Chapter 14 Study Guide Notes

Major Landmarks in the Brain

• Familiarize yourself with key terms from sheep brain dissection relevant for Lab Practical 4.

Brain Development Stages

• Week 3: Formation of the neural tube begins; the precursor to the central nervous system.

• Week 4: The neural tube closes; the three primary brain vesicles form: forebrain, midbrain, and hindbrain.

• Week 5: Further specialization into five secondary brain vesicles happens:

  • Forebrain: Telencephalon (cerebral cortex, basal ganglia) and Diencephalon (thalamus, hypothalamus).

  • Midbrain: Mesencephalon (remains as midbrain).

  • Hindbrain: Metencephalon (pons, cerebellum) and Myelencephalon (medulla oblongata).

Meninges Layers

• Understand the distinct layers of the meninges in the brain versus the spinal cord:

  • Dura Mater: Outermost layer; tough and protective.

  • Arachnoid Mater: Middle layer; web-like appearance.

  • Pia Mater: Innermost layer; delicate and adheres directly to the brain surface.

Ventricles of the Brain

• Recognize the four ventricles of the brain:

  • Lateral Ventricles (2), Third Ventricle, Fourth Ventricle.

• Location and significance of each ventricle.

Cerebrospinal Fluid (CSF)

• Production: Made in the choroid plexus located within the ventricles.

• Pathway: Circulates from the lateral ventricles to the third ventricle, then to the fourth ventricle and central canal of the spinal cord.

• Functions:

  1. Cushioning the brain and spinal cord.

  2. Providing buoyancy to reduce net weight of brain.

  3. Removing waste products from the brain.

• Choroid Plexus: A network of cells that produces CSF.

• Absorption: CSF is absorbed into the bloodstream through arachnoid granulations.

Brain Barrier System

• Blood-Brain Barrier (BBB):

  • Formed by tight junctions between endothelial cells in brain capillaries.

  • Serves to protect the brain from toxins and pathogens.

• Crossing the Blood-Brain Barrier:

  • Substances that can cross: Oxygen, glucose, and some lipid-soluble substances.

  • Substances that cannot cross: Large molecules, most antibiotics, and certain toxins.

Components of the Brainstem

• Medulla Oblongata: Contains vital centers for autonomic functions:

  • Pyramids: Major motor pathways crossing over (decussation).

  • Centers: Cardiac center (heart rate), vasomotor center (blood pressure), and respiratory centers (breathing regulation).

  • Associated cranial nerves: IX (Glossopharyngeal), X (Vagus), XI (Accessory), XII (Hypoglossal).

• Pons: Connects to the cerebellum via the cerebellar peduncles.

  • Contains cranial nerves V (Trigeminal), VI (Abducens), VII (Facial), VIII (Vestibulocochlear).

  • Functions include hearing, balance, sleep regulation, and relaying signals to/from the cerebellum.

• Cerebellum Anatomy: Structure includes the cerebellar cortex and the arbor vitae (tree-like structure of white matter).

By thoroughly reviewing and understanding these points, you'll have a comprehensive knowledge base for your exam.