Vertebral ArteryEdit
The vertebral artery is a key vessel in the brain’s posterior circulation. It arises from the subclavian artery on each side and ascends through the foramina transversaria of the cervical spine, typically starting at the level of the sixth cervical vertebra (C6). After passing through the atlas (C1) and looping posterolaterally, it enters the skull through the foramen magnum and joins its counterpart to form the basilar artery. This arterial system supplies the brainstem, cerebellum, and the posterior portions of the cerebral hemispheres, and it works in concert with the carotid system to preserve perfusion in critical regions. Variations in the anatomy are not rare, and they can influence both clinical presentation and treatment decisions in disease states.
The vertebral arteries contribute to the posterior circulation and are integral to the Circle of Willis, providing collateral pathways that help protect the brain when one vessel is compromised. They give off small branches along their ascent, including spinal branches to the spinal cord and the posterior inferior cerebellar artery (PICA) near the skull base, which nourishes portions of the cerebellum and medulla. Anatomical variants include hypoplasia (underdevelopment) on one side, duplication or fenestration of portions of the artery, and atypical entry points into the skull. These variants can alter hemodynamics and may be relevant in planning surgical or endovascular procedures. For overview and terminology, see Vertebral Artery and related structures such as Basilar Artery and Circle of Willis.
Anatomy and course
Origin and passage
The vertebral arteries originate primarily from the posterosuperior aspect of the subclavian arteries and ascend in a vertical fashion through the foramina transversaria of the cervical vertebrae, commonly from C6 up to C1. They then course posteriorly around the upper cervical spine before penetrating the dural membranes at the level of the foramen magnum. At this point, the left and right vertebral arteries join to form the basilar artery, giving rise to the posterior circulation that complements the anterior circulation supplied by the internal carotid arteries.
Branches and supply
Along their course, the vertebral arteries supply small meningeal and spinal branches and give off the PICA just before entering the skull. The PICA supplies parts of the cerebellum and medulla. The vertebral arteries, together with the basilar artery, contribute to the perfusion of the brainstem, cerebellum, thalamus, occipital lobes, and deeper structures that support coordination, balance, and vision. For broader context on the vascular network, see Posterior circulation and Cerebellum.
Variants
Anatomic variants include unilateral or bilateral vertebral artery hypoplasia, atypical levels of entry into the skull, or duplication of segments. Such variants are increasingly recognized in imaging studies and can influence the risk profile for posterior circulation ischemia or complicate surgical planning. Discussions of vascular variants often reference general principles in Anatomical variation and are connected to the broader framework of cerebrovascular anatomy in articles like Circle of Willis.
Function and clinical significance
Perfusion territory
The vertebral arteries supply the brainstem (including the medulla and pons), portions of the cerebellum, and posterior cerebral regions. Through their contribution to the basilar artery and ultimately the posterior cerebral arteries, they help sustain functions such as balance, coordination, certain aspects of vision, and many autonomic and cranial nerve–related processes.
Clinical presentations
Damage or compromise of the vertebral arteries can lead to vertebrobasilar insufficiency or infarction, presenting with dizziness, imbalance, difficulty with swallowing or speaking, limb weakness, vertigo, nausea, and bilateral motor or sensory deficits depending on the level and extent of ischemia. Vertebral artery dissection, often triggered by neck trauma or spontaneously, can produce neck pain or occipital headache with posterior circulation stroke symptoms. In trauma settings, vertebral artery injury (VAI) is a recognized concern during cervical spine injuries and may require prompt imaging to define the injury and guide therapy. See Vertebral Artery Dissection and Stroke for broader context on presentation and outcomes.
Imaging and diagnosis
Noninvasive imaging—such as magnetic resonance angiography (Magnetic resonance angiography), CT angiography (Computed tomography angiography), and duplex ultrasound in selected scenarios—plays a central role in evaluating the vertebral arteries. Digital subtraction angiography (DSA) remains a reference standard in some diagnostic or interventional contexts. For related techniques and indications, see Imaging and Aneurysm where appropriate.
Pathology and disease
Vertebral artery dissection
Dissection involves a tear in the vessel wall with intramural hematoma that can narrow the lumen or form thrombi, potentially causing posterior circulation stroke. It may be spontaneous or follow minor trauma. Management typically emphasizes antithrombotic therapy (antiplatelet agents or anticoagulation) and meticulous risk-factor control, with a focus on ensuring adequate cerebral perfusion while minimizing propagation of the dissection. See Dissection (medicine) for a broad treatment framework and Vertebral Artery Dissection for specifics.
Aneurysm and other vascular lesions
Vertebral artery aneurysms are less common than aneurysms in other cerebral vessels but carry a risk of subarachnoid hemorrhage when they rupture. Treatment options range from endovascular approaches to microsurgical clipping or bypass procedures in selected cases, guided by a multidisciplinary team.
Stenosis and atherosclerosis
Atherosclerotic disease can affect the vertebral arteries, contributing to posterior circulation ischemia. Management focuses on risk-factor modification, antithrombotic therapy, and, in some cases, revascularization when symptoms persist despite medical therapy. See Atherosclerosis and Stroke for related considerations.
Trauma and vertebral artery injury
High-energy trauma, particularly with cervical spine injury, can injure the vertebral arteries. Early recognition through appropriate imaging reduces the risk of missed injuries and downstream stroke. See Trauma and Vertebral Artery Dissection for context on injury mechanisms and management.
Management and treatment considerations
Clinical decision-making around vertebral artery disease balances the goals of preserving brain perfusion, preventing stroke, and avoiding unnecessary procedures. Medical therapy often centers on risk-factor modification and antithrombotic strategies. Endovascular or surgical interventions are considered in select cases (e.g., complicated dissections, aneurysms, or persistent ischemia despite optimal medical therapy). In trauma, imaging-based grading guides whether conservative management or intervention is appropriate. See Antiplatelet therapy, Anticoagulation, and Endovascular therapy for related discussions.
In planning care, clinicians consider not only the anatomy of the vertebral arteries themselves but also the integrity and sufficiency of the entire posterior circulation, including contributions from the Circle of Willis and the contralateral vertebral artery. For surgical and radiologic planning, preoperative and pre-procedural imaging is essential to minimize iatrogenic injury to these vessels and to optimize outcomes. See also Cervical spine anatomy and Brainstem function in evaluating potential deficits and compensatory mechanisms.