Functional Neuroanatomy Class NEU 212 Lesson 4

Meninges

• Protective coverings of the brain made of non-nervous connective tissue.
• Contain cerebrospinal fluid (CSF), allowing the brain to float, preventing damage during impact.
• Composed of three layers: Dura Mater, Arachnoid, and Pia Mater (DAP).

Dura Mater

• Toughest and outermost layer, also called Pachymenix.
• Must be penetrated in traumatic brain injuries (TBI) for diagnosis.
• Between dura mater and arachnoid lies the subdural space, which protects against hemorrhagic injury.

Arachnoid

• Middle layer of the meninges that houses CSF, serving as a cushion.
• Subarachnoid space located between arachnoid and pia mater is crucial for CSF flow and is accessible for spinal tap procedures.

Pia Mater

• Fuses with ependyma to form the choroid plexus, responsible for CSF production.

Ventricles and Cerebrospinal Fluid

• Comprises three main ventricles: lateral (most superior), third (near brain stem), and fourth (inferior).
• Reduces the weight of the head, prevents excessive brain growth, and provides buoyancy.

CSF Functions (PINCH)

• Protection: Cushions the brain, reduces impact force, and aids detection/removal of foreign substances.
• Intracranial Pressure Regulation: Excess CSF can lead to hydrocephalus, causing dangerous pressure increases.
• Nutrition: Transports nutrients to brain tissue.
• Cushioning: Provides buoyancy to the brain.
• Homeostasis: Maintains a stable internal environment.

CSF Flow

• Produced in choroid plexus of lateral ventricles, flows through interventricular foramina to the third ventricle.
• Additional CSF produced in the third and fourth ventricles, moving through the aqueduct of Sylvius.
• Flows to subarachnoid space via medial (Foramen of Magendie) and lateral (Foramen of Luschka) apertures.
• Distributes CSF to the brain and spinal cord; drained through arachnoid villi into superior sagittal sinus to be excreted via blood.

Circle of Willis

• A crucial vascular structure that supplies blood to the brain.

Neurophysiology

• Focuses on glial cells and their role within the nervous system.

Cerebrum

• Largest brain region, consists of left (dominant) and right (non-dominant) hemispheres.
• Hemispheres control contralateral functions; left side governs right body actions and vice versa.
• Comprises gray matter (cerebral cortex) and white matter, with basal nuclei/ganglia located in the white matter's central core.

Meninges

• Protective membranes surrounding the brain, composed of non-nervous connective tissue.
• Contains cerebrospinal fluid (CSF), which allows the brain to float and cushions it from injury.
• Three layers: Dura Mater, Arachnoid, Pia Mater (referred to as DAP).

Dura Mater

• Toughest and outermost layer, also called Pachymenix.
• Essential to penetrate for a traumatic brain injury (TBI) diagnosis.
• Forms folds in the brain; subdural space is located between dura mater and arachnoid, protecting from hemorrhagic injuries.

Arachnoid

• Middle layer that houses CSF, acting as a cushion for the brain.
• Subarachnoid space, located between arachnoid and pia mater, is the site for spinal tapping and CSF flow.

Pia Mater

• Fuses with ependyma to create the choroid plexus.
• Choroid plexus is responsible for CSF production.

Ventricles and Cerebrospinal Fluid (CSF)

• Brain has three main ventricles (lateral, third, and fourth) that decrease head weight.
• CSF functions:
  • Protection: Absorbs forces and helps detect and remove foreign substances.
  • Intracranial Pressure Regulation: Increased CSF can elevate pressure, harmful to the brain.

Gyri and Sulci

• Gyri (elevated tissue ridges) and sulci (shallow grooves) form anatomical landmarks in the cerebral hemisphere.
• Fissures are deeper grooves separating major brain regions:
  • Median Longitudinal Fissure: divides left and right hemispheres.
  • Central Sulcus: separates frontal and parietal lobes, anchored by precentral (motor) and postcentral (sensory) gyri.

Fiber Connections

• Commissural fibers: Connect left and right brain structures (e.g., Corpus Callosum).
• Association fibers: Connect structures within the same hemisphere (e.g., Arcuate Fasciculus linking Wernicke's and Broca’s areas).
• Projection fibers: Extend from the brain to other structures (e.g., corticospinal tracts).

Cerebral Lobes

• Brain comprises five lobes: Frontal, Parietal, Temporal, Occipital, Insula.
• Each hemisphere contains three regions: superficial cortex (gray matter), internal white matter, and basal nuclei (gray matter).

Brodmann Areas

• The cerebral cortex consists of 52 areas, each associated with various functions:
  • Area 4: Primary motor area responsible for movement.
  • Area 6: Premotor and supplementary motor cortex for planning movements.
  • Area 44, 45: Broca’s area for speech production.
  • Areas 1, 2, 3: Primary somatosensory cortex processing sensory information.

Basal Ganglia

• Monitors movement intensity and neurotransmitter production (e.g., Acetylcholine, Dopamine).
• Key components include Corpus Striatum (Putamen, Globus Pallidus) and Neostriatum (caudate nucleus).
• Substantia Nigra produces dopamine, critical for motor function; deficiency linked to Parkinson's disease.

Brainstem

• Comprised of Midbrain, Pons, and Medulla Oblongata.
• Midbrain: Connects brain regions and contains reflex centers for vision and hearing.
• Pons: Connects left and right cerebellum; involved in respiration and sleep regulation.
• Medulla Oblongata: Hosts autonomic centers for heart rate and respiration.

Spinal Cord

• Extends from the foramen magnum to L1 in adults and L3 in children.
• Tapers to conus medullaris; filum terminale anchors it.
• Length varies by gender (48 cm in males, 45 cm in females).
• Cervical region connects to the brachial plexus, while lumbar region connects to the lumbosacral plexus.

Test your knowledge of the meninges in this preliminary quiz for Functional Neuroanatomy Class NEU 212, Lesson 4. Learn about the protective layers of the brain, including the Dura Mater, and the role of cerebrospinal fluid (CSF) in brain function.