Intrinsic Shoulder Structures

Question 1

Which bones form the shoulder joint?

Answer 1

Humerus and scapula, forming the glenohumeral joint

Question 2

Muscles of the rotator cuff?

Answer 2

SITS
Supraspinatus muscle 
Infraspinatus muscle
Teres minor muscle
Subscapularis muscle

Question 3

Ligaments of rotator cuff?

Answer 3

Glenohumeral ligaments (superior, middle, inferior)
Transverse humeral ligament -goes between greater and lesser humeral tuberosities
Coracoclavicular ligament (conoid and trapezoid ligaments)
Coracohumeral ligament
Coraco-acromial ligament
Acromioclavicular ligament

Question 4

Intrinsic shoulder muscles
Supraspinatus 
- Origin and insertion?
- Actions?
- Innervation?

Answer 4

• Origin: supraspinous fossa of scapula
• Insertion: greater tubercle of humerus
• Innervation: suprascapular nerve
• Actions: initial abduction of arm 0-15 degrees

Question 5

Intrinsic shoulder muscles
Infraspinatus
- Origin and insertion?
- Actions?
- Innervation?

Answer 5

• Origin: infraspinous fossa of scapula
• Insertion: greater tubercle of humerus
• Actions: lateral rotation of arm
• Innervation: suprascapular nerve

Question 6

Intrinsic shoulder muscles
Teres minor
- Origin and insertion?
- Actions?
- Innervation?

Answer 6

• Origin: posterior surface of scapula, near lateral border
• Insertion: greater tubercle of humerus
• Innervation: axillary nerve
• Action: lateral rotation of arm

Question 7

Intrinsic shoulder muscles
Subscapularis
- Origin and insertion?
- Actions?
- Innervation?

Answer 7

• Origin: subscapular fossa
• Insertion: lesser tubercle of humerus
• Actions: medial rotation of arm
• Innervation: upper and lower subscapular nerves

Question 8

Intrinsic shoulder muscles
Deltoid
- Origin and insertion?
- Actions?
- Innervation?

Answer 8

• Origin: scapula (acromion and spine) and clavicle
• Insertion: deltoid tuberosity on lateral surface of humerus (about halfway down)
• Actions: anterior fibres flex arm at shoulder, middle fibres abduct shoulder, posterior fibres extend arm at shoulder
• Innervation: axillary nerve

Question 9

Intrinsic shoulder muscles 
Teres major
- Origin and insertion?
- Actions?
- Innervation?

Answer 9

• Origin: posterior surface of inferior border of scapula
• Insertion: medial side of intertubercular groove of humerus
• Actions: shoulder adduction, medial rotation of arm
• Innervation: lower subscapular nerve

Question 10

Name the two main bursae of the shoulder joint.

Answer 10

Subacromial and subscapular bursae

Question 11

What is contained within the subacromial space?

Answer 11

• subacromial bursa
• supraspinatus tendon
• joint capsule
• long head of biceps