Brain Anatomy and Structure Study Notes

Lab 13: Brain (BIOX 2401)

Model Inventory List for Brain Regions and Structures

  • Key Terms: Any term marked with * indicates a major brain region.
      - All listed structures should be identifiable on a model, diagram, or dissected sheep brain.
Major Brain Regions:
  • Meninges
      - Pia Mater: The delicate innermost layer.
      - Dura Mater: The tough outer layer.
  • Cerebrum*
      - Gyrus: Ridge on the brain surface.
      - Sulcus: Shallow groove separating gyri.
      - Longitudinal Fissure: Deep groove that separates the two cerebral hemispheres.
      - Cerebral Lobes:
        - Frontal Lobe: Involved in reasoning, motor control, emotion, and language.
        - Parietal Lobe: Processes sensory information regarding the location of parts of the body and interpreting visual information.
        - Temporal Lobe: Involved in processing auditory information and encoding memory.
        - Occipital Lobe: Responsible for vision processing.
      - Central Sulcus: Separates frontal and parietal lobes.
      - Pre-central Gyrus: Contains the primary motor cortex.
      - Post-central Gyrus: Contains the primary somatosensory cortex.
      - Corpus Callosum: A thick band of nerve fibers that divides the cerebrum into left and right hemispheres.
      - Transverse Fissure: Separates the cerebrum and cerebellum.
  • Cerebellum*
      - Folia: Transversely oriented gyri in the cerebellum.
      - Vermis: A thin, worm-like structure that connects the two cerebellar hemispheres.
  • Pons*: A structure located above the medulla oblongata and below the midbrain.
  • Medulla Oblongata*: Located below the pons; controls autonomic functions such as breathing and heart rate.
  • Midbrain*: Contains structures involved in vision, hearing, and motor control.
      - Corpora Quadrigemina: A landmark composed of the superior and inferior colliculi.
  • Pineal Gland: Part of the epithalamus; regulates sleep-wake cycles.
  • Spinal Cord: Continuation of the brain stem.

Inferior Surface Model Inventory

  • Major Brain Regions:
      - **Cerebrum: Includes olfactory bulbs and tracts, optic nerves, chiasma, and tracts.   - **Diencephalon:
        - Hypothalamus: Controls various metabolic processes and autonomic nervous system functions.
        - Infundibulum: A stalk connecting the pituitary gland to the hypothalamus.
        - Mammillary Body: Involved in memory processing.
      - **Midbrain: Contains cerebral peduncles and corpora quadrigemina.   - *Pons
      - Medulla Oblongata
      - Cerebellum*
      - Meninges: Including dura mater and pia mater.
      - Pituitary Gland (Hypophysis): Major endocrine gland situated below the hypothalamus.

Midsagittal Section Model Inventory

  • Cerebrum*:
      - Corpus Callosum: Connects the left and right cerebral hemispheres.
      - Lateral Ventricles: Paired, C-shaped ventricles in the cerebral hemispheres.
      - Pineal Gland
  • Midbrain*: Includes the cerebral aqueduct.
  • Diencephalon*:
      - Intermediate Mass of Thalamus: A central structure connecting the two thalami.
      - Third Ventricle: Located in the diencephalon.
      - Hypothalamus
        - Mammillary Body
        - Infundibulum
  • Cerebellum*:
      - Arbor Vitae: The treelike pattern of white matter in the cerebellum.
      - Folia
  • Optic Chiasma: The crossing of optic nerves.
  • Choroid Plexus: Produces cerebrospinal fluid (CSF).
  • Pons*
  • Medulla Oblongata*
  • Spinal Cord.

Brain Development (Figure 12.2c)

  • Stages of Brain Development:
      - By birth: Shows an adult pattern of brain structures and convolutions.
      - Notable regions in blue need to be memorized for identification.

