CNS

The Brain

• Divisions of the brain

  • Forebrain

  • Midbrain

  • Hindbrain 

Forebrain

• Largest brain division

• Lateral and third cerebral ventricles are here

• Two subdivisons

  • Telencephalon

    • Cerebral cortex

    • Basal ganglia

• Diencephalon

  • Thalamus

  • Hypothalamus

  • Pineal gland

Telencephalon

• Cerebral cortex

  • Frontal  (Broca’s area)

  • Parietal

  • Occipital 

  • Temporal (Wernicke’s area)

  • deep grooves (fissures)

  • Shallow grooves (sulci)

  • Ridges (gyri)

• Basal ganglia clusters of cell bodies

Diencephalon

• Composed of centers for homeostasis

  • Thalamus

  • Hypothalamus

    • Pituitary gland

      • Release hormones that help carry out body functions

  • Epithalamus

  • Pineal glands

Limbic system

• Several structures involved in emotions, olfaction, memory

• Functional classification, located between diencephalon and cerebrum

  • Amygdala

  • Hippocampus

  • Cingulate gyrus

  • Septal nuclei

  • Dentate gyrus

  • Fornix

  • Mammillary body

  • Medial olfactory striae

  • Olfactory bulb

Mesencephalon (midbrain)

• Midbrain (part of midbrain), pons, medulla (parts of the hindbrain)

• Connects the forebrain to hindbrain

• Regulates movement and aids in processing auditory and visual information

• Component of the midbrain

  • Cerebral aqueduct

  • Tectum

  • Cerebral peduncle

  • Substantia nigra

Rhombencephalon (Hindbrain)

• Regulation of autonomic functions, maintaining balance and equilibrium, movement coordination and the relay of sensory information

• Two subregions

  • Metencephalon

  • Myelencephalon

Brain stem (first structure to develop in babies

• Most primitive region of brain

• Essential for basic life

• Includes

  • Midbrain

  • Pons

  • Medulla

Cerebellum 

• inferior to occipital lobe

• Coordinates motor commands

• Balance, posture

Cerebrospinal fluid 

• Protects and supports nervous system

• Produced in choroid plexus on ventricle walls

• Circulates through ventricles, meninges, spinal cord

• Cushion for the brain

Blood supply to the brain 

• Internal carotid, vertebral arteries → dural venous sinuses → internal jugular vein

• Astrocytes join to capillary walls to form blood brain barrier

Cranial protection of the brain 

• Bones of cranium

• Cranial meninges (superficial to deep)

  • Dura mater

  • Arachnoid mater

  • Pia mater

• Cerebrospinal fluid

Spinal cord 

• Begins at the foramen magnum 

• Ends at the conus medullaris 

• Meninges are also found here, similar to the brain

• Total of 32 spinal nerve pairs

• Plexus of the spinal cord:

  • Cervical

  • Brachial

  • Lumbar

  • Sacral 

• Cauda Equina

• Two enlargements

  • Cervical 

  • Lumbar 

Spinal cord histology

• Gray matter

  • Neural cell bodies, axon terminals, and dendrites

• White matter

  • Bundles of axons