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• Brain

  Cerebrum - Largest part that most of us think of as 'the brain'
• Cerebrum


  • Two hemispheres - right and left
  • Cerebral Cortex - outer layer of gray matter
  • Gyri - elevated ridges that increase surface area
  • Sulci - shallow depressions
  • Fissures - deeper grooves
• Cerebrum


  • Rat
  • Dog
  • Dolphin
• Brain


  Cerebrum - Largest part that most of us think of as 'the brain'
• Gyrus


  Singular of Gyri
• Sulcus


  Singular of Sulci
• Major Parts of the Brain


  • Cerebrum
  • Cerebellum
  • Diencephalon
  • Thalamus
  • Hypothalamus
  • Brainstem
  • Midbrain
  • Pons
  • Medulla Oblongata
• Ventricular System


  Ventricles and Passageways
• Four Ventricles


  • Lateral Ventricles - one in each hemisphere
  • Third Ventricle - located in diencephalon
  • Fourth Ventricle - located between pons and cerebellum; extends into medulla oblongata
• Connecting Passageways


  1. Interventricular Foramina - connects lateral ventricles to the 3rd ventricle

  2. Cerebral Aqueduct - connects 3rd & 4th ventricles

  3. 4th Ventricle narrows and becomes central canal of spinal cord
• Cranial Meninges


  Continuous with the spinal meninges, similar layers but with some key differences
• Layers of Cranial Meninges


  • Dura Mater - outermost layer
  • Arachnoid Mater - middle layer
  • Pia Mater - innermost layer
• Cerebrum


  • Rat
  • Dog
  • Dolphin
• Gyrus


  Singular of Gyri
• Dura Mater


  • Divided into two layers: Periosteal Cranial Dura - fused to the periosteum of cranial bones, no epidural space like in the spinal cord
  • Meningeal Cranial Dura - inner layer, can extend into the brain in places, creating dural folds, gap between layers contains sinuses for blood drainage, largest collecting veins are located within the dural folds, small space underneath is called the subdural space, normally nothing here except in disease/trauma conditions
• Sulcus


  Singular of Sulci
• Arachnoid Mater


  • Resembles a spider web, Subarachnoid Space - delicate network of collagen and elastic fibers (arachnoid trabeculae), filled with cerebrospinal fluid (CSF)
• Major Parts of the Brain


  • Cerebrum
  • Cerebellum
  • Diencephalon
  • Thalamus
  • Hypothalamus
  • Brainstem
  • Midbrain
  • Pons
  • Medulla Oblongata
• Pia Mater


  • Anchored to outer surface of brain by astrocytes, also surrounds cerebral blood vessels penetrating into the brain
• Ventricular System


  Ventricles and Passageways
• Functions of Cranial Meninges


  • Offers protection from physical forces, Circulates and drains CSF
• Four Ventricles


  • Lateral Ventricles - one in each hemisphere
  • Third Ventricle - located in diencephalon
  • Fourth Ventricle - located between pons and cerebellum; extends into medulla oblongata
• Cerebrospinal Fluid (CSF)


  Functions: Cushioning against physical trauma, Support (reduces weight), Transport of nutrients, gases, wastes
• Connecting Passageways


  1. Interventricular Foramina - connects lateral ventricles to the 3rd ventricle

  2. Cerebral Aqueduct - connects 3rd & 4th ventricles

  3. 4th Ventricle narrows and becomes central canal of spinal cord
• Creation, Circulation, and Reabsorption of CSF


  Formed by the choroid plexus - specialized ependymal cells and permeable capillaries, created from blood, located in 3rd and 4th ventricles, extend into lateral ventricles, circulates through ventricles, passageways, central canal, and subarachnoid space, re-absorbed through arachnoid granulations in the superior sagittal sinus
• Cranial Meninges


  Continuous with the spinal meninges, similar layers but with some key differences
• Hydrocephalous - build-up of CSF due to blockage or problem with reabsorption
• Layers of Cranial Meninges


  • Dura Mater - outermost layer
  • Arachnoid Mater - middle layer
  • Pia Mater - innermost layer
• Brain's Blood Supply


  Brain needs extensive blood supply to meet oxygen and energy demands, interruption of blood flow quickly causes unconsciousness, after 4 minutes, permanent neural damage can occur
• Dura Mater


  • Divided into two layers: Periosteal Cranial Dura - fused to the periosteum of cranial bones, no epidural space like in the spinal cord
  • Meningeal Cranial Dura - inner layer, can extend into the brain in places, creating dural folds, gap between layers contains sinuses for blood drainage, largest collecting veins are located within the dural folds, small space underneath is called the subdural space, normally nothing here except in disease/trauma conditions
• Major Arteries


  • Internal Carotid Arteries
  • Vertebral Arteries
• Arachnoid Mater


  • Resembles a spider web, Subarachnoid Space - delicate network of collagen and elastic fibers (arachnoid trabeculae), filled with cerebrospinal fluid (CSF)
• Major Veins


  • Drain into dural sinuses, largest is the superior sagittal sinus, all sinuses drain into the internal jugular vein
• Epidural Hemorrhage


  Damaged blood vessels force blood between dura mater and cranium
• Cerebrospinal Fluid (CSF)


  Functions: Cushioning against physical trauma, Support (reduces weight), Transport of nutrients, gases, wastes
• Cerebrovascular Accident (CVA)


  Also known as "stroke", blood supply to a particular region is cut off - effects depend on region affected, usually damage to the venous sinuses
• Creation, Circulation, and Reabsorption of CSF


  Formed by the choroid plexus - specialized ependymal cells and permeable capillaries, created from blood, located in 3rd and 4th ventricles, extend into lateral ventricles, circulates through ventricles, passageways, central canal, and subarachnoid space, re-absorbed through arachnoid granulations in the superior sagittal sinus
• Blood Brain Barrier (BBB)


  Created by astrocytes wrapping around blood vessels, damage to astrocytes will damage the BBB, allows the interstitial fluid around the neurons to be tightly controlled
• Hydrocephalous - build-up of CSF due to blockage or problem with reabsorption
• Blood-CSF Barrier


  In places where there is a choroid plexus