The suprascapular artery is a branch of the thyrocervical trunk, which arises from the first part of the subclavian artery. It is responsible for providing blood to the supraspinatus and infraspinatus muscles, as well as portions of the shoulder joint and scapular region.
Location
The suprascapular artery originates from the thyrocervical trunk, which branches off the first part of the subclavian artery. After its origin, the artery travels laterally across the anterior scalene muscle and passes posteriorly over the clavicle. It then enters the suprascapular notch of the scapula, traveling over the superior transverse scapular ligament (unlike the suprascapular nerve, which travels under the ligament). From here, it supplies the supraspinous fossa and infraspinous fossa, nourishing the surrounding muscles and tissues. The artery anastomoses with the circumflex scapular artery and dorsal scapular artery in the scapular region.
Structure and Anatomy
Origin
The suprascapular artery typically arises from the thyrocervical trunk, a branch of the first part of the subclavian artery. However, anatomical variations exist where it may originate directly from the subclavian artery or from the internal thoracic artery. The thyrocervical trunk also gives rise to other important arteries like the inferior thyroid artery and the transverse cervical artery.
Course
After originating from the thyrocervical trunk, the suprascapular artery passes laterally and posteriorly across the anterior surface of the anterior scalene muscle. It continues over the phrenic nerve and then crosses over the clavicle, moving toward the scapular region. As the artery approaches the scapula, it travels through the suprascapular notch or groove. One key anatomical distinction is that the suprascapular artery typically passes over the superior transverse scapular ligament, while the suprascapular nerve travels beneath this ligament.
Relations
- Anteriorly: In the neck, the artery lies superficial to the anterior scalene muscle, and it runs close to the phrenic nerve.
- Posteriorly: As it moves toward the scapula, the artery passes posteriorly across the shoulder region, staying superficial to the supraspinatus muscle.
- Superiorly: The suprascapular artery travels over the superior transverse scapular ligament at the suprascapular notch.
- Inferiorly: The artery runs superior to the suprascapular nerve and is positioned above the supraspinatus muscle.
Branches
The suprascapular artery provides several small branches as it courses through the shoulder region:
- Muscular branches: These branches supply the supraspinatus and infraspinatus muscles, which are critical for shoulder movement, especially in arm rotation and abduction.
- Acromial branches: These smaller branches extend toward the acromion and sometimes contribute to the vascularization of the acromioclavicular joint.
- Articular branches: These branches supply the shoulder joint, particularly the glenohumeral joint.
- Subscapular branches: In some cases, small branches may also contribute to vascularizing the subscapularis muscle.
Termination
After passing through the supraspinous fossa, the suprascapular artery descends into the infraspinous fossa, supplying the infraspinatus muscle. The artery terminates by anastomosing with the circumflex scapular artery (a branch of the subscapular artery) and the dorsal scapular artery. These anastomoses help form a collateral network that ensures adequate blood flow to the scapular region.
Anastomoses
The suprascapular artery forms several important anastomoses in the scapular region, providing collateral circulation. The main arteries with which it anastomoses include:
- Circumflex scapular artery: A branch of the subscapular artery, this artery anastomoses with the suprascapular artery in the infraspinous fossa, ensuring vascular redundancy for the scapula and shoulder.
- Dorsal scapular artery: This artery, originating from the subclavian artery or transverse cervical artery, anastomoses with the suprascapular artery along the medial border of the scapula.
Course Through the Supraspinous and Infraspinous Fossae
In the supraspinous fossa, the artery runs above the supraspinatus muscle and beneath the fascia that covers it. It continues around the lateral border of the spine of the scapula to enter the infraspinous fossa, where it runs above the infraspinatus muscle, providing blood supply to both the muscle and the surrounding tissues.
Function
The suprascapular artery plays a crucial role in the vascular supply to the upper shoulder region, particularly the scapular muscles and shoulder joint. Its primary functions are centered around providing oxygenated blood to key muscles involved in shoulder movement, as well as supporting the surrounding connective tissue and maintaining collateral circulation in the scapular region.
