of ulna
iii) action: extends forearm; extends arm

Question 24

Flexor carpi radialis

Answer 24

i) origin: medial epicondyle of humerus
ii) insertion: second and third metacarpals
iii) action: flexes and abducts wrist

Question 25

Flexor carpi ulnaris

Answer 25

i) origin: medial epicondyle of humerus and superior posterior border of ulna ii) insertion: pisiform, hamate, and fifth metacarpal iii) action: flexes and adducts wrist

Question 26

Flexor digitorum superficialis

Answer 26

i) origin: medial epicondyle of humerus, coronoid process of ulna, and a ridge along lateral margin of anterior surface of radius ii) insertion: middle phalanges iii) action: flexes middle phalanges of each finger

Question 27

Extensor carpi radialis longus

Answer 27

i) origin: lateral epicondyle of humerus ii) insertion: second metacarpal iii) action: extends and abducts wrist

Question 28

Extensor digitorum

Answer 28

i) origin: lateral epicondyle of humerus ii) insertion: second through fifth distal and middle phalanges iii) action: extend phalanges

Question 29

Extensor carpi ulnaris

Answer 29

i) origin: lateral epicondyle of humerus and posterior border of ulna ii) insertion: fifth metacarpal iii) action: extends and adducts wrist

Question 30

Erector spinae (collective group)

Answer 30

Longissimus Thoracis Longissimus Cervicis Longissimus Capitis

Question 31

Longissimus Capitis (erector spinae group)

Answer 31

Origin: Transverse processes of upper five thoracic vertebrae (T1-T5), articular processes of lower three cervical vertebrae (C5-C7) Insertion: Posterior part of mastoid process of temporal bone Action: Extends and rotates head

Question 32

Longissimus Cervicis (erector spinae group)

Answer 32

Origin: Transverse processes of upper four or five thoracic vertebrae (T1-T5) Insertion: Transverse processes of second through sixth cervical vertebrae Action: Extends vertebral column, and lateral flexion

Question 33

Longissimus Thoracis (erector spinae group)

Answer 33

Origin: Medial and lateral sacral crests, spinous processes and supraspinal ligament of lumbar and eleventh and twelfth thoracic vertebrae, and medial part of iliac crests Insertion: Transverse processes of all thoracic vertebrae, between tubercles and angles of lower nine or ten ribs Action: Extends vertebral column, also lateral flexion, and rotates ribs for forceful inspiration

Question 34

Biceps femoris

Answer 34

i) origins: 2 a) long head arises from ischial tuberosity b) short head arises from linea aspera of femur ii) insertion: head of fibula and lateral condyle of tibia iii) action: flexes leg and extends thigh

Question 35

Semitendinosus

Answer 35

i) origin: ischial tuberosity ii) insertion: proximal part of medial surface of shaft of tibia iii) action: flexes lower leg and extends thigh

Question 36

Semimembranosus

Answer 36

i) origin: ischial tuberosity ii) insertion: medial condyle of tibia iii) action: flexes lower leg and extends thigh

Question 37

Gluteus medius

Answer 37

i) origin: ilium ii) insertion: greater trochanter of femur iii) action: abducts and rotates thigh medially

Question 38

Iliacus

Answer 38

i) origin: iliac fossa and sacrum ii) insertion: psoas major into lesser trochanter of femur iii) action: psoas major and iliacus muscles acting together flex thigh at hip joint, rotate thigh laterally, and flex trunk on hip

Question 39

Psoas major

Answer 39

i) origin: transverse processes and bodies of lumbar vertebrae ii) insertion: with iliacus into lesser trochanter of femur iii) action: psoas major and iliacus muscles acting together flex thigh at hip joint, rotate thigh laterally, and flex trunk on hip

Question 40

Piriformis

Answer 40

i) origin: anterior sacrum ii) insertion: superior border of greater trochanter of femur iii) action: laterally rotates and abducts the thigh at the hip joint

Question 41

Erector Spinae (summarized)

Answer 41

Origin: Several origins including iliac crest, ribs, vertebrae Insertion: Several insertions including skull bones, vertebrae, ribs Action: chief extensor of vertebral column. Unilaterally: lateral flexion of vertebral column.

Question 42

Adductor longus

Answer 42

i) origin: pubic crest and pubic symphysis (anterior body of pubis) ii) insertion: linea aspera of femur (mid-posterior) iii) action: adducts, laterally rotates, and flexes thigh

Question 43

Tensor fasciae latae

Answer 43

i) origin: iliac crest ii) insertion: tibia by way of the iliotibial tract iii) action: flexes and abducts thigh

Question 44

Adductor magnus

Answer 44

i) origin: inferior ramus of pubis, and ramus and lower part of tuberosity of ischium ii) insertion: linea aspera (anterior), adductor tubercle of femur iii) action: adducts thigh, assists in medial rotation

Question 45

Adductor magnus

Answer 45

i) origin: inferior ramus of pubis, and ramus and lower part of tuberosity of ischium ii) insertion: linea aspera (anterior), adductor tubercle of femur iii) action: adducts thigh, assists in medial rotation

Question 46

Gluteus maximus

Answer 46

i) origin: iliac crest, sacrum, coccyx, and aponeurosis of sacrospinalis ii) insertion: iliotibial tract of fascia lata and lateral part of linea aspera inferior to grater trochanter of femur iii) action: extends and rotates thigh laterally

Question 47

Gracilis

Answer 47

i) origin: pubic symphysis and pubic arch ii) insertion: medial surface of body of tibia iii) action: adducts thigh and flexes leg

Question 48

Rectus femoris (one of quadriceps femoris)

Answer 48

i) origin: anterior inferior iliac spine ii) insertion: patella and tibial tuberosity iii) action: flexes thigh and extends leg

Question 49

Vastus medialis

Answer 49

i) origin: linea aspera of femur ii) insertion: patella and tibial tuberosity iii) action: extends leg at knee

Question 50

Vastus Lateralis

Answer 50

i) origin: greater trochanter and linea aspera of femur ii) insertion: patella via quadriceps tendon and then tibial tuberosity via patellar ligament iii) action: extends leg at knee joint

Question 51

Gastrocnemius

Answer 51

i) origin: lateral and medial condyles of femur and posterior capsule of knee ii) insertion: calcaneus by way of calcaneal (Achilles) tendon iii) action: plantar flexes foot and flexes leg

Question 52

Tibialis anterior

Answer 52

i) origin: lateral condyle and body of tibia and interosseous membrane ii) insertion: first metatarsal and first (medial) cuneiform iii) action: dorsiflexes and inverts foot

Question 53

Flexor digitorum longus

Answer 53

i) origin: middle third of posterior surface of tibia ii) insertion: distal phalanges of toes II – V. iii) action: plantarflexion at ankle, flexes phalanges.

Question 54

Peroneus (fibularis) longus

Answer 54

i) origin: head and body of fibula and lateral condyle of tibia ii) insertion: first metatarsal and first cuneiform iii) action: plantar flexes and everts foot

Question 55

Extensor Digitorum Longus

Answer 55

i) origin: head and body of fibula and lateral condyle of tibia ii) insertion: first metatarsal and first cuneiform iii) action: plantar flexes and everts foot