Muscles of the Shoulder

Question 1

Answer 1

Latissimus Dorsi

• O: SP’s T7 L5; thoracolumbar fascia, illiac crest, posterior sacrum; ribs 9-12; inferior angle of scapula
• I: Medial lip of bicipital groove of humerous
• A: adduction, medial rotation & extension of shoulder; anertior pelvic tilt; downward rotation of scapula
• N: thoracodorsal nerve (C6,C7,C8)

Question 2

Answer 2

Rhomboid Major

• SP’s T2-T5, supraspinous ligament
• I: medial border of scapula ( scapular spine to inferior angle)
• A: retraction of scapula; elevation & downward rotation of scap
• N: dorsal scapular nerve (C4, C5)

Question 3

Answer 3

Rhomboid minor

• O: SP’s C7/T1, supraspinatus ligament
• I: medial border at root of spine of the scapula
• A: retraction of scapula, elevation& downward rotation of scap
• N: dorsal scapular nerve (C4, C5)

Question 4

Answer 4

Serratus Anterior

• O:lateral surfaces & superior borders of ribs 1-8/9
• I: costal surface of medial border of scap
• A: protraction and upward rotation of scap; stabilizes scap for upper extremity movements
• N: long thoracic nerve (C5 - C7)

Question 5

Answer 5

Serratus Posterior

• O: SP’s C7-T2/3
• I: ribs 2-5 (superior external border)
• A: elevation of ribs
• N: intercostal & subcostal nerves

Question 6

Answer 6

Deltoid

• O: Lateral 1/3 of clav, acromion process & spine of scap
• I: deltoid tuberocity of humerus
• A: Abduction of shoulder( middle fibers)
  
  • flexion, horizontal adduction & medial rotation of shoulder (anterior fibers)
  • extension, horizontal abduction & lateral rotation of shoulder (posterior fibers)
• N: axillary nerve (C5, C6)

Question 7

Answer 7

Supraspinatus

• O: medial 2/3 of the supraspinatus fossa of scap
• I: superior faccet of the greater tubricle of humerous
• A: abduction of shoulder, stabilizes GH joint
• N: suprascapular nerve (C5, C6)

Question 8

Answer 8

Infraspinatus

• O: medial 2/3 of the infraspinatus fossa & inferior portion of spine of scap
• I: middle facet of the greater tubercle of the humerus & shoulder joint capsule
• A: lateral rotation of shoulder, stabilizes GH joint
• N: suprascapular nerve C5, C6

Question 9

Answer 9

Teres Minor

• O: superior lateral border of scap
• I: inferior facet of greater tubercle of humerus & shoulder joint capsule
• A: lateral rotaion of shoulder, stabilizes GH joint, adduction of shoulder (weak action)
• N: axillary nerve C5, C6

Question 10

Answer 10

subscapularis

• O: subscapular fossa of scap
• I: lesser tubercle of humerus & shoulder joint capsule
• A: medial rotation of joint & stabilizes GH joint
• N: upper and lower subscapular nerves C5, C6

Question 11

Answer 11

Teres Major

• O: dorsal surfaces of the inferior angle and lower 1/3 of the lateral border of the scapula
• I: medial lip of bicipital groove of humerus (just medial to insertion of latissimus dorsi)
• A: medial rotation, adduction, extension of the shoulder from a flexed position, upward scapular rotaion (closed chain action)
• N: lower subscapular nerve C5, C6, C7

Question 12

Answer 12

Pectoralis Major

• O: Clavicular fibers - medial 1/2 of the clavicle
  
  • sternal fibers - anterior surface of sternum
  • costal fibers - costal cartilage of ribs 1-6
• I: crest of the greater tubercle of humerus (lateral lip of bicipital groove)
• A: adduction and medial rotation of shoulder; horizantal adduction of shoulder, flexion of shoulder (clavicular portion)
• N: medial and lateral pectoral nerve C8, T1

Question 13

Answer 13

Pectoralis Minor

• O: superior margins of ribs 3-5 (anterior lateral portion), facia over corresponding intercostal muscles
• I: coracoid process of scapula (medial aspect)
• A: stabilizes scapula for arm movements; depresses and downwardly rotates scapula; assits in scapular protraction from retracted position; elevates ribs 3-5 (forced expiration)
• N: medial pectoral nerve C8, T1

Question 14

Answer 14

Trapezius Middle anr Lower

• O: Middle: SP’s C7-T5 & nuchal ligament
  
  • Lower: SP’s T5-T12
• I: lateral 1/3 of clavicle, acromion process, spine of scapula
• A: elevation & retraction of scapula, upward rotation of scapula, stabilization of scapula for upper arm movements
  
  • extension of head
  • lateral flexion of head
• N: Spinal accessory nerve CN XI vetral rami C2-C4