Blood Supply of the Brain (BM 1052) PDF

Blood Supply of the Brain BM 1052 A/Prof. Monika Zimanyi Department of Anatomy and Pathology School of Medicine and Dentistry James Cook University [email protected] Learning Outcomes After attending this lecture, students will be...

Blood Supply of the Brain BM 1052 A/Prof. Monika Zimanyi Department of Anatomy and Pathology School of Medicine and Dentistry James Cook University [email protected] Learning Outcomes After attending this lecture, students will be able to: Describe the arterial circulation to the head and neck. Name and identify the major components of the arterial circle involved in supplying blood to the cerebrum, brainstem, cerebellum and spinal cord. Describe the organisation of the dural venous sinuses, and how deoxygenated blood is drained from the cerebrum, brainstem, cerebellum and spinal cord. Outline the basic factors involved in regulating cerebral blood flow. Describe how the metabolic demands of the brain relates to cerebral blood flow. Outline the basic factors involved in regulating cerebral blood flow.  Blood Supply = arterial supply  Blood Supply to the Head and Neck Blood supply is from the aortic arch via: Brachiocephalic trunk Right common carotid artery Left common carotid artery Moore & Persaud 2003 The developing Human: Clinically oriented embryology. 7 th Ed. Saunders Blood Supply to the Head and Neck Aorta Brachiocephalic a. (R only) Common carotid a. Internal carotid External carotid Common carotid  Internal Carotid Artery Passes superiorly in the neck Enters the carotid canal and passes anteriorly and medially In skull it lies lateral to the optic chiasm No branches in the neck Internal Carotid Artery (ICA) They have the following branches: Anterior cerebral Ophthalmic ICA Middle cerebral Posterior communicating Vertebral Artery Vertebral arise from subclavian arteries Travel through transverse foramina Over the posterior arch of atlas Travel through foramen magnum Unite to form the basilar artery & ends as posterior cerebral arteries Vertebral artery Vertebral Arteries They have the following branches: Posterior communicating Posterior cerebral Superior cerebellar Basilar Pontine Anterior inferior cerebellar Vertebral Arterial Circle of Willis Anterior cerebral a. Anterior communicating a. Internal carotid a. Middle cerebral a. Posterior communicating a. Posterior cerebral a. Superior cerebellar a. Basilar a. Anterior inferior cerebellar a. Vertebral a. Arterial Circle of Willis Anterior communicating a. Anterior cerebral a. Middle cerebral a. Posterior communicating a. Internal carotid a. Posterior cerebral a. Superior cerebellar a. Basilar a. Anterior inferior cerebellar a. Vertebral a. Anterior spinal a. Posterior inferior cerebellar a. Anterior Cerebral Artery (ACA) Arises from ICA Travels anteriorly Supplies medial cortex, frontal & parietal lobes Middle Cerebral Artery (MCA) Continuation of ICA Travels through lateral fissure Supplies lateral surface, temporal, parietal & frontal lobes Posterior Cerebral Artery (PCA) Arises from basilar artery Travels along inferior surface of cerebrum & posteriorly Supplies inferior surface, parietal & occipital lobes Blood Distribution Anastomosis Dual blood supply - 2 different arteries supply the same region of tissue No difference in a normal organ with normal blood flow, but provides alternate flow if one of the vessels is blocked Venous Drainage Dural Venous Sinuses Dura has two layers, periosteal and meningeal Where the endosteal and meningeal layers are separated they form dural venous sinuses Dural Venous Sinuses Venous Sinuses Cerebrovascular Accidents  Cerebrovascular Accident = Stroke CVA is the 3rd largest cause of death Different forms : Ischemic (thrombotic and embolic) Haemorrhagic Cerebral blood flow can also be affected by infection, trauma etc. Arterial Occlusion Thrombus or embolus Atherosclerotic plaque (common cause) Plaques often form at branches or curve points Obstruction of blood flow  reduced oxygen  causes infarction Associated with cerebral oedema and increase intracranial pressure https://www.brainhq.com/brain-resources/image-gallery/brain-anatomy-images Haemorrhage Also known as intracerebral haemorrhage Caused by rupture rather than blockage Symptoms include severe headache Often involves deeper structures Blood is bypassing the BBB  Subarachnoid Haemorrhage CSF is in this space, which dilutes the blood and so it does not clot (unless haemorrhage is massive) A large subarachnoid haemorrhage raises intracranial pressure, which can significantly impair cerebral perfusion http://neuropathology-web.org/chapter4/chapter4aSubduralepidural.html Epidural Hematoma Epi = upon, so between calvaria and dura http://brainandspine.titololawoffice.com/2011/09/articles/ traumatic-brain-injury-tbi/subdural-hematoma-and-epidural- http://neuropathology-web.org/chapter4/chapter4aSubduralepidural.html hematoma/ Subdural Hematoma emissary vein Sub = under, so deep to the dura Subdural Hematoma Sub = under, so deep to the dura http://brainandspine.titololawoffice.com/2011/09/articles/ http://neuropathology-web.org/chapter4/chapter4aSubduralepidural.html traumatic-brain-injury-tbi/subdural-hematoma-and-epidural- hematoma/