The costocervical trunk is a short, thick arterial branch that arises from the second part of the subclavian artery. It serves as the origin for two key branches: the deep cervical artery and the highest (supreme) intercostal artery, which supply blood to the deep muscles of the neck and the upper intercostal spaces, respectively.
Location
The costocervical trunk is located in the lower neck, typically arising from the second part of the subclavian artery, posterior to the anterior scalene muscle. It courses posteriorly and superiorly, situated deep in the neck between the anterior scalene muscle and the longus colli muscle. The trunk quickly bifurcates into its two main branches, providing blood supply to the deep cervical and upper thoracic regions.
Structure and Anatomy
Origin
The costocervical trunk originates from the second part of the subclavian artery. The subclavian artery is divided into three parts relative to the anterior scalene muscle, with the costocervical trunk arising posterior to this muscle. It is typically located near the base of the neck, just above the first rib, and behind or medial to the anterior scalene.
Course
After its origin, the costocervical trunk courses posteriorly and superiorly in a short trajectory before branching into its two main arteries: the deep cervical artery and the supreme (or highest) intercostal artery. It passes between the anterior scalene and the longus colli muscles, running in close proximity to the transverse processes of the lower cervical vertebrae.
Relations
- Anteriorly: The costocervical trunk lies deep to the anterior scalene muscle and may be covered by other structures in the lower neck, including the subclavian vein and phrenic nerve.
- Posteriorly: It is positioned against the longus colli muscle, which separates it from the vertebral column and the vertebral artery.
- Laterally: The trunk is bordered by the second part of the subclavian artery and is close to the brachial plexus.
- Medially: The trunk is near the first rib and runs adjacent to the pleura covering the apex of the lung, making it vulnerable in cases of chest or neck trauma.
Branches
The costocervical trunk bifurcates shortly after its origin into two main branches:
- Deep Cervical Artery: This branch ascends into the posterior neck region, supplying the deep muscles of the cervical spine, including the semispinalis capitis and cervicis, and anastomoses with the occipital artery.
- Supreme (Highest) Intercostal Artery: This branch descends to supply the first and second intercostal spaces, providing blood to the intercostal muscles and nearby tissues.
Termination
The costocervical trunk itself terminates as it divides into its two branches, the deep cervical artery and the supreme intercostal artery. These branches continue their respective courses to supply the deep cervical and upper thoracic regions.
Anastomoses
The branches of the costocervical trunk participate in significant anastomoses. The deep cervical artery anastomoses with the occipital and vertebral arteries, while the supreme intercostal artery connects with the internal thoracic artery and other intercostal arteries. These anastomoses ensure that there is sufficient collateral blood flow to the regions supplied by these arteries, particularly in cases of vascular occlusion or trauma.
Function
The costocervical trunk serves as an important vascular branch of the subclavian artery, providing critical blood supply to the deep muscles of the neck and the upper thoracic region. Through its two major branches—the deep cervical artery and the supreme (highest) intercostal artery—it plays a vital role in nourishing structures within the neck and upper chest.
Blood Supply to Deep Cervical Muscles
The costocervical trunk, via its deep cervical artery, is responsible for supplying oxygenated blood to the muscles of the posterior neck, including the semispinalis capitis, semispinalis cervicis, and other deeper muscles associated with the cervical vertebrae. These muscles are crucial for head and neck extension, rotation, and stability, making the artery essential for neck movements and posture. The deep cervical artery also supplies adjacent ligaments and vertebrae, which contribute to the support and mobility of the cervical spine.
Blood Supply to Upper Intercostal Spaces
Through its supreme (highest) intercostal artery, the costocervical trunk supplies the first and second intercostal spaces. This artery provides blood to the intercostal muscles, which are responsible for assisting in respiration by stabilizing and moving the ribs. The upper intercostal spaces are critical for the movement of the upper ribs during breathing, and the supreme intercostal artery ensures adequate blood flow to these muscles and the tissues surrounding them.
Anastomosis and Collateral Circulation
The branches of the costocervical trunk, particularly the deep cervical artery, play an essential role in establishing collateral circulation. The deep cervical artery forms anastomoses with the occipital artery and vertebral artery, creating a network of vascular connections that ensure continued blood supply even if other arteries in the region are compromised. Similarly, the supreme intercostal artery anastomoses with lower intercostal arteries, forming connections that allow for redistribution of blood flow in cases of arterial obstruction or damage.
Nourishment of Cervical Vertebrae and Surrounding Ligaments
The deep cervical artery also contributes to the nourishment of the cervical vertebrae and the surrounding ligaments, such as the ligamentum nuchae, which is a key stabilizer of the cervical spine. This vascularization supports the integrity and function of the spine, ensuring that the vertebrae and ligaments are supplied with oxygen and nutrients necessary for their maintenance and function in neck movement and stability.
Support to the Upper Thoracic Wall
In addition to supplying the intercostal muscles, the supreme intercostal artery contributes to the vascularization of the thoracic wall, especially in the region of the first and second ribs. This support is essential in maintaining the function of the upper thoracic wall in relation to respiration, ensuring that the muscles and bones in the region receive adequate blood supply during respiratory movements.
Clinical Significance
The costocervical trunk holds significant clinical relevance, particularly in surgical interventions and trauma involving the neck and upper thoracic region. Its branches, the deep cervical artery and the supreme (highest) intercostal artery, supply blood to vital structures, including the deep cervical muscles, cervical vertebrae, and upper intercostal spaces. During surgical procedures such as cervical spine surgeries or thoracic surgeries, knowledge of the costocervical trunk’s location and course is essential to avoid accidental injury and excessive bleeding.
The trunk’s contribution to collateral circulation is also clinically important. In cases of arterial occlusion, trauma, or compression of larger vessels like the subclavian or vertebral arteries, the anastomoses formed by the costocervical trunk can provide alternative pathways for blood supply, minimizing ischemic damage. Understanding its role in these compensatory mechanisms is critical in managing vascular disorders affecting the neck and upper thorax.
