MUSCLES ACTING ON THE SHOULDER (pectoral girdle)

Question 1

What is the pectoral girdle made of?

Answer 1

3 bones: Clavicle, scapula, humerus and rib cage

Question 2

Glenohumeral joint

Answer 2

-Synovial ball- and-socket joint
-3 dof
Flex, extend
Adduct and abduct
Int. and Ext rot
Circumduction

Question 3

glenohumeral joint ligaments

Answer 3

• coracohumeral ligament
• superior/middle/inferior glenohumeral

Question 4

Muscles involved in shoulder flexion

Answer 4

Deltoid Anterior
Pec major
Biceps brachii
Coracobrachialis

Question 5

Muscles involved for shoulder extension

Answer 5

Deltoid posterior
Latissimus Dorsi
Teres Major
Triceps Brachii

Question 6

Deltoid

Answer 6

O: Ant border and upper surface of lateral 1/3 of clavicle, acromion and spine of the scapula.
I: Deltoid tuberosity of the humerus
Action: Abduct,
Flexion and extension of shoulder
Inn: axillary Nerve (C5-6)

Question 7

Coracobrachialis

Answer 7

O: tip of the coracoid process of the scapula
I: Middle 1/3 of the medial surface of humerus
Action: Flexes and adducts the shoulder joint

Question 8

Latissimus dorsi

Answer 8

O: Spinous processes of inferior 6 thoracic vertebrae, throacolumbar fascia, iliac crest, and inferior 3-4 ribs
I: Floor of the intertubercular groove
Action: Extends, adducts and medially rotates the humerus, climbing movement

Inn: thoracodorsal nerve (C6,7,8)

Question 9

Teres Major

Answer 9

O: Posterior aspect of inferior angle of scapula
I: Medial lip of the bicipital groove.
Action: Adduct, medial rotation the shoulder, extend shoulder from flexed position
Inn: lower subscapular nerve (C5-6)

Question 10

Muscles involved in shoulder abduction

Answer 10

Deltoid
Supraspinatus

Question 11

Muscles involved in shoulder adduction

Answer 11

Coracobrachialis
pec major
latissimus dorsi
teres major

Question 12

Muscles involved in medial rotation of shoulder

Answer 12

Pec maj
Latissimus dorsi
teres maj
subscapularis

Question 13

Muscles involved in lateral rotation of shoulder

Answer 13

Infraspinatus
teres minor

Question 14

Muscles of the rotator cuff

Answer 14

Supraspinatus
infraspinatus
teres minor
subscapularis

Question 15

Infraspinatus

Answer 15

O: infraspinatous fossa of scapula
I: Middle facet of greater tubercle of humerus
Action: Laterally rotates arm, rotator cuff
Inn: suprascapular nerve (C5-6)

Question 16

Supraspinatus

Answer 16

O: supraspinatous fossa of scapula
I: Superior facet of greater tubercle of humerus
Action: initiates and assists deltoid in abduction, rotator cuff
Inn: Suprascapular nerve ( C4,5,6)

Question 17

Subscapularis

Answer 17

O: subscapular fossa
I: lesser tubercle of humerus
Action: Medial rotation of arm,rotator cuff
Inn: upper and lower subscapular nerves (C5,6,7)

Question 18

teres minor

Answer 18

O: Middle part of lateral border of scapula
I: inferior facet of greater tubercle of humerus
Action: lateral rotation of arm, rotator cuff
Inn: axillary nerve (C5,6)

Question 19

Muscles involved in horizontal adduction of the shoulder/arm

Answer 19

Pec maj
pec minor
lat dorsi

Question 20

Muscles involved in horizontal abduction of the shoulder/arm

Answer 20

teres minor
post deltoid

Question 21

During a pull up (upward phase), what action is happening at the shoulder?
what muscles are used?
what type of muscle contraction is it?

Answer 21

Adduction
latissimus dorsi, pec maj, coracobrachialis

concentric