Muscles that Act on the shoulder

Question 1

What three bones is the pectoral girdle made of?

Answer 1

Clavicle, scapula, humerus

Question 2

What is the role of the pectoral girdle?

Answer 2

Connects axial to appendicular skeleton, full range of motion in upper limb.

Question 3

What are the joints and articulations of the pectoral girdle?

Answer 3

Sternocostal, sternoclavicular, acromioclavicular, glenohumeral, costovertebral, scapulothoracic, interclavicular

Question 4

How does the glenohumeral joint stay in place?

Answer 4

Muscles, joint capsule, ligaments

Question 5

What is the glenoid labrum?

Answer 5

Fibrocartilage, deepends glenoid fossa by 5-9 mm, creates a wall that creates for articular space for humeral head.

Question 6

What are the ranges of motion for the glenohumeral joint?

Answer 6

Flexion/extension, adduction and abduction, internal and external rotation, circumduction

Question 7

Coracohumeral ligament

Answer 7

Resists inferior and posterior translation, connects at coracoid process and greater tubercle of humerus

Question 8

Glenohumeral ligament

Answer 8

Resists anterior displacement of the humeral head. Connects anatomical neck of humerus and scapula. Tightens with external rotation

Question 9

What muscles flex the shoulder?

Answer 9

Deltoid, pectoralis major, biceps brachii, coracobrachialis

Question 10

What muscles extend the shoulder?

Answer 10

Deltoid, latissimus dorsi, teres major, pec major, triceps brachii

Question 11

Deltoid muscle:

Answer 11

Origin: Anterior border and upper surface of the lateral 1/3 of the clavicle, acromion and the spine of the scapula.
Insertion: Deltoid tuberosity of the humerus
Action: Abduction, flexion, extension of the shoulder
Innervation: Axillary nerve

Question 12

Pectoralis Major

Answer 12

Origin: Sternocostal head: superior costal 6 cartilages, ant surface sternum
Clavicular head: ant surface medial half clavicle
Insertion: lateral lip of the bicipital groove of humerus
Action: adducts, medially rotates humerus, flexion
Innervation: Lateral and medical pectoral nerves

Question 13

Coracobrachialis

Answer 13

Origin: Coracoid process of scapula
Insertion: middle 1/3 medial surface of humerus
Action: flexion and adduction of shoulder
Innervation: musculocutaneous nerve

Question 14

Latissimus Dorsi

Answer 14

Origin: spinous processes of 6 thoracic vertebrae, iliac crest, thoracolumbar fascia, inferior ribs 3-5
Insertion: Floor of the intertubercular groove
Action: extends, adducts, and medially rotates the humerus. Tilts pelvis anteriorly and laterally, bilaterally acts in hyperextending the spine depending on the orientation of the pelvis
Innervation: Thoracodorsal nerve

Question 15

Teres major

Answer 15

Origin: Posterior aspect of the inferior angle of the scapula
Insertion: medial lip of the bicipital groove of the humerus
Action: adduction, medial rotation, extension
Innervation: Lower subscapular

Question 16

What muscles ABduct the shoulder?

Answer 16

Deltoid, supraspinatus

Question 17

What muscles ADDuct the shoulder?

Answer 17

Coracobrachialis, pec major, latissimus dorsi, teres major

Question 18

What muscles medial rotate the shoulder?

Answer 18

Pec major, latissiumus dorsi, teres major, subscapularis

Question 19

What muscles laterally rotate the shoulder?

Answer 19

Infraspinatus, teres minor

Question 20

Infraspinatus

Answer 20

Origin: infraspinous fossa of the scapula
Insertion: middle facet of greater tubercle
Action: laterally rotates
Innervation: Subscapular nerve

Question 21

Teres minor

Answer 21

Origin: Middle part of the lateral border of the scapula
Insertion: Inferior facet of greater tubercle
Action: laterally rotates
Innervation: Axillary nerve

Question 22

Subscapularis

Answer 22

Origin: Subscapular fossa of the scapula
Insertion: Lesser tubercle of the humerus
Action: Medially rotates

Question 23

Supraspinatus

Answer 23

Origin: Supraspinous fossa of the scapula
Insertion: Superior facet of the greater tubercle of the humerus
Action: Abduction

Question 24

Where is the medial wall of the Axilla?

Answer 24

Serratus anterior/thoracic wall

Question 25

Lateral wall of the axilla?

Answer 25

Bicipital groove

Question 26

Anterior wall of axilla?

Answer 26

Pec major and minor

Question 27

The posterior wall of axilla?

Answer 27

Subscapularis, latissimus dorsi, teres major

Question 28

What are the contents of the axilla?

Answer 28

Axillary artery, axillary vein, brachial plexus, lymph nodes