Blood Supply to the Supraspinatus Muscle
One of the most critical functions of the suprascapular artery is to supply the supraspinatus muscle with oxygenated blood. The supraspinatus muscle, located in the supraspinous fossa of the scapula, is an essential component of the rotator cuff. It is involved in initiating the abduction of the arm and stabilizing the shoulder joint during movement. The artery provides the necessary nutrients and oxygen to the muscle fibers, enabling proper contraction and function during shoulder movements, especially when the arm is raised or lifted.
Blood Supply to the Infraspinatus Muscle
The suprascapular artery also supplies blood to the infraspinatus muscle, which lies in the infraspinous fossa of the scapula. This muscle is also part of the rotator cuff and is responsible for the lateral rotation of the humerus. The artery descends from the supraspinous region into the infraspinous fossa, where it delivers oxygen-rich blood to the infraspinatus, ensuring the muscle has the energy to function properly during activities that require arm rotation, such as throwing or lifting objects.
Blood Supply to the Shoulder Joint
In addition to the rotator cuff muscles, the suprascapular artery contributes to the vascularization of the glenohumeral joint (the shoulder joint). It sends articular branches that supply the ligaments and capsule surrounding the shoulder joint, helping to maintain the health of these structures and ensuring proper joint lubrication and movement. The artery’s blood supply is critical for the function and stability of the shoulder, one of the most mobile joints in the human body.
Support for Connective Tissue and Ligaments
The suprascapular artery provides blood supply not only to muscles but also to the connective tissues and ligaments that support the shoulder region. For example, the supraspinatus tendon, which attaches the supraspinatus muscle to the humerus, requires a steady blood supply to maintain its structural integrity. Similarly, the coracoacromial ligament and other soft tissues in the region benefit from the artery’s vascular support, promoting healing and maintenance of these structures.
Formation of Collateral Circulation
The suprascapular artery plays a key role in maintaining collateral circulation in the shoulder and scapular regions. It forms anastomoses with other nearby arteries, including the circumflex scapular artery (a branch of the subscapular artery) and the dorsal scapular artery. These anastomoses are crucial in ensuring that blood flow to the scapular region is maintained even if there is a blockage or injury to one of the main arteries. This collateral network helps protect the scapular muscles and surrounding tissues from ischemic damage and allows alternative blood flow routes in cases of arterial obstruction.
Nourishment of the Acromioclavicular Joint
The suprascapular artery also provides small branches that contribute to the vascularization of the acromioclavicular (AC) joint, the joint between the acromion (part of the scapula) and the clavicle. Though not a primary supply, this function supports the joint’s structural health and helps maintain its mobility and function, especially during shoulder elevation and other arm movements.
Support for Scapular Bone and Periosteum
In addition to supplying muscles and joints, the suprascapular artery provides blood to the scapular bone itself, particularly the periosteum, the outer covering of the bone. Adequate blood supply is essential for bone health, growth, and repair, ensuring that the scapula remains strong and resilient in the event of injury or stress. The periosteal branches of the artery help support bone maintenance and healing after fractures or other injuries involving the scapula.
Clinical Significance
The suprascapular artery holds clinical importance due to its role in supplying blood to key structures in the shoulder, including the supraspinatus and infraspinatus muscles, which are critical components of the rotator cuff. Injury or occlusion of this artery can lead to muscle ischemia, weakness, or atrophy, particularly affecting shoulder movement and stability. This is particularly relevant in cases of rotator cuff injuries, where damage to the artery can complicate healing.
In surgical procedures, such as shoulder reconstructions, rotator cuff repairs, or clavicle surgeries, careful consideration of the suprascapular artery’s course is crucial to avoid accidental damage and to preserve blood flow to the shoulder region. Additionally, the artery’s anastomoses with other scapular arteries provide collateral circulation, making it an important consideration in cases of arterial occlusion or injury.
The suprascapular artery may also be involved in vascular conditions such as aneurysms or compression syndromes (like thoracic outlet syndrome), where blood flow through the artery is compromised, leading to shoulder pain, restricted mobility, or muscle dysfunction. Understanding its anatomy and vascular contribution is essential in managing these conditions effectively.
