The anterior cerebral artery (ACA) is one of a pair of

cerebral arteries The cerebral arteries describe three main pairs of arteries and their branches, which perfuse the cerebrum of the brain. The three main arteries are the: * '' Anterior cerebral artery'' (ACA) * ''Middle cerebral artery The middle cerebral arte ...

that supplies oxygenated blood to most midline portions of the

frontal lobe The frontal lobe is the largest of the four major lobes of the brain in mammals, and is located at the front of each cerebral hemisphere (in front of the parietal lobe and the temporal lobe). It is parted from the parietal lobe by a groove be ...

s and superior medial parietal

lobes of the brain The lobes of the brain are the major identifiable zones of the cerebral cortex, and they comprise the surface of each hemisphere of the cerebrum. The two hemispheres are roughly symmetrical in structure, and are connected by the corpus callosum. ...

. The two anterior cerebral arteries arise from the internal carotid artery and are part of the

circle of Willis The circle of Willis (also called Willis' circle, loop of Willis, cerebral arterial circle, and Willis polygon) is a circulatory anastomosis that supplies blood to the brain and surrounding structures in reptiles, birds and mammals, including huma ...

. The left and right anterior cerebral arteries are connected by the

anterior communicating artery In human anatomy, the anterior communicating artery is a blood vessel of the brain that connects the left and right anterior cerebral arteries. Anatomy The anterior communicating artery connects the two anterior cerebral arteries across the co ...

Anterior cerebral artery syndrome Anterior cerebral artery syndrome is a condition whereby the blood supply from the anterior cerebral artery (ACA) is restricted, leading to a reduction of the function of the portions of the brain supplied by that vessel: the medial aspects of the ...

refers to symptoms that follow a stroke occurring in the area normally supplied by one of the arteries. It is characterized by

weakness Weakness is a symptom of a number of different conditions. The causes are many and can be divided into conditions that have true or perceived muscle weakness. True muscle weakness is a primary symptom of a variety of skeletal muscle diseases, i ...

and sensory loss in the lower leg and foot opposite to the lesion and behavioral changes.

Structure

The anterior cerebral artery is divided into 5 segments. Its smaller branches: the callosal (supracallosal) arteries are considered to be the A4 and A5 segments. *A1 originates from the internal carotid artery and extends to the ''anterior communicating artery'' (AComm). The ''anteromedial central'' (medial lenticulostriate) arteries arise from this segment as well as the AComm, which irrigates the

caudate nucleus The caudate nucleus is one of the structures that make up the corpus striatum, which is a component of the basal ganglia in the human brain. While the caudate nucleus has long been associated with motor processes due to its role in Parkinson's d ...

and the anterior limb of the

internal capsule The internal capsule is a white matter structure situated in the inferomedial part of each cerebral hemisphere of the brain. It carries information past the basal ganglia, separating the caudate nucleus and the thalamus from the putamen and the ...

*A2 extends from the AComm to the bifurcation forming the ''pericallosal'' and ''callosomarginal arteries''. The '' recurrent artery of Heubner'' (distal medial striate artery), which irrigates the internal capsule, usually arises at the beginning of this segment near the AComm. Two branches arise from this segment: **''Orbitofrontal artery'' (medial frontal basal): Arises a small distance away from the AComm **''Frontopolar artery'' (polar frontal): Arises after the ''orbitofrontal'', close to the curvature of A2 over the

corpus callosum The corpus callosum (Latin for "tough body"), also callosal commissure, is a wide, thick nerve tract, consisting of a flat bundle of commissural fibers, beneath the cerebral cortex in the brain. The corpus callosum is only found in placental m ...

. It can also originate from the ''callosal marginal''. *A3, also termed the ''pericallosal artery'', is one of the (or the only) main terminal branches of the ACA, which extends posteriorly in the pericallosal sulcus to form the ''internal parietal arteries'' (superior, inferior) and the ''precuneal artery''. This artery may form an anastomosis with the ''

posterior cerebral artery The posterior cerebral artery (PCA) is one of a pair of cerebral arteries that supply oxygenated blood to the occipital lobe, part of the back of the human brain. The two arteries originate from the distal end of the basilar artery, where it bifur ...

''. **''Callosal marginal artery'': A commonly present terminal branch of the ACA, which bifurcates from the ''pericallosal artery''. This artery in turn branches into the ''medial frontal arteries'' (anterior, intermediate, posterior), and the ''paracentral artery'', with the cingulate branches arising throughout its length. Depending on

anatomical variation An anatomical variation, anatomical variant, or anatomical variability is a presentation of body structure with morphological features different from those that are typically described in the majority of individuals. Anatomical variations are categ ...

