Chapter 14

• Rostral— toward the forehead, front
• Caudal— toward the spinal cord, back
• Three main portions of the brain- cerebrum, cerebellum, brainstem
• The brainstem is composed of- diencephalon, midbrain, pons, and medulla oblongata
• Longitudinal fissure- deep groove that separates cerebral hemispheres
• gyri - thick folds of the brain
• sulci- shallow grooves in the brain that are the result of the folding of the cerebral cortex
• corpus callosum - thick nerve bundle at bottom of longitudinal fissure that connects hemispheres
• What remains of the brain if the cerebrum and cerebellum are removed?

  Brainstem
• Label the following picture

  A) Rostral

  B) Caudal

  C) Central sulcus

  D) Gyri

  E) Lateral sulcus

  F) temporal lobe

  G) cerebellum

  H) cerebrum

  I) brainstem

  J) spinal cord

  
• Label the Picture

  A) Corpus Callosum

  B) thalamus

  C) Hypothalamus

  D) Pituitary Gland

  E) Tegmentum

  F) Pons

  G) Medulla

  H) Spinal Cord

  I) 4th ventricle

  J) cerebellum

  K) 3rd ventricle

  L) Lateral Ventricles

  M) Central Sulcus

  
• Gray Matter- the seat of neuromas, dendrites, and synapses
• Characteristics of grey matter: dull color due to little myelin, forms surface layer (cortex) over cerebrum and cerebellum, forms nuclei deep within the brain
• label this picture

  A) Gray matter

  B) White matter

  
• white matter - bundles of axons
• characteristics of white matter: lies deep to cortical gray matter, the opposite relationship in the spinal cord, pearly white color from myelin around nerve fibers, composed of tracts to bundles of axons that connect one part of the brain to another and to the spinal cord
• The nervous system develops from the - ectoderm ( outermost tissue layer of the embryo)
• meninges - three connective tissues membranes that envelop the brain
• meninges characteristics: lie between the nervous tissue and bone: as in the spinal cord they are the dura mater, arachnoid mater and pia mater: protect the brain and provide structural framework for its arteries and veins
• Cranial dura mater: has two layers- outer periosteal and inner meningeal; layers separated by dural sinuses, has no epidural space
• Arachnoid mater - transparent membrane over brain surface, subarachnoid space separates it from pia mater below, subdural space separates it from dura mater above in certain places
• Pia mater - very thin membrane that follows contours of the brain, even dipping into sulci, not visible without microscope
• three layers of meninges - dura mater, arachnoid mater, pia mater
• Which cells secret CSF?- Ependyma
• Where are the cells of the secret CSF found?

  The choroid plexus ( which is found in each ventricle)
• How is the flow of CSF?

  Lateral ventricles -> interventricular foramen -> third ventricle -> cerebral aqueduct -> fourth ventricle -> spinal cord -> reabsorbed by arachnoid granulations
• Which layer is the CSF Flow system found?

  Subarachnoid space
• Where does CSF get reabsorbed?

  By arachnoid granulations
• Ventricles - four internal chambers within the brain that carries CSF
• Ventricles spilt up: Lateral Ventricle (2), third ventricle, fourth ventricle
• Lateral ventricle - one in each cerebral hemisphere, contains the interventricular foramen which is a tiny pore that connects to this ventricle
• Third ventricle - narrow medial space beneath corpus callosum, has the cerebral aqueduct which runs through midbrain anad connects to third and fourth ventricle
• fourth ventricle - small triangular chamber between pons and cerebellum, connects to the central canal that runs through spinal cord
• Cerebrospinal fluid (CSF) - clear, colorless liquid that fills the ventricles and canals of CNS, the brain produces 500 mL/day, 100 to 160 mL normally present at one time
• Functions of CSF: Buoyancy, Protection, Chemical Stability


  B: allows the brain to attain its weight, P: protects the brain from striking the skull when the head is jolted except in shaken baby syndrome and concussions, C: flow of CSF rinses away metabolic wastes from nervous tissue and homeostasis
• Brain recieves 15% of blood, 10 sec without blood = unconsciousness, 1-2 mins without blood = impairment of function, 4+ min without blood = irreversible brain damage
• Brain barrier system- regulates what substances can get from bloodstream into tissue fluid of the brain, Two points of entry must be guarded: blood capillaries throughout the brain tissue, capillaries of the choroid plexus
• BBS is highly permeable to water, glucose, and lipid-soluble substances such as oxygen, carbon dioxide, alcohol, caffeine, nicotine, and anesthetics
• Circumvenentricular organs (CVO's)- places in the third and fourth ventricles where the barrier is absent
• Medulla oblongata comes from embryonic myelencephalon