Rotator Cuff Muscles

What is the Rotator Cuff

The rotator cuff (RC) is a muscular structure consisting of 4 muscles surrounding the glenohumeral or shoulder joint. These muscles are primarily responsible for stabilizing the shoulder and helping with all its movements.

Rotator Cuff Muscles Location with Basic Anatomy

The shoulder is a ball and socket joint. It’s called the glenohumeral joint because it is where the head of the humerus or the ‘ball’ articulates with the scapula’s glenoid cavity or the ‘socket.’ The rotator cuff muscles surround this joint to hold it in place.

The following 4 shoulder muscles make up the rotator cuff:

Muscle Name	Origin	Insertion	Function	Innervation
Supraspinatus	Supraspinous fossa of scapula	Upper facet of the greater tubercle of humerus	Initiating abduction of the arm	Suprascapular nerve (C5 and C6)
Infraspinatus	Infraspinous fossa of scapula	Middle facet of the greater tubercle of humerus	Lateral rotation of the arm	Suprascapular nerve (C5 and C6)
Teres minor	Lateral border of scapula	Lower facet of the greater tubercle of humerus	Lateral rotation of the arm	Subscapular nerves (C5, C6)
Subscapularis	Subscapular fossa of scapula	Lesser tubercle of humerus	Medial rotation of the arm	Axillary nerve (C5 and C6)

All 4 of these muscles originate at the scapula or shoulder blade, extending into strong tendons that wrap around the ‘ball’ or humeral head to form something like a thick band or cuff. It ensures that the humerus does not pop out of the socket of the glenoid cavity when we rotate the shoulder or extend our arm.

The rotator cuff is one of the most common sites for an injury or muscle tear due to overuse, with over 2 million people complaining of such issues each year in the United States alone. Sportsmen, swimmers, carpenters, and any other profession involving repetitive overhead arm movement are more at risk of rotator cuff injuries.

Mnemonic

These four muscles are often collectively referred to as the SITS muscles, using the first letter of their names:

• Supraspinatus
• Infraspinatus
• Teres minor
• Subscapularis

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