Lecture Notes: Primary and Secondary Brain Vesicles and Cerebrospinal Fluid

Brain Vesicles

• Primary and Secondary Vesicles
  • Telencephalon, Diencephalon, Mesencephalon.
  • Mesencephalon develops into Metencephalon.
  • Myelencephalon develops into Medulla Oblongata.

Cerebrospinal Fluid (CSF)

• Function: Floats the brain, provides nutritional support.

• Production:

  • Produced in choroid plexuses by ependymal cells.
  • Ependymal cells filter blood, allowing smaller nutrients like glucose into CSF.
  • 500 mls produced per day, but only 150 mls present at any time.
  • Drains into arachnoid villi.

• Ventricles and CSF Flow:

  • Brain is cushioned by meninges and CSF to prevent damage.
  • Ventricles:
    • Four ventricles: Two lateral, third, and fourth.
    • Lateral ventricles connect to the third via interventricular foramen.
    • Third and fourth ventricles are connected by cerebral aqueduct.
    • CSF flows around brain and spinal cord.

• Hydrocephalus:

  • Caused by impaired drainage of CSF.
  • Accumulation of CSF increases pressure on the brain.
  • More dangerous in adults due to rigid skull.
  • Treatment involves shunting excess CSF into the abdomen.

Meninges and Brain Protection

• Layers of Meninges:

  • Dura Mater: Outermost, durable layer, with periosteal and meningeal layers.
    • Periosteal layer attaches to the skull, meningeal to lower meninges.
    • Separation forms venous sinus (triangular vein).
  • Arachnoid Mater: Middle layer.
  • Pia Mater: Innermost layer, clings to the brain.

• Subarachnoid Space:

  • Contains CSF and blood vessels.
  • Important for brain protection and nutrient supply.

Traumatic Brain Injury (TBI)

• Concussion and Contusion:

  • Concussions involve brain hitting skull due to rapid movement.
  • Leads to coup-contrecoup injury (impact and rebound).
  • Repeated concussions can lead to cumulative brain damage.

• Subarachnoid and Subdural Hematomas:

  • Result from bleeding in subarachnoid or subdural spaces.
  • Increased intracranial pressure can be fatal.

Stroke

• Types of Stroke:

  • Ischemic Stroke: Caused by blood clots, often from deep vein thrombosis, affecting blood flow to the brain.
  • Hemorrhagic Stroke: Often from aneurysms, caused by high blood pressure, leading to blood vessel rupture.

• Stroke Statistics:

  • Fifth leading cause of death in the U.S.
  • Ischemic strokes account for about 70% of cases.

• Historical Treatments:

  • Bloodletting used historically to reduce blood pressure.

Additional Remarks

• Real-life example illustrating aneurysm and its impact.
• Emphasis on the severity and need for quick professional evaluation of head injuries.