, the ''callosal marginal artery'' may be none discrete or not be visible. In the latter case, the branches mentioned will originate from the ''pericallosal artery''. In a study of 76 hemispheres, the artery was present in only 60% of the cases. Angiography studies cite that the vessel can be seen 67% or 50% of the time.

Development

The anterior cerebral artery develops from a primitive anterior division of the internal carotid artery that initially supplies the optic and olfactory regions. This anterior division, which appears at the twenty-eighth day of development, also forms the

middle cerebral artery The middle cerebral artery (MCA) is one of the three major paired cerebral arteries that supply blood to the cerebrum. The MCA arises from the internal carotid artery and continues into the lateral sulcus where it then branches and projects to ma ...

and the

anterior choroidal artery The anterior choroidal artery originates from the internal carotid artery. However, it may (rarely) arise from the middle cerebral artery. Structure The anterior choroidal artery originates from the distal carotid artery 5 mm after the origin of ...

. The anterior cerebral arteries grow toward each other and form the

at the 21–24 mm stage of the embryo.

Variation

The anterior cerebral artery shows considerable variation. In a study made using MRA, the most common variation was an underdeveloped A1 segment (5.6%), followed by the presence of an extra A2 segment (3%). In 2% of cases there was only one A2 segment.

Function

The anterior cerebral artery supplies a part of the frontal lobe, specifically its medial surface and the upper border. It also supplies the front four–fifths of the

, and provides blood to deep structures such as the anterior limb of the

, part of the

, and the anterior part of the globus pallidus.

Clinical significance

Occlusion

Strokes that occur in a part of the artery prior to the anterior communicating usually do not produce many symptoms because of

collateral circulation Collateral circulation is the alternate circulation around a blocked artery or vein via another path, such as nearby minor vessels. It may occur via preexisting vascular redundancy (analogous to engineered redundancy), as in the circle of Wil ...

. If a blockage occurs in the A2 segment or later, the following signs and symptoms may be noted: * Paralysis or weakness of the foot and leg on the opposite side, due to involvement of leg part of the

motor cortex The motor cortex is the region of the cerebral cortex believed to be involved in the planning, control, and execution of voluntary movements. The motor cortex is an area of the frontal lobe located in the posterior precentral gyrus immediately ...

* Cortical sensory loss in the opposite foot and leg * Gait apraxia (impairment of gait and stance) *

Abulia In neurology, abulia, or aboulia (from grc, βουλή, meaning "will"),Bailly, A. (2000). Dictionnaire Grec Français, Éditions Hachette. refers to a lack of will or initiative and can be seen as a ''disorder of diminished motivation'' (''DDM' ...

, akinetic mutism, slowness and lack of spontaneity *

Urinary incontinence Urinary incontinence (UI), also known as involuntary urination, is any uncontrolled leakage of urine. It is a common and distressing problem, which may have a large impact on quality of life. It has been identified as an important issue in geri ...

which usually occurs with

bilateral Bilateral may refer to any concept including two sides, in particular: *Bilateria, bilateral animals *Bilateralism, the political and cultural relations between two states *Bilateral, occurring on both sides of an organism ( Anatomical terms of l ...

damage in the acute phase * Frontal cortical release reflexes: Contralateral

grasp reflex Palmar grasp reflex (or grasp reflex) is a primitive and involuntary reflex found in infants of humans and most primates. When an object, such as an adult finger, is placed in an infant's palm, the infant's fingers reflexively grasp the object. ...

, sucking reflex, paratonic rigidity

Additional images

File:Circle of Willis 5.jpg, Anterior cerebral artery File:Sobo 1909 3 548.png, Cerebral arteries seen from beneath. Anterior cerebral artery visible at centre. File:Circle of Willis en.svg, The arterial circle and arteries of the brain (inferior view). The anterior cerebral arteries (top of figure) arise from the trifurcations of the

internal carotid arteries The internal carotid artery (Latin: arteria carotis interna) is an artery in the neck which supplies the anterior circulation of the brain. In human anatomy, the internal and external carotids arise from the common carotid arteries, where these ...

References

External links

* * * http://neuroangio.org/anatomy-and-variants/anterior-cerebral-artery/ * * * {{Authority control Arteries of the head and neck