greater tuberosity of humerus

3 min read 19-03-2025

The greater tuberosity of the humerus is a crucial anatomical landmark of the shoulder joint. Understanding its structure, function, and susceptibility to injury is vital for healthcare professionals and anyone interested in musculoskeletal anatomy. This article will delve into these aspects, providing a comprehensive overview of this important bony structure.

Anatomy of the Greater Tuberosity

The humerus, the long bone of the upper arm, features several prominent features. The greater tuberosity is a large, bony prominence located on the lateral aspect of the proximal humerus (the upper part of the humerus). It's situated superiorly and laterally to the lesser tuberosity.

Key Anatomical Relationships:

Superiorly: It lies directly below the head of the humerus, articulating with the glenoid cavity of the scapula (shoulder blade) to form the glenohumeral joint.
Laterally: It's easily palpable on the outer side of the upper arm.
Inferiorly: It's separated from the surgical neck of the humerus by a slight constriction.
Muscular Attachments: Three crucial rotator cuff muscles—supraspinatus, infraspinatus, and teres minor—attach to the greater tuberosity. These muscles are critical for shoulder stability and movement.

Function of the Greater Tuberosity

The primary function of the greater tuberosity is to serve as an attachment site for the aforementioned rotator cuff muscles. These muscles play a vital role in:

Shoulder Stability: The rotator cuff muscles help to stabilize the glenohumeral joint, preventing dislocation and maintaining proper alignment.
Shoulder Rotation: These muscles facilitate both external and internal rotation of the arm.
Shoulder Abduction: The supraspinatus, specifically, is involved in the initial phase of shoulder abduction (lifting the arm away from the body).

Common Injuries Affecting the Greater Tuberosity

Given its crucial role in shoulder function and its prominent position, the greater tuberosity is prone to several injuries:

1. Greater Tuberosity Fracture:

This is a common injury, often occurring due to a fall onto the outstretched hand or a direct blow to the shoulder. Fractures can range in severity, from small avulsion fractures (a piece of bone breaks off where a tendon or ligament attaches) to large, comminuted fractures (bone breaks into multiple pieces).

2. Rotator Cuff Tear:

Often associated with greater tuberosity injuries, rotator cuff tears can occur due to overuse, repetitive motions, or trauma. The tendons of the rotator cuff muscles attach to the greater tuberosity; a tear can disrupt this attachment and lead to significant pain and loss of shoulder function.

3. Calcific Tendinitis:

This condition involves the deposition of calcium salts in the rotator cuff tendons, particularly near their insertion point on the greater tuberosity. This causes inflammation, pain, and restricted movement.

4. Impingement Syndrome:

Also known as subacromial impingement, this syndrome involves the compression of the rotator cuff tendons and subacromial bursa (a fluid-filled sac that cushions the tendons) under the acromion process (part of the scapula). This can lead to inflammation and damage to the greater tuberosity area.

Diagnosis and Treatment

Diagnosing injuries to the greater tuberosity typically involves a physical examination, imaging studies (X-rays, MRI, CT scans), and sometimes electromyography (EMG) to assess muscle function. Treatment options depend on the specific injury and its severity, and may include:

Conservative Management: This includes rest, ice, pain medication, physical therapy, and sometimes corticosteroid injections.
Surgical Intervention: Surgical repair may be necessary for significant fractures or rotator cuff tears. Surgical techniques can range from arthroscopic procedures (minimally invasive surgery) to open surgery.

Conclusion

The greater tuberosity of the humerus is a vital anatomical structure that plays a critical role in shoulder function. Understanding its anatomy, function, and susceptibility to injury is crucial for accurate diagnosis and appropriate management of associated conditions. Proper rehabilitation and preventative measures are key to maintaining the health and integrity of this important bony landmark.