Shoulder Muscles and Their Functions

The video tutorial explains the categorization of shoulder muscles into intrinsic and extrinsic based on their attachment points. It details the intrinsic muscles, including the deltoid and rotator cuff muscles, and their functions. The extrinsic muscles, such as the rhomboids and trapezius, are also discussed, highlighting their origins, insertions, and actions.

What are the two main categories of shoulder muscles based on their attachment points?

• Intrinsic and extrinsic

• Anterior and posterior

• Superior and inferior

• Medial and lateral

Which muscle is part of the scapulohumoral group and assists in arm abduction?

• Teres major

• Deltoid

• Pectoralis major

• Latissimus dorsi

Which head of the deltoid muscle is responsible for arm flexion and medial rotation?

• Anterior

• Intermediate

• Lateral

• Posterior

What is the primary function of the teres major muscle?

• Elevates the scapula

• Flexes the forearm

• Extends and medially rotates the humerus

• Abducts the arm

Which rotator cuff muscle is the main external rotator of the shoulder?

• Infraspinatus

• Supraspinatus

• Subscapularis

• Teres minor

What is the role of the supraspinatus muscle in shoulder movement?

• Medially rotates the arm

• Adducts the arm

• Abducts the arm up to 15 degrees

• Laterally rotates the arm

Which deep extrinsic shoulder muscle is responsible for elevating the scapula?

• Trapezius

• Rhomboid minor

• Levator scapulae

• Rhomboid major

Where do the rhomboid muscles attach on the scapula?

• Superior angle

• Medial border

• Lateral border

• Inferior angle

Which part of the trapezius muscle is responsible for retracting the scapula?

• Upper fibers

• Middle fibers

• Lower fibers

• All fibers

What is the primary action of the latissimus dorsi muscle?

• Flexes the arm

• Abducts the arm

• Extends and medially rotates the humerus

• Elevates the scapula