Exam 2: Axial & Appendicular Skeletal Muscles

Question 1

Frontal belly of occipitofrontalis

Answer 1

origin- epicranial aponeurosis
insertion- eyebrow skin
action- wrinkles skin of forehead

Question 2

orbicularis oculi

Answer 2

origin- medial wall or margin of orbit
insertion- skin surrounding eyelids
action- closes eye

Question 3

zygomaticus major

Answer 3

origin- zygomatic bone
insertion- skin at superolateral edge of mouth
action- elevates corner of mouth

Question 4

depressor anguli oris

Answer 4

origin- body of mandible
insertion- skin at inferior corner of mouth
action- frown muscle

Question 5

masseter

Answer 5

origin- zygomatic arch
insertion- ramus & angle of mandible
action- chewer

Question 6

sternocleidomastoid

Answer 6

origin- manubrium & sternal end of clavicle
insertion- mastoid process
action- lateral flexion, rotation of head to opposite side (unilateral) flexes neck (bilateral)

Question 7

splenius capitis

Answer 7

origin- ligamentum nuchae & spinous processes of C7-T13
insertion- occipital bone & mastoid process of temporal bone
action- turns head to same side (unilateral), extends head/neck (bilateral)

Question 8

diaphragm

Answer 8

action- contraction causes flattening, expansion of thoracic cavity, increases pressure in abdominopelvic cavity

Question 9

external oblique

Answer 9

origin- external & inferior borders of the inferior 8 ribs
insertion- linea alba by a broad aponeurosis; some to iliac crest
action- lateral flexion of vertebral column; rotation of vertebral column to opposite side (unilateral) flexes vertebral column & compresses abdominal wall; used in forced exhalation (bilateral)

Question 10

rectus abdominis

Answer 10

origin- superior surface of pubic near symphysis
insertion- xiphoid process of sternum; inferior surfaces of ribs 5-7
action- flexes vertebral column; compresses abdominal wall; used in forced exhalation

Question 11

trapezius

Answer 11

origin- occipital bone (superior nuchal line); ligamentum nuchae; spinous processes of C7-T12
insertion- clavicle; acromion process & spine of scapula
action- elevate & superiorly rotate scapula (superior fibers), retract scapula (middle fibers), depress scapula (inferior fibers)

Question 12

latissimus dorsi

Answer 12

origin- spinous processes of T7-T12; ribs 8-12; iliac crest; thoracolumbar fascia
insertion- intertubular sulcus of humerus
action- agonist of arm extension; also adducts and medially rotates arm

Question 13

deltoid

Answer 13

origin- acromial end of clavicle; acromion & spine of scapula
insertion- deltoid tuberosity of humerus
action- flex & medially rotate arm (anterior fibers), agonist of arm abduction (middle fibers), extend & laterally rotate arm (posterior fibers)

Question 14

pectoralis major

Answer 14

origin- medial clavicle; costal cartilage of ribs 2-6; body of sternum
insertion- lateral part of intertubercular sulcus of humerus
action- agonist of arm flexion; adducts & medially rotates arm; horizontal adduction of arm

Question 15

biceps brachii (short & long heads)

Answer 15

origin- supraglenoid tubercle of scapula (long head), coracoid process of scapula (short head)
insertion- radial tuberosity & bicipital aponeurosis

Question 16

illacus

Answer 16

origin- iliac fossa
insertion- lesser trochanter of femur with psoas major
action- flexes thigh

Question 17

psoas major

Answer 17

origin- transverse processes & bodies of T12-L5 vertebrae
insertion- lesser trochanter of femur with iliacus
action- flexes thigh

Question 18

gluteus maximus

Answer 18

origin- iliac crest, sacrum, coccyx
insertion- iliotibial tract of fascia lata, linea aspera & gluteal tuberosity of femur
action- extends thigh, laterally rotates thigh

Question 19

rectus femoris

Answer 19

origin- anterior inferior iliac spine
insertion- quadriceps tendon to patella and then patellar ligament to tibial tuberosity
action- flexes thigh, extends leg

Question 20

tibialis anterior

Answer 20

origin- lateral condyle and proximal shaft of tibia, interosseous membrane
insertion- metatarsal I & first medial cuneiform
action- dorsiflexes foot, inverts foot

Question 21

gastrocnemius (medial & lateral heads)

Answer 21

origin- superior posterior surfaces of lateral & medial condyles of femur
insertion- calcaneus
action- flexes leg, plantar flexes foot