Surface Markings of Cerebral Hemispheres

  • Ridges (Gyri): Raised areas on the surface of the brain.
  • Shallow Grooves (Sulci): Separating gyri.
  • Deep Grooves (Fissures):
      - Longitudinal Fissure: Separates the two cerebral hemispheres.
      - Transverse Cerebral Fissure: Separates cerebrum from cerebellum.

Four Lobes of the Cerebral Hemispheres

  • Frontal Lobe
  • Parietal Lobe
  • Temporal Lobe
  • Occipital Lobe

Important Sulci and their locations

  • Central Sulcus: Separates the frontal lobe from the parietal lobe.
  • Parieto-Occipital Sulcus: Separates the parietal lobe from the occipital lobe.
  • Lateral Sulcus: Outlines the temporal lobe.

Basic Regions of the Cerebral Hemispheres

  • Cerebral Cortex: The outer layer of the brain, composed of gray matter.
  • White Matter: Deep to the cortex; includes areas like the corpus callosum.

Figures and Structures to Know:

  • Figures 12.5a, 12.5b, and 12.5c illustrate the lobes, sulci, and fissures of the cerebral hemispheres and emphasize regions highlighted in blue for study.

Ventricles of the Brain

  • Cerebral Ventricles:
      - Paired, C-shaped lateral ventricles located in the cerebral hemispheres.
      - Third Ventricle: Located in the diencephalon.
      - Fourth Ventricle: Located in the hindbrain.
  • Cerebrospinal Fluid (CSF): Fills the ventricles, providing cushioning and maintaining chemical stability.
  • Connections:
      - Lateral Ventricles to Third Ventricle: Connected via interventricular foramen.
      - Third Ventricle to Fourth Ventricle: Connected via cerebral aqueduct.

Diencephalon

  • Composed of Three Paired Structures:
      1. Thalamus:
         - Accounts for 80% of the diencephalon.
         - Bilateral nuclei connected by the intermediate mass.
      2. Hypothalamus:
         - Contains many nuclei, including mammillary bodies.
         - Infundibulum: The stalk that connects it to the pituitary gland.
      3. Epithalamus:
         - Encloses the third ventricle.

Brain Stem Areas

  • Consists of Three Regions:
      - Midbrain: Located between the diencephalon and pons.
        - Contains Cerebral Peduncles (motor tracts) and the Cerebral Aqueduct.
      - Pons:
        - Separates from the cerebellum by the fourth ventricle.
        - Connects higher brain centers and the spinal cord.
        - Relays impulses between the motor cortex and cerebellum.
        - Origin of cranial nerves V, VI, VII.
        - Involved in rhythm of breathing through nuclei of reticular formation.
      - Medulla Oblongata:
        - Joins the spinal cord at the foramen magnum.
        - Contributes to the ventral wall of the fourth ventricle.
        - Contains choroid plexus of the fourth ventricle.
        - Features Pyramids: Two longitudinal ridges formed by pyramidal tracts.
        - Decussation of the Pyramids: The crossover of corticospinal tracts.

Cerebellum

  • Location: Dorsal to the pons and medulla.
  • Regions:
      - Cerebellar Hemispheres: Connected by the vermis.
      - Folia: Transversely oriented gyri within the cerebellum.
      - Arbor Vitae: Tree-like pattern of cerebellar white matter.
  • Function: Coordinates smooth movements and is involved in cognitive functions like thinking and emotion.

Sheep Brain Dissection Views:

  • Superior View: Shows longitudinal fissure, cerebellum, various gyri, central sulcus, and spinal cord.
  • Inferior View: Highlights olfactory bulbs, optic tracts, mammillary body, and hypothalamus.
  • Midsagittal View: Displays key brain structures like the corpus callosum, cerebral aqueduct, and various major brain regions.

Summary of Ventricles in Midsagittal View

  • Choroid Plexus: Found in the lateral, third, and fourth ventricles.
  • All structures highlighted in blue from figures and diagrams should be emphasized for study.