Midbrain and Hindbrain
நடுமூளையும் பின்மூளையும்
The medulla controls breathing, heartbeat and gastric secretions — damage it and life itself stops. The cerebellum, by contrast, handles balance and coordination.
The idea
The midbrain is located between the thalamus/hypothalamus of the forebrain and the pons of the hindbrain. A canal called the cerebral aqueduct passes through the midbrain. The dorsal portion of the midbrain consists mainly of four round swellings (lobes) called corpora quadrigemina. The midbrain and hindbrain form the brain stem. The hindbrain comprises the pons, cerebellum and medulla (also called the medulla oblongata). The pons consists of fibre tracts that interconnect different regions of the brain. The cerebellum has a very convoluted surface in order to provide the additional space for many more neurons. The medulla of the brain is connected to the spinal cord. The medulla contains centres which control respiration, cardiovascular reflexes and gastric secretions. Three major regions make up the brain stem: midbrain, pons and medulla oblongata; the brain stem forms the connection between the brain and the spinal cord.
Why it matters
Life-support functions such as breathing and heartbeat must run automatically; placing them in the brain stem keeps them working even when we sleep or are unconscious.
NEET lens
Remember: midbrain — cerebral aqueduct, corpora quadrigemina (four lobes on dorsal side). Hindbrain — pons (fibre tracts interconnecting brain regions), cerebellum (convoluted surface, more neurons), medulla (respiration, cardiovascular reflexes, gastric secretions; connects to spinal cord). Brain stem = midbrain + pons + medulla oblongata.
Clinical significance
Injury to the medulla, for example from a severe blow at the back of the head, can stop breathing and heart control and is often fatal. Alcohol affects the cerebellum first, which is why intoxicated people lose balance and coordination.
Introduction
The midbrain and hindbrain together form the brain stem along with parts that control balance and vital functions.
Core concept
Midbrain: between thalamus/hypothalamus and pons; cerebral aqueduct passes through; dorsal side has four round lobes = corpora quadrigemina. Hindbrain: pons — fibre tracts interconnecting different brain regions; cerebellum — highly convoluted surface (space for more neurons); medulla oblongata — connected to spinal cord; centres for respiration, cardiovascular reflexes, gastric secretions. Brain stem = midbrain + pons + medulla oblongata; connects brain and spinal cord.
Go deeper
Respiratory rhythm centres are in the medulla, with a pneumotaxic centre in the pons that moderates them — covered in Breathing and Exchange of Gases.
From Class 10
Class 10 said the hindbrain controls involuntary actions and balance. NEET names the exact parts and their centres.