Lecture on the Brainstem
Overview of the Brainstem
- The brainstem connects various parts of the nervous system:
- Cerebrum (above)
- Spinal cord (below)
- Cerebellum (behind)
- Connects most cranial nerves
- Complex anatomy, despite its small size
Structure of the Brainstem
- Divided into three main parts:
- Characteristics of each section:
- Midbrain: Features prominent parts at the front and bumps at the back
- Pons: Large protrusion at the front
- Medulla: Distinct shape, resembles spinal cord connection
- Grey and white matter:
- Grey matter mostly internal, white matter external
- More mixed than in the spinal cord
Reticular Formation
- Distributed neurons forming much of the brainstem's grey matter
- Plays a critical role in autonomic functions:
- Circulation
- Respiration
- Digestion
- Projects axons to the cerebrum
- Involved in higher functions:
- Cognition
- Emotion
- Consciousness
Long Tracts
- Connect cerebrum and spinal cord, passing through the brainstem
- Two main types:
- Motor Long Tracts: Involve upper motor neurons originating in the cerebrum, crossing in brainstem to reach spinal cord
- Somatosensory Long Tracts: Carry sensory information from spinal cord to cerebrum, often crossing over in the brainstem
Cranial Nerves
- 12 pairs, most attach to the brainstem
- Perform diverse functions:
- Motor
- Sensory
- Special senses (e.g., hearing, taste)
- Autonomic functions (e.g., reflexes)
- Associative with brainstem's grey matter and nuclei
- Neuron somas form distinct nuclei
- Nerves carry information to/from these nuclei
- Functions in head, neck, and some reach trunk and limbs
- E.g., sensation of the face, movements of eyes, face, jaw, throat, influence on heart and intestines
Conclusion
- Brainstem is a vital connector in the nervous system with numerous functions
- Future discussions will delve into specific structures and details
This lecture provides an introductory overview of the brainstem, highlighting its connectivity, structure, key functionalities, and the role of cranial nerves.