chapter 14 brain and cranial nerves

• Major components of the brain include:

  • Diencephalon
  • Midbrain
  • Pons
  • Medulla oblongata
• Gray matter is the seat of neurosomas, dendrites, and synapses
• Gray matter has a dull color due to little myelin
• White matter consists of bundles of axons
• White matter lies deep to cortical gray matter and is composed of tracts that connect different parts of the brain
• The nervous system develops from ectoderm, which is the outermost tissue layer of the embryo
• Meninges are three connective tissue membranes that envelop the brain and lie between the nervous tissue and bone
• Cranial dura mater has two layers: outer periosteal and inner meningeal
• Falx cerebri separates two cerebral hemispheres
• Tentorium cerebelli separates cerebrum from cerebellum
• Arachnoid mater is a transparent membrane over the brain surface
• Pia mater is a very thin membrane that follows the contours of the brain
• Ependyma is the cell that secretes cerebrospinal fluid (CSF)
• CSF is secreted by choroid plexus in each lateral ventricle and flows through different ventricles
• Functions of CSF include buoyancy, protection, and chemical stability
• Medulla oblongata is derived from the embryonic myelencephalon and contains cardiac, vasomotor, and respiratory centers
• Pons is an anterior bulge in the brainstem, containing sensory and motor tracts, pathways to the cerebellum, and cranial nerves V, VI, VII, and VIII
• Cerebellum is the largest part of the hindbrain and is important for motor coordination and other nonmotor functions
• Hypothalamus is a major control center of the autonomic nervous system and endocrine system
• Different brain lobes have specific functions:

  • Frontal lobe: voluntary motor functions, motivation, memory, and social judgment
  • Parietal lobe: integrates general senses, taste, and some visual information
  • Occipital lobe: primary visual center of the brain
  • Temporal lobe: functions in hearing, smell, learning, memory, and vision
  • Insula: involved in spoken language, taste, and integration
• Neural integration occurs in the gray matter of the cerebrum, which includes the cerebral cortex, basal nuclei, and limbic system
• Cerebral lateralization refers to the structural and functional differences between the cerebral hemispheres
• Left hemisphere is usually specialized for language and analytical reasoning
• Right hemisphere is usually specialized for perception, imagination, and artistic skills
• Lateralization is correlated with handedness and differs with age and sex
• CSF (cerebrospinal fluid) is secreted by the choroid plexus in each lateral ventricle
• CSF flows through the interventricular foramina into the third ventricle
• Choroid plexus in the third ventricle adds more CSF
• CSF then flows down the cerebral aqueduct to the fourth ventricle
• Choroid plexus in the fourth ventricle adds more CSF
• CSF flows out through two lateral apertures and one median aperture
• CSF fills the subarachnoid space and bathes the external surfaces of the brain and spinal cord
• At the arachnoid villi, CSF is reabsorbed into the venous blood of the dural venous sinuses
• Ependyma is the cell that secretes cerebrospinal fluid (CSF)
• Ependymal cells are found in the choroid plexus in each ventricle of the brain
• Cerebrospinal fluid (CSF) is located between the subarachnoid space
• CSF is reabsorbed in the arachnoid granulations
• CSF protrudes through the dura mater into the superior sagittal sinus
• The brain barrier system is highly permeable to:

  • Water
  • Glucose
  • Lipid-soluble substances such as oxygen, carbon dioxide, alcohol, caffeine, nicotine, and anesthetics
• Cerebrospinal fluid (CSF) is a clear, colorless liquid that fills the ventricles and canals of the central nervous system (CNS)