Brainstem

Anatomy

• It is the posterior stalk-like part of the brain that connects the cerebrum with the spinal cord.
• It is composed of
  1. Midbrain
  2. Pons
  3. Medulla oblongata
  4. Sometimes the diencephalon

• It is very small, making up around only 2.6 % of the brain's total weight.

Clinic

• Integrative functions: It is involved in
  1. Controling heart rate
  2. Controling breathing rate
  3. Pain sensitivity control
  4. Alertness / Awareness / Consciousness
  5. Regulation of sleep cycle
• Ten pairs of cranial nerves
  1. Oculomotor nerve (III)
  2. Trochlear nerve (IV)
  3. Trigeminal nerve (V)
  4. Abducens nerve (VI)
  5. Facial nerve (VII): Motor and sensory innervation of Face / Neck
  6. Vestibulocochlear nerve (VIII)
  7. Glossopharyngeal nerve (IX)
  8. Vagus nerve (X)
  9. Accessory nerve (XI)
  10. Hypoglossal nerve (XII)

Pathways

Descending tracts

• Upper motor neurons destined to synapse on lower motor neurons in the ventral horn and posterior horn.
• Upper motor neurons that originate in the brainstem's vestibular, red, tectal and reticular nuclei descend in spinal cord.
• Corticospinal tract (Motor function)

Ascending pathways

• Dorsal column-medial lemniscus pathway (Fine touch, Vibration sensation, Pressure and Proprioception)
• Spinothalamic tract (Pain, Temperature, Itch, and Crude touch).
• Facial sensations have similar pathways and will travel in the spinothalamic tract and the DCML.

Clinical significance

• Visual disturbances
• Pupil abnormalities
• Changes in sensation
• Muscle weakness
• Hearing problems
• Vertigo
• Swallowing difficulty
• Speech difficulty/ Voice change
• Co-ordination problems

Related disease

• Brainstem encephalitis
• Bulbar palsy
• Progressive bulbar palsy
• Pseudobulbar palsy

Related entities