Anterior Cerebral Circulatione

Anterior circulation of the brain comprises of internal carotid artery and its branches.

Introduction

  • The brain is a highly vascularized structure receiving 20% of cardiac output
  • Understanding neurovascular anatomy is important to recognize signs and symptoms of various vascular pathologies
  • The arterial supply of the brain can be divided into two parts:
    • Anterior circulation: consisting of the internal carotid artery and its branches
    • Posterior circulation: consisting of vertebral arteries, basilar artery, and their branches
 
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Anterior Circulation

Internal Carotid Artery

  • The terminal branch of the common carotid artery and supplies intracranial structures
  • Houses carotid bulb or sinus just superior to its origin which contains carotid body
  • Bouthillier Classification divides it into the following parts on the basis of the angiographic appearance of the vessel:
    • C1 - Cervical segment
    • C2 - Petrous segment
    • C3 - Lacerum segment
    • C4 - Cavernous segment
    • C5 - Clinoid Segment
    • C6 - Ophthalmic segment
    • C7 - Communication segment
  • Three terminal branches:
    • Anterior cerebral artery
    • Middle cerebral artery
    • Anterior choroidal artery

Anterior Cerebral Artery

  • Wide variation in the area of vascular perfusion
  • Divided into five segments
    • A1- Horizontal or pre-communicating segment (From ICA to the anterior communicating artery)
    • A2 - Vertical or post-communicating segment (From anterior communicating artery to genu of corpus callosum)
    • A3 - Precallosal Segment (Starts distally from callosomarginal artery to just before the posterior turn of the artery)
    • A4 - Supracallosal Segment (Above the body of corpus callosum anterior to plane of coronal suture)
    • A5 - Postcallosal segment (Above the body of corpus callosum posterior to plane of coronal suture)
  • Terminates in the roof of the third ventricle
  • Precallosal artery along with supracallosal and postcallosal artery is referred to as peri-callosal artery

Table 1: Vascular Territory of the Anterior Cerebral Artery and its Branches

Branches
Area Supplied
Globus pallidus Putamen (Medial part)
Lamina terminalis Para-olfactory areas Optic chiasma Cingulate gyrus Hypothalamus Anterior columns of the fornix
Head of the caudate nucleus Anteromedial part of the anterior limb of the internal capsule Globus pallidus (Medial Portion) Uncinate fasciculus Nucleus accumbens Basal nucleus of Meynert Diagonal band of Broca Anterior hypothalamus
Orbital gyri Frontal lobe
Part of frontal lobe
Corpus callosum
Paracentral area Anterior parietal lobe Frontal lobe
Precuneus Gyrus rectus Medial frontal gyrus Cingulate gyrus Medial orbital gyrus Paracentral lobule Olfactory cortex Corpus callosum (Except splenium)
Anterior perforated substance Lamina terminalis Rostrum of the corpus callosum Septum pellucidum Anterior part of the putamen
Clinical Importance
  • Unilateral occlusion of anterior cerebral artery distal to the origin of anterior communicating artery results in:
    • Sensorimotor deficits on the contralateral side of the body (more pronounced in lower extremities)
    • Sparring of face and hands
  • Bilateral occlusion results in loss of blood supply to the anteromedial surface of both cerebral hemispheres and results in:
    • Paraplegia of lower extremities
    • Motor aphasia
    • Personality and behavioral changes (due to frontal lobe infarction)
    • Incontinence
    • Sparring of face and hands
    • Grasp reflex on the contralateral side

Figure 1: Territorial Distribution of Cerebral Arteries

notion image
 

Middle Cerebral Artery

  • Direct branch of internal carotid artery
  • Following anatomic parts:
  • M1: Sphenoidal or horizontal segment (From bifurcation of ICA to genu/limen insulae)
  • M2: Insular segment (From limen insulae to circular sulcus of insula)
  • M3: Opercular segment (From circular sulcus to superior surface of Sylvian fissure)
  • M4: Cortical segment (From Sylvian fissure to the final cortical area)
 
Vascular Territory of Middle Cerebral Artery and its Branches
Branches
Area Supplied
Putamen (Lateral Portion) External capsule Upper internal capsule
Putamen (Medial Portion) Globus Pallidus
Anterior 1/3rd of the Superior, Middle and Inferior temporal gyri
Orbital gyri Orbitofrontal cortex Inferomedial frontal lobe
Temporal lobe (Polar and anterolateral part)
Inferior frontal gyrus
Middle and inferior frontal gyri (Posterior part) Pre-central gyrus (Lower part) Pre-central gyrus (Posterior part) Post-central gyrus (Inferior part)
Inferior and middle frontal gyrus
Anterior branch supply antero-lateral temporal lobe Middle branch supply middle temporal lobe (superior and middle portion) Posterior branches supply posterior portion of the temporal lobe and Insula
Anterior and posterior branches supply different parts of parietal lobe and supramarginal gyrus
Angular gyrus Parietooccipital arcus Posterior superior temporal gyrus Supramarginal gyrus
Superior and Inferior occipital gyri
Clinical Importance
  • Most common artery involved in acute ischemic stroke
  • Occlusion of the middle cerebral artery causes middle cerebral artery syndrome which presents with the following features:
    • Hemispatial neglect: failure to acknowledge things on the contralateral side
    • Apraxia: inability to perform certain movements despite intentions to do that.
    • Anosognosia: Inability to recognize one’s own mental or psychiatric illness.
    • Contralateral homonymous hemianopsia
    • Sensory loss of the contralateral face, arm (more marked), and leg (Less marked)
    • Ataxia of opposite limbs
    • Motor, sensory, or global aphasia depending upon the area involved (Dominant side)
    • Hemiplegia of the lower half of contralateral face
    • Hemiplegia of contralateral upper and lower extremities

Further Reading

  • Prince, E. A., & Ahn, S. H. (2013). Basic vascular neuroanatomy of the brain and spine: what the general interventional radiologist needs to know. Seminars in interventional radiology, 30(3), 234–239. https://doi.org/10.1055/s-0033-1353475
  • Siddiqui, A. H., & Chen, P. R. (2009). Intracranial collateral anastomoses: relevance to endovascular procedures. Neurosurgery clinics of North America, 20(3), 279–296. https://doi.org/10.1016/j.nec.2009.04.013

Bibliography

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