What Stabilizes the Glenohumeral Joint? [Part 1]

The video tutorial explains the stabilization mechanisms of the glenohumeral joint, focusing on non-ligamentous methods like muscle balance and concavity compression. It reviews shoulder anatomy, including the clavicle, scapula, and humerus, and discusses how muscle mechanics and pull directions contribute to joint stability. The tutorial emphasizes the importance of balancing vertical and horizontal forces to prevent dislocation.

Which of the following is NOT a mechanism for stabilizing the glenohumeral joint?

• Bone density

• Ligamentous support

• Concavity compression

• Muscle balance

What is the joint called where the clavicle meets the acromion?

• Sternoclavicular joint

• Acromioclavicular joint

• Scapulothoracic joint

• Glenohumeral joint

Which part of the humerus fits into the glenoid fossa?

• Humeral head

• Lesser tubercle

• Bicipital groove

• Greater tubercle

What is the primary action of the middle deltoid muscle?

• Flexion of the shoulder

• Abduction of the shoulder

• Adduction of the shoulder

• Extension of the shoulder

Which muscle is NOT part of the rotator cuff?

• Supraspinatus

• Subscapularis

• Deltoid

• Infraspinatus

What happens when the rotator cuff muscles are weak or damaged?

• Increased inferior pull on the humerus

• Increased superior pull on the humerus

• Decreased lateral pull on the humerus

• Decreased medial pull on the humerus

What is the role of concavity compression in shoulder stability?

• It stabilizes the joint horizontally.

• It decreases the size of the humeral head.

• It increases the size of the glenoid fossa.

• It stabilizes the joint vertically.

Which muscle contributes to the medial pull on the humerus?

• Trapezius

• Pectoralis major

• Biceps brachii

• Deltoid

What is the effect of a medial pull on the humeral head?

• It decreases the size of the glenoid fossa.

• It increases the size of the humeral head.

• It stabilizes the humeral head against the glenoid fossa.

• It causes the humeral head to dislocate.

Which of the following muscles does NOT have a medial pull on the humerus?

• Latissimus dorsi

• Pectoralis major

• Deltoid

• Trapezius