anterior deltoid
origin- lateral one third of the clavicle
insertion- deltoid tuberosity of humerus
action- shoulder flexion and medial rotation
innervation- axillary nerve
middle deltoid
origin- acromion of scapula
insertion- deltoid tuberosity of humerus
action- shoulder abduction
innervation- axillary nerve
posterior deltoid
action- spine of scapula
insertion- deltoid tuberosity of humerus
action- shoulder extension, lateral rotation
innervation- axillary nerve
What are the four muscles of the rotator cuff?
supraspinatus, infraspinatus, teres minor, subscapularis
What is one of the major functions of the rotator cuff?
to hold and stabilize the head of the humerus in the glenoid cavity
Supraspinatus
origin- supraspinous fossa of scapula
insertion- greater tubercle of humerus
action- initiate and assist the deltoid in shoulder abduction
innervation- suprascapular nerve
infraspinatus
origin- infraspinous fossa of scapula
insertion- greater tubercle of humerus
action- shoulder lateral rotation
innervation- suprascapular nerve
teres minor
origin- lateral border of the scapula
insertion- greater tubercle of humerus
action- shoulder lateral rotation and weak adduction
innervation- axillary nerve
subscapularis
origin- subscapular fossa of the scapula
insertion- lesser tubercle of humerus
action- shoulder medial rotation
innervation- upper and lower subscapular nerves
teres major
origin- inferior angle and lateral border of scapula
insertion- intertubercular groove of humerus
action- shoulder medial rotation, adduction, and extension
innervation- lower subscapular nerve
coracobrachialis
origin- coracoid process of scapula
insertion- middle one third of the medial shaft of the humerus
action- shoulder flexion and adduction
innervation- musculocutaneous nerve
serratus anterior
origin- lateral surface of ribs 1-8
insertion- medial border of the scapula
action- upper fibers- scapular downward rotation, middle fibers- scapular protraction, lower fibers- scapular upward rotation
innervation- long thoracic nerve