11.2 Musculature and Movements of the Pectoral Girdle and Shoulder

Question 1

What are the three parts of the deltoid?

Answer 1

1. Clavicular part (attaches to clavicle)
2. Middle part
3. Spinal part (scapular spine)

Question 2

Origin and insertion of latissimus dorsi

Answer 2

Origin: T7-T12 (5 = big, like sciatic nerve), thoracolumbar fascia, iliac crest

Insertion: Medial floor of intertubercular groove of humerus

Question 3

Origin and insertion of trapezius

Answer 3

Origin: Base of skull, nucchal ligament, and C7-T12 spinous processes

Insertion: Spine of scapula, lateral third of clavicle

Question 4

Origin and insertion of the rhomboids

Answer 4

Minor origin: Nucchal ligament, C7-T1 spinous processes

Major origin: T2-T5 spinous processes

Insertion (both): medial border of scapula

Question 5

Origin and insertion of levator scapulae

Answer 5

Origin: C1-C4

Insertion: superior angle of scapulae

Question 6

Which nerve innervates levator scap and the rhomboids?

Answer 6

The dorsal scapular nerve

Question 7

Which nerve innervates the latissimus dorsi?

Answer 7

Thoracodorsal nerve

Question 8

Origin and insertion of teres major

Answer 8

Origin: inferior angle of the scapula

Insertion: Medial lip of intertubercular groove of the humerus (posterior to lat)

Action: Medially rotates and extends shoulder joint

Question 9

Origin, insertion, and action of deltoid

Answer 9

Origin: clavicle, acromion, and spine of scapula (three parts)

Insertion: deltoid tuberosity of lateral humerus

Action: shoulder abduction/flexion/extension (depending on which fibres contract; much like glute medius)

Question 10

List the four muscles of the rotator cuff and their story cues

Answer 10

1. Supraspinatis (the rich kid)
2. Infraspinatus (friends with teres minor)
3. Teres minor (friends with infraspinatus)
4. Subscapularis (the loner)

Question 11

List the action of each of the rotator cuff muscles

Answer 11

• Subscapularis: protraction
• Supraspinatus: initiates abduction (then deltoid rocks up and does all the hard work)
• Infraspinatus and teres minor: retraction of scapula

Question 12

What nerves innervate the rotator cuff muscles? List the common root of all of them.

Answer 12

1. Infra/supraspinatus muscle: suprascapular nerve
2. Teres minor (axillary)
3. Subscapularis (subscapular nerve)

Common root: C5-C6

Question 13

Origin, insertion, and action of serratus anterior.

Answer 13

Origin: lateral surface of ribs 1-9

Insertion: medial border of scapula

Action: protraction, depression, and elevation of the scapula (much like glute medius and deltoid; depends on which fibres contract)

Question 14

Which nerve innervates serratus anterior?

Answer 14

Long thoracic nerve

Question 15

Origin, insertion, and action of pectoralis major

Answer 15

Origin: sternocostal head and clavicular head

Insertion: Lateral lip of intertubercular groove of humerus

Question 16

Which nerve(s) innervate pec major and pec minor?

Answer 16

Lateral and medial pectoral nerve

Question 17

Origin, insertion, innervation, and action of coracobrachialis

Answer 17

Origin: Coracoid process

Insertion: humeral shaft

Innervation: musculocutaneous nerve

Action: flexion and adduction

Question 18

Origin, insertion, and action of pec minor

Answer 18

Origin: Ribs 2-5

Insertion: Coracoid process

Action: scapula protraction

Question 19

What is the course & action of subclavius? Why is its innervation “fancy”?

Answer 19

• Runs under clavicle, pulls it down into sternoclavicular joint
• Fancy because it has its won subclaviun nerve from brachial plexus

Question 20

Where does the long/short head of the biceps brachii originate? Where does it insert? What are the actions of the muscle? How is it innervated?

Answer 20

Long: supraglenoid tubercle
Short: coracoid process

Insertion: radial tuberosity and biccipital aponeurosis

Actions: flexion and supination

Innervation: musculocutaneous nerve

Question 21

Origin, insertion, innervation, and action of brachialis

Answer 21

Origin: anterior humerus

Insertion: Ulnar tuberosity

Action: elbow flexion

Innervation: musculocutaneous nerve

Question 22

Origin, insertion, action, and innervation of triceps

Answer 22

Origins: infraglenoid tubercle (long head), posterior humerus (medial and lateral heads)

Insertion: Distal olecranon

Action: elbow extension

Innervation: radial nerve