The dorsal scapular artery is a branch of the subclavian artery, though in some anatomical variations, it can arise from the transverse cervical artery. It plays a crucial role in supplying blood to the muscles and structures around the scapula (shoulder blade). This artery is sometimes referred to as the descending scapular artery in older anatomical literature.
Location
The dorsal scapular artery typically originates from the third part of the subclavian artery, though variations exist where it branches from the transverse cervical artery. From its origin, it travels posteriorly, running along the medial border of the scapula. The artery passes deep to the levator scapulae and rhomboid muscles, eventually coursing along the serratus anterior. It provides branches that supply the scapular muscles, including the rhomboids and trapezius, and forms anastomoses with other scapular arteries, such as the suprascapular artery and circumflex scapular artery.
Structure and Anatomy
Origin
The dorsal scapular artery typically arises from the third part of the subclavian artery, which lies lateral to the anterior scalene muscle. However, there are anatomical variations where it originates from the transverse cervical artery as one of its branches, commonly referred to as the deep branch of the transverse cervical artery. This variation occurs in a significant percentage of individuals, and understanding this variability is important when considering the vascular anatomy of the shoulder region.
Course
After originating from the subclavian artery or the transverse cervical artery, the dorsal scapular artery travels posteriorly and inferiorly towards the scapular region. It runs deep to the levator scapulae muscle, which is located in the neck and upper shoulder. As the artery continues its descent, it passes along the medial border of the scapula, coursing beneath the rhomboid major and rhomboid minor muscles.
The artery continues its path down the back of the thoracic wall, running parallel to the vertebral column and along the medial edge of the scapula, where it supplies the scapular muscles.
Relations
- Anteriorly: The dorsal scapular artery lies deep to the trapezius muscle, the levator scapulae, and the rhomboids as it courses along the medial scapula.
- Posteriorly: The artery runs close to the deep surface of the rhomboid muscles and the superior portion of the scapula.
- Medially: It is positioned near the vertebral column and the deep muscles of the back, such as the erector spinae and serratus posterior superior.
- Laterally: It is closely related to the medial border of the scapula, where it sends branches to supply the surrounding musculature.
Branches
Along its course, the dorsal scapular artery gives off several small muscular branches. These branches supply blood to the muscles attached to the scapula, including:
- Rhomboid major and minor muscles: These muscles are responsible for retracting the scapula and are closely associated with the dorsal scapular artery.
- Levator scapulae muscle: This muscle elevates the scapula and receives vascular support from the dorsal scapular artery.
- Trapezius muscle: In some cases, the dorsal scapular artery provides minor branches to the lower portion of the trapezius.
- Serratus anterior muscle: The artery occasionally supplies branches to the serratus anterior, particularly as it descends toward the lower border of the scapula.
Termination
The dorsal scapular artery continues along the medial border of the scapula and terminates by anastomosing with other arteries in the scapular region. These include the suprascapular artery (arising from the thyrocervical trunk) and the circumflex scapular artery (a branch of the subscapular artery). This network of anastomoses plays a role in ensuring consistent blood flow to the shoulder and scapular region.
Anastomoses
The dorsal scapular artery forms several important anastomoses with other arteries in the shoulder region:
- Suprascapular artery: This artery originates from the thyrocervical trunk and travels across the supraspinous fossa, anastomosing with the dorsal scapular artery along the medial border of the scapula.
- Circumflex scapular artery: A branch of the subscapular artery, the circumflex scapular artery supplies the posterior aspect of the scapula and also forms anastomoses with the dorsal scapular artery. These anastomoses provide alternative pathways for blood flow to the scapular muscles and tissues, which is important in the case of vascular compromise in the region.
Function
The dorsal scapular artery serves several key functions, primarily centered around providing blood supply to the muscles and structures of the scapular region and upper back. Its role is crucial in maintaining the functionality of the muscles that stabilize and move the scapula, as well as providing important vascular connections through anastomoses in the shoulder area.
