Muscle Actions

Question 1

Trapezius

Answer 1

• descending fibers: elevation of scapula
• medial fibers: retraction of scapula
• ascending fibers: depression of scapula
• rotation of glenoid cavity superiorly

Question 2

Brachialis

Answer 2

• Elbow flexion

Question 3

Biceps Brachii

Answer 3

• Forearm supination
• Elbow flexion

Question 4

Coracobrachialis

Answer 4

• Shoulder flexion
• Shoulder adduction

Question 5

Segmentals

(Interspinales, Intertransversarii, Levator Costarum)

Answer 5

• Extension of vertebral column
• Lateral flexion of vertebral column
• Stabilize vertebral column
• Levator Costarum: elevate ribs, assist in respiration, assist in lateral flexion of vertebral column

Question 6

Latissimus Dorsi

Answer 6

• medial rotation of humerus
• adduction of humerus
• extends humerus
• raises body toward upper limbs when climbing

Question 7

Transversospinales

(Semispinalis, Multifidus, Rotatores)

Answer 7

• Extends vertebral column
• Laterally flexes / rotates vertebral column
• Stabilizes vertebral column
• Rotatores: proprioceptive function?

Question 8

Levator Scapulae

Answer 8

• retracts scapula
• rotates glenoid cavity inferiorly

Question 9

Rhomboids (major & minor)

Answer 9

• retracts scapula
• rotates glenoid cavity inferiorly
• fixes scapula against thoracic wall

Question 10

Erector Spinae

(Iliocostalis, Longissimus, Spinalis)

Answer 10

• Extends vertebral column
• Laterally flexes vertebral column
• Stabilizes vertebral column

Question 11

Deltoid

Answer 11

• anterior fibers: medial rotation and flexion of humerus
• middle fibers: abduction of humerus
• posterior fibers: laterally rotates and extends humerus

Question 12

Splenius (capitis & cervicis)

Answer 12

• Flexes neck laterally
• Rotates head
• Extends head and neck

Question 13

Serratus Posterior (superior & inferior)

Answer 13

• Active during respiration?
• Proprioceptive function?

Question 14

Serratus Anterior

Answer 14

• Protracts scapula
• Rotates scapula
• Holds scapula against thorax

Question 15

Teres Major

Answer 15

• medial rotation of humerus
• adduction of humerus

Question 16

Subscapularis

Answer 16

• medial rotation of humerus
• stabilizes shoulder joint

Question 17

Subclavius

Answer 17

• Stabilizes /anchors clavicle,
• Depresses clavicle

Question 18

Pectoralis Minor

Answer 18

• Stabilizes scapula (draws scapula
  anteriorly and inferiorly against
  thorax)

Question 19

Supraspinatus

Answer 19

• abduction of humerus
• stabilizes shoulder joint

Question 20

Pectoralis Major

Answer 20

• Adducts humerus
• Medially rotates humerus
• Clavicular head: flexes humerus
• Sternocostal head: extends humerus from flexed position

Question 21

Infraspinatus

Answer 21

• lateral rotation of humerus
• stabilizes shoulder joint

Question 22

Teres Minor

Answer 22

• laterally rotates humerus
• stabilizes shoulder joint