Brainstem

Old presentation

• Parts of brain hidden by cerebral hemispheres and cerebellum
• Contains third and fourth ventricles and cerebral aqueduct
• Composed of
  • Midbrain (mesencephalon)
    • At junction of middle and posterior cranial fossae
    • Contains narrow canal: cerebral aqueduct
  • Pons
    • Found in anterior region of posterior cranial cavity
    • Contains cavity that contributes to fourth ventricle
  • Medulla oblongata
    • Lies in posterior cranial fossa
    • Continuous with spinal cord
    • Contains inferior portion of fourth ventricle
• Contains masses of gray matter, many of which are sensory and motor nuclei of cranial nerves.

• The brain stem subdivided into three segments:
  • Tectum - “roof,” dorsal aspect
  • Tegmentum - ventral aspect
  • Basis - most ventral aspect of tegmentum (crus cerebri + substantia nigra)