Glenohumeral Joint Anatomy

Question 1

What is the primary role of the rotator cuff muscles?

Answer 1

stabilizing the glenohumeral joint by compressing the humeral head against the glenoid

Question 2

What are the function of the glenohumeral ligaments?

SGHL, MGHL, IGHL, CHL

Answer 2

SGHL- restraint to inferior translation at 0° abduction
MGHL- restraint to anterior-posterior translation at 45° abdcution
IGHL- (anterior band) restraint to anterior/inferior translation 90° abduction and maximum ER (late cocking phase of throwing); weak link in Bankhart
(posterior band) restraint to posterior subluxation at 90° flexion and IR; linked to SLAP lesions
CHL- limits posterior translation with shoulder in flexion,adduction, and internal rotation
limits inferior translation and external rotation at adducted position

Question 3

Where is the pathology in a “frozen shoulder” or adhesive capsulitis?

Answer 3

Contracture of the rotator interval

Question 4

What are osteology specifics about the proximal humerus and glenoid?

Answer 4

Humeral head- retroverted 30°, avg diameter is 43mm, inclination of 130°
Glenoid- pear shaped, inclination of 5°, 7° retroversion to 10° anteversion from scapular body

Question 5

What is the normal acromiohumeral interval?

Answer 5

7-8mm

Question 6

What is the optimal position of a GH arthrodesis?

Answer 6

15-20° of abduction
20-25° of forward flexion
40-50° of internal rotation

Question 7

What provides the primary blood supply to the humeral head?

Answer 7

posterior humeral circumflex artery provided 64% of the blood supply to the humeral head, whereas the anterior humeral circumflex artery supplied 36%

Question 8

What are the boundaries of the rotator interval and what structures are in the interval?

Answer 8

medially by lateral coracoid base
superiorly by anterior edge of supraspinatus
inferiorly by superior border of subscapularis
lateral apex formed by transverse humeral ligament
Structures- capsule, SGHL, CHL and long head biceps tendon