Scapulohumeral Muscles (Quiz 1)

Question 1

What are the 6 scapulohumeral (intrinsic shoulder) muscles?

Answer 1

1) deltoid
2) supraspinatus
3) infraspinatus
4) teres minor
5) teres major
6) subscapularis

Question 2

What is the origin/proximal attachment for the deltoid?

Answer 2

-lateral third of clavicle
-acromion and spine of scapula

Question 3

What is the insertion/distal attachment for the deltoid?

Answer 3

deltoid tuberosity of the humerus

Question 4

What innervates the deltoid?

Answer 4

axillary n.

Question 5

What are the actions of the deltoid?

Answer 5

-clavicular head (anterior part) flexes and medially rotates arm
-acromial (middle) part abducts the arm
-spinal (posterior) part extends and laterally rotates the arm

Question 6

What is the origin/proximal attachment of the supraspinatus?

Answer 6

supraspinous fossa of the scapula

Question 7

What is the insertion/distal attachment of the supraspinatus?

Answer 7

superior facet of greater tubercle of the humerus

Question 8

What innervates the supraspinatus?

Answer 8

suprascapular n.

Question 9

What are the actions of the supraspinatus?

Answer 9

initiates and assists the deltoid in abduction of the arm and acts with rotator cuff muscles

Question 10

What is the origin/proximal attachment of the infraspinatus?

Answer 10

infraspinous fossa of the scapula

Question 11

What is the insertion/distal attachment of the infraspinatus?

Answer 11

middle facet of the greater tubercle of the humerus

Question 12

What innervates the infraspinatus?

Answer 12

suprascapular n.

Question 13

What are the actions of the infraspinatus?

Answer 13

-laterally rotates the arm
-acts with rotator cuff muscles

Question 14

What is the origin/proximal attachment for the teres minor?

Answer 14

middle part of the lateral border of the scapula

Question 15

What is the insertion/distal attachment for the teres minor?

Answer 15

inferior facet of the greater tubercle of the humerus

Question 16

What innervates the teres minor?

Answer 16

axillary n.

Question 17

What are the actions of the teres minor?

Answer 17

-laterally rotates arm
-acts with rotator cuff muscles

Question 18

What is the origin/proximal attachment for the teres major?

Answer 18

posterior surface of the inferior angle of the scapula

Question 19

What is the insertion/distal attachment for the teres major?

Answer 19

medial lip of the inter-tubercular sulcus of the humerus

Question 20

What innervates the teres major?

Answer 20

lower scapular n.

Question 21

What are the actions of the teres major?

Answer 21

adducts and medially rotates arm

Question 22

What is the origin/proximal attachment for the subscapularis?

Answer 22

subscapular fossa (most of the anterior surface of the scapula)

Question 23

What is the insertion/distal attachment of the subscapularis?

Answer 23

lesser tubercle of the humerus

Question 24

What innervates the subscapularis?

Answer 24

upper and lower subscapular nerves

Question 25

What are the actions of the subscapularis?

Answer 25

-medially rotates arm
-part of the rotator cuff
-holds head of humerus in the glenoid cavity

Question 26

Collectively, the __________________________________ muscles are referred to as the rotator cuff or SITS muscles

Answer 26

-supraspinatus
-infraspinatus
-teres minor
-subscapularis

(The tendons of the SITS muscles blend with and reinforce the fibrous layer of the joint capsule of the glenohumeral joint, thus forming the rotator cuff that protects the joint and gives it stability)

Question 27

What is the primary function of the rotator cuff muscles?

Answer 27

during all movements of the glenohumeral (shoulder) joint is to hold the humeral head in the glenoid cavity of the scapula

Question 28

All of the rotator cuff muscles are rotators of the humerus, except the…..

Answer 28

supraspinatus