Arterial System PDF

Arterial System Prof Dara M Cannon The Arterial System • Arteries supply oxygenated blood to target tissues or territories • There are extracranial and intracranial arteries • Passing through the neck-level prior to entering the intracranial cavity observe the internal carotid arteries (a pair) an...

Arterial System Prof Dara M Cannon The Arterial System • Arteries supply oxygenated blood to target tissues or territories • There are extracranial and intracranial arteries • Passing through the neck-level prior to entering the intracranial cavity observe the internal carotid arteries (a pair) and the vertebral arteries (a pair) Objectives • Be able to identify and describe the route and territories of the major arterial supply • Develop a knowledge of the significance of anatomical features that relate to disorders of the cerebrovascular system • Be able to identify the major vessels depicted in the basic types of angiogram and the territories affected by stenosis or blockage of the major vessels in CT/MR images • Terminates as bifurcation • • • • From branch PCOM origin to bifurcation Forming ACA and MCA Branch from this segment is the anterior choroidal artery Ophthalmic segment • • INTERNAL CAROTID ARTERY From distal dural ring to PCOM branch Ophthalmic and superior hypophyseal arteries branch MIDBRAIN • Clinoid segment • • • Cavernous segment • • • • Short, above foramen lacerum and ends at petrolingual ligament Petrous segment • • • Petrolingual ligament to a promimal dural ring Carotid siphon Meningohypophyseal trunk and tentorial artery Lacerum segment • • Short, from dural ring exiting cavernous sinus to a distal dural ring thus entering subarachnoind space At the clinoid process Inside petrous part temporal bone carotid canal to exit where it passes above foramen lacerum Cervical segment • Extracranial from cervical vertebra C3 or C4 to entry at carotid canal PITUITARY HYPOPHYSEAL PONS ANTERIOR CEREBRAL ARTERY • A1 Precommunicating • ACA origin to the Anterior communicating artery (ACOM) • supplies septal nuclei, anterior potion of the hypothalamus and striatum • A2 Postcommunicating • ACOM to origin of callosomarginal artery (in cingulate sulcus) • A3 Cortical Branches • Pericallosal artery (callosal sulcus), distal to the origin of the callosomarginal artery • Supplies medial aspect of frontal lobe incl corpus callosum, cingulum, fornix and AC TERRITORY KEY MIDDLE CEREBRAL ARTERY M1 Horizontal • ICA bifurcation to superior flexion in the lateral fissure • • • Insular branches Anterior temporal artery to temp pole and gyri Branches to basal ganglia M2 Insular • from flexion these branches course within the insular sulcus (loop back to begin to exit) M3 Opercular • from within the insular sulcus to emerge at the lateral fissure ** * * * * M4 Cortical • from the lateral fissure these ramify over the lateral cerebral surface as multiple cortical branches • ascending and descending branches TERRITORY KEY VERTEBRAL & BASILAR ARTERIES • Vertebral Arteries • Bilateral • Branch supplies the cerebellum • Meningeal branches • Anterior spinal artery arises • Basilar Artery • Union of the vertebral arteries • Over ventral medulla • Pontine branches • Some supply to the cerebellum POSTERIOR CEREBRAL ARTERY • Basilar bifurcates • P1 Precommunicating • P2 ambient • P3 Quadrigemminal • P4 Calcarine TERRITORY KEY THE CIRCLE OF WILLIS: Bringing the Internal Carotid & Vertebrobasilar Systems together Summary of Territories ▪ Limits of vascular territories are highly variable ▪ based on anatomical and hemodynamic factors ▪ So one vessels territory can expand to take another’s in the case of an occlusion or high flow arterio-venous malformations, ‘sump’ effect ARTERIES SUPPLYING THE CEREBELLUM • Superior cerebellar artery - from superior basilar • Anterior Inferior Cerebellar Artery, AICA - from inferior basilar • Posterior Inferior Cerebellar Artery, PICA – from vertebral arts • Numerous anastomoses over the surface of the cerebellum between branches of these vessels CEREBROVASCULAR DISEASE & WATERSHED ZONES • Ischemic • • • • Hemorrhagic - bleed • • • • occlusion, narrowing, thrombus or embolism 10% are watershed areas core, prenumbra Rupture BV, hypertension, or vascular malformations or trauma Aneurysms (berry), arterio-venous malformations (AVMs), can lead to hemorrhage hypoplasia or absence of vessels occurs in some brains Transient Cerebral Ischemia, TIA • Can occur without infarct • Degenerative Diseases • Inflammation disorders of the arteries • Arteritis – several types, can cause occlusion and infarct ANTERIOR CEREBRAL ARTERY ACA Lateral view carotid artery angiogram | ACA branches – orbitofrontal (a), frontopolar (b), pericallosal ©, callosomarginal (d), anterior, middle and posterior internal frontal (e,f,g), paracentral lobule artery (h), superior internal parietal (i) and inferior internal parietal (j).