The greater tuberosity is a prominent bony structure on the humerus, or upper arm bone, located near the shoulder joint. This bony landmark is a crucial component of the shoulder’s ball-and-socket anatomy, allowing for an extensive range of motion. It functions as a powerful anchor point, translating muscle contractions into the dynamic movements and stability required for arm function.
Where Exactly Is the Greater Tuberosity?
The greater tuberosity is positioned on the lateral side of the head of the humerus, just below the rounded surface that forms the “ball” of the shoulder joint. It is a large, rough prominence that serves as a robust attachment site for multiple tendons and ligaments.
This bony projection is separated from the lesser tuberosity by a vertical indentation called the intertubercular groove, or bicipital groove. The greater tuberosity is the most lateral feature of the proximal humerus. It contains three distinct, flattened facets on its surface, which correspond to the specific tendons that attach there.
The Rotator Cuff Connection
The greater tuberosity’s primary functional role is its connection to the rotator cuff, the group of four muscles and tendons that stabilize the shoulder joint. Three of the four rotator cuff muscles attach directly to these distinct facets. The superior facet is the insertion point for the supraspinatus muscle, which initiates the abduction, or lifting, of the arm away from the body.
The infraspinatus muscle attaches to the middle facet, while the teres minor muscle anchors to the inferior facet. These two muscles work together to produce external rotation of the arm. This coordinated action helps keep the head of the humerus centered within the shallow socket, providing dynamic stability during movement. Without this anchoring mechanism, the powerful deltoid muscle would cause the humerus to ride upward and out of the socket.
Common Injuries Involving the Greater Tuberosity
Due to its role as a major tendon attachment point, the greater tuberosity is frequently involved in traumatic and degenerative shoulder injuries. Rotator cuff tears are a common issue, often involving the supraspinatus tendon where it connects to the superior facet. Tears can occur acutely from a fall, but they often develop gradually from repetitive stress and tendon degeneration.
Greater tuberosity fractures typically result from a fall directly onto the shoulder or a forceful shoulder dislocation. These fractures can be isolated breaks or occur as part of a more complex fracture of the upper humerus. When the bone fragments, the attached rotator cuff tendons can pull the piece away from its normal position, resulting in a displaced fracture.
Impingement syndrome, or tendinitis, is a third frequent concern that centers on the greater tuberosity area. This condition involves inflammation and friction as the rotator cuff tendons pass beneath the bony arch of the acromion. The friction often occurs at the tendon’s point of insertion onto the tuberosity, leading to pain, especially during overhead arm movements. The supraspinatus tendon is particularly vulnerable in this narrow space.
Diagnosis and Treatment of Tuberosity Injuries
Diagnosis of a greater tuberosity injury involves a physical examination to assess tenderness, range of motion, and strength. Imaging is then used to confirm the nature and extent of the damage. Standard X-rays are performed first to check for fractures or bone displacement.
Undisplaced fractures of the greater tuberosity can sometimes be difficult to see on X-ray, leading to the use of a CT scan for detailed bone assessment. An MRI or ultrasound is used to visualize soft tissues, which is useful for identifying associated rotator cuff tears or tendinitis.
Treatment depends on whether a fracture is present and how far bony fragments or torn tendons have been pulled out of place. Non-surgical management, successful for most minimally displaced fractures and tendon tears, involves rest, anti-inflammatory medications, and immobilization in a sling. This is followed by physical therapy to restore strength and full range of motion.
If a fracture fragment is displaced by more than five millimeters, or if a severe tendon tear does not respond to conservative care, surgical intervention may be recommended. Surgical options focus on repairing the rotator cuff tendons or securing the bone fragment back into place, often using techniques like screws, plates, or suture anchors.