Meninges and Cranial Structures

Meninges

• Three layers of connective tissue surrounding and protecting the central nervous system:
  • Dura Mater: The outermost, tough layer
  • Arachnoid Mater: Middle layer with web-like extensions
  • Pia Mater: Innermost layer, closely adheres to brain tissue
• Spaces between these layers:
  • Epidural Space: Between dura mater and skull (potential)
  • Subdural Space: Between dura mater and arachnoid mater (potential)
  • Subarachnoid Space: Between arachnoid mater and pia mater (actual), filled with cerebrospinal fluid (CSF)

Dural Folds

• Dural folds: Infoldings of the dura mater which compartmentalize brain tissue
• Falx Cerebri: Separates the two cerebral hemispheres
• Falx Cerebelli: Separates the two cerebellar hemispheres
• Tentorium Cerebelli: Separates cerebrum from cerebellum

Cranial Fractures

• Pterion: A specific area on the skull, the junction of four bones (temporal, parietal, frontal, sphenoid)
• Vulnerable Location: Situated directly over the middle meningeal artery
• Potential for Hemorrhage: A fracture here can damage the middle meningeal artery and cause an extradural hematoma

Arachnoid Granulations

• Allow for the circulation of CSF
• Project into the cerebral sinuses to return CSF to the ventricles

Subarachnoid Cisterns

• Large areas of subarachnoid space
• Created where the arachnoid mater doesn’t follow the brain’s contours
• Important for CSF circulation and access for lumbar puncture

Ventricles

• Interconnected chambers within the brain filled with CSF
• Four ventricles:
  • Two lateral ventricles: In each cerebral hemisphere
  • Third Ventricle: In the diencephalon
  • Fourth Ventricle: Connects to the central canal of the spinal cord
• CSF production: Choroid plexus
• CSF Functions:
  • Protection: Shock absorber
  • Buoyancy: Reduces brain weight
  • Waste removal: Carries metabolic byproducts
  • Transport: Carries nutrients and hormones

Hydrocephalus

• “Water on the brain” - An accumulation of CSF
• Caused by an imbalance in CSF production and drainage
• Main symptom: Enlarged head, especially in infants

Ventricular-Peritoneal Shunt

• A medical treatment for hydrocephalus
• Catheter drains excess CSF from the ventricles to the peritoneal cavity for absorption

Venous System

• Responsible for returning deoxygenated blood from the brain to the heart

Dural Sinuses

• Blood-filled channels within the dura mater, receiving blood drainage from the brain
• Key sinuses:
  • Superior Sagittal Sinus: Along the midline of the skull’s roof
  • Inferior Sagittal Sinus: Runs along the lower edge of the falx cerebri
  • Transverse Sinus: Across the back of the skull

Test your knowledge on the meninges, their layers, and the related cranial structures. This quiz covers the protective layers of the central nervous system, dural folds, and critical areas like the pterion. Ideal for students of anatomy and neuroscience.