Blood Supply to Scapular Muscles
The dorsal scapular artery is the main artery responsible for supplying oxygenated blood to the muscles attached to the medial border of the scapula. These muscles are critical for scapular movement and shoulder stability. The primary muscles that receive blood from the dorsal scapular artery include:
- Rhomboid Major and Minor Muscles: These muscles are essential for retracting the scapula towards the vertebral column. They play a key role in stabilizing the scapula, which is vital for proper shoulder movement and strength during activities like pulling or lifting. The dorsal scapular artery ensures that these muscles have sufficient blood flow to function effectively.
- Levator Scapulae Muscle: This muscle is responsible for elevating the scapula, allowing upward movements of the shoulder. The dorsal scapular artery provides critical blood supply to this muscle, ensuring its strength and endurance during shoulder elevation.
- Trapezius Muscle (Lower Fibers): Although the trapezius has a broader supply from other arteries, the lower portion of the muscle, near the scapula, can receive branches from the dorsal scapular artery. This helps support scapular depression and retraction during shoulder movements.
- Serratus Anterior Muscle: The dorsal scapular artery sometimes supplies blood to the upper part of the serratus anterior, which is responsible for the protraction and upward rotation of the scapula. Adequate blood flow to this muscle helps in maintaining shoulder mobility and stability.
Support for Scapular Stability and Movement
The dorsal scapular artery supports the essential functions of the scapula, which include stabilization and smooth movement across the ribcage. By providing blood supply to the muscles responsible for scapular rotation, elevation, depression, and retraction, the dorsal scapular artery plays a central role in movements such as raising the arm, pulling, and pushing.
Proper vascularization of these muscles ensures that they have the energy and oxygen they need for contraction and endurance during prolonged physical activity. Without adequate blood flow from the dorsal scapular artery, these muscles could become fatigued or damaged, leading to impaired scapular function.
Anastomoses and Collateral Circulation
The dorsal scapular artery forms important anastomoses with nearby arteries, including the suprascapular artery and the circumflex scapular artery. These connections are crucial for maintaining collateral circulation in the shoulder region, especially in cases where one of the major arteries may be compromised due to injury or surgical procedures. Collateral circulation ensures that blood can still reach critical areas of the scapular and shoulder muscles, providing a backup route for blood flow.
For example, if the subclavian artery or one of its branches becomes blocked or narrowed, the anastomoses involving the dorsal scapular artery allow blood to continue flowing to the scapular region through alternative paths. This redundancy is vital in maintaining muscle function and avoiding ischemic damage to the shoulder girdle.
Vascularization of the Scapula and Adjacent Tissues
In addition to supplying muscles, the dorsal scapular artery also provides blood to the tissues surrounding the scapula, including the periosteum (the outer covering of the scapula). This support is crucial for the maintenance and repair of bone tissue in the scapula. The artery also contributes to nourishing the skin and superficial tissues overlying the upper back region, although this is a secondary function compared to its role in muscular blood supply.
Support for Shoulder Movement
The dorsal scapular artery indirectly supports the movement of the shoulder joint by supplying blood to muscles that control the movement of the scapula. Proper scapular motion is essential for full shoulder mobility. The muscles nourished by the dorsal scapular artery play a crucial role in controlling scapular motion, which is key in arm elevation, abduction, and rotation. The artery’s function ensures that these muscles can maintain their strength and endurance during repeated or strenuous activities.
Clinical Significance
The dorsal scapular artery is clinically significant due to its role in supplying blood to key muscles involved in scapular movement and shoulder stability. Its anatomical course makes it vulnerable to injury during shoulder surgeries, such as scapular or clavicle fracture repairs, as well as during procedures involving the cervical spine. Accidental damage to this artery can lead to excessive bleeding or compromised blood flow to the surrounding muscles, affecting shoulder and scapular function.
The dorsal scapular artery’s role in anastomoses with the suprascapular and circumflex scapular arteries is vital for maintaining collateral circulation in the shoulder region. This is particularly important in cases where the main arteries, such as the subclavian artery, are blocked or damaged, as these anastomoses help maintain blood supply to the scapular muscles and tissues.
In cases of trauma, like penetrating injuries or fractures near the shoulder or neck, the dorsal scapular artery can be at risk, leading to hematomas or ischemic conditions in the scapular muscles. Understanding its anatomical variability and course is crucial for surgeons to minimize complications during procedures involving the upper back and shoulder.
