Glenohumeral Joint

Question 1

Type of Joint

Answer 1

Synovial, multiaxial ball and socket capable of 3 degrees of freedom:

• flex/ext
• add/abd
• med/lat rot

Between glenoid fossa and head of humerus

Question 2

Articular Surfaces and Capsule

Answer 2

• Covered in hyaline cartilage
• Unstable as numeral head larger than glenoid fossa
• Shallow but deepened by Glenoid Labrum

Capsule loosely surrounds and has inf fold for help with abd, lined by synovial membrane which has communicating and free bursae
-strengthened/supported by ligt and tendons of rotator cuff muscles

Question 3

Joint Line

Answer 3

Ant margin (lower part of jt)- 3cm long running just lat to tip of coracoid process

Upper margin- line just inf to acromion process

AP joint line- line passing through jt joining coracoid process anteriorly to acromion process posteriorly

Question 4

Supporting Ligaments

Answer 4

Superior Glenohumeral- reinforces ant part of joint capsule

• from upper glenoid margin and labrum
• to upper surface of lesser humeral tubercle

Middle GH- reinforcers ant part of joint capsule

• from below sup ligt
• to front of lesser tubercle

Inferior GH(best developed)- reinforces ant part of joint capsule

• from glenoid margin
• to anteroinferior part of anatomical neck of humerus

Transverse Humeral- bridges gap between greater and lesser tubercles at upper end of intertubercular groove

Coracohumeral- strong flat band

• from lat border of coracoid process
• to TH ligt and adjacent part of anatomical neck

Coracoacromial- strong, triangular
-between coracoid and acromion processes above head of humerus

Question 5

Instability

Answer 5

Causes:

• shallow glenoid fossa
• large humeral head
• loose articular capsule

Solutions:

• deepened by glenoid labrum
• ligts hold humerus in place
• rotator cuff muscles increase control over joint

Question 6

Common Pathologies

Answer 6

• Shoulder dislocation, humerus comes out of joint: ant (most common)/post (rare, most likely by electrocution)
• Fractured neck of humerus
• Adhesive Capsulitis (frozen shoulder): less mobile, pain/stiffness, inflammation of capsule

Question 7

Accessory Movements

Answer 7

A->P movement
P->A movement
Longitudinal Caudad
Lateral Glide

Question 8

Scapular Plane

Answer 8

In anatomical pos scapula is ~45deg between sagittal and frontal planes, referred to as scapular in analysis