Shoulder Muscles and Movements: Anatomy and Innervation

What muscles are involved in scapular elevation?

Trapezius (upper fibers) and Levator scapulae

What muscles are involved in scapular depression?

Trapezius (lower fibers) and Pectoralis minor

What are the three actions of the deltoid muscle?

Shoulder flexion (anterior), shoulder abduction (middle), shoulder extension (posterior)

What does 'action' mean in the context of muscle movement?

An action is the movement a muscle produces when it contracts.

Which two muscles perform shoulder flexion?

Anterior deltoid and Pectoralis major

What nerve innervates the deltoid and teres minor muscles?

Axillary nerve

What are the four rotator cuff muscles?

Supraspinatus, Infraspinatus, Teres minor, Subscapularis (SITS)

Which rotator cuff muscles insert on the greater tubercle of the humerus?

Supraspinatus, Infraspinatus, Teres minor

Where does the subscapularis muscle insert?

Lesser tubercle of the humerus

What is the primary function of the rotator cuff?

Stability of the shoulder

What is shoulder adduction?

Bringing your arm toward your body

Which two muscles are primarily involved in shoulder adduction?

Pectoralis major and Latissimus dorsi

What is shoulder abduction?

Moving your arm away from your body

Which two muscles are primarily involved in shoulder abduction?

Middle deltoid and Supraspinatus

What action do the rhomboids perform?

Scapular retraction (pulling shoulder blades toward the spine)

What is the mnemonic to remember the rotator cuff muscles?

SITS (Supraspinatus, Infraspinatus, Teres minor, Subscapularis)

What does scapular retraction mean?

Pulling the shoulder blades toward the spine

What is the relationship between the supraspinatus and middle deltoid in shoulder abduction?

Supraspinatus starts abduction, while the middle deltoid is the major abductor.

What is the easy way to remember the actions of the deltoid?

Front = Flexion, Middle = Abduction, Back = Extension

What is a good way to remember which muscles perform shoulder flexion?

Use Anterior deltoid and Pectoralis major as primary examples.