Hindbrain: Life and Balance
The hindbrain sits at the base of the skull, keeping the body alive moment to moment. The medulla oblongata controls heartbeat and breathing; damage here is fatal.
The pons connects the cerebellum to the brain and regulates sleep. The cerebellum manages motor coordination, balance, and procedural memory.
| Region | Primary Function | Damage Result |
|---|---|---|
| Medulla | Autonomic life-support | Fatal |
| Pons | Sleep and arousal bridge | Disrupted sleep |
| Cerebellum | Balance and motor memory | Ataxia (jerky movement) |
Distinction: The cerebellum attaches via the pons, but it is not part of the brainstem, which consists only of the medulla, pons, and midbrain.
Midbrain: Reflexes and Arousal
The midbrain is a relay region above the hindbrain containing the tectum and tegmentum.
The tectum houses the superior colliculus (visual orienting reflexes) and inferior colliculus (auditory orienting reflexes), letting you snap your head toward a flash or bang instantly.
| Tectum Structure | Reflex Type |
|---|---|
| Superior colliculus | Visual |
| Inferior colliculus | Auditory |
Pitfall: Mix-up trap! Superior handles sight, while inferior handles auditory.
The tegmentum contains the substantia nigra (dopamine production; degeneration causes Parkinson's motor symptoms) and part of the reticular formation, which regulates arousal.