Blood Supply of the Brain PDF

## CHAPTER 7 Blood Supply of the Brain ### ILOS: By the end of this chapter the student should be able to: - Describe the origin, course and distribution of the arteries of the brain (anterior cerebral, middle cerebral, posterior cerebral, basilar and 4th part of vertebral arteries) - Describe the...

## CHAPTER 7 Blood Supply of the Brain ### ILOS: By the end of this chapter the student should be able to: - Describe the origin, course and distribution of the arteries of the brain (anterior cerebral, middle cerebral, posterior cerebral, basilar and 4th part of vertebral arteries) - Describe the effects of the occlusion of the brain arteries and interpret some related clinical problems - Outline the sites and draining areas of the veins of the brain. - Identify the arteries and veins of the brain on cadavers and angiography. - Describe the formation, site and clinical importance of the circle of wills ### Arterial Supply of the Brain Brain receives its blood supply from 2 sources: 1. Vertebro-basilar system (2 vertebral arteries forming basilar artery) 2. Internal carotid system #### Vertebro-basilar System - **Beginning:** it arises from the 1st part of the subclavian artery at the root of the neck. - **Course:** - It enters foramen transversarium of the 6th cervical vertebra, then ascends in the foramina transversaria till it leaves foramen transversarium of atlas vertebra. - At foramen magnum, it pierces the dura and runs upwards, forwards and medially along the lateral aspect of medulla oblongata. - **Termination:** at lower border of the pons, the 2 vertebral arteries unite to form the basilar artery. - **Branches:** 1. **Anterior spinal artery:** descends along the anterior median fissure of the spinal cord, supplies anterior 2/3 of the cross sectional area of the spinal cord as well as the medial part of medulla oblongata. 2. **Posterior spinal artery:** descends along the posterior roots of the spinal nerves, supplies posterior 1/3 of the cross sectional area of the spinal cord. 3. **Posterior inferior cerebellar artery (PICA):** - It is the largest branch of the vertebral artery. - It runs backwards below the olive of medulla to reach the inferior surface of the cerebellum. - **Distribution:** it supplies the following areas: - Posterior part of inferior surface of cerebellum (including inferior vermis). - Inferior cerebellar peduncle. - Choroid plexus of 4th ventricle. - Lateral part of medulla oblongata and (occlusion of the artery causes lateral medullary syndrome "PICA syndrome or Wallenberg's syndrome"). - Posterior spinal artery may arise from it. 4. **Medullary branches:** throughout its course. **Image:** A diagram of the brain showing the arterial supply of the brain. - **Top:** Anterior cerebral artery, Middle cerebral artery, Posterior cerebral artery. - **Bottom:** Vertebral artery, Anterior spinal artery, Basilar artery, Anterior inferior cerebellar artery, Posterior inferior cerebellar artery. ***