Central Nervous System

Central Nervous System

1. Brain

   • outer portion is gray matter called Cortex
   • Meninges
   • composed of three portions
     • Brain Stem
       • continuous with spinal cord
         • Medulla Oblongata
           • extends between pons and spinal cord
           • lower third of Hindbrain
           • all tracks between brain and spinal cord pass through
         • Pons
           • bridge between Cerebrum, Cerebellum, and Medulla Oblongata
           • upper part of hindbrain
         • Midbrain
           • stem like portion that connects Cerebrum to Pons and Cerebellum
     • Cerebellum
       • Hindbrain
       • largest part of Hindbrain
       • hemispheres connected by Vermis
       • separated by transverse cleft
     • Cerebrum
       • largest part of brain called Forebrain
       • sulci and grooves divide it into lobes and lobules
       • separated into right and left by a deep cleft called Longitudinal Sulcus
         • biggest connection between hemispheres is Corpus Callosum
   • inner portion is white matter
   • Ventricular System
     • four irregular fluid filled cavities
       • lateral ventricles
         • U shaped
         • aside Midsagittal plane
       • third ventricle
         • quadrilateral shaped
         • inferior to lateral ventricles
       • fourth ventricle
         • diamond shaped
         • in hindbrain

2. Spinal Cord

   • Conus Medullaris
     • the nerves
       • resemble a horses tail
   • Filum Terminale
     • Delicate fibrous strand
       • extends from terminal tip
         • attaches cord to upper coccygeal segment
   • Cauda Equina
     • End of spinal cord
       • Pointed extremity
   • Slender elongated structure
     • inner grey cellular structure
       • Extends from brain
     • outer white fibrous structure
       • Extends from brain
         • Connected to medulla oblongata
           • At level of foramen magnum
     • 18-20 inches long
       • connected to 31 pairs of spinal nerves
   • it transmits and receives sensory, motor, and reflex messages to and from the brain
   • Meninges
     • encloses both spinal cord and brain
       • inner sheath
         • called Pia matter
           • Highly vascular
           • very close to brain and cord structure
       • central sheath
         • Called Arachnoid
           • Separated by Subarachnoid Space
             • areas of increased width are Subarachnoid Cisterns
               • Widest area is Cisterna Magna
             • Continuous with ventricular system of brain
       • outermost sheath
         • called Dura Mater
           • forms strong fibrous covering
           • Composed of two layers
             • Outer layer lines cranial bones
             • inner layer protects brain and supports blood vessels
               • has four partitions for support and protection
           • Separated by Subdural Space