The Shoulder

Question 1

What are the six intrinsic muscles of the shoulder?

Answer 1

Deltoid 
Teres Major 
Supraspinatus 
Infraspinatus 
Teres Minor 
Subscapularis

Question 2

Deltoid

Answer 2

Origin:
Anterior: lateral 1/3 of the clavicle
Middle: acromion of the scapula
Posterior: spine of the scapula

Insertion: deltoid tuberosity on the humerus

Actions: 
   All parts together: abducts
   Anterior: flexes/medial rotate arm
   Middle: abducts the arm 
   Posterior:extend/lateral rotate arm

Innervation: axillary nerve

Question 3

Teres Major

Answer 3

Origin: inferior angle and lower part of lateral border of the scapula

Insertion: medial lip of the intertubercular sulcus (humerus)

Action: extends, adducts, and medially rotates the arm

Innervation: lower subscapular nerve

Question 4

Supraspinatus

Answer 4

Origin: supraspinous fossa

Insertion: greater tubercle (superior facet)

Action: abducts the arm

Innervation: suprascapular nerve

Question 5

Infraspinatus

Answer 5

Origin: infraspinous fossa

Insertion: greater tubercle (middle facet)

Action: laterally rotates the arm

Innervation: suprascapular nerve

Question 6

Teres Minor

Answer 6

Origin: lateral border of the scapula
(above the origin of teres major)

Insertion: greater tubercle (inferior facet)

Action: laterally rotates the arm

Innervation: axillary nerve

Question 7

Subscapularis

Answer 7

Origin: subscapular fossa

Insertion: lesser tubercle (humerus)

Action: medially rotates the arm

Innervation: upper and lower subscapular nerves

Question 8

What 4 muscles are part of the rotator cuff?

Answer 8

Supraspinatus
Infraspinatus
Teres minor
Subscapularis

Question 9

Subscapular artery

Answer 9

Branch of thryrocervical trunk
Branch of the subclavian

Supplies: supraspinatus and infraspinatus

Question 10

Posterior circumflex humoral artery

Answer 10

Arises from the axillary artery

Supplies: teres minor

Question 11

Circumflex scapular artery

Answer 11

Branch of the subscapular artery

Contributes to scapular anastomosis

Supplies: teres major and teres minor

Question 12

Pectoralis Major

Answer 12

Origin: medial half of the clavicular head, sternum, costal cartilages 1-6, and aponeurosis of external oblique muscle

Insertion: lateral lip of intertubercular sulcus

Action:
Both heads: adducts, medially rotates the arm, depresses, protracts scapula
Clavicular head: flexes the arm
Sternocostal head: extends arm from flexed position

Innervation: lateral and medial pectoral nerves

Question 13

Pectoralis Minor

Answer 13

Origin: Ribs 3-5 (near the costal cartilages

Insertion: coracoid process

Action: depresses and protracts the scapula

Innervation: medial pectoral nerve

Question 14

Subclavius

Answer 14

Origin: Junction of rib 1 and its costal cartilage

Insertion: subclavian groove on the inferior surface

Action: protracts and rotates the scapula

Innervation: nerve to the subclavius

Question 15

Serratus Anterior

Answer 15

Origin: Ribs 1-9

Insertion: medial border of the scapula

Action: protracts and superiorly rotates the scapula

Innervation: long thoracic nerve

Question 16

Thoracoarcomial trunk

Answer 16

Clavicular branch: supplies the subclavius

Acromial: supplies part of the deltoid

Deltoid: supplies part of the deltoid

Pectoral: supplies the pectoralis minor and part of the pectoralis major

Question 17

Lateral Thoracic Artery

Answer 17

Supplies the lateral structures of the thorax and breast

Supplies the serratus anterior and part of the pectoralis major

Question 18

What are the 3 joints that make up the shoulder complex?

Answer 18

Glenohumeral Joint

Acromioclavicular Joint

Sternoclavicular joint

Question 19

What are the 4 muscles of the pectoral region?

Answer 19

Pectoralis Major

Pectoralis Minor

Subclavius

Serratus anterior

Question 20

What are some important things about the glenohumeral joint?

Answer 20

The head of the humerus articulates with the glenoid fossa

Ball and socket joint (synovial)

The glenoid fossa is shallow: permits movements over stability

It is the most mobile joint